From: Zhang Yi <[email protected]>
Hello,
This is the third version of RFC patch series that convert ext4 regular
file's buffered IO path to iomap and enable large folio. It's rebased on
6.7 and Christoph's "map multiple blocks per ->map_blocks in iomap
writeback" series [1]. I've fixed all issues found in the last about 3
weeks of stress tests and fault injection tests in v2. I hope I've
covered most of the corner cases, and any comments are welcome. :)
Changes since v2:
- Update patch 1-6 to v3 [2].
- iomap_zero and iomap_unshare don't need to update i_size and call
iomap_write_failed(), introduce a new helper iomap_write_end_simple()
to avoid doing that.
- Factor out ext4_[ext|ind]_map_blocks() parts from ext4_map_blocks(),
introduce a new helper ext4_iomap_map_one_extent() to allocate
delalloc blocks in writeback, which is always under i_data_sem in
write mode. This is done to prevent the writing back delalloc
extents become stale if it raced by truncate.
- Add a lock detection in mapping_clear_large_folios().
Changes since v1:
- Introduce seq count for iomap buffered write and writeback to protect
races from extents changes, e.g. truncate, mwrite.
- Always allocate unwritten extents for new blocks, drop dioread_lock
mode, and make no distinctions between dioread_lock and
dioread_nolock.
- Don't add ditry data range to jinode, drop data=ordered mode, and
make no distinctions between data=ordered and data=writeback mode.
- Postpone updating i_disksize to endio.
- Allow splitting extents and use reserved space in endio.
- Instead of reimplement a new delayed mapping helper
ext4_iomap_da_map_blocks() for buffer write, try to reuse
ext4_da_map_blocks().
- Add support for disabling large folio on active inodes.
- Support online defragmentation, make file fall back to buffer_head
and disable large folio in ext4_move_extents().
- Move ext4_nonda_switch() in advance to prevent deadlock in mwrite.
- Add dirty_len and pos trace info to trace_iomap_writepage_map().
- Update patch 1-6 to v2.
This series only support ext4 with the default features and mount
options, doesn't support inline_data, bigalloc, dax, fs_verity, fs_crypt
and data=journal mode, ext4 would fall back to buffer_head path
automatically if you enabled these features/options. Although it has
many limitations now, it can satisfy the requirements of common cases
and bring a great performance benefit.
Patch 1-6: this is a preparation series, it changes ext4_map_blocks()
and ext4_set_iomap() to recognize delayed only extents, I've send it out
separately [2].
Patch 7-8: these are two minor iomap changes, the first one is don't
update i_size and don't call iomap_write_failed() in zero_range, the
second one is for debug in iomap writeback path that I've discussed whit
Christoph [3].
Patch 9-15: this is another preparation series, including some changes
for delayed extents. Firstly, it factor out buffer_head from
ext4_da_map_blocks(), make it to support adding multi-blocks once a
time. Then make unwritten to written extents conversion in endio use to
reserved space, reduce the risk of potential data loss. Finally,
introduce a sequence counter for extent status tree, which is useful
for iomap buffer write and write back.
Patch 16-22: Implement buffered IO iomap path for read, write, mmap,
zero range, truncate and writeback, replace current buffered_head path.
Please look at the following patch for details.
Patch 23-26: Convert to iomap for regular file's buffered IO path
besides inline_data, bigalloc, dax, fs_verity, fs_crypt, and
data=journal mode, and enable large folio. It should be note that
buffered iomap path hasn't support Online defrag yet, so we need fall
back to buffer_head and disable large folio automatically if user call
EXT4_IOC_MOVE_EXT.
About Tests:
- kvm-xfstests in auto mode, and about 3 weeks of stress tests and
fault injection tests.
- A performance tests below.
Fio tests with psync on my machine with Intel Xeon Gold 6240 CPU
with 400GB system ram, 200GB ramdisk and 1TB nvme ssd disk.
== buffer read ==
buffer head iomap with large folio
type bs IOPS BW(MiB/s) IOPS BW(MiB/s)
----------------------------------------------------
hole 4K 565k 2206 811k 3167
hole 64K 45.1k 2820 78.1k 4879
hole 1M 2744 2744 4890 4891
ramdisk 4K 436k 1703 554k 2163
ramdisk 64K 29.6k 1848 44.0k 2747
ramdisk 1M 1994 1995 2809 2809
nvme 4K 306k 1196 324k 1267
nvme 64K 19.3k 1208 24.3k 1517
nvme 1M 1694 1694 2256 2256
== buffer write ==
buffer head ext4_iomap
type Overwrite Sync Writeback bs IOPS BW IOPS BW
-------------------------------------------------------------
cache N N N 4K 395k 1544 415k 1621
cache N N N 64K 30.8k 1928 80.1k 5005
cache N N N 1M 1963 1963 5641 5642
cache Y N N 4K 423k 1652 443k 1730
cache Y N N 64K 33.0k 2063 80.8k 5051
cache Y N N 1M 2103 2103 5588 5589
ramdisk N N Y 4K 362k 1416 307k 1198
ramdisk N N Y 64K 22.4k 1399 64.8k 4050
ramdisk N N Y 1M 1670 1670 4559 4560
ramdisk N Y N 4K 9830 38.4 13.5k 52.8
ramdisk N Y N 64K 5834 365 10.1k 629
ramdisk N Y N 1M 1011 1011 2064 2064
ramdisk Y N Y 4K 397k 1550 409k 1598
ramdisk Y N Y 64K 29.2k 1827 73.6k 4597
ramdisk Y N Y 1M 1837 1837 4985 4985
ramdisk Y Y N 4K 173k 675 182k 710
ramdisk Y Y N 64K 17.7k 1109 33.7k 2105
ramdisk Y Y N 1M 1128 1129 1790 1791
nvme N N Y 4K 298k 1164 290k 1134
nvme N N Y 64K 21.5k 1343 57.4k 3590
nvme N N Y 1M 1308 1308 3664 3664
nvme N Y N 4K 10.7k 41.8 12.0k 46.9
nvme N Y N 64K 5962 373 8598 537
nvme N Y N 1M 676 677 1417 1418
nvme Y N Y 4K 366k 1430 373k 1456
nvme Y N Y 64K 26.7k 1670 56.8k 3547
nvme Y N Y 1M 1745 1746 3586 3586
nvme Y Y N 4K 59.0k 230 61.2k 239
nvme Y Y N 64K 13.0k 813 21.0k 1311
nvme Y Y N 1M 683 683 1368 1369
TODO
- Keep on doing stress tests and fixing.
- I will rebase and resend my another patch set "ext4: more accurate
metadata reservaion for delalloc mount option[4]" later, it's useful
for iomap conversion. After this series, I suppose we could totally
drop ext4_nonda_switch() and prevent the risk of data loss caused by
extents splitting.
- Support for more features and mount options in the future.
[1] https://lore.kernel.org/linux-fsdevel/[email protected]/
[2] https://lore.kernel.org/linux-ext4/[email protected]/
[3] https://lore.kernel.org/linux-fsdevel/[email protected]/
[4] https://lore.kernel.org/linux-ext4/[email protected]/
Thanks,
Yi.
---
v2: https://lore.kernel.org/linux-ext4/[email protected]/
v1: https://lore.kernel.org/linux-ext4/[email protected]/
Zhang Yi (26):
ext4: refactor ext4_da_map_blocks()
ext4: convert to exclusive lock while inserting delalloc extents
ext4: correct the hole length returned by ext4_map_blocks()
ext4: add a hole extent entry in cache after punch
ext4: make ext4_map_blocks() distinguish delalloc only extent
ext4: make ext4_set_iomap() recognize IOMAP_DELALLOC map type
iomap: don't increase i_size if it's not a write operation
iomap: add pos and dirty_len into trace_iomap_writepage_map
ext4: allow inserting delalloc extents with multi-blocks
ext4: correct delalloc extent length
ext4: also mark extent as delalloc if it's been unwritten
ext4: factor out bh handles to ext4_da_get_block_prep()
ext4: use reserved metadata blocks when splitting extent in endio
ext4: factor out ext4_map_{create|query}_blocks()
ext4: introduce seq counter for extent entry
ext4: add a new iomap aops for regular file's buffered IO path
ext4: implement buffered read iomap path
ext4: implement buffered write iomap path
ext4: implement writeback iomap path
ext4: implement mmap iomap path
ext4: implement zero_range iomap path
ext4: writeback partial blocks before zero range
ext4: fall back to buffer_head path for defrag
ext4: partially enable iomap for regular file's buffered IO path
filemap: support disable large folios on active inode
ext4: enable large folio for regular file with iomap buffered IO path
fs/ext4/ext4.h | 14 +-
fs/ext4/ext4_jbd2.c | 6 +
fs/ext4/ext4_jbd2.h | 7 +
fs/ext4/extents.c | 149 +++---
fs/ext4/extents_status.c | 39 +-
fs/ext4/extents_status.h | 4 +-
fs/ext4/file.c | 19 +-
fs/ext4/ialloc.c | 5 +
fs/ext4/inode.c | 891 +++++++++++++++++++++++++++---------
fs/ext4/move_extent.c | 35 ++
fs/ext4/page-io.c | 107 +++++
fs/ext4/super.c | 3 +
fs/iomap/buffered-io.c | 30 +-
fs/iomap/trace.h | 43 +-
include/linux/pagemap.h | 14 +
include/trace/events/ext4.h | 31 +-
mm/readahead.c | 6 +-
17 files changed, 1109 insertions(+), 294 deletions(-)
--
2.39.2
From: Zhang Yi <[email protected]>
In order to cache hole extents in the extent status tree and keep the
hole length as long as possible, re-add a hole entry to the cache just
after punching a hole.
Signed-off-by: Zhang Yi <[email protected]>
Reviewed-by: Jan Kara <[email protected]>
---
fs/ext4/inode.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)
diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index 142c67f5c7fc..1b5e6409f958 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -4000,12 +4000,12 @@ int ext4_punch_hole(struct file *file, loff_t offset, loff_t length)
/* If there are blocks to remove, do it */
if (stop_block > first_block) {
+ ext4_lblk_t hole_len = stop_block - first_block;
down_write(&EXT4_I(inode)->i_data_sem);
ext4_discard_preallocations(inode, 0);
- ext4_es_remove_extent(inode, first_block,
- stop_block - first_block);
+ ext4_es_remove_extent(inode, first_block, hole_len);
if (ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS))
ret = ext4_ext_remove_space(inode, first_block,
@@ -4014,6 +4014,8 @@ int ext4_punch_hole(struct file *file, loff_t offset, loff_t length)
ret = ext4_ind_remove_space(handle, inode, first_block,
stop_block);
+ ext4_es_insert_extent(inode, first_block, hole_len, ~0,
+ EXTENT_STATUS_HOLE);
up_write(&EXT4_I(inode)->i_data_sem);
}
ext4_fc_track_range(handle, inode, first_block, stop_block);
--
2.39.2
From: Zhang Yi <[email protected]>
Increase i_size in iomap_zero_range() and iomap_unshare_iter() is not
needed, the caller should handle it. Especially, when truncate partial
block, we could not increase i_size beyond the new EOF here. It dosn't
affect xfs and gfs2 now because they reset the new file size after zero
out, it doesn't matter that a brief increase in i_size, but it will
affect ext4 because it set file size before truncate. At the same time,
iomap_write_failed() is also not needed for above two cases too, so
let's introduce a new helper iomap_write_end_simple() to replace the
common iomap_write_end() helper which designed for buffer write, and
also move out iomap_write_failed() from iomap_write_begin() to
iomap_write_iter().
Signed-off-by: Zhang Yi <[email protected]>
---
fs/iomap/buffered-io.c | 28 ++++++++++++++++++++++++----
1 file changed, 24 insertions(+), 4 deletions(-)
diff --git a/fs/iomap/buffered-io.c b/fs/iomap/buffered-io.c
index e0c9cede82ee..2ae936e5af74 100644
--- a/fs/iomap/buffered-io.c
+++ b/fs/iomap/buffered-io.c
@@ -834,7 +834,6 @@ static int iomap_write_begin(struct iomap_iter *iter, loff_t pos,
out_unlock:
__iomap_put_folio(iter, pos, 0, folio);
- iomap_write_failed(iter->inode, pos, len);
return status;
}
@@ -881,6 +880,25 @@ static size_t iomap_write_end_inline(const struct iomap_iter *iter,
return copied;
}
+static size_t iomap_write_end_simple(struct iomap_iter *iter, loff_t pos,
+ size_t len, struct folio *folio)
+{
+ const struct iomap *srcmap = iomap_iter_srcmap(iter);
+ size_t ret;
+
+ if (srcmap->type == IOMAP_INLINE) {
+ ret = iomap_write_end_inline(iter, folio, pos, len);
+ } else if (srcmap->flags & IOMAP_F_BUFFER_HEAD) {
+ ret = block_write_end(NULL, iter->inode->i_mapping, pos, len,
+ len, &folio->page, NULL);
+ } else {
+ ret = __iomap_write_end(iter->inode, pos, len, len, folio);
+ }
+
+ __iomap_put_folio(iter, pos, ret, folio);
+ return ret;
+}
+
/* Returns the number of bytes copied. May be 0. Cannot be an errno. */
static size_t iomap_write_end(struct iomap_iter *iter, loff_t pos, size_t len,
size_t copied, struct folio *folio)
@@ -960,8 +978,10 @@ static loff_t iomap_write_iter(struct iomap_iter *iter, struct iov_iter *i)
}
status = iomap_write_begin(iter, pos, bytes, &folio);
- if (unlikely(status))
+ if (unlikely(status)) {
+ iomap_write_failed(iter->inode, pos, bytes);
break;
+ }
if (iter->iomap.flags & IOMAP_F_STALE)
break;
@@ -1343,7 +1363,7 @@ static loff_t iomap_unshare_iter(struct iomap_iter *iter)
if (bytes > folio_size(folio) - offset)
bytes = folio_size(folio) - offset;
- bytes = iomap_write_end(iter, pos, bytes, bytes, folio);
+ bytes = iomap_write_end_simple(iter, pos, bytes, folio);
if (WARN_ON_ONCE(bytes == 0))
return -EIO;
@@ -1407,7 +1427,7 @@ static loff_t iomap_zero_iter(struct iomap_iter *iter, bool *did_zero)
folio_zero_range(folio, offset, bytes);
folio_mark_accessed(folio);
- bytes = iomap_write_end(iter, pos, bytes, bytes, folio);
+ bytes = iomap_write_end_simple(iter, pos, bytes, folio);
if (WARN_ON_ONCE(bytes == 0))
return -EIO;
--
2.39.2
From: Zhang Yi <[email protected]>
Introduce a new helper ext4_insert_delayed_blocks() to replace
ext4_insert_delayed_block() that we could add multi-delayed blocks into
the extent status tree once a time. But for now, it doesn't support
bigalloc feature yet. Also rename ext4_es_insert_delayed_block() to
ext4_es_insert_delayed_extent(), which matches the name style of other
ext4_es_{insert|remove}_extent() functions.
Signed-off-by: Zhang Yi <[email protected]>
---
fs/ext4/extents_status.c | 26 ++++++++++++++-----------
fs/ext4/extents_status.h | 4 ++--
fs/ext4/inode.c | 39 ++++++++++++++++++++++---------------
include/trace/events/ext4.h | 12 +++++++-----
4 files changed, 47 insertions(+), 34 deletions(-)
diff --git a/fs/ext4/extents_status.c b/fs/ext4/extents_status.c
index 4a00e2f019d9..324a6b0a6283 100644
--- a/fs/ext4/extents_status.c
+++ b/fs/ext4/extents_status.c
@@ -2052,19 +2052,21 @@ bool ext4_is_pending(struct inode *inode, ext4_lblk_t lblk)
}
/*
- * ext4_es_insert_delayed_block - adds a delayed block to the extents status
- * tree, adding a pending reservation where
- * needed
+ * ext4_es_insert_delayed_extent - adds delayed blocks to the extents status
+ * tree, adding a pending reservation where
+ * needed
*
* @inode - file containing the newly added block
- * @lblk - logical block to be added
+ * @lblk - first logical block to be added
+ * @len - length of blocks to be added
* @allocated - indicates whether a physical cluster has been allocated for
* the logical cluster that contains the block
*/
-void ext4_es_insert_delayed_block(struct inode *inode, ext4_lblk_t lblk,
- bool allocated)
+void ext4_es_insert_delayed_extent(struct inode *inode, ext4_lblk_t lblk,
+ unsigned int len, bool allocated)
{
struct extent_status newes;
+ ext4_lblk_t end = lblk + len - 1;
int err1 = 0, err2 = 0, err3 = 0;
struct extent_status *es1 = NULL;
struct extent_status *es2 = NULL;
@@ -2073,13 +2075,15 @@ void ext4_es_insert_delayed_block(struct inode *inode, ext4_lblk_t lblk,
if (EXT4_SB(inode->i_sb)->s_mount_state & EXT4_FC_REPLAY)
return;
- es_debug("add [%u/1) delayed to extent status tree of inode %lu\n",
- lblk, inode->i_ino);
+ es_debug("add [%u/%u) delayed to extent status tree of inode %lu\n",
+ lblk, len, inode->i_ino);
+ if (!len)
+ return;
newes.es_lblk = lblk;
- newes.es_len = 1;
+ newes.es_len = len;
ext4_es_store_pblock_status(&newes, ~0, EXTENT_STATUS_DELAYED);
- trace_ext4_es_insert_delayed_block(inode, &newes, allocated);
+ trace_ext4_es_insert_delayed_extent(inode, &newes, allocated);
ext4_es_insert_extent_check(inode, &newes);
@@ -2092,7 +2096,7 @@ void ext4_es_insert_delayed_block(struct inode *inode, ext4_lblk_t lblk,
pr = __alloc_pending(true);
write_lock(&EXT4_I(inode)->i_es_lock);
- err1 = __es_remove_extent(inode, lblk, lblk, NULL, es1);
+ err1 = __es_remove_extent(inode, lblk, end, NULL, es1);
if (err1 != 0)
goto error;
/* Free preallocated extent if it didn't get used. */
diff --git a/fs/ext4/extents_status.h b/fs/ext4/extents_status.h
index d9847a4a25db..24493e682ab4 100644
--- a/fs/ext4/extents_status.h
+++ b/fs/ext4/extents_status.h
@@ -249,8 +249,8 @@ extern void ext4_exit_pending(void);
extern void ext4_init_pending_tree(struct ext4_pending_tree *tree);
extern void ext4_remove_pending(struct inode *inode, ext4_lblk_t lblk);
extern bool ext4_is_pending(struct inode *inode, ext4_lblk_t lblk);
-extern void ext4_es_insert_delayed_block(struct inode *inode, ext4_lblk_t lblk,
- bool allocated);
+extern void ext4_es_insert_delayed_extent(struct inode *inode, ext4_lblk_t lblk,
+ unsigned int len, bool allocated);
extern unsigned int ext4_es_delayed_clu(struct inode *inode, ext4_lblk_t lblk,
ext4_lblk_t len);
extern void ext4_clear_inode_es(struct inode *inode);
diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index 0458d7f0c059..bc29c2e92750 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -1452,7 +1452,7 @@ static int ext4_journalled_write_end(struct file *file,
/*
* Reserve space for a single cluster
*/
-static int ext4_da_reserve_space(struct inode *inode)
+static int ext4_da_reserve_space(struct inode *inode, unsigned int len)
{
struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
struct ext4_inode_info *ei = EXT4_I(inode);
@@ -1463,18 +1463,18 @@ static int ext4_da_reserve_space(struct inode *inode)
* us from metadata over-estimation, though we may go over by
* a small amount in the end. Here we just reserve for data.
*/
- ret = dquot_reserve_block(inode, EXT4_C2B(sbi, 1));
+ ret = dquot_reserve_block(inode, EXT4_C2B(sbi, len));
if (ret)
return ret;
spin_lock(&ei->i_block_reservation_lock);
- if (ext4_claim_free_clusters(sbi, 1, 0)) {
+ if (ext4_claim_free_clusters(sbi, len, 0)) {
spin_unlock(&ei->i_block_reservation_lock);
- dquot_release_reservation_block(inode, EXT4_C2B(sbi, 1));
+ dquot_release_reservation_block(inode, EXT4_C2B(sbi, len));
return -ENOSPC;
}
- ei->i_reserved_data_blocks++;
- trace_ext4_da_reserve_space(inode);
+ ei->i_reserved_data_blocks += len;
+ trace_ext4_da_reserve_space(inode, len);
spin_unlock(&ei->i_block_reservation_lock);
return 0; /* success */
@@ -1620,18 +1620,21 @@ static void ext4_print_free_blocks(struct inode *inode)
return;
}
+
/*
- * ext4_insert_delayed_block - adds a delayed block to the extents status
- * tree, incrementing the reserved cluster/block
- * count or making a pending reservation
- * where needed
+ * ext4_insert_delayed_blocks - adds multi-delayed blocks to the extents
+ * status tree, incrementing the reserved
+ * cluster/block count or making a pending
+ * reservation where needed.
*
* @inode - file containing the newly added block
- * @lblk - logical block to be added
+ * @lblk - start logical block to be added
+ * @len - length of blocks to be added
*
* Returns 0 on success, negative error code on failure.
*/
-static int ext4_insert_delayed_block(struct inode *inode, ext4_lblk_t lblk)
+static int ext4_insert_delayed_blocks(struct inode *inode, ext4_lblk_t lblk,
+ ext4_lblk_t len)
{
struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
int ret;
@@ -1649,10 +1652,14 @@ static int ext4_insert_delayed_block(struct inode *inode, ext4_lblk_t lblk)
* extents status tree doesn't get a match.
*/
if (sbi->s_cluster_ratio == 1) {
- ret = ext4_da_reserve_space(inode);
+ ret = ext4_da_reserve_space(inode, len);
if (ret != 0) /* ENOSPC */
return ret;
} else { /* bigalloc */
+ /* TODO: support bigalloc for multi-blocks. */
+ if (len != 1)
+ return -EOPNOTSUPP;
+
if (!ext4_es_scan_clu(inode, &ext4_es_is_delonly, lblk)) {
if (!ext4_es_scan_clu(inode,
&ext4_es_is_mapped, lblk)) {
@@ -1661,7 +1668,7 @@ static int ext4_insert_delayed_block(struct inode *inode, ext4_lblk_t lblk)
if (ret < 0)
return ret;
if (ret == 0) {
- ret = ext4_da_reserve_space(inode);
+ ret = ext4_da_reserve_space(inode, 1);
if (ret != 0) /* ENOSPC */
return ret;
} else {
@@ -1673,7 +1680,7 @@ static int ext4_insert_delayed_block(struct inode *inode, ext4_lblk_t lblk)
}
}
- ext4_es_insert_delayed_block(inode, lblk, allocated);
+ ext4_es_insert_delayed_extent(inode, lblk, len, allocated);
return 0;
}
@@ -1774,7 +1781,7 @@ static int ext4_da_map_blocks(struct inode *inode, sector_t iblock,
add_delayed:
down_write(&EXT4_I(inode)->i_data_sem);
- retval = ext4_insert_delayed_block(inode, map->m_lblk);
+ retval = ext4_insert_delayed_blocks(inode, map->m_lblk, map->m_len);
up_write(&EXT4_I(inode)->i_data_sem);
if (retval)
return retval;
diff --git a/include/trace/events/ext4.h b/include/trace/events/ext4.h
index 65029dfb92fb..53aa7a7fb3be 100644
--- a/include/trace/events/ext4.h
+++ b/include/trace/events/ext4.h
@@ -1249,14 +1249,15 @@ TRACE_EVENT(ext4_da_update_reserve_space,
);
TRACE_EVENT(ext4_da_reserve_space,
- TP_PROTO(struct inode *inode),
+ TP_PROTO(struct inode *inode, int reserved_blocks),
- TP_ARGS(inode),
+ TP_ARGS(inode, reserved_blocks),
TP_STRUCT__entry(
__field( dev_t, dev )
__field( ino_t, ino )
__field( __u64, i_blocks )
+ __field( int, reserved_blocks )
__field( int, reserved_data_blocks )
__field( __u16, mode )
),
@@ -1265,16 +1266,17 @@ TRACE_EVENT(ext4_da_reserve_space,
__entry->dev = inode->i_sb->s_dev;
__entry->ino = inode->i_ino;
__entry->i_blocks = inode->i_blocks;
+ __entry->reserved_blocks = reserved_blocks;
__entry->reserved_data_blocks = EXT4_I(inode)->i_reserved_data_blocks;
__entry->mode = inode->i_mode;
),
- TP_printk("dev %d,%d ino %lu mode 0%o i_blocks %llu "
+ TP_printk("dev %d,%d ino %lu mode 0%o i_blocks %llu reserved_blocks %u "
"reserved_data_blocks %d",
MAJOR(__entry->dev), MINOR(__entry->dev),
(unsigned long) __entry->ino,
__entry->mode, __entry->i_blocks,
- __entry->reserved_data_blocks)
+ __entry->reserved_blocks, __entry->reserved_data_blocks)
);
TRACE_EVENT(ext4_da_release_space,
@@ -2481,7 +2483,7 @@ TRACE_EVENT(ext4_es_shrink,
__entry->scan_time, __entry->nr_skipped, __entry->retried)
);
-TRACE_EVENT(ext4_es_insert_delayed_block,
+TRACE_EVENT(ext4_es_insert_delayed_extent,
TP_PROTO(struct inode *inode, struct extent_status *es,
bool allocated),
--
2.39.2
From: Zhang Yi <[email protected]>
Since commit "iomap: map multiple blocks at a time", we could map
multi-blocks once a time, and the dirty_len indicates the expected map
length, map_len won't large than it. The pos and dirty_len means the
dirty range that should be mapped to write, add them into
trace_iomap_writepage_map() could be more useful for debug.
Signed-off-by: Zhang Yi <[email protected]>
---
fs/iomap/buffered-io.c | 2 +-
fs/iomap/trace.h | 43 +++++++++++++++++++++++++++++++++++++++++-
2 files changed, 43 insertions(+), 2 deletions(-)
diff --git a/fs/iomap/buffered-io.c b/fs/iomap/buffered-io.c
index 2ae936e5af74..9a9f1bfe80b4 100644
--- a/fs/iomap/buffered-io.c
+++ b/fs/iomap/buffered-io.c
@@ -1806,7 +1806,7 @@ static int iomap_writepage_map_blocks(struct iomap_writepage_ctx *wpc,
error = wpc->ops->map_blocks(wpc, inode, pos, dirty_len);
if (error)
break;
- trace_iomap_writepage_map(inode, &wpc->iomap);
+ trace_iomap_writepage_map(inode, pos, dirty_len, &wpc->iomap);
map_len = min_t(u64, dirty_len,
wpc->iomap.offset + wpc->iomap.length - pos);
diff --git a/fs/iomap/trace.h b/fs/iomap/trace.h
index c16fd55f5595..3ef694f9489f 100644
--- a/fs/iomap/trace.h
+++ b/fs/iomap/trace.h
@@ -154,7 +154,48 @@ DEFINE_EVENT(iomap_class, name, \
TP_ARGS(inode, iomap))
DEFINE_IOMAP_EVENT(iomap_iter_dstmap);
DEFINE_IOMAP_EVENT(iomap_iter_srcmap);
-DEFINE_IOMAP_EVENT(iomap_writepage_map);
+
+TRACE_EVENT(iomap_writepage_map,
+ TP_PROTO(struct inode *inode, u64 pos, unsigned int dirty_len,
+ struct iomap *iomap),
+ TP_ARGS(inode, pos, dirty_len, iomap),
+ TP_STRUCT__entry(
+ __field(dev_t, dev)
+ __field(u64, ino)
+ __field(u64, pos)
+ __field(u64, dirty_len)
+ __field(u64, addr)
+ __field(loff_t, offset)
+ __field(u64, length)
+ __field(u16, type)
+ __field(u16, flags)
+ __field(dev_t, bdev)
+ ),
+ TP_fast_assign(
+ __entry->dev = inode->i_sb->s_dev;
+ __entry->ino = inode->i_ino;
+ __entry->pos = pos;
+ __entry->dirty_len = dirty_len;
+ __entry->addr = iomap->addr;
+ __entry->offset = iomap->offset;
+ __entry->length = iomap->length;
+ __entry->type = iomap->type;
+ __entry->flags = iomap->flags;
+ __entry->bdev = iomap->bdev ? iomap->bdev->bd_dev : 0;
+ ),
+ TP_printk("dev %d:%d ino 0x%llx bdev %d:%d pos 0x%llx dirty len 0x%llx "
+ "addr 0x%llx offset 0x%llx length 0x%llx type %s flags %s",
+ MAJOR(__entry->dev), MINOR(__entry->dev),
+ __entry->ino,
+ MAJOR(__entry->bdev), MINOR(__entry->bdev),
+ __entry->pos,
+ __entry->dirty_len,
+ __entry->addr,
+ __entry->offset,
+ __entry->length,
+ __print_symbolic(__entry->type, IOMAP_TYPE_STRINGS),
+ __print_flags(__entry->flags, "|", IOMAP_F_FLAGS_STRINGS))
+);
TRACE_EVENT(iomap_iter,
TP_PROTO(struct iomap_iter *iter, const void *ops,
--
2.39.2
From: Zhang Yi <[email protected]>
When adding a delalloc extent in ext4_da_map_blocks(), the extent
length can be incorrect if we found a cached hole extent entry and the
hole length is smaller than the origin map->m_len. Fortunately, it
should not be able to trigger any issue now because the map->m_len is
always 1. Fix this by adjust length before inserting delalloc extent.
Signed-off-by: Zhang Yi <[email protected]>
---
fs/ext4/inode.c | 9 +++++----
1 file changed, 5 insertions(+), 4 deletions(-)
diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index bc29c2e92750..44033828db44 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -1712,6 +1712,11 @@ static int ext4_da_map_blocks(struct inode *inode, sector_t iblock,
/* Lookup extent status tree firstly */
if (ext4_es_lookup_extent(inode, iblock, NULL, &es)) {
+ retval = es.es_len - (iblock - es.es_lblk);
+ if (retval > map->m_len)
+ retval = map->m_len;
+ map->m_len = retval;
+
if (ext4_es_is_hole(&es))
goto add_delayed;
@@ -1727,10 +1732,6 @@ static int ext4_da_map_blocks(struct inode *inode, sector_t iblock,
}
map->m_pblk = ext4_es_pblock(&es) + iblock - es.es_lblk;
- retval = es.es_len - (iblock - es.es_lblk);
- if (retval > map->m_len)
- retval = map->m_len;
- map->m_len = retval;
if (ext4_es_is_written(&es))
map->m_flags |= EXT4_MAP_MAPPED;
else if (ext4_es_is_unwritten(&es))
--
2.39.2
From: Zhang Yi <[email protected]>
Factor out two new helpers, ext4_map_query_blocks() query blocks
mapping, and ext4_map_create_blocks() allocate new blocks and map a new
extent, no logic changes.
Signed-off-by: Zhang Yi <[email protected]>
---
fs/ext4/inode.c | 219 ++++++++++++++++++++++++++----------------------
1 file changed, 117 insertions(+), 102 deletions(-)
diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index 9f9b1fce8da8..125d0665fa10 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -453,6 +453,121 @@ static void ext4_map_blocks_es_recheck(handle_t *handle,
}
#endif /* ES_AGGRESSIVE_TEST */
+static int ext4_map_query_blocks(handle_t *handle, struct inode *inode,
+ struct ext4_map_blocks *map, int flags)
+{
+ unsigned int status;
+ int retval;
+
+ if (ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS))
+ retval = ext4_ext_map_blocks(handle, inode, map, 0);
+ else
+ retval = ext4_ind_map_blocks(handle, inode, map, 0);
+
+ if (retval <= 0)
+ return retval;
+
+ if (unlikely(retval != map->m_len)) {
+ ext4_warning(inode->i_sb,
+ "ES len assertion failed for inode "
+ "%lu: retval %d != map->m_len %d",
+ inode->i_ino, retval, map->m_len);
+ WARN_ON(1);
+ }
+
+ status = map->m_flags & EXT4_MAP_UNWRITTEN ?
+ EXTENT_STATUS_UNWRITTEN : EXTENT_STATUS_WRITTEN;
+ if (!(flags & EXT4_GET_BLOCKS_DELALLOC_RESERVE) &&
+ !(status & EXTENT_STATUS_WRITTEN) &&
+ ext4_es_scan_range(inode, &ext4_es_is_delayed, map->m_lblk,
+ map->m_lblk + map->m_len - 1))
+ status |= EXTENT_STATUS_DELAYED;
+ ext4_es_insert_extent(inode, map->m_lblk, map->m_len,
+ map->m_pblk, status);
+
+ return retval;
+}
+
+static int ext4_map_create_blocks(handle_t *handle, struct inode *inode,
+ struct ext4_map_blocks *map, int flags)
+{
+ struct extent_status es;
+ unsigned int status;
+ int err, retval = 0;
+
+ /*
+ * Here we clear m_flags because after allocating an new extent,
+ * it will be set again.
+ */
+ map->m_flags &= ~EXT4_MAP_FLAGS;
+
+ /*
+ * We need to check for EXT4 here because migrate could have
+ * changed the inode type in between.
+ */
+ if (ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS)) {
+ retval = ext4_ext_map_blocks(handle, inode, map, flags);
+ } else {
+ retval = ext4_ind_map_blocks(handle, inode, map, flags);
+
+ /*
+ * We allocated new blocks which will result in i_data's
+ * format changing. Force the migrate to fail by clearing
+ * migrate flags.
+ */
+ if (retval > 0 && map->m_flags & EXT4_MAP_NEW)
+ ext4_clear_inode_state(inode, EXT4_STATE_EXT_MIGRATE);
+ }
+ if (retval <= 0)
+ return retval;
+
+ if (unlikely(retval != map->m_len)) {
+ ext4_warning(inode->i_sb,
+ "ES len assertion failed for inode %lu: "
+ "retval %d != map->m_len %d",
+ inode->i_ino, retval, map->m_len);
+ WARN_ON(1);
+ }
+
+ /*
+ * We have to zeroout blocks before inserting them into extent
+ * status tree. Otherwise someone could look them up there and
+ * use them before they are really zeroed. We also have to
+ * unmap metadata before zeroing as otherwise writeback can
+ * overwrite zeros with stale data from block device.
+ */
+ if (flags & EXT4_GET_BLOCKS_ZERO &&
+ map->m_flags & EXT4_MAP_MAPPED && map->m_flags & EXT4_MAP_NEW) {
+ err = ext4_issue_zeroout(inode, map->m_lblk, map->m_pblk,
+ map->m_len);
+ if (err)
+ return err;
+ }
+
+ /*
+ * If the extent has been zeroed out, we don't need to update
+ * extent status tree.
+ */
+ if (flags & EXT4_GET_BLOCKS_PRE_IO &&
+ ext4_es_lookup_extent(inode, map->m_lblk, NULL, &es)) {
+ if (ext4_es_is_written(&es))
+ return retval;
+ }
+
+ status = map->m_flags & EXT4_MAP_UNWRITTEN ?
+ EXTENT_STATUS_UNWRITTEN : EXTENT_STATUS_WRITTEN;
+ if (!(flags & EXT4_GET_BLOCKS_DELALLOC_RESERVE) &&
+ !(status & EXTENT_STATUS_WRITTEN) &&
+ ext4_es_scan_range(inode, &ext4_es_is_delayed, map->m_lblk,
+ map->m_lblk + map->m_len - 1))
+ status |= EXTENT_STATUS_DELAYED;
+
+ ext4_es_insert_extent(inode, map->m_lblk, map->m_len,
+ map->m_pblk, status);
+
+ return retval;
+}
+
/*
* The ext4_map_blocks() function tries to look up the requested blocks,
* and returns if the blocks are already mapped.
@@ -546,32 +661,7 @@ int ext4_map_blocks(handle_t *handle, struct inode *inode,
* file system block.
*/
down_read(&EXT4_I(inode)->i_data_sem);
- if (ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS)) {
- retval = ext4_ext_map_blocks(handle, inode, map, 0);
- } else {
- retval = ext4_ind_map_blocks(handle, inode, map, 0);
- }
- if (retval > 0) {
- unsigned int status;
-
- if (unlikely(retval != map->m_len)) {
- ext4_warning(inode->i_sb,
- "ES len assertion failed for inode "
- "%lu: retval %d != map->m_len %d",
- inode->i_ino, retval, map->m_len);
- WARN_ON(1);
- }
-
- status = map->m_flags & EXT4_MAP_UNWRITTEN ?
- EXTENT_STATUS_UNWRITTEN : EXTENT_STATUS_WRITTEN;
- if (!(flags & EXT4_GET_BLOCKS_DELALLOC_RESERVE) &&
- !(status & EXTENT_STATUS_WRITTEN) &&
- ext4_es_scan_range(inode, &ext4_es_is_delayed, map->m_lblk,
- map->m_lblk + map->m_len - 1))
- status |= EXTENT_STATUS_DELAYED;
- ext4_es_insert_extent(inode, map->m_lblk, map->m_len,
- map->m_pblk, status);
- }
+ retval = ext4_map_query_blocks(handle, inode, map, 0);
up_read((&EXT4_I(inode)->i_data_sem));
found:
@@ -601,12 +691,6 @@ int ext4_map_blocks(handle_t *handle, struct inode *inode,
if (!(flags & EXT4_GET_BLOCKS_CONVERT_UNWRITTEN))
return retval;
- /*
- * Here we clear m_flags because after allocating an new extent,
- * it will be set again.
- */
- map->m_flags &= ~EXT4_MAP_FLAGS;
-
/*
* New blocks allocate and/or writing to unwritten extent
* will possibly result in updating i_data, so we take
@@ -614,76 +698,7 @@ int ext4_map_blocks(handle_t *handle, struct inode *inode,
* with create == 1 flag.
*/
down_write(&EXT4_I(inode)->i_data_sem);
-
- /*
- * We need to check for EXT4 here because migrate
- * could have changed the inode type in between
- */
- if (ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS)) {
- retval = ext4_ext_map_blocks(handle, inode, map, flags);
- } else {
- retval = ext4_ind_map_blocks(handle, inode, map, flags);
-
- if (retval > 0 && map->m_flags & EXT4_MAP_NEW) {
- /*
- * We allocated new blocks which will result in
- * i_data's format changing. Force the migrate
- * to fail by clearing migrate flags
- */
- ext4_clear_inode_state(inode, EXT4_STATE_EXT_MIGRATE);
- }
- }
-
- if (retval > 0) {
- unsigned int status;
-
- if (unlikely(retval != map->m_len)) {
- ext4_warning(inode->i_sb,
- "ES len assertion failed for inode "
- "%lu: retval %d != map->m_len %d",
- inode->i_ino, retval, map->m_len);
- WARN_ON(1);
- }
-
- /*
- * We have to zeroout blocks before inserting them into extent
- * status tree. Otherwise someone could look them up there and
- * use them before they are really zeroed. We also have to
- * unmap metadata before zeroing as otherwise writeback can
- * overwrite zeros with stale data from block device.
- */
- if (flags & EXT4_GET_BLOCKS_ZERO &&
- map->m_flags & EXT4_MAP_MAPPED &&
- map->m_flags & EXT4_MAP_NEW) {
- ret = ext4_issue_zeroout(inode, map->m_lblk,
- map->m_pblk, map->m_len);
- if (ret) {
- retval = ret;
- goto out_sem;
- }
- }
-
- /*
- * If the extent has been zeroed out, we don't need to update
- * extent status tree.
- */
- if ((flags & EXT4_GET_BLOCKS_PRE_IO) &&
- ext4_es_lookup_extent(inode, map->m_lblk, NULL, &es)) {
- if (ext4_es_is_written(&es))
- goto out_sem;
- }
- status = map->m_flags & EXT4_MAP_UNWRITTEN ?
- EXTENT_STATUS_UNWRITTEN : EXTENT_STATUS_WRITTEN;
- if (!(flags & EXT4_GET_BLOCKS_DELALLOC_RESERVE) &&
- !(status & EXTENT_STATUS_WRITTEN) &&
- ext4_es_scan_range(inode, &ext4_es_is_delayed, map->m_lblk,
- map->m_lblk + map->m_len - 1))
- status |= EXTENT_STATUS_DELAYED;
- ext4_es_insert_extent(inode, map->m_lblk, map->m_len,
- map->m_pblk, status);
- }
-
-out_sem:
+ retval = ext4_map_create_blocks(handle, inode, map, flags);
up_write((&EXT4_I(inode)->i_data_sem));
if (retval > 0 && map->m_flags & EXT4_MAP_MAPPED) {
ret = check_block_validity(inode, map);
--
2.39.2
From: Zhang Yi <[email protected]>
Introduce a new iomap address space operations ext4_iomap_aops to
support regular file's buffered IO path and add an inode state flag
EXT4_STATE_BUFFERED_IOMAP to indicate that one inode use the iomap
path. Most of their callbacks should be able to use general
implementation, the left over read_folio, readahead and writepages
should be implemented later.
Signed-off-by: Zhang Yi <[email protected]>
---
fs/ext4/ext4.h | 1 +
fs/ext4/inode.c | 33 +++++++++++++++++++++++++++++++++
2 files changed, 34 insertions(+)
diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
index 287284a3f128..3461cb3ff524 100644
--- a/fs/ext4/ext4.h
+++ b/fs/ext4/ext4.h
@@ -1913,6 +1913,7 @@ enum {
EXT4_STATE_VERITY_IN_PROGRESS, /* building fs-verity Merkle tree */
EXT4_STATE_FC_COMMITTING, /* Fast commit ongoing */
EXT4_STATE_ORPHAN_FILE, /* Inode orphaned in orphan file */
+ EXT4_STATE_BUFFERED_IOMAP, /* Inode use iomap for buffered IO */
};
#define EXT4_INODE_BIT_FNS(name, field, offset) \
diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index 125d0665fa10..eca9bf5dd255 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -3507,6 +3507,22 @@ const struct iomap_ops ext4_iomap_report_ops = {
.iomap_begin = ext4_iomap_begin_report,
};
+static int ext4_iomap_read_folio(struct file *file, struct folio *folio)
+{
+ return 0;
+}
+
+static void ext4_iomap_readahead(struct readahead_control *rac)
+{
+
+}
+
+static int ext4_iomap_writepages(struct address_space *mapping,
+ struct writeback_control *wbc)
+{
+ return 0;
+}
+
/*
* For data=journal mode, folio should be marked dirty only when it was
* writeably mapped. When that happens, it was already attached to the
@@ -3596,6 +3612,21 @@ static const struct address_space_operations ext4_da_aops = {
.swap_activate = ext4_iomap_swap_activate,
};
+static const struct address_space_operations ext4_iomap_aops = {
+ .read_folio = ext4_iomap_read_folio,
+ .readahead = ext4_iomap_readahead,
+ .writepages = ext4_iomap_writepages,
+ .dirty_folio = iomap_dirty_folio,
+ .bmap = ext4_bmap,
+ .invalidate_folio = iomap_invalidate_folio,
+ .release_folio = iomap_release_folio,
+ .direct_IO = noop_direct_IO,
+ .migrate_folio = filemap_migrate_folio,
+ .is_partially_uptodate = iomap_is_partially_uptodate,
+ .error_remove_page = generic_error_remove_page,
+ .swap_activate = ext4_iomap_swap_activate,
+};
+
static const struct address_space_operations ext4_dax_aops = {
.writepages = ext4_dax_writepages,
.direct_IO = noop_direct_IO,
@@ -3618,6 +3649,8 @@ void ext4_set_aops(struct inode *inode)
}
if (IS_DAX(inode))
inode->i_mapping->a_ops = &ext4_dax_aops;
+ else if (ext4_test_inode_state(inode, EXT4_STATE_BUFFERED_IOMAP))
+ inode->i_mapping->a_ops = &ext4_iomap_aops;
else if (test_opt(inode->i_sb, DELALLOC))
inode->i_mapping->a_ops = &ext4_da_aops;
else
--
2.39.2
From: Zhang Yi <[email protected]>
Add ext4_iomap_buffered_io_begin() to query map blocks, and use
ext4_set_iomap() to convert ext4 map to iomap, after that we can
convert buffered read path to iomap simply.
Signed-off-by: Zhang Yi <[email protected]>
---
fs/ext4/inode.c | 36 ++++++++++++++++++++++++++++++++++--
1 file changed, 34 insertions(+), 2 deletions(-)
diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index eca9bf5dd255..5d542ce13d2a 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -3507,14 +3507,46 @@ const struct iomap_ops ext4_iomap_report_ops = {
.iomap_begin = ext4_iomap_begin_report,
};
-static int ext4_iomap_read_folio(struct file *file, struct folio *folio)
+static int ext4_iomap_buffered_io_begin(struct inode *inode, loff_t offset,
+ loff_t length, unsigned int iomap_flags,
+ struct iomap *iomap, struct iomap *srcmap)
{
+ int ret;
+ struct ext4_map_blocks map;
+ u8 blkbits = inode->i_blkbits;
+
+ if (unlikely(ext4_forced_shutdown(inode->i_sb)))
+ return -EIO;
+ if ((offset >> blkbits) > EXT4_MAX_LOGICAL_BLOCK)
+ return -EINVAL;
+ if (WARN_ON_ONCE(ext4_has_inline_data(inode)))
+ return -ERANGE;
+
+ /* Calculate the first and last logical blocks respectively. */
+ map.m_lblk = offset >> blkbits;
+ map.m_len = min_t(loff_t, (offset + length - 1) >> blkbits,
+ EXT4_MAX_LOGICAL_BLOCK) - map.m_lblk + 1;
+
+ ret = ext4_map_blocks(NULL, inode, &map, 0);
+ if (ret < 0)
+ return ret;
+
+ ext4_set_iomap(inode, iomap, &map, offset, length, iomap_flags);
return 0;
}
-static void ext4_iomap_readahead(struct readahead_control *rac)
+const struct iomap_ops ext4_iomap_buffered_read_ops = {
+ .iomap_begin = ext4_iomap_buffered_io_begin,
+};
+
+static int ext4_iomap_read_folio(struct file *file, struct folio *folio)
{
+ return iomap_read_folio(folio, &ext4_iomap_buffered_read_ops);
+}
+static void ext4_iomap_readahead(struct readahead_control *rac)
+{
+ iomap_readahead(rac, &ext4_iomap_buffered_read_ops);
}
static int ext4_iomap_writepages(struct address_space *mapping,
--
2.39.2
From: Zhang Yi <[email protected]>
Implement buffered write iomap path, use ext4_da_map_blocks() to map
delalloc extents and add ext4_iomap_get_blocks() to allocate blocks if
delalloc is disabled or free space is about to run out.
Note that we don't want to support dioread_lock mount option any more,
so we drop the branch of ext4_should_dioread_nolock() and always
allocate unwritten extents for new blocks, also make
ext4_should_dioread_nolock() not controlled by the DIOREAD_NOLOCK mount
option and always return true. Besides, the i_disksize updating is also
postponed to after writeback.
After this, now we map or allocate batch of blocks once a time, so it
should be able to bring a lot of performance gains.
Signed-off-by: Zhang Yi <[email protected]>
---
fs/ext4/ext4.h | 3 +
fs/ext4/ext4_jbd2.h | 7 ++
fs/ext4/file.c | 19 ++++-
fs/ext4/inode.c | 168 ++++++++++++++++++++++++++++++++++++++++++--
4 files changed, 190 insertions(+), 7 deletions(-)
diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
index 3461cb3ff524..03cdcf3d86a5 100644
--- a/fs/ext4/ext4.h
+++ b/fs/ext4/ext4.h
@@ -2970,6 +2970,7 @@ int ext4_walk_page_buffers(handle_t *handle,
struct buffer_head *bh));
int do_journal_get_write_access(handle_t *handle, struct inode *inode,
struct buffer_head *bh);
+int ext4_nonda_switch(struct super_block *sb);
#define FALL_BACK_TO_NONDELALLOC 1
#define CONVERT_INLINE_DATA 2
@@ -3827,6 +3828,8 @@ static inline void ext4_clear_io_unwritten_flag(ext4_io_end_t *io_end)
extern const struct iomap_ops ext4_iomap_ops;
extern const struct iomap_ops ext4_iomap_overwrite_ops;
extern const struct iomap_ops ext4_iomap_report_ops;
+extern const struct iomap_ops ext4_iomap_buffered_write_ops;
+extern const struct iomap_ops ext4_iomap_buffered_da_write_ops;
static inline int ext4_buffer_uptodate(struct buffer_head *bh)
{
diff --git a/fs/ext4/ext4_jbd2.h b/fs/ext4/ext4_jbd2.h
index 0c77697d5e90..c1194ba8d6f2 100644
--- a/fs/ext4/ext4_jbd2.h
+++ b/fs/ext4/ext4_jbd2.h
@@ -499,6 +499,13 @@ static inline int ext4_free_data_revoke_credits(struct inode *inode, int blocks)
*/
static inline int ext4_should_dioread_nolock(struct inode *inode)
{
+ /*
+ * Always enable dioread_nolock for inode which use buffered
+ * iomap path.
+ */
+ if (ext4_test_inode_state(inode, EXT4_STATE_BUFFERED_IOMAP))
+ return 1;
+
if (!test_opt(inode->i_sb, DIOREAD_NOLOCK))
return 0;
if (!S_ISREG(inode->i_mode))
diff --git a/fs/ext4/file.c b/fs/ext4/file.c
index 6aa15dafc677..d15bd6ff1b20 100644
--- a/fs/ext4/file.c
+++ b/fs/ext4/file.c
@@ -282,6 +282,20 @@ static ssize_t ext4_write_checks(struct kiocb *iocb, struct iov_iter *from)
return count;
}
+static ssize_t ext4_iomap_buffered_write(struct kiocb *iocb,
+ struct iov_iter *from)
+{
+ struct inode *inode = file_inode(iocb->ki_filp);
+ const struct iomap_ops *iomap_ops;
+
+ if (test_opt(inode->i_sb, DELALLOC) && !ext4_nonda_switch(inode->i_sb))
+ iomap_ops = &ext4_iomap_buffered_da_write_ops;
+ else
+ iomap_ops = &ext4_iomap_buffered_write_ops;
+
+ return iomap_file_buffered_write(iocb, from, iomap_ops);
+}
+
static ssize_t ext4_buffered_write_iter(struct kiocb *iocb,
struct iov_iter *from)
{
@@ -296,7 +310,10 @@ static ssize_t ext4_buffered_write_iter(struct kiocb *iocb,
if (ret <= 0)
goto out;
- ret = generic_perform_write(iocb, from);
+ if (ext4_test_inode_state(inode, EXT4_STATE_BUFFERED_IOMAP))
+ ret = ext4_iomap_buffered_write(iocb, from);
+ else
+ ret = generic_perform_write(iocb, from);
out:
inode_unlock(inode);
diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index 5d542ce13d2a..c48aca637896 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -2842,7 +2842,7 @@ static int ext4_dax_writepages(struct address_space *mapping,
return ret;
}
-static int ext4_nonda_switch(struct super_block *sb)
+int ext4_nonda_switch(struct super_block *sb)
{
s64 free_clusters, dirty_clusters;
struct ext4_sb_info *sbi = EXT4_SB(sb);
@@ -3238,6 +3238,15 @@ static bool ext4_inode_datasync_dirty(struct inode *inode)
return inode->i_state & I_DIRTY_DATASYNC;
}
+static bool ext4_iomap_valid(struct inode *inode, const struct iomap *iomap)
+{
+ return iomap->validity_cookie == READ_ONCE(EXT4_I(inode)->i_es_seq);
+}
+
+static const struct iomap_folio_ops ext4_iomap_folio_ops = {
+ .iomap_valid = ext4_iomap_valid,
+};
+
static void ext4_set_iomap(struct inode *inode, struct iomap *iomap,
struct ext4_map_blocks *map, loff_t offset,
loff_t length, unsigned int flags)
@@ -3268,6 +3277,9 @@ static void ext4_set_iomap(struct inode *inode, struct iomap *iomap,
!ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS))
iomap->flags |= IOMAP_F_MERGED;
+ iomap->validity_cookie = READ_ONCE(EXT4_I(inode)->i_es_seq);
+ iomap->folio_ops = &ext4_iomap_folio_ops;
+
/*
* Flags passed to ext4_map_blocks() for direct I/O writes can result
* in m_flags having both EXT4_MAP_MAPPED and EXT4_MAP_UNWRITTEN bits
@@ -3507,11 +3519,42 @@ const struct iomap_ops ext4_iomap_report_ops = {
.iomap_begin = ext4_iomap_begin_report,
};
-static int ext4_iomap_buffered_io_begin(struct inode *inode, loff_t offset,
+static int ext4_iomap_get_blocks(struct inode *inode,
+ struct ext4_map_blocks *map)
+{
+ handle_t *handle;
+ int ret, needed_blocks;
+
+ /*
+ * Reserve one block more for addition to orphan list in case
+ * we allocate blocks but write fails for some reason.
+ */
+ needed_blocks = ext4_writepage_trans_blocks(inode) + 1;
+ handle = ext4_journal_start(inode, EXT4_HT_WRITE_PAGE, needed_blocks);
+ if (IS_ERR(handle))
+ return PTR_ERR(handle);
+
+ ret = ext4_map_blocks(handle, inode, map,
+ EXT4_GET_BLOCKS_CREATE_UNWRIT_EXT);
+ /*
+ * Have to stop journal here since there is a potential deadlock
+ * caused by later balance_dirty_pages(), it might wait on the
+ * ditry pages to be written back, which might start another
+ * handle and wait this handle stop.
+ */
+ ext4_journal_stop(handle);
+
+ return ret;
+}
+
+#define IOMAP_F_EXT4_DELALLOC IOMAP_F_PRIVATE
+
+static int __ext4_iomap_buffered_io_begin(struct inode *inode, loff_t offset,
loff_t length, unsigned int iomap_flags,
- struct iomap *iomap, struct iomap *srcmap)
+ struct iomap *iomap, struct iomap *srcmap,
+ bool delalloc)
{
- int ret;
+ int ret, retries = 0;
struct ext4_map_blocks map;
u8 blkbits = inode->i_blkbits;
@@ -3521,20 +3564,133 @@ static int ext4_iomap_buffered_io_begin(struct inode *inode, loff_t offset,
return -EINVAL;
if (WARN_ON_ONCE(ext4_has_inline_data(inode)))
return -ERANGE;
-
+retry:
/* Calculate the first and last logical blocks respectively. */
map.m_lblk = offset >> blkbits;
map.m_len = min_t(loff_t, (offset + length - 1) >> blkbits,
EXT4_MAX_LOGICAL_BLOCK) - map.m_lblk + 1;
+ if (iomap_flags & IOMAP_WRITE) {
+ if (delalloc)
+ ret = ext4_da_map_blocks(inode, &map);
+ else
+ ret = ext4_iomap_get_blocks(inode, &map);
- ret = ext4_map_blocks(NULL, inode, &map, 0);
+ if (ret == -ENOSPC &&
+ ext4_should_retry_alloc(inode->i_sb, &retries))
+ goto retry;
+ } else {
+ ret = ext4_map_blocks(NULL, inode, &map, 0);
+ }
if (ret < 0)
return ret;
ext4_set_iomap(inode, iomap, &map, offset, length, iomap_flags);
+ if (delalloc)
+ iomap->flags |= IOMAP_F_EXT4_DELALLOC;
+
+ return 0;
+}
+
+static inline int ext4_iomap_buffered_io_begin(struct inode *inode,
+ loff_t offset, loff_t length, unsigned int flags,
+ struct iomap *iomap, struct iomap *srcmap)
+{
+ return __ext4_iomap_buffered_io_begin(inode, offset, length, flags,
+ iomap, srcmap, false);
+}
+
+static inline int ext4_iomap_buffered_da_write_begin(struct inode *inode,
+ loff_t offset, loff_t length, unsigned int flags,
+ struct iomap *iomap, struct iomap *srcmap)
+{
+ return __ext4_iomap_buffered_io_begin(inode, offset, length, flags,
+ iomap, srcmap, true);
+}
+
+/*
+ * Drop the staled delayed allocation range from the write failure,
+ * including both start and end blocks. If not, we could leave a range
+ * of delayed extents covered by a clean folio, it could lead to
+ * inaccurate space reservation.
+ */
+static int ext4_iomap_punch_delalloc(struct inode *inode, loff_t offset,
+ loff_t length)
+{
+ ext4_es_remove_extent(inode, offset >> inode->i_blkbits,
+ DIV_ROUND_UP(length, EXT4_BLOCK_SIZE(inode->i_sb)));
return 0;
}
+static int ext4_iomap_buffered_write_end(struct inode *inode, loff_t offset,
+ loff_t length, ssize_t written,
+ unsigned int flags,
+ struct iomap *iomap)
+{
+ handle_t *handle;
+ loff_t end;
+ int ret = 0, ret2;
+
+ /* delalloc */
+ if (iomap->flags & IOMAP_F_EXT4_DELALLOC) {
+ ret = iomap_file_buffered_write_punch_delalloc(inode, iomap,
+ offset, length, written, ext4_iomap_punch_delalloc);
+ if (ret)
+ ext4_warning(inode->i_sb,
+ "Failed to clean up delalloc for inode %lu, %d",
+ inode->i_ino, ret);
+ return ret;
+ }
+
+ /* nodelalloc */
+ end = offset + length;
+ if (!(iomap->flags & IOMAP_F_SIZE_CHANGED) && end <= inode->i_size)
+ return 0;
+
+ handle = ext4_journal_start(inode, EXT4_HT_INODE, 2);
+ if (IS_ERR(handle))
+ return PTR_ERR(handle);
+
+ if (iomap->flags & IOMAP_F_SIZE_CHANGED) {
+ ext4_update_i_disksize(inode, inode->i_size);
+ ret = ext4_mark_inode_dirty(handle, inode);
+ }
+
+ /*
+ * If we have allocated more blocks and copied less.
+ * We will have blocks allocated outside inode->i_size,
+ * so truncate them.
+ */
+ if (end > inode->i_size)
+ ext4_orphan_add(handle, inode);
+
+ ret2 = ext4_journal_stop(handle);
+ ret = ret ? : ret2;
+
+ if (end > inode->i_size) {
+ ext4_truncate_failed_write(inode);
+ /*
+ * If truncate failed early the inode might still be
+ * on the orphan list; we need to make sure the inode
+ * is removed from the orphan list in that case.
+ */
+ if (inode->i_nlink)
+ ext4_orphan_del(NULL, inode);
+ }
+
+ return ret;
+}
+
+
+const struct iomap_ops ext4_iomap_buffered_write_ops = {
+ .iomap_begin = ext4_iomap_buffered_io_begin,
+ .iomap_end = ext4_iomap_buffered_write_end,
+};
+
+const struct iomap_ops ext4_iomap_buffered_da_write_ops = {
+ .iomap_begin = ext4_iomap_buffered_da_write_begin,
+ .iomap_end = ext4_iomap_buffered_write_end,
+};
+
const struct iomap_ops ext4_iomap_buffered_read_ops = {
.iomap_begin = ext4_iomap_buffered_io_begin,
};
--
2.39.2
From: Zhang Yi <[email protected]>
Implement buffered writeback iomap path, include map_blocks() and
prepare_ioend() callbacks in iomap_writeback_ops and the corresponding
end io process. Add ext4_iomap_map_blocks() to query mapping status,
start journal handle and allocate new blocks if it's not allocated. Add
ext4_iomap_prepare_ioend() to register the end io handler of converting
unwritten extents to mapped extents.
In order to reduce the number of map times, we map an entire delayed
extent once a time, it means that we could map more blocks than we
expected, so we have to calculate the length through wbc->range_end
carefully. Besides, we won't be able to avoid splitting extents in
endio, so we would allow that because we have been using reserved blocks
in endio, it doesn't bring more risks of data loss than splitting before
submitting IO.
Since we always allocate unwritten extents and keep them until data have
been written to disk, we don't need to write back the data before the
metadata is updated to disk, there is no risk of exposing stale data, so
the data=ordered journal mode becomes useless. We don't need to attach
data to the jinode, and the journal thread won't have to write any
dependent data any more. In the meantime, we don't have to reserve
journal credits for the extent status conversion and we also could
postpone i_disksize updating into endio.
Signed-off-by: Zhang Yi <[email protected]>
---
fs/ext4/ext4.h | 4 +
fs/ext4/ext4_jbd2.c | 6 ++
fs/ext4/extents.c | 23 +++---
fs/ext4/inode.c | 190 +++++++++++++++++++++++++++++++++++++++++++-
fs/ext4/page-io.c | 107 +++++++++++++++++++++++++
fs/ext4/super.c | 2 +
6 files changed, 322 insertions(+), 10 deletions(-)
diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
index 03cdcf3d86a5..eaf29bade606 100644
--- a/fs/ext4/ext4.h
+++ b/fs/ext4/ext4.h
@@ -1147,6 +1147,8 @@ struct ext4_inode_info {
*/
struct list_head i_rsv_conversion_list;
struct work_struct i_rsv_conversion_work;
+ struct list_head i_iomap_ioend_list;
+ struct work_struct i_iomap_ioend_work;
atomic_t i_unwritten; /* Nr. of inflight conversions pending */
spinlock_t i_block_reservation_lock;
@@ -3755,6 +3757,8 @@ int ext4_bio_write_folio(struct ext4_io_submit *io, struct folio *page,
size_t len);
extern struct ext4_io_end_vec *ext4_alloc_io_end_vec(ext4_io_end_t *io_end);
extern struct ext4_io_end_vec *ext4_last_io_end_vec(ext4_io_end_t *io_end);
+extern void ext4_iomap_end_io(struct work_struct *work);
+extern void ext4_iomap_end_bio(struct bio *bio);
/* mmp.c */
extern int ext4_multi_mount_protect(struct super_block *, ext4_fsblk_t);
diff --git a/fs/ext4/ext4_jbd2.c b/fs/ext4/ext4_jbd2.c
index d1a2e6624401..94c8073b49e7 100644
--- a/fs/ext4/ext4_jbd2.c
+++ b/fs/ext4/ext4_jbd2.c
@@ -11,6 +11,12 @@ int ext4_inode_journal_mode(struct inode *inode)
{
if (EXT4_JOURNAL(inode) == NULL)
return EXT4_INODE_WRITEBACK_DATA_MODE; /* writeback */
+ /*
+ * Ordered mode is no longer needed for the inode that use the
+ * iomap path, always use writeback mode.
+ */
+ if (ext4_test_inode_state(inode, EXT4_STATE_BUFFERED_IOMAP))
+ return EXT4_INODE_WRITEBACK_DATA_MODE; /* writeback */
/* We do not support data journalling with delayed allocation */
if (!S_ISREG(inode->i_mode) ||
ext4_test_inode_flag(inode, EXT4_INODE_EA_INODE) ||
diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c
index 48d6d125ec37..46805b8e7bdc 100644
--- a/fs/ext4/extents.c
+++ b/fs/ext4/extents.c
@@ -3708,18 +3708,23 @@ static int ext4_convert_unwritten_extents_endio(handle_t *handle,
ext_debug(inode, "logical block %llu, max_blocks %u\n",
(unsigned long long)ee_block, ee_len);
- /* If extent is larger than requested it is a clear sign that we still
- * have some extent state machine issues left. So extent_split is still
- * required.
- * TODO: Once all related issues will be fixed this situation should be
- * illegal.
+ /*
+ * For the inodes that use the buffered iomap path need to split
+ * extents in endio, other inodes not.
+ *
+ * TODO: Reserve enough sapce for splitting extents, always split
+ * extents here, and totally remove this warning.
*/
if (ee_block != map->m_lblk || ee_len > map->m_len) {
#ifdef CONFIG_EXT4_DEBUG
- ext4_warning(inode->i_sb, "Inode (%ld) finished: extent logical block %llu,"
- " len %u; IO logical block %llu, len %u",
- inode->i_ino, (unsigned long long)ee_block, ee_len,
- (unsigned long long)map->m_lblk, map->m_len);
+ if (!ext4_test_inode_state(inode, EXT4_STATE_BUFFERED_IOMAP)) {
+ ext4_warning(inode->i_sb,
+ "Inode (%ld) finished: extent logical block %llu, "
+ "len %u; IO logical block %llu, len %u",
+ inode->i_ino, (unsigned long long)ee_block,
+ ee_len, (unsigned long long)map->m_lblk,
+ map->m_len);
+ }
#endif
err = ext4_split_convert_extents(handle, inode, map, ppath,
EXT4_GET_BLOCKS_CONVERT |
diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index c48aca637896..8ee0eca6a1e8 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -43,6 +43,7 @@
#include <linux/iversion.h>
#include "ext4_jbd2.h"
+#include "ext4_extents.h"
#include "xattr.h"
#include "acl.h"
#include "truncate.h"
@@ -3705,10 +3706,197 @@ static void ext4_iomap_readahead(struct readahead_control *rac)
iomap_readahead(rac, &ext4_iomap_buffered_read_ops);
}
+struct ext4_writeback_ctx {
+ struct iomap_writepage_ctx ctx;
+ struct writeback_control *wbc;
+ unsigned int data_seq;
+};
+
+static int ext4_iomap_map_one_extent(struct inode *inode,
+ struct ext4_map_blocks *map)
+{
+ struct extent_status es;
+ handle_t *handle = NULL;
+ int credits, map_flags;
+ int retval;
+
+ credits = ext4_da_writepages_trans_blocks(inode);
+ handle = ext4_journal_start(inode, EXT4_HT_WRITE_PAGE, credits);
+ if (IS_ERR(handle))
+ return PTR_ERR(handle);
+
+ map->m_flags = 0;
+ /*
+ * In order to protect from the race of truncate, we have to lookup
+ * extent stats and map blocks under i_data_sem, otherwise the
+ * delalloc extent could be stale.
+ */
+ down_write(&EXT4_I(inode)->i_data_sem);
+ if (likely(ext4_es_lookup_extent(inode, map->m_lblk, NULL, &es))) {
+ retval = es.es_len - (map->m_lblk - es.es_lblk);
+ map->m_len = min_t(unsigned int, retval, map->m_len);
+
+ if (likely(ext4_es_is_delonly(&es))) {
+ trace_ext4_da_write_pages_extent(inode, map);
+ /*
+ * Call ext4_map_create_blocks() to allocate any delayed
+ * allocation blocks. It is possible that we're going to
+ * need more metadata blocks, however we must not fail
+ * because we're in writeback and there is nothing we
+ * can do so it might result in data loss. So use
+ * reserved blocks to allocate metadata if possible.
+ *
+ * We pass in the magic EXT4_GET_BLOCKS_DELALLOC_RESERVE
+ * indicates that the blocks and quotas has already been
+ * checked when the data was copied into the page cache.
+ */
+ map_flags = EXT4_GET_BLOCKS_CREATE_UNWRIT_EXT |
+ EXT4_GET_BLOCKS_METADATA_NOFAIL |
+ EXT4_GET_BLOCKS_DELALLOC_RESERVE;
+
+ retval = ext4_map_create_blocks(handle, inode, map,
+ map_flags);
+ }
+ if (ext4_es_is_written(&es) || ext4_es_is_unwritten(&es)) {
+ map->m_pblk = ext4_es_pblock(&es) + map->m_lblk -
+ es.es_lblk;
+ map->m_flags = ext4_es_is_written(&es) ?
+ EXT4_MAP_MAPPED : EXT4_MAP_UNWRITTEN;
+ }
+ } else {
+ retval = ext4_map_query_blocks(handle, inode, map, 0);
+ }
+
+ up_write(&EXT4_I(inode)->i_data_sem);
+ ext4_journal_stop(handle);
+ return retval < 0 ? retval : 0;
+}
+
+static int ext4_iomap_map_blocks(struct iomap_writepage_ctx *wpc,
+ struct inode *inode, loff_t offset,
+ unsigned int dirty_len)
+{
+ struct ext4_writeback_ctx *ewpc =
+ container_of(wpc, struct ext4_writeback_ctx, ctx);
+ struct super_block *sb = inode->i_sb;
+ struct journal_s *journal = EXT4_SB(sb)->s_journal;
+ struct ext4_inode_info *ei = EXT4_I(inode);
+ struct ext4_map_blocks map;
+ unsigned int blkbits = inode->i_blkbits;
+ unsigned int index = offset >> blkbits;
+ unsigned int end, len;
+ int ret;
+
+ if (unlikely(ext4_forced_shutdown(inode->i_sb)))
+ return -EIO;
+
+ /* Check validity of the cached writeback mapping. */
+ if (offset >= wpc->iomap.offset &&
+ offset < wpc->iomap.offset + wpc->iomap.length &&
+ ewpc->data_seq == READ_ONCE(ei->i_es_seq))
+ return 0;
+
+ end = min_t(unsigned int,
+ (ewpc->wbc->range_end >> blkbits), (UINT_MAX - 1));
+ len = (end > index + dirty_len) ? end - index + 1 : dirty_len;
+
+retry:
+ map.m_lblk = index;
+ map.m_len = min_t(unsigned int, EXT_UNWRITTEN_MAX_LEN, len);
+ ret = ext4_map_blocks(NULL, inode, &map, 0);
+ if (ret < 0)
+ return ret;
+
+ /*
+ * The map isn't a delalloc extent, it must be a hole or have
+ * already been allocated.
+ */
+ if (!(map.m_flags & EXT4_MAP_DELAYED))
+ goto out;
+
+ /* Map one delalloc extent. */
+ ret = ext4_iomap_map_one_extent(inode, &map);
+ if (ret < 0) {
+ if (ext4_forced_shutdown(sb))
+ return ret;
+
+ /*
+ * Retry transient ENOSPC errors, if
+ * ext4_count_free_blocks() is non-zero, a commit
+ * should free up blocks.
+ */
+ if (ret == -ENOSPC && ext4_count_free_clusters(sb)) {
+ jbd2_journal_force_commit_nested(journal);
+ goto retry;
+ }
+
+ ext4_msg(sb, KERN_CRIT,
+ "Delayed block allocation failed for "
+ "inode %lu at logical offset %llu with "
+ "max blocks %u with error %d",
+ inode->i_ino, (unsigned long long)map.m_lblk,
+ (unsigned int)map.m_len, -ret);
+ ext4_msg(sb, KERN_CRIT,
+ "This should not happen!! Data will "
+ "be lost\n");
+ if (ret == -ENOSPC)
+ ext4_print_free_blocks(inode);
+ return ret;
+ }
+out:
+ ewpc->data_seq = READ_ONCE(ei->i_es_seq);
+ ext4_set_iomap(inode, &wpc->iomap, &map, offset,
+ map.m_len << blkbits, 0);
+ return 0;
+}
+
+static int ext4_iomap_prepare_ioend(struct iomap_ioend *ioend, int status)
+{
+ struct ext4_inode_info *ei = EXT4_I(ioend->io_inode);
+
+ /* Need to convert unwritten extents when I/Os are completed. */
+ if (ioend->io_type == IOMAP_UNWRITTEN ||
+ ioend->io_offset + ioend->io_size > READ_ONCE(ei->i_disksize))
+ ioend->io_bio.bi_end_io = ext4_iomap_end_bio;
+
+ return status;
+}
+
+static void ext4_iomap_discard_folio(struct folio *folio, loff_t pos)
+{
+ struct inode *inode = folio->mapping->host;
+
+ ext4_iomap_punch_delalloc(inode, pos,
+ folio_pos(folio) + folio_size(folio) - pos);
+}
+
+static const struct iomap_writeback_ops ext4_writeback_ops = {
+ .map_blocks = ext4_iomap_map_blocks,
+ .prepare_ioend = ext4_iomap_prepare_ioend,
+ .discard_folio = ext4_iomap_discard_folio,
+};
+
static int ext4_iomap_writepages(struct address_space *mapping,
struct writeback_control *wbc)
{
- return 0;
+ struct inode *inode = mapping->host;
+ struct super_block *sb = inode->i_sb;
+ long nr = wbc->nr_to_write;
+ int alloc_ctx, ret;
+ struct ext4_writeback_ctx ewpc = {
+ .wbc = wbc,
+ };
+
+ if (unlikely(ext4_forced_shutdown(sb)))
+ return -EIO;
+
+ alloc_ctx = ext4_writepages_down_read(sb);
+ trace_ext4_writepages(inode, wbc);
+ ret = iomap_writepages(mapping, wbc, &ewpc.ctx, &ext4_writeback_ops);
+ trace_ext4_writepages_result(inode, wbc, ret, nr - wbc->nr_to_write);
+ ext4_writepages_up_read(sb, alloc_ctx);
+
+ return ret;
}
/*
diff --git a/fs/ext4/page-io.c b/fs/ext4/page-io.c
index dfdd7e5cf038..a499208500e4 100644
--- a/fs/ext4/page-io.c
+++ b/fs/ext4/page-io.c
@@ -22,6 +22,7 @@
#include <linux/bio.h>
#include <linux/workqueue.h>
#include <linux/kernel.h>
+#include <linux/iomap.h>
#include <linux/slab.h>
#include <linux/mm.h>
#include <linux/sched/mm.h>
@@ -565,3 +566,109 @@ int ext4_bio_write_folio(struct ext4_io_submit *io, struct folio *folio,
return 0;
}
+
+static void ext4_iomap_finish_ioend(struct iomap_ioend *ioend)
+{
+ struct inode *inode = ioend->io_inode;
+ struct ext4_inode_info *ei = EXT4_I(inode);
+ loff_t pos = ioend->io_offset;
+ size_t size = ioend->io_size;
+ loff_t new_disksize;
+ handle_t *handle;
+ int credits;
+ int ret, err;
+
+ ret = blk_status_to_errno(ioend->io_bio.bi_status);
+ if (unlikely(ret))
+ goto out;
+
+ /*
+ * We may need to convert up to one extent per block in
+ * the page and we may dirty the inode.
+ */
+ credits = ext4_chunk_trans_blocks(inode,
+ EXT4_MAX_BLOCKS(size, pos, inode->i_blkbits));
+ handle = ext4_journal_start(inode, EXT4_HT_EXT_CONVERT, credits);
+ if (IS_ERR(handle)) {
+ ret = PTR_ERR(handle);
+ goto out_err;
+ }
+
+ if (ioend->io_type == IOMAP_UNWRITTEN) {
+ ret = ext4_convert_unwritten_extents(handle, inode, pos, size);
+ if (ret)
+ goto out_journal;
+ }
+
+ /*
+ * Update on-disk size after IO is completed. Races with
+ * truncate are avoided by checking i_size under i_data_sem.
+ */
+ new_disksize = pos + size;
+ if (new_disksize > READ_ONCE(ei->i_disksize)) {
+ down_write(&ei->i_data_sem);
+ new_disksize = min(new_disksize, i_size_read(inode));
+ if (new_disksize > ei->i_disksize)
+ ei->i_disksize = new_disksize;
+ up_write(&ei->i_data_sem);
+ ret = ext4_mark_inode_dirty(handle, inode);
+ if (ret)
+ EXT4_ERROR_INODE_ERR(inode, -ret,
+ "Failed to mark inode dirty");
+ }
+
+out_journal:
+ err = ext4_journal_stop(handle);
+ if (!ret)
+ ret = err;
+out_err:
+ if (ret < 0 && !ext4_forced_shutdown(inode->i_sb)) {
+ ext4_msg(inode->i_sb, KERN_EMERG,
+ "failed to convert unwritten extents to "
+ "written extents or update inode size -- "
+ "potential data loss! (inode %lu, error %d)",
+ inode->i_ino, ret);
+ }
+out:
+ iomap_finish_ioends(ioend, ret);
+}
+
+/*
+ * Work on buffered iomap completed IO, to convert unwritten extents to
+ * mapped extents
+ */
+void ext4_iomap_end_io(struct work_struct *work)
+{
+ struct ext4_inode_info *ei = container_of(work, struct ext4_inode_info,
+ i_iomap_ioend_work);
+ struct iomap_ioend *ioend;
+ struct list_head ioend_list;
+ unsigned long flags;
+
+ spin_lock_irqsave(&ei->i_completed_io_lock, flags);
+ list_replace_init(&ei->i_iomap_ioend_list, &ioend_list);
+ spin_unlock_irqrestore(&ei->i_completed_io_lock, flags);
+
+ iomap_sort_ioends(&ioend_list);
+ while (!list_empty(&ioend_list)) {
+ ioend = list_entry(ioend_list.next, struct iomap_ioend, io_list);
+ list_del_init(&ioend->io_list);
+ iomap_ioend_try_merge(ioend, &ioend_list);
+ ext4_iomap_finish_ioend(ioend);
+ }
+}
+
+void ext4_iomap_end_bio(struct bio *bio)
+{
+ struct iomap_ioend *ioend = iomap_ioend_from_bio(bio);
+ struct ext4_inode_info *ei = EXT4_I(ioend->io_inode);
+ struct ext4_sb_info *sbi = EXT4_SB(ioend->io_inode->i_sb);
+ unsigned long flags;
+
+ /* Only reserved conversions from writeback should enter here */
+ spin_lock_irqsave(&ei->i_completed_io_lock, flags);
+ if (list_empty(&ei->i_iomap_ioend_list))
+ queue_work(sbi->rsv_conversion_wq, &ei->i_iomap_ioend_work);
+ list_add_tail(&ioend->io_list, &ei->i_iomap_ioend_list);
+ spin_unlock_irqrestore(&ei->i_completed_io_lock, flags);
+}
diff --git a/fs/ext4/super.c b/fs/ext4/super.c
index d4afaae8ab38..811a46f83bb9 100644
--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -1431,11 +1431,13 @@ static struct inode *ext4_alloc_inode(struct super_block *sb)
#endif
ei->jinode = NULL;
INIT_LIST_HEAD(&ei->i_rsv_conversion_list);
+ INIT_LIST_HEAD(&ei->i_iomap_ioend_list);
spin_lock_init(&ei->i_completed_io_lock);
ei->i_sync_tid = 0;
ei->i_datasync_tid = 0;
atomic_set(&ei->i_unwritten, 0);
INIT_WORK(&ei->i_rsv_conversion_work, ext4_end_io_rsv_work);
+ INIT_WORK(&ei->i_iomap_ioend_work, ext4_iomap_end_io);
ext4_fc_init_inode(&ei->vfs_inode);
mutex_init(&ei->i_fc_lock);
return &ei->vfs_inode;
--
2.39.2
From: Zhang Yi <[email protected]>
Implement mmap iomap path, add ext4_iomap_page_mkwrite() to map blocks
and dirty folio, almost everying have been done in iomap_page_mkwrite(),
so invoke it directly.
Signed-off-by: Zhang Yi <[email protected]>
---
fs/ext4/inode.c | 25 +++++++++++++++++++++++++
1 file changed, 25 insertions(+)
diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index 8ee0eca6a1e8..dee661e64a69 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -6466,6 +6466,26 @@ static int ext4_bh_unmapped(handle_t *handle, struct inode *inode,
return !buffer_mapped(bh);
}
+static vm_fault_t ext4_iomap_page_mkwrite(struct vm_fault *vmf)
+{
+ struct inode *inode = file_inode(vmf->vma->vm_file);
+ const struct iomap_ops *iomap_ops;
+
+ /*
+ * ext4_nonda_switch() could writeback this folio, so have to
+ * call it before lock folio.
+ *
+ * TODO: drop ext4_nonda_switch() after reserving enough sapce
+ * for metadata and merge delalloc and nodelalloc operations.
+ */
+ if (test_opt(inode->i_sb, DELALLOC) && !ext4_nonda_switch(inode->i_sb))
+ iomap_ops = &ext4_iomap_buffered_da_write_ops;
+ else
+ iomap_ops = &ext4_iomap_buffered_write_ops;
+
+ return iomap_page_mkwrite(vmf, iomap_ops);
+}
+
vm_fault_t ext4_page_mkwrite(struct vm_fault *vmf)
{
struct vm_area_struct *vma = vmf->vma;
@@ -6489,6 +6509,11 @@ vm_fault_t ext4_page_mkwrite(struct vm_fault *vmf)
filemap_invalidate_lock_shared(mapping);
+ if (ext4_test_inode_state(inode, EXT4_STATE_BUFFERED_IOMAP)) {
+ ret = ext4_iomap_page_mkwrite(vmf);
+ goto out;
+ }
+
err = ext4_convert_inline_data(inode);
if (err)
goto out_ret;
--
2.39.2
From: Zhang Yi <[email protected]>
Partially enable iomap for regular file's buffered IO path on default
mount option and default filesystem features. Set inode state flag
EXT4_STATE_BUFFERED_IOMAP when creating one inode to indicate that this
inode choice the iomap path.
Now it still have many limitations, it doesn't support inline data,
fs_verity, fs_crypt, defrag, bigalloc, dax and data=journal mode yet, so
we have to fallback to buffered_head path if these options/features were
enabled. I hope these would be supported gradually in the future.
Signed-off-by: Zhang Yi <[email protected]>
---
fs/ext4/ext4.h | 1 +
fs/ext4/ialloc.c | 3 +++
fs/ext4/inode.c | 34 ++++++++++++++++++++++++++++++++++
3 files changed, 38 insertions(+)
diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
index eaf29bade606..16dce8701c5e 100644
--- a/fs/ext4/ext4.h
+++ b/fs/ext4/ext4.h
@@ -2972,6 +2972,7 @@ int ext4_walk_page_buffers(handle_t *handle,
struct buffer_head *bh));
int do_journal_get_write_access(handle_t *handle, struct inode *inode,
struct buffer_head *bh);
+bool ext4_should_use_buffered_iomap(struct inode *inode);
int ext4_nonda_switch(struct super_block *sb);
#define FALL_BACK_TO_NONDELALLOC 1
#define CONVERT_INLINE_DATA 2
diff --git a/fs/ext4/ialloc.c b/fs/ext4/ialloc.c
index e9bbb1da2d0a..956b9d69c559 100644
--- a/fs/ext4/ialloc.c
+++ b/fs/ext4/ialloc.c
@@ -1336,6 +1336,9 @@ struct inode *__ext4_new_inode(struct mnt_idmap *idmap,
}
}
+ if (ext4_should_use_buffered_iomap(inode))
+ ext4_set_inode_state(inode, EXT4_STATE_BUFFERED_IOMAP);
+
if (ext4_handle_valid(handle)) {
ei->i_sync_tid = handle->h_transaction->t_tid;
ei->i_datasync_tid = handle->h_transaction->t_tid;
diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index f8e9f566ef6a..30067775e828 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -774,6 +774,8 @@ static int _ext4_get_block(struct inode *inode, sector_t iblock,
if (ext4_has_inline_data(inode))
return -ERANGE;
+ if (WARN_ON(ext4_test_inode_state(inode, EXT4_STATE_BUFFERED_IOMAP)))
+ return -EINVAL;
map.m_lblk = iblock;
map.m_len = bh->b_size >> inode->i_blkbits;
@@ -2552,6 +2554,9 @@ static int ext4_do_writepages(struct mpage_da_data *mpd)
trace_ext4_writepages(inode, wbc);
+ if (WARN_ON(ext4_test_inode_state(inode, EXT4_STATE_BUFFERED_IOMAP)))
+ return -EINVAL;
+
/*
* No pages to write? This is mainly a kludge to avoid starting
* a transaction for special inodes like journal inode on last iput()
@@ -5089,6 +5094,32 @@ static const char *check_igot_inode(struct inode *inode, ext4_iget_flags flags)
return NULL;
}
+bool ext4_should_use_buffered_iomap(struct inode *inode)
+{
+ struct super_block *sb = inode->i_sb;
+
+ if (ext4_has_feature_inline_data(sb))
+ return false;
+ if (ext4_has_feature_verity(sb))
+ return false;
+ if (ext4_has_feature_bigalloc(sb))
+ return false;
+ if (test_opt(sb, DATA_FLAGS) == EXT4_MOUNT_JOURNAL_DATA)
+ return false;
+ if (!S_ISREG(inode->i_mode))
+ return false;
+ if (IS_DAX(inode))
+ return false;
+ if (!(ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS)))
+ return false;
+ if (ext4_test_inode_flag(inode, EXT4_INODE_EA_INODE))
+ return false;
+ if (ext4_test_inode_flag(inode, EXT4_INODE_ENCRYPT))
+ return false;
+
+ return true;
+}
+
struct inode *__ext4_iget(struct super_block *sb, unsigned long ino,
ext4_iget_flags flags, const char *function,
unsigned int line)
@@ -5353,6 +5384,9 @@ struct inode *__ext4_iget(struct super_block *sb, unsigned long ino,
if (ret)
goto bad_inode;
+ if (ext4_should_use_buffered_iomap(inode))
+ ext4_set_inode_state(inode, EXT4_STATE_BUFFERED_IOMAP);
+
if (S_ISREG(inode->i_mode)) {
inode->i_op = &ext4_file_inode_operations;
inode->i_fop = &ext4_file_operations;
--
2.39.2
From: Zhang Yi <[email protected]>
Online defrag doesn't support iomap path yet, so we have to fall back to
buffer_head path for inodes which have been useing iomap. Fall back
active inode is dangerous, we must writeback and drop all dirty pages
under inode lock and mapping->invalidate_lock, those can protect us from
adding new folios into mapping.
Signed-off-by: Zhang Yi <[email protected]>
---
fs/ext4/move_extent.c | 34 ++++++++++++++++++++++++++++++++++
1 file changed, 34 insertions(+)
diff --git a/fs/ext4/move_extent.c b/fs/ext4/move_extent.c
index 3aa57376d9c2..7a9ca71d4cac 100644
--- a/fs/ext4/move_extent.c
+++ b/fs/ext4/move_extent.c
@@ -538,6 +538,34 @@ mext_check_arguments(struct inode *orig_inode,
return 0;
}
+/*
+ * Disable buffered iomap path for the inode that requiring move extents,
+ * fallback to buffer_head path.
+ */
+static int ext4_disable_buffered_iomap_aops(struct inode *inode)
+{
+ int err;
+
+ /*
+ * The buffered_head aops don't know how to handle folios
+ * dirtied by iomap, so before falling back, flush all dirty
+ * folios the inode has.
+ */
+ filemap_invalidate_lock(inode->i_mapping);
+ err = filemap_write_and_wait(inode->i_mapping);
+ if (err < 0) {
+ filemap_invalidate_unlock(inode->i_mapping);
+ return err;
+ }
+ truncate_inode_pages(inode->i_mapping, 0);
+
+ ext4_clear_inode_state(inode, EXT4_STATE_BUFFERED_IOMAP);
+ ext4_set_aops(inode);
+ filemap_invalidate_unlock(inode->i_mapping);
+
+ return 0;
+}
+
/**
* ext4_move_extents - Exchange the specified range of a file
*
@@ -609,6 +637,12 @@ ext4_move_extents(struct file *o_filp, struct file *d_filp, __u64 orig_blk,
inode_dio_wait(orig_inode);
inode_dio_wait(donor_inode);
+ /* Fallback to buffer_head aops for inodes with buffered iomap aops */
+ if (ext4_test_inode_state(orig_inode, EXT4_STATE_BUFFERED_IOMAP))
+ ext4_disable_buffered_iomap_aops(orig_inode);
+ if (ext4_test_inode_state(donor_inode, EXT4_STATE_BUFFERED_IOMAP))
+ ext4_disable_buffered_iomap_aops(donor_inode);
+
/* Protect extent tree against block allocations via delalloc */
ext4_double_down_write_data_sem(orig_inode, donor_inode);
/* Check the filesystem environment whether move_extent can be done */
--
2.39.2
From: Zhang Yi <[email protected]>
After we convert buffered IO path to iomap for regular files, we can
enable large foilo for them together, that should be able to bring a lot
of performance gains for large IO.
Signed-off-by: Zhang Yi <[email protected]>
---
fs/ext4/ialloc.c | 4 +++-
fs/ext4/inode.c | 4 +++-
fs/ext4/move_extent.c | 1 +
3 files changed, 7 insertions(+), 2 deletions(-)
diff --git a/fs/ext4/ialloc.c b/fs/ext4/ialloc.c
index 956b9d69c559..5a22fe5aa46b 100644
--- a/fs/ext4/ialloc.c
+++ b/fs/ext4/ialloc.c
@@ -1336,8 +1336,10 @@ struct inode *__ext4_new_inode(struct mnt_idmap *idmap,
}
}
- if (ext4_should_use_buffered_iomap(inode))
+ if (ext4_should_use_buffered_iomap(inode)) {
ext4_set_inode_state(inode, EXT4_STATE_BUFFERED_IOMAP);
+ mapping_set_large_folios(inode->i_mapping);
+ }
if (ext4_handle_valid(handle)) {
ei->i_sync_tid = handle->h_transaction->t_tid;
diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index 30067775e828..a1dbfc2b904c 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -5384,8 +5384,10 @@ struct inode *__ext4_iget(struct super_block *sb, unsigned long ino,
if (ret)
goto bad_inode;
- if (ext4_should_use_buffered_iomap(inode))
+ if (ext4_should_use_buffered_iomap(inode)) {
ext4_set_inode_state(inode, EXT4_STATE_BUFFERED_IOMAP);
+ mapping_set_large_folios(inode->i_mapping);
+ }
if (S_ISREG(inode->i_mode)) {
inode->i_op = &ext4_file_inode_operations;
diff --git a/fs/ext4/move_extent.c b/fs/ext4/move_extent.c
index 7a9ca71d4cac..aecd6112d8a2 100644
--- a/fs/ext4/move_extent.c
+++ b/fs/ext4/move_extent.c
@@ -560,6 +560,7 @@ static int ext4_disable_buffered_iomap_aops(struct inode *inode)
truncate_inode_pages(inode->i_mapping, 0);
ext4_clear_inode_state(inode, EXT4_STATE_BUFFERED_IOMAP);
+ mapping_clear_large_folios(inode->i_mapping);
ext4_set_aops(inode);
filemap_invalidate_unlock(inode->i_mapping);
--
2.39.2
Looks good:
Reviewed-by: Christoph Hellwig <[email protected]>
Can you submit this for inclusion in the vfs tree?
On Sat, Jan 27, 2024 at 09:57:59AM +0800, Zhang Yi wrote:
> From: Zhang Yi <[email protected]>
>
> Hello,
>
> This is the third version of RFC patch series that convert ext4 regular
> file's buffered IO path to iomap and enable large folio. It's rebased on
> 6.7 and Christoph's "map multiple blocks per ->map_blocks in iomap
> writeback" series [1]. I've fixed all issues found in the last about 3
> weeks of stress tests and fault injection tests in v2. I hope I've
> covered most of the corner cases, and any comments are welcome. :)
>
> Changes since v2:
> - Update patch 1-6 to v3 [2].
> - iomap_zero and iomap_unshare don't need to update i_size and call
> iomap_write_failed(), introduce a new helper iomap_write_end_simple()
> to avoid doing that.
> - Factor out ext4_[ext|ind]_map_blocks() parts from ext4_map_blocks(),
> introduce a new helper ext4_iomap_map_one_extent() to allocate
> delalloc blocks in writeback, which is always under i_data_sem in
> write mode. This is done to prevent the writing back delalloc
> extents become stale if it raced by truncate.
> - Add a lock detection in mapping_clear_large_folios().
> Changes since v1:
> - Introduce seq count for iomap buffered write and writeback to protect
> races from extents changes, e.g. truncate, mwrite.
> - Always allocate unwritten extents for new blocks, drop dioread_lock
> mode, and make no distinctions between dioread_lock and
> dioread_nolock.
> - Don't add ditry data range to jinode, drop data=ordered mode, and
> make no distinctions between data=ordered and data=writeback mode.
> - Postpone updating i_disksize to endio.
> - Allow splitting extents and use reserved space in endio.
> - Instead of reimplement a new delayed mapping helper
> ext4_iomap_da_map_blocks() for buffer write, try to reuse
> ext4_da_map_blocks().
> - Add support for disabling large folio on active inodes.
> - Support online defragmentation, make file fall back to buffer_head
> and disable large folio in ext4_move_extents().
> - Move ext4_nonda_switch() in advance to prevent deadlock in mwrite.
> - Add dirty_len and pos trace info to trace_iomap_writepage_map().
> - Update patch 1-6 to v2.
>
> This series only support ext4 with the default features and mount
> options, doesn't support inline_data, bigalloc, dax, fs_verity, fs_crypt
> and data=journal mode, ext4 would fall back to buffer_head path
Do you plan to add bigalloc or !extents support as a part 2 patchset?
An ext2 port to iomap has been (vaguely) in the works for a while,
though iirc willy never got the performance to match because iomap
didn't have a mechanism for the caller to tell it "run the IO now even
though you don't have a complete page, because the indirect block is the
next block after the 11th block".
--D
> automatically if you enabled these features/options. Although it has
> many limitations now, it can satisfy the requirements of common cases
> and bring a great performance benefit.
>
> Patch 1-6: this is a preparation series, it changes ext4_map_blocks()
> and ext4_set_iomap() to recognize delayed only extents, I've send it out
> separately [2].
>
> Patch 7-8: these are two minor iomap changes, the first one is don't
> update i_size and don't call iomap_write_failed() in zero_range, the
> second one is for debug in iomap writeback path that I've discussed whit
> Christoph [3].
>
> Patch 9-15: this is another preparation series, including some changes
> for delayed extents. Firstly, it factor out buffer_head from
> ext4_da_map_blocks(), make it to support adding multi-blocks once a
> time. Then make unwritten to written extents conversion in endio use to
> reserved space, reduce the risk of potential data loss. Finally,
> introduce a sequence counter for extent status tree, which is useful
> for iomap buffer write and write back.
>
> Patch 16-22: Implement buffered IO iomap path for read, write, mmap,
> zero range, truncate and writeback, replace current buffered_head path.
> Please look at the following patch for details.
>
> Patch 23-26: Convert to iomap for regular file's buffered IO path
> besides inline_data, bigalloc, dax, fs_verity, fs_crypt, and
> data=journal mode, and enable large folio. It should be note that
> buffered iomap path hasn't support Online defrag yet, so we need fall
> back to buffer_head and disable large folio automatically if user call
> EXT4_IOC_MOVE_EXT.
>
> About Tests:
> - kvm-xfstests in auto mode, and about 3 weeks of stress tests and
> fault injection tests.
> - A performance tests below.
>
> Fio tests with psync on my machine with Intel Xeon Gold 6240 CPU
> with 400GB system ram, 200GB ramdisk and 1TB nvme ssd disk.
>
> == buffer read ==
>
> buffer head iomap with large folio
> type bs IOPS BW(MiB/s) IOPS BW(MiB/s)
> ----------------------------------------------------
> hole 4K 565k 2206 811k 3167
> hole 64K 45.1k 2820 78.1k 4879
> hole 1M 2744 2744 4890 4891
> ramdisk 4K 436k 1703 554k 2163
> ramdisk 64K 29.6k 1848 44.0k 2747
> ramdisk 1M 1994 1995 2809 2809
> nvme 4K 306k 1196 324k 1267
> nvme 64K 19.3k 1208 24.3k 1517
> nvme 1M 1694 1694 2256 2256
>
> == buffer write ==
>
> buffer head ext4_iomap
> type Overwrite Sync Writeback bs IOPS BW IOPS BW
> -------------------------------------------------------------
> cache N N N 4K 395k 1544 415k 1621
> cache N N N 64K 30.8k 1928 80.1k 5005
> cache N N N 1M 1963 1963 5641 5642
> cache Y N N 4K 423k 1652 443k 1730
> cache Y N N 64K 33.0k 2063 80.8k 5051
> cache Y N N 1M 2103 2103 5588 5589
> ramdisk N N Y 4K 362k 1416 307k 1198
> ramdisk N N Y 64K 22.4k 1399 64.8k 4050
> ramdisk N N Y 1M 1670 1670 4559 4560
> ramdisk N Y N 4K 9830 38.4 13.5k 52.8
> ramdisk N Y N 64K 5834 365 10.1k 629
> ramdisk N Y N 1M 1011 1011 2064 2064
> ramdisk Y N Y 4K 397k 1550 409k 1598
> ramdisk Y N Y 64K 29.2k 1827 73.6k 4597
> ramdisk Y N Y 1M 1837 1837 4985 4985
> ramdisk Y Y N 4K 173k 675 182k 710
> ramdisk Y Y N 64K 17.7k 1109 33.7k 2105
> ramdisk Y Y N 1M 1128 1129 1790 1791
> nvme N N Y 4K 298k 1164 290k 1134
> nvme N N Y 64K 21.5k 1343 57.4k 3590
> nvme N N Y 1M 1308 1308 3664 3664
> nvme N Y N 4K 10.7k 41.8 12.0k 46.9
> nvme N Y N 64K 5962 373 8598 537
> nvme N Y N 1M 676 677 1417 1418
> nvme Y N Y 4K 366k 1430 373k 1456
> nvme Y N Y 64K 26.7k 1670 56.8k 3547
> nvme Y N Y 1M 1745 1746 3586 3586
> nvme Y Y N 4K 59.0k 230 61.2k 239
> nvme Y Y N 64K 13.0k 813 21.0k 1311
> nvme Y Y N 1M 683 683 1368 1369
>
> TODO
> - Keep on doing stress tests and fixing.
> - I will rebase and resend my another patch set "ext4: more accurate
> metadata reservaion for delalloc mount option[4]" later, it's useful
> for iomap conversion. After this series, I suppose we could totally
> drop ext4_nonda_switch() and prevent the risk of data loss caused by
> extents splitting.
> - Support for more features and mount options in the future.
>
> [1] https://lore.kernel.org/linux-fsdevel/[email protected]/
> [2] https://lore.kernel.org/linux-ext4/[email protected]/
> [3] https://lore.kernel.org/linux-fsdevel/[email protected]/
> [4] https://lore.kernel.org/linux-ext4/[email protected]/
>
> Thanks,
> Yi.
>
> ---
> v2: https://lore.kernel.org/linux-ext4/[email protected]/
> v1: https://lore.kernel.org/linux-ext4/[email protected]/
>
> Zhang Yi (26):
> ext4: refactor ext4_da_map_blocks()
> ext4: convert to exclusive lock while inserting delalloc extents
> ext4: correct the hole length returned by ext4_map_blocks()
> ext4: add a hole extent entry in cache after punch
> ext4: make ext4_map_blocks() distinguish delalloc only extent
> ext4: make ext4_set_iomap() recognize IOMAP_DELALLOC map type
> iomap: don't increase i_size if it's not a write operation
> iomap: add pos and dirty_len into trace_iomap_writepage_map
> ext4: allow inserting delalloc extents with multi-blocks
> ext4: correct delalloc extent length
> ext4: also mark extent as delalloc if it's been unwritten
> ext4: factor out bh handles to ext4_da_get_block_prep()
> ext4: use reserved metadata blocks when splitting extent in endio
> ext4: factor out ext4_map_{create|query}_blocks()
> ext4: introduce seq counter for extent entry
> ext4: add a new iomap aops for regular file's buffered IO path
> ext4: implement buffered read iomap path
> ext4: implement buffered write iomap path
> ext4: implement writeback iomap path
> ext4: implement mmap iomap path
> ext4: implement zero_range iomap path
> ext4: writeback partial blocks before zero range
> ext4: fall back to buffer_head path for defrag
> ext4: partially enable iomap for regular file's buffered IO path
> filemap: support disable large folios on active inode
> ext4: enable large folio for regular file with iomap buffered IO path
>
> fs/ext4/ext4.h | 14 +-
> fs/ext4/ext4_jbd2.c | 6 +
> fs/ext4/ext4_jbd2.h | 7 +
> fs/ext4/extents.c | 149 +++---
> fs/ext4/extents_status.c | 39 +-
> fs/ext4/extents_status.h | 4 +-
> fs/ext4/file.c | 19 +-
> fs/ext4/ialloc.c | 5 +
> fs/ext4/inode.c | 891 +++++++++++++++++++++++++++---------
> fs/ext4/move_extent.c | 35 ++
> fs/ext4/page-io.c | 107 +++++
> fs/ext4/super.c | 3 +
> fs/iomap/buffered-io.c | 30 +-
> fs/iomap/trace.h | 43 +-
> include/linux/pagemap.h | 14 +
> include/trace/events/ext4.h | 31 +-
> mm/readahead.c | 6 +-
> 17 files changed, 1109 insertions(+), 294 deletions(-)
>
> --
> 2.39.2
>
>
"Darrick J. Wong" <[email protected]> writes:
> On Sat, Jan 27, 2024 at 09:57:59AM +0800, Zhang Yi wrote:
>> From: Zhang Yi <[email protected]>
>>
>> Hello,
>>
>> This is the third version of RFC patch series that convert ext4 regular
>> file's buffered IO path to iomap and enable large folio. It's rebased on
>> 6.7 and Christoph's "map multiple blocks per ->map_blocks in iomap
>> writeback" series [1]. I've fixed all issues found in the last about 3
>> weeks of stress tests and fault injection tests in v2. I hope I've
>> covered most of the corner cases, and any comments are welcome. :)
>>
>> Changes since v2:
>> - Update patch 1-6 to v3 [2].
>> - iomap_zero and iomap_unshare don't need to update i_size and call
>> iomap_write_failed(), introduce a new helper iomap_write_end_simple()
>> to avoid doing that.
>> - Factor out ext4_[ext|ind]_map_blocks() parts from ext4_map_blocks(),
>> introduce a new helper ext4_iomap_map_one_extent() to allocate
>> delalloc blocks in writeback, which is always under i_data_sem in
>> write mode. This is done to prevent the writing back delalloc
>> extents become stale if it raced by truncate.
>> - Add a lock detection in mapping_clear_large_folios().
>> Changes since v1:
>> - Introduce seq count for iomap buffered write and writeback to protect
>> races from extents changes, e.g. truncate, mwrite.
>> - Always allocate unwritten extents for new blocks, drop dioread_lock
>> mode, and make no distinctions between dioread_lock and
>> dioread_nolock.
>> - Don't add ditry data range to jinode, drop data=ordered mode, and
>> make no distinctions between data=ordered and data=writeback mode.
>> - Postpone updating i_disksize to endio.
>> - Allow splitting extents and use reserved space in endio.
>> - Instead of reimplement a new delayed mapping helper
>> ext4_iomap_da_map_blocks() for buffer write, try to reuse
>> ext4_da_map_blocks().
>> - Add support for disabling large folio on active inodes.
>> - Support online defragmentation, make file fall back to buffer_head
>> and disable large folio in ext4_move_extents().
>> - Move ext4_nonda_switch() in advance to prevent deadlock in mwrite.
>> - Add dirty_len and pos trace info to trace_iomap_writepage_map().
>> - Update patch 1-6 to v2.
>>
>> This series only support ext4 with the default features and mount
>> options, doesn't support inline_data, bigalloc, dax, fs_verity, fs_crypt
>> and data=journal mode, ext4 would fall back to buffer_head path
>
> Do you plan to add bigalloc or !extents support as a part 2 patchset?
>
Hi Darrick,
> An ext2 port to iomap has been (vaguely) in the works for a while,
yes, we have [1][2]. I am in the process of rebasing that work on the latest
upstream. It's been a while since my last post since I have been pulled
into some other internal work, sorry about that.
> though iirc willy never got the performance to match because iomap
Ohh, can you help me provide details on what performance benchmark was
run? I can try and run them when I rebase.
> didn't have a mechanism for the caller to tell it "run the IO now even
> though you don't have a complete page, because the indirect block is the
> next block after the 11th block".
Do you mean this for a large folio? I still didn't get the problem you
are referring here. Can you please help me explain why could that be a
problem?
[1]: https://lore.kernel.org/linux-ext4/9cdd449fc1d63cf2dba17cfa2fa7fb29b8f96a46.1700506526.git.ritesh.list@gmail.com/
[2]: https://lore.kernel.org/linux-ext4/[email protected]/
-ritesh
On Mon, Feb 12, 2024 at 02:46:10PM +0530, Ritesh Harjani wrote:
> "Darrick J. Wong" <[email protected]> writes:
> > though iirc willy never got the performance to match because iomap
>
> Ohh, can you help me provide details on what performance benchmark was
> run? I can try and run them when I rebase.
I didn't run a benchmark, we just knew what would happen (on rotating
storage anyway).
> > didn't have a mechanism for the caller to tell it "run the IO now even
> > though you don't have a complete page, because the indirect block is the
> > next block after the 11th block".
>
> Do you mean this for a large folio? I still didn't get the problem you
> are referring here. Can you please help me explain why could that be a
> problem?
A classic ext2 filesystem lays out a 16kB file like this (with 512
byte blocks):
file offset disk block
0-6KiB 1000-1011
6KiB-16KiB 1013-1032
What's in block 1012? The indirect block! The block which tells ext2
that blocks 12-31 of the file are in disk blocks 1013-1032. So we can't
issue the read for them until we've finished the read for block 1012.
Buffer heads have a solution for this, BH_Boundary. ext2 sets it for
block 11 which prompts mpage.c to submit the read immediately (see
the various calls to buffer_boundary()). Then ext2 will submit the read
for block 1012 and the two reads will be coalesced by the IO scheduler.
So we still end up doing two reads instead of one, but that's
unavoidable because fragmentation might have meant that 6KiB-16KiB were
not stored at 1013-1032.
There's no equivalent iomap solution. What needs to happen is:
- iomap_folio_state->read_bytes_pending needs to be initialised to
folio_size(), not 0.
- Remove "ifs->read_bytes_pending += plen" from iomap_readpage_iter()
- Subtract plen in the iomap_block_needs_zeroing() case
- Submit a bio at the end of each iomap_readpage_iter() call
Now iomap will behave the same way as mpage, only without needing a
flag to do it (instead it will assume that the filesystem coalesces
adjacent ranges, which it should do anyway for good performance).
On 2024/2/13 13:46, Christoph Hellwig wrote:
> Wouldn't it make more sense to just move the size manipulation to the
> write-only code? An untested version of that is below. With this
Sorry for the late reply and thanks for your suggestion, The reason why
I introduced this new helper iomap_write_end_simple() is I don't want to
open code __iomap_put_folio() in each caller since corresponding to
iomap_write_begin(), it's the responsibility for iomap_write_end_*() to
put and unlock folio, so I'd like to keep it in iomap_write_end_*().
But I don't feel strongly about it, it's also fine by me to just move
the size manipulation to the write-only code if you think it's better.
> the naming of the status variable becomes even more confusing than
> it already is, maybe we need to do a cleanup of the *_write_end
> calling conventions as it always returns the passed in copied value
> or 0.
Indeed, it becomes more confused and deserve a cleanup.
Thanks,
Yi.
>
> diff --git a/fs/iomap/buffered-io.c b/fs/iomap/buffered-io.c
> index 3dab060aed6d7b..8401a9ca702fc0 100644
> --- a/fs/iomap/buffered-io.c
> +++ b/fs/iomap/buffered-io.c
> @@ -876,34 +876,13 @@ static size_t iomap_write_end(struct iomap_iter *iter, loff_t pos, size_t len,
> size_t copied, struct folio *folio)
> {
> const struct iomap *srcmap = iomap_iter_srcmap(iter);
> - loff_t old_size = iter->inode->i_size;
> - size_t ret;
> -
> - if (srcmap->type == IOMAP_INLINE) {
> - ret = iomap_write_end_inline(iter, folio, pos, copied);
> - } else if (srcmap->flags & IOMAP_F_BUFFER_HEAD) {
> - ret = block_write_end(NULL, iter->inode->i_mapping, pos, len,
> - copied, &folio->page, NULL);
> - } else {
> - ret = __iomap_write_end(iter->inode, pos, len, copied, folio);
> - }
> -
> - /*
> - * Update the in-memory inode size after copying the data into the page
> - * cache. It's up to the file system to write the updated size to disk,
> - * preferably after I/O completion so that no stale data is exposed.
> - */
> - if (pos + ret > old_size) {
> - i_size_write(iter->inode, pos + ret);
> - iter->iomap.flags |= IOMAP_F_SIZE_CHANGED;
> - }
> - __iomap_put_folio(iter, pos, ret, folio);
>
> - if (old_size < pos)
> - pagecache_isize_extended(iter->inode, old_size, pos);
> - if (ret < len)
> - iomap_write_failed(iter->inode, pos + ret, len - ret);
> - return ret;
> + if (srcmap->type == IOMAP_INLINE)
> + return iomap_write_end_inline(iter, folio, pos, copied);
> + if (srcmap->flags & IOMAP_F_BUFFER_HEAD)
> + return block_write_end(NULL, iter->inode->i_mapping, pos, len,
> + copied, &folio->page, NULL);
> + return __iomap_write_end(iter->inode, pos, len, copied, folio);
> }
>
> static loff_t iomap_write_iter(struct iomap_iter *iter, struct iov_iter *i)
> @@ -918,6 +897,7 @@ static loff_t iomap_write_iter(struct iomap_iter *iter, struct iov_iter *i)
>
> do {
> struct folio *folio;
> + loff_t old_size;
> size_t offset; /* Offset into folio */
> size_t bytes; /* Bytes to write to folio */
> size_t copied; /* Bytes copied from user */
> @@ -964,7 +944,24 @@ static loff_t iomap_write_iter(struct iomap_iter *iter, struct iov_iter *i)
>
> copied = copy_folio_from_iter_atomic(folio, offset, bytes, i);
> status = iomap_write_end(iter, pos, bytes, copied, folio);
> + /*
> + * Update the in-memory inode size after copying the data into
> + * the page cache. It's up to the file system to write the
> + * updated size to disk, preferably after I/O completion so that
> + * no stale data is exposed.
> + */
> + old_size = iter->inode->i_size;
> + if (pos + status > old_size) {
> + i_size_write(iter->inode, pos + status);
> + iter->iomap.flags |= IOMAP_F_SIZE_CHANGED;
> + }
> + __iomap_put_folio(iter, pos, status, folio);
>
> + if (old_size < pos)
> + pagecache_isize_extended(iter->inode, old_size, pos);
> + if (status < bytes)
> + iomap_write_failed(iter->inode, pos + status,
> + bytes - status);
> if (unlikely(copied != status))
> iov_iter_revert(i, copied - status);
>
> @@ -1334,6 +1331,7 @@ static loff_t iomap_unshare_iter(struct iomap_iter *iter)
> bytes = folio_size(folio) - offset;
>
> bytes = iomap_write_end(iter, pos, bytes, bytes, folio);
> + __iomap_put_folio(iter, pos, bytes, folio);
> if (WARN_ON_ONCE(bytes == 0))
> return -EIO;
>
> @@ -1398,6 +1396,7 @@ static loff_t iomap_zero_iter(struct iomap_iter *iter, bool *did_zero)
> folio_mark_accessed(folio);
>
> bytes = iomap_write_end(iter, pos, bytes, bytes, folio);
> + __iomap_put_folio(iter, pos, bytes, folio);
> if (WARN_ON_ONCE(bytes == 0))
> return -EIO;
>
>
On 2024/2/12 14:18, Darrick J. Wong wrote:
> On Sat, Jan 27, 2024 at 09:57:59AM +0800, Zhang Yi wrote:
>> From: Zhang Yi <[email protected]>
>>
>> Hello,
>>
>> This is the third version of RFC patch series that convert ext4 regular
>> file's buffered IO path to iomap and enable large folio. It's rebased on
>> 6.7 and Christoph's "map multiple blocks per ->map_blocks in iomap
>> writeback" series [1]. I've fixed all issues found in the last about 3
>> weeks of stress tests and fault injection tests in v2. I hope I've
>> covered most of the corner cases, and any comments are welcome. :)
>>
>> Changes since v2:
>> - Update patch 1-6 to v3 [2].
>> - iomap_zero and iomap_unshare don't need to update i_size and call
>> iomap_write_failed(), introduce a new helper iomap_write_end_simple()
>> to avoid doing that.
>> - Factor out ext4_[ext|ind]_map_blocks() parts from ext4_map_blocks(),
>> introduce a new helper ext4_iomap_map_one_extent() to allocate
>> delalloc blocks in writeback, which is always under i_data_sem in
>> write mode. This is done to prevent the writing back delalloc
>> extents become stale if it raced by truncate.
>> - Add a lock detection in mapping_clear_large_folios().
>> Changes since v1:
>> - Introduce seq count for iomap buffered write and writeback to protect
>> races from extents changes, e.g. truncate, mwrite.
>> - Always allocate unwritten extents for new blocks, drop dioread_lock
>> mode, and make no distinctions between dioread_lock and
>> dioread_nolock.
>> - Don't add ditry data range to jinode, drop data=ordered mode, and
>> make no distinctions between data=ordered and data=writeback mode.
>> - Postpone updating i_disksize to endio.
>> - Allow splitting extents and use reserved space in endio.
>> - Instead of reimplement a new delayed mapping helper
>> ext4_iomap_da_map_blocks() for buffer write, try to reuse
>> ext4_da_map_blocks().
>> - Add support for disabling large folio on active inodes.
>> - Support online defragmentation, make file fall back to buffer_head
>> and disable large folio in ext4_move_extents().
>> - Move ext4_nonda_switch() in advance to prevent deadlock in mwrite.
>> - Add dirty_len and pos trace info to trace_iomap_writepage_map().
>> - Update patch 1-6 to v2.
>>
>> This series only support ext4 with the default features and mount
>> options, doesn't support inline_data, bigalloc, dax, fs_verity, fs_crypt
>> and data=journal mode, ext4 would fall back to buffer_head path
>
> Do you plan to add bigalloc or !extents support as a part 2 patchset?
Hello,
Sorry for the late reply since I was on the vacation of Chinese New Year.
I've been working on bigalloc support recently and it's going relatively
well, but have no plans to support !extents yet, I would start looking
into it after I finish rebasing my another patch set "ext4: more
accurate metadata reservaion for delalloc mount option" mentioned in my
TODO list.
>
> An ext2 port to iomap has been (vaguely) in the works for a while,
> though iirc willy never got the performance to match because iomap
> didn't have a mechanism for the caller to tell it "run the IO now even
> though you don't have a complete page, because the indirect block is the
> next block after the 11th block".
>
Thanks for pointing this out and the explanation given by Matthew. IIUC,
this problem also affects ext4 in !extents mode, but not affects bigalloc,
right?
Thanks,
Yi.
On 2024/2/12 14:02, Christoph Hellwig wrote:
> Looks good:
>
> Reviewed-by: Christoph Hellwig <[email protected]>
>
> Can you submit this for inclusion in the vfs tree?
> .
>
Sure, I will send it out separately.
Thanks,
Yi.
On Wed, Feb 28, 2024 at 04:53:32PM +0800, Zhang Yi wrote:
> So, we have to handle above case for xfs. I suppose we could keep
> increasing i_size if the zeroed folio is entirely outside of i_size,
> make sure we could write back and allocate blocks for the
> zeroed & delayed extent, something like below, any suggestions ?
Sorry for being dumb, but what was the problem solved by not updating
the size for ext4 again? (for unshare I can't see any reason to
ever update the inode size)
On Thu, Feb 29, 2024 at 04:59:34PM +0800, Zhang Yi wrote:
> Hello, Dave!
>
> On 2024/2/29 6:25, Dave Chinner wrote:
> > On Wed, Feb 28, 2024 at 04:53:32PM +0800, Zhang Yi wrote:
> >> On 2024/2/13 13:46, Christoph Hellwig wrote:
> >>> Wouldn't it make more sense to just move the size manipulation to the
> >>> write-only code? An untested version of that is below. With this
> >>> the naming of the status variable becomes even more confusing than
> >>> it already is, maybe we need to do a cleanup of the *_write_end
> >>> calling conventions as it always returns the passed in copied value
> >>> or 0.
> >>>
> >>> diff --git a/fs/iomap/buffered-io.c b/fs/iomap/buffered-io.c
> >>> index 3dab060aed6d7b..8401a9ca702fc0 100644
> >>> --- a/fs/iomap/buffered-io.c
> >>> +++ b/fs/iomap/buffered-io.c
> >>> @@ -876,34 +876,13 @@ static size_t iomap_write_end(struct iomap_iter *iter, loff_t pos, size_t len,
> >>> size_t copied, struct folio *folio)
> >>> {
> >>> const struct iomap *srcmap = iomap_iter_srcmap(iter);
> >>> - loff_t old_size = iter->inode->i_size;
> >>> - size_t ret;
> >>> -
> >>> - if (srcmap->type == IOMAP_INLINE) {
> >>> - ret = iomap_write_end_inline(iter, folio, pos, copied);
> >>> - } else if (srcmap->flags & IOMAP_F_BUFFER_HEAD) {
> >>> - ret = block_write_end(NULL, iter->inode->i_mapping, pos, len,
> >>> - copied, &folio->page, NULL);
> >>> - } else {
> >>> - ret = __iomap_write_end(iter->inode, pos, len, copied, folio);
> >>> - }
> >>> -
> >>> - /*
> >>> - * Update the in-memory inode size after copying the data into the page
> >>> - * cache. It's up to the file system to write the updated size to disk,
> >>> - * preferably after I/O completion so that no stale data is exposed.
> >>> - */
> >>> - if (pos + ret > old_size) {
> >>> - i_size_write(iter->inode, pos + ret);
> >>> - iter->iomap.flags |= IOMAP_F_SIZE_CHANGED;
> >>> - }
> >>
> >> I've recently discovered that if we don't increase i_size in
> >> iomap_zero_iter(), it would break fstests generic/476 on xfs. xfs
> >> depends on iomap_zero_iter() to increase i_size in some cases.
> >>
> >> generic/476 75s ... _check_xfs_filesystem: filesystem on /dev/pmem2 is inconsistent (r)
> >> (see /home/zhangyi/xfstests-dev/results//xfs/generic/476.full for details)
> >>
> >> _check_xfs_filesystem: filesystem on /dev/pmem2 is inconsistent (r)
> >> *** xfs_repair -n output ***
> >> Phase 1 - find and verify superblock...
> >> Phase 2 - using internal log
> >> - zero log...
> >> - scan filesystem freespace and inode maps...
> >> sb_fdblocks 10916, counted 10923
> >> - found root inode chunk
> >> ...
> >>
> >> After debugging and analysis, I found the root cause of the problem is
> >> related to the pre-allocations of xfs. xfs pre-allocates some blocks to
> >> reduce fragmentation during buffer append writing, then if we write new
> >> data or do file copy(reflink) after the end of the pre-allocating range,
> >> xfs would zero-out and write back the pre-allocate space(e.g.
> >> xfs_file_write_checks() -> xfs_zero_range()), so we have to update
> >> i_size before writing back in iomap_zero_iter(), otherwise, it will
> >> result in stale delayed extent.
> >
> > Ok, so this is long because the example is lacking in clear details
> > so to try to understand it I've laid it out in detail to make sure
> > I've understood it correctly.
> >
>
> Thanks for the graph, the added detail makes things clear and easy to
> understand. To be honest, it's not exactly the same as the results I
> captured and described (the position A\B\C\D\E\F I described is
> increased one by one), but the root cause of the problem is the same,
> so it doesn't affect our understanding of the problem.
OK, good :)
.....
> > However, if this did actually write zeroes to disk, this would end
> > up with:
> >
> > A C B E F D
> > +wwwwwwwwww+DDDDDDDDDDD+zzzzz+rrrrrrr+dddddd+
> > EOF EOF
> > (in memory) (on disk)
> >
> > Which is wrong - the file extension and zeros should not get exposed
> > to the user until the entire reflink completes. This would expose
> > zeros at the EOF and a file size that the user never asked for after
> > a crash. Experience tells me that they would report this as
> > "filesystem corrupting data on crash".
> >
> > If we move where i_size gets updated by iomap_zero_iter(), we get:
> >
> > A C B E F D
> > +wwwwwwwwww+DDDDDDDDDDD+zzzzz+rrrrrrr+dddddd+
> > EOF
> > (in memory)
> > (on disk)
> >
> > Which is also wrong, because now the user can see the size change
> > and read zeros in the middle of the clone operation, which is also
> > wrong.
> >
> > IOWs, we do not want to move the in-memory or on-disk EOF as a
> > result of zeroing delalloc extents beyond EOF as it opens up
> > transient, non-atomic on-disk states in the event of a crash.
> >
> > So, catch-22: we need to move the in-memory EOF to write back zeroes
> > beyond EOF, but that would move the on-disk EOF to E before the
> > clone operation starts. i.e. it makes clone non-atomic.
>
> Make sense. IIUC, I also notice that xfs_file_write_checks() zero
> out EOF blocks if the later write offset is beyond the size of the
> file. Think about if we replace the reflink operation to a buffer
> write E to F, although it doesn't call xfs_flush_unmap_range()
> directly, but if it could be raced by another background write
> back, and trigger the same problem (I've not try to reproduce it,
> so please correct me if I understand wrong).
Correct, but the write is about to extend the file size when it
writes into the cache beyond the zeroed region. There is no cache
invalidate possible in this path, so the write of data moves the
in-memory EOF past the zeroes in cache and everything works just
fine.
If it races with concurrent background writeback, the writeback will
skip the zeroed range beyond EOF until they are exposed by the first
data write beyond the zeroed post-eof region which moves the
in-memory EOF.
truncate(to a larger size) also does this same zeroing - the page
cache is zeroed before we move the EOF in memory, and so the
writeback will only occur once the in-memory EOF is moved. i.e. it
effectively does:
xfs_zero_range(oldsize to newsize)
truncate_setsize(newsize)
filemap_write_and_wait_range(old size to new size)
> > What should acutally result from the iomap_zero_range() call from
> > xfs_reflink_remap_prep() is a state like this:
> >
> > A C B E F D
> > +wwwwwwwwww+DDDDDDDDDDD+uuuuu+rrrrrrr+dddddd+
> > EOF EOF
> > (on disk) (in memory)
> >
> > where 'u' are unwritten extent blocks.
> >
>
> Yeah, this is a good solution.
>
> In xfs_file_write_checks(), I don't fully understand why we need
> the xfs_zero_range().
The EOF block may only be partially written. Hence on extension, we
have to guarantee the part of that block beyond the current EOF is
zero if the write leaves a hole between the current EOF and the
start of the new extending write.
> Theoretically, iomap have already handled
> partial block zeroing for both buffered IO and DIO, so I guess
> the only reason we still need it is to handle pre-allocated blocks
> (no?).
Historically speaking, Linux is able to leak data beyond EOF on
writeback of partial EOF blocks (e.g. mmap() can write to the EOF
page beyond EOF without failing. We try to mitigate these cases
where we can, but we have to consider that at any time the data in
the cache beyond EOF can be non-zero thanks to mmap() and so any
file extension *must* zero any region beyond EOF cached in the page
cache.
> If so，would it be better to call xfs_free_eofblocks() to
> release all the preallocated extents in range? If not, maybe we
> could only zero out mapped partial blocks and also release
> preallocated extents?
No, that will cause all sorts of other performance problems,
especially for reflinked files that triggering COW
operations...
>
> In xfs_reflink_remap_prep(), I read the commit 410fdc72b05a ("xfs:
> zero posteof blocks when cloning above eof"), xfs used to release
> preallocations, the change log said it didn't work because of the
> PREALLOC flag, but the 'force' parameter is 'true' when calling
> xfs_can_free_eofblocks(), so I don't get the problem met. Could we
> fall back to use xfs_free_eofblocks() and make a state like this?
>
> A C B E F D
> +wwwwwwwwww+DDDDDDDDDDD+hhhhh+rrrrrrr+dddddd+
> EOF EOF
> (on disk) (in memory)
It could, but that then requires every place that may call
xfs_zero_range() to be aware of this need to trim EOF blocks to do
the right thing in all cases. We don't want to remove speculative
delalloc in the write() path nor in the truncate(up) case, and so it
doesn't fix the general problem of zeroing specualtive delalloc
beyond EOF requiring writeback to push page caceh pages to disk
before the inode size has been updated.
The general solution is to have zeroing of speculative prealloc
extents beyond EOF simply convert the range to unwritten and then
invalidate any cached pages over that range. At this point, we are
guaranteed to have zeroes across that range, all without needing to
do any IO at all...
-Dave.
--
Dave Chinner
[email protected]
Hello Christoph!
On 2024/2/29 6:13, Christoph Hellwig wrote:
> On Wed, Feb 28, 2024 at 04:53:32PM +0800, Zhang Yi wrote:
>> So, we have to handle above case for xfs. I suppose we could keep
>> increasing i_size if the zeroed folio is entirely outside of i_size,
>> make sure we could write back and allocate blocks for the
>> zeroed & delayed extent, something like below, any suggestions ?
>
> Sorry for being dumb, but what was the problem solved by not updating
> the size for ext4 again? (for unshare I can't see any reason to
> ever update the inode size)
>
The problem I want to slove by not updating the size for ext4 is
truncate. Now ext4 use iomap_zero_range() for the case of zero
partial blocks, and ext4's truncate is different from xfs.
Let's think about a simple case, we have a reg file with size 3K,
then truncate it to 1K. ext4 first set i_size to 1K and then call
ext4_block_truncate_page() to zero out data after 1K(EOF) through
iomap_zero_range(). But now it will update i_size in
iomap_write_end(), so the size of the file will increase to 4K,
this is wrong. xfs first zero out data through iomap_truncate_page()
and then set file size to 1K, so the file size is 3K->4K->1K.
Although the result is correct, but the increasing in
iomap_zero_range() is also not necessary, so so I'm just gonna
delete the i_size updating in iomap_zero_range(). It's not for
unhare.
Thanks,
Yi.
On 2024/2/13 13:46, Christoph Hellwig wrote:
> Wouldn't it make more sense to just move the size manipulation to the
> write-only code? An untested version of that is below. With this
> the naming of the status variable becomes even more confusing than
> it already is, maybe we need to do a cleanup of the *_write_end
> calling conventions as it always returns the passed in copied value
> or 0.
>
> diff --git a/fs/iomap/buffered-io.c b/fs/iomap/buffered-io.c
> index 3dab060aed6d7b..8401a9ca702fc0 100644
> --- a/fs/iomap/buffered-io.c
> +++ b/fs/iomap/buffered-io.c
> @@ -876,34 +876,13 @@ static size_t iomap_write_end(struct iomap_iter *iter, loff_t pos, size_t len,
> size_t copied, struct folio *folio)
> {
> const struct iomap *srcmap = iomap_iter_srcmap(iter);
> - loff_t old_size = iter->inode->i_size;
> - size_t ret;
> -
> - if (srcmap->type == IOMAP_INLINE) {
> - ret = iomap_write_end_inline(iter, folio, pos, copied);
> - } else if (srcmap->flags & IOMAP_F_BUFFER_HEAD) {
> - ret = block_write_end(NULL, iter->inode->i_mapping, pos, len,
> - copied, &folio->page, NULL);
> - } else {
> - ret = __iomap_write_end(iter->inode, pos, len, copied, folio);
> - }
> -
> - /*
> - * Update the in-memory inode size after copying the data into the page
> - * cache. It's up to the file system to write the updated size to disk,
> - * preferably after I/O completion so that no stale data is exposed.
> - */
> - if (pos + ret > old_size) {
> - i_size_write(iter->inode, pos + ret);
> - iter->iomap.flags |= IOMAP_F_SIZE_CHANGED;
> - }
I've recently discovered that if we don't increase i_size in
iomap_zero_iter(), it would break fstests generic/476 on xfs. xfs
depends on iomap_zero_iter() to increase i_size in some cases.
generic/476 75s ... _check_xfs_filesystem: filesystem on /dev/pmem2 is inconsistent (r)
(see /home/zhangyi/xfstests-dev/results//xfs/generic/476.full for details)
_check_xfs_filesystem: filesystem on /dev/pmem2 is inconsistent (r)
*** xfs_repair -n output ***
Phase 1 - find and verify superblock...
Phase 2 - using internal log
- zero log...
- scan filesystem freespace and inode maps...
sb_fdblocks 10916, counted 10923
- found root inode chunk
...
After debugging and analysis, I found the root cause of the problem is
related to the pre-allocations of xfs. xfs pre-allocates some blocks to
reduce fragmentation during buffer append writing, then if we write new
data or do file copy(reflink) after the end of the pre-allocating range,
xfs would zero-out and write back the pre-allocate space(e.g.
xfs_file_write_checks() -> xfs_zero_range()), so we have to update
i_size before writing back in iomap_zero_iter(), otherwise, it will
result in stale delayed extent.
For more details, let's think about this case,
1. Buffered write from range [A, B) of an empty file foo, and
xfs_buffered_write_iomap_begin() prealloc blocks for it, then create
a delayed extent from [A, D).
2. Write back process map blocks but only convert above delayed extent
from [A, C) since the lack of a contiguous physical blocks, now we
have a left over delayed extent from [C, D), and the file size is B.
3. Copy range from another file to range [E, F), then
xfs_reflink_zero_posteof() would zero-out post eof range [B, E), it
writes zero, dirty and write back [C, E).
4. Since we don't update i_size in iomap_zero_iter()，the writeback
doesn't write anything back, also doesn't convert the delayed extent.
After copy range, the file size will update to F.
5. Finally, the delayed extent becomes stale, and the free blocks count
becomes incorrect.
So, we have to handle above case for xfs. I suppose we could keep
increasing i_size if the zeroed folio is entirely outside of i_size,
make sure we could write back and allocate blocks for the
zeroed & delayed extent, something like below, any suggestions ?
@@ -1390,6 +1390,7 @@ static loff_t iomap_zero_iter(struct iomap_iter *iter, bool *did_zero)
do {
struct folio *folio;
+ loff_t old_size;
int status;
size_t offset;
size_t bytes = min_t(u64, SIZE_MAX, length);
@@ -1408,6 +1409,28 @@ static loff_t iomap_zero_iter(struct iomap_iter *iter, bool *did_zero)
folio_mark_accessed(folio);
bytes = iomap_write_end(iter, pos, bytes, bytes, folio);
+
+ /*
+ * If folio is entirely outside of i_size, update the
+ * in-memory inode size after zeroing the data in the page
+ * cache to prevent the write-back process from not writing
+ * back zeroed pages.
+ */
+ old_size = iter->inode->i_size;
+ if (pos + bytes > old_size) {
+ size_t offset = offset_in_folio(folio, old_size);
+ pgoff_t end_index = old_size >> PAGE_SHIFT;
+
+ if (folio->index > end_index ||
+ (folio->index == end_index && offset == 0)) {
+ i_size_write(iter->inode, pos + bytes);
+ iter->iomap.flags |= IOMAP_F_SIZE_CHANGED;
+ }
+ }
+ __iomap_put_folio(iter, pos, bytes, folio);
+ if (old_size < pos)
+ pagecache_isize_extended(iter->inode, old_size, pos);
+
if (WARN_ON_ONCE(bytes == 0))
return -EIO;
Thansk,
Yi.