This is the first draft of the patches that rewrite ext4's I/O
submission paths to use the block I/O layer directly instead of using
the buffer layer. This reduces lock contention on the block queue
submission layers, and it should reduce CPU usage significantly.
There is still some cleanup and testing to be done, but this should be
good enough for benchmarking purposes. This patch series survives
xfstests with 4k blocks, and minimal testing with 1k blocks.
- Ted
Theodore Ts'o (6):
ext4: call mpage_da_submit_io() from mpage_da_map_blocks()
ext4: simplify ext4_writepage()
ext4: inline ext4_writepage() into mpage_da_submit_io()
ext4: inline walk_page_buffers() into mpage_da_submit_io
ext4: move mpage_put_bnr_to_bhs()'s functionality to
mpage_da_submit_io()
ext4: use bio layer instead of buffer layer in mpage_da_submit_io
fs/ext4/Makefile | 2 +-
fs/ext4/ext4.h | 33 ++++-
fs/ext4/extents.c | 4 +-
fs/ext4/inode.c | 429 +++++++++++++++++++----------------------------------
fs/ext4/page-io.c | 363 ++++++++++++++++++++++++++++++++++++++++++++
fs/ext4/super.c | 8 +-
6 files changed, 555 insertions(+), 284 deletions(-)
create mode 100644 fs/ext4/page-io.c
As a prepratory step to switching to bio_submit, inline
ext4_writepage() into mpage_da_submit() and then simplify things a
bit. This makes it clearer what mpage_da_submit needs to do.
Also, move the ClearPageChecked(page) call into
__ext4_journalled_writepage(), as a minor bit of cleanup refactoring.
This also allows us to pull i_size_read() and
ext4_should_journal_data() out of the loop, which should be a very
minor CPU savings.
Signed-off-by: "Theodore Ts'o" <[email protected]>
---
fs/ext4/inode.c | 70 ++++++++++++++++++++++++++++++++++++++++++++++--------
1 files changed, 59 insertions(+), 11 deletions(-)
diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index 58b7008..f97fc46 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -60,7 +60,12 @@ static inline int ext4_begin_ordered_truncate(struct inode *inode,
}
static void ext4_invalidatepage(struct page *page, unsigned long offset);
-static int ext4_writepage(struct page *page, struct writeback_control *wbc);
+static int noalloc_get_block_write(struct inode *inode, sector_t iblock,
+ struct buffer_head *bh_result, int create);
+static int ext4_set_bh_endio(struct buffer_head *bh, struct inode *inode);
+static void ext4_end_io_buffer_write(struct buffer_head *bh, int uptodate);
+static int __ext4_journalled_writepage(struct page *page, unsigned int len);
+static int ext4_bh_delay_or_unwritten(handle_t *handle, struct buffer_head *bh);
/*
* Test whether an inode is a fast symlink.
@@ -2000,12 +2005,15 @@ static void ext4_da_page_release_reservation(struct page *page,
*/
static int mpage_da_submit_io(struct mpage_da_data *mpd)
{
- long pages_skipped;
struct pagevec pvec;
unsigned long index, end;
int ret = 0, err, nr_pages, i;
struct inode *inode = mpd->inode;
struct address_space *mapping = inode->i_mapping;
+ loff_t size = i_size_read(inode);
+ unsigned int len;
+ struct buffer_head *page_bufs = NULL;
+ int journal_data = ext4_should_journal_data(inode);
BUG_ON(mpd->next_page <= mpd->first_page);
/*
@@ -2023,28 +2031,69 @@ static int mpage_da_submit_io(struct mpage_da_data *mpd)
if (nr_pages == 0)
break;
for (i = 0; i < nr_pages; i++) {
+ int commit_write = 0;
struct page *page = pvec.pages[i];
index = page->index;
if (index > end)
break;
+
+ if (index == size >> PAGE_CACHE_SHIFT)
+ len = size & ~PAGE_CACHE_MASK;
+ else
+ len = PAGE_CACHE_SIZE;
index++;
BUG_ON(!PageLocked(page));
BUG_ON(PageWriteback(page));
- pages_skipped = mpd->wbc->pages_skipped;
- err = ext4_writepage(page, mpd->wbc);
- if (!err && (pages_skipped == mpd->wbc->pages_skipped))
+ /*
+ * If the page does not have buffers (for
+ * whatever reason), try to create them using
+ * block_prepare_write. If this fails,
+ * redirty the page and move on.
+ */
+ if (!page_has_buffers(page)) {
+ if (block_prepare_write(page, 0, len,
+ noalloc_get_block_write)) {
+ redirty_page:
+ redirty_page_for_writepage(mpd->wbc,
+ page);
+ unlock_page(page);
+ continue;
+ }
+ commit_write = 1;
+ }
+ page_bufs = page_buffers(page);
+ if (walk_page_buffers(NULL, page_bufs, 0, len, NULL,
+ ext4_bh_delay_or_unwritten)) {
/*
- * have successfully written the page
- * without skipping the same
+ * We couldn't do block allocation for
+ * some reason.
*/
+ goto redirty_page;
+ }
+
+ if (commit_write)
+ /* mark the buffer_heads as dirty & uptodate */
+ block_commit_write(page, 0, len);
+
+ if (journal_data && PageChecked(page))
+ err = __ext4_journalled_writepage(page, len);
+ else if (buffer_uninit(page_bufs)) {
+ ext4_set_bh_endio(page_bufs, inode);
+ err = block_write_full_page_endio(page,
+ noalloc_get_block_write,
+ mpd->wbc, ext4_end_io_buffer_write);
+ } else
+ err = block_write_full_page(page,
+ noalloc_get_block_write, mpd->wbc);
+
+ if (!err)
mpd->pages_written++;
/*
* In error case, we have to continue because
* remaining pages are still locked
- * XXX: unlock and re-dirty them?
*/
if (ret == 0)
ret = err;
@@ -2624,6 +2673,7 @@ static int __ext4_journalled_writepage(struct page *page,
int ret = 0;
int err;
+ ClearPageChecked(page);
page_bufs = page_buffers(page);
BUG_ON(!page_bufs);
walk_page_buffers(handle, page_bufs, 0, len, NULL, bget_one);
@@ -2746,14 +2796,12 @@ static int ext4_writepage(struct page *page,
/* now mark the buffer_heads as dirty and uptodate */
block_commit_write(page, 0, len);
- if (PageChecked(page) && ext4_should_journal_data(inode)) {
+ if (PageChecked(page) && ext4_should_journal_data(inode))
/*
* It's mmapped pagecache. Add buffers and journal it. There
* doesn't seem much point in redirtying the page here.
*/
- ClearPageChecked(page);
return __ext4_journalled_writepage(page, len);
- }
if (buffer_uninit(page_bufs)) {
ext4_set_bh_endio(page_bufs, inode);
--
1.7.1
The actual code in ext4_writepage() is unnecessarily convoluted.
Simplify it so it is easier to understand, but otherwise logically
equivalent.
Signed-off-by: "Theodore Ts'o" <[email protected]>
---
fs/ext4/inode.c | 73 +++++++++++++++++++------------------------------------
1 files changed, 25 insertions(+), 48 deletions(-)
diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index c3cc036..58b7008 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -2701,7 +2701,7 @@ static void ext4_end_io_buffer_write(struct buffer_head *bh, int uptodate);
static int ext4_writepage(struct page *page,
struct writeback_control *wbc)
{
- int ret = 0;
+ int ret = 0, commit_write = 0;
loff_t size;
unsigned int len;
struct buffer_head *page_bufs = NULL;
@@ -2714,60 +2714,37 @@ static int ext4_writepage(struct page *page,
else
len = PAGE_CACHE_SIZE;
- if (page_has_buffers(page)) {
- page_bufs = page_buffers(page);
- if (walk_page_buffers(NULL, page_bufs, 0, len, NULL,
- ext4_bh_delay_or_unwritten)) {
- /*
- * We don't want to do block allocation
- * So redirty the page and return
- * We may reach here when we do a journal commit
- * via journal_submit_inode_data_buffers.
- * If we don't have mapping block we just ignore
- * them. We can also reach here via shrink_page_list
- */
+ /*
+ * If the page does not have buffers (for whatever reason),
+ * try to create them using block_prepare_write. If this
+ * fails, redirty the page and move on.
+ */
+ if (!page_buffers(page)) {
+ if (block_prepare_write(page, 0, len,
+ noalloc_get_block_write)) {
+ redirty_page:
redirty_page_for_writepage(wbc, page);
unlock_page(page);
return 0;
}
- } else {
+ commit_write = 1;
+ }
+ page_bufs = page_buffers(page);
+ if (walk_page_buffers(NULL, page_bufs, 0, len, NULL,
+ ext4_bh_delay_or_unwritten)) {
/*
- * The test for page_has_buffers() is subtle:
- * We know the page is dirty but it lost buffers. That means
- * that at some moment in time after write_begin()/write_end()
- * has been called all buffers have been clean and thus they
- * must have been written at least once. So they are all
- * mapped and we can happily proceed with mapping them
- * and writing the page.
- *
- * Try to initialize the buffer_heads and check whether
- * all are mapped and non delay. We don't want to
- * do block allocation here.
+ * We don't want to do block allocation So redirty the
+ * page and return We may reach here when we do a
+ * journal commit via
+ * journal_submit_inode_data_buffers. If we don't
+ * have mapping block we just ignore them. We can also
+ * reach here via shrink_page_list
*/
- ret = block_prepare_write(page, 0, len,
- noalloc_get_block_write);
- if (!ret) {
- page_bufs = page_buffers(page);
- /* check whether all are mapped and non delay */
- if (walk_page_buffers(NULL, page_bufs, 0, len, NULL,
- ext4_bh_delay_or_unwritten)) {
- redirty_page_for_writepage(wbc, page);
- unlock_page(page);
- return 0;
- }
- } else {
- /*
- * We can't do block allocation here
- * so just redity the page and unlock
- * and return
- */
- redirty_page_for_writepage(wbc, page);
- unlock_page(page);
- return 0;
- }
+ goto redirty_page;
+ }
+ if (commit_write)
/* now mark the buffer_heads as dirty and uptodate */
block_commit_write(page, 0, len);
- }
if (PageChecked(page) && ext4_should_journal_data(inode)) {
/*
@@ -2778,7 +2755,7 @@ static int ext4_writepage(struct page *page,
return __ext4_journalled_writepage(page, len);
}
- if (page_bufs && buffer_uninit(page_bufs)) {
+ if (buffer_uninit(page_bufs)) {
ext4_set_bh_endio(page_bufs, inode);
ret = block_write_full_page_endio(page, noalloc_get_block_write,
wbc, ext4_end_io_buffer_write);
--
1.7.1
This massively simplifies the ext4_da_writepages() code path by
completely removing mpage_put_bnr_bhs(), which is almost 100 lines of
code iterating over a set of pages using pagevec_lookup(), and folds
that functionality into mpage_da_submit_io()'s existing
pagevec_lookup() loop.
Signed-off-by: "Theodore Ts'o" <[email protected]>
---
fs/ext4/inode.c | 139 +++++++++++++++----------------------------------------
1 files changed, 38 insertions(+), 101 deletions(-)
diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index 9fda16c..93668ca 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -2003,7 +2003,8 @@ static void ext4_da_page_release_reservation(struct page *page,
*
* As pages are already locked by write_cache_pages(), we can't use it
*/
-static int mpage_da_submit_io(struct mpage_da_data *mpd)
+static int mpage_da_submit_io(struct mpage_da_data *mpd,
+ struct ext4_map_blocks *map)
{
struct pagevec pvec;
unsigned long index, end;
@@ -2014,6 +2015,7 @@ static int mpage_da_submit_io(struct mpage_da_data *mpd)
unsigned int len, block_start;
struct buffer_head *bh, *page_bufs = NULL;
int journal_data = ext4_should_journal_data(inode);
+ sector_t pblock = 0, cur_logical = 0;
BUG_ON(mpd->next_page <= mpd->first_page);
/*
@@ -2031,7 +2033,7 @@ static int mpage_da_submit_io(struct mpage_da_data *mpd)
if (nr_pages == 0)
break;
for (i = 0; i < nr_pages; i++) {
- int commit_write = 0;
+ int commit_write = 0, redirty_page = 0;
struct page *page = pvec.pages[i];
index = page->index;
@@ -2042,6 +2044,12 @@ static int mpage_da_submit_io(struct mpage_da_data *mpd)
len = size & ~PAGE_CACHE_MASK;
else
len = PAGE_CACHE_SIZE;
+ if (map) {
+ cur_logical = index << (PAGE_CACHE_SHIFT -
+ inode->i_blkbits);
+ pblock = map->m_pblk + (cur_logical -
+ map->m_lblk);
+ }
index++;
BUG_ON(!PageLocked(page));
@@ -2068,13 +2076,34 @@ static int mpage_da_submit_io(struct mpage_da_data *mpd)
bh = page_bufs = page_buffers(page);
block_start = 0;
do {
- /* redirty page if block allocation undone */
- if (!bh || buffer_delay(bh) ||
- buffer_unwritten(bh))
+ if (!bh)
goto redirty_page;
+ if (map && (cur_logical >= map->m_lblk) &&
+ (cur_logical <= (map->m_lblk +
+ (map->m_len - 1)))) {
+ if (buffer_delay(bh)) {
+ clear_buffer_delay(bh);
+ bh->b_blocknr = pblock;
+ }
+ if (buffer_unwritten(bh) ||
+ buffer_mapped(bh))
+ BUG_ON(bh->b_blocknr != pblock);
+ if (map->m_flags & EXT4_MAP_UNINIT)
+ set_buffer_uninit(bh);
+ clear_buffer_unwritten(bh);
+ }
+
+ /* redirty page if block allocation undone */
+ if (buffer_delay(bh) || buffer_unwritten(bh))
+ redirty_page = 1;
bh = bh->b_this_page;
block_start += bh->b_size;
- } while ((bh != page_bufs) && (block_start < len));
+ cur_logical++;
+ pblock++;
+ } while (bh != page_bufs);
+
+ if (redirty_page)
+ goto redirty_page;
if (commit_write)
/* mark the buffer_heads as dirty & uptodate */
@@ -2105,91 +2134,6 @@ static int mpage_da_submit_io(struct mpage_da_data *mpd)
return ret;
}
-/*
- * mpage_put_bnr_to_bhs - walk blocks and assign them actual numbers
- *
- * the function goes through all passed space and put actual disk
- * block numbers into buffer heads, dropping BH_Delay and BH_Unwritten
- */
-static void mpage_put_bnr_to_bhs(struct mpage_da_data *mpd,
- struct ext4_map_blocks *map)
-{
- struct inode *inode = mpd->inode;
- struct address_space *mapping = inode->i_mapping;
- int blocks = map->m_len;
- sector_t pblock = map->m_pblk, cur_logical;
- struct buffer_head *head, *bh;
- pgoff_t index, end;
- struct pagevec pvec;
- int nr_pages, i;
-
- index = map->m_lblk >> (PAGE_CACHE_SHIFT - inode->i_blkbits);
- end = (map->m_lblk + blocks - 1) >> (PAGE_CACHE_SHIFT - inode->i_blkbits);
- cur_logical = index << (PAGE_CACHE_SHIFT - inode->i_blkbits);
-
- pagevec_init(&pvec, 0);
-
- while (index <= end) {
- /* XXX: optimize tail */
- nr_pages = pagevec_lookup(&pvec, mapping, index, PAGEVEC_SIZE);
- if (nr_pages == 0)
- break;
- for (i = 0; i < nr_pages; i++) {
- struct page *page = pvec.pages[i];
-
- index = page->index;
- if (index > end)
- break;
- index++;
-
- BUG_ON(!PageLocked(page));
- BUG_ON(PageWriteback(page));
- BUG_ON(!page_has_buffers(page));
-
- bh = page_buffers(page);
- head = bh;
-
- /* skip blocks out of the range */
- do {
- if (cur_logical >= map->m_lblk)
- break;
- cur_logical++;
- } while ((bh = bh->b_this_page) != head);
-
- do {
- if (cur_logical > map->m_lblk + (blocks - 1))
- break;
-
- if (buffer_delay(bh) || buffer_unwritten(bh)) {
-
- BUG_ON(bh->b_bdev != inode->i_sb->s_bdev);
-
- if (buffer_delay(bh)) {
- clear_buffer_delay(bh);
- bh->b_blocknr = pblock;
- } else {
- /*
- * unwritten already should have
- * blocknr assigned. Verify that
- */
- clear_buffer_unwritten(bh);
- BUG_ON(bh->b_blocknr != pblock);
- }
-
- } else if (buffer_mapped(bh))
- BUG_ON(bh->b_blocknr != pblock);
-
- if (map->m_flags & EXT4_MAP_UNINIT)
- set_buffer_uninit(bh);
- cur_logical++;
- pblock++;
- } while ((bh = bh->b_this_page) != head);
- }
- pagevec_release(&pvec);
- }
-}
-
-
static void ext4_da_block_invalidatepages(struct mpage_da_data *mpd,
sector_t logical, long blk_cnt)
{
@@ -2252,7 +2196,7 @@ static void ext4_print_free_blocks(struct inode *inode)
static void mpage_da_map_and_submit(struct mpage_da_data *mpd)
{
int err, blks, get_blocks_flags;
- struct ext4_map_blocks map;
+ struct ext4_map_blocks map, *mapp = NULL;
sector_t next = mpd->b_blocknr;
unsigned max_blocks = mpd->b_size >> mpd->inode->i_blkbits;
loff_t disksize = EXT4_I(mpd->inode)->i_disksize;
@@ -2343,6 +2287,7 @@ static void mpage_da_map_and_submit(struct mpage_da_data *mpd)
}
BUG_ON(blks == 0);
+ mapp = ↦
if (map.m_flags & EXT4_MAP_NEW) {
struct block_device *bdev = mpd->inode->i_sb->s_bdev;
int i;
@@ -2351,14 +2296,6 @@ static void mpage_da_map_and_submit(struct mpage_da_data *mpd)
unmap_underlying_metadata(bdev, map.m_pblk + i);
}
- /*
- * If blocks are delayed marked, we need to
- * put actual blocknr and drop delayed bit
- */
- if ((mpd->b_state & (1 << BH_Delay)) ||
- (mpd->b_state & (1 << BH_Unwritten)))
- mpage_put_bnr_to_bhs(mpd, &map);
Call the block I/O layer directly instad of going through the buffer
layer. This should give us much better performance and scalability,
as well as lowering our CPU utilization when doing buffered writeback.
Signed-off-by: "Theodore Ts'o" <[email protected]>
---
fs/ext4/Makefile | 2 +-
fs/ext4/ext4.h | 33 +++++-
fs/ext4/extents.c | 4 +-
fs/ext4/inode.c | 118 ++---------------
fs/ext4/page-io.c | 363 +++++++++++++++++++++++++++++++++++++++++++++++++++++
fs/ext4/super.c | 8 +-
6 files changed, 419 insertions(+), 109 deletions(-)
create mode 100644 fs/ext4/page-io.c
diff --git a/fs/ext4/Makefile b/fs/ext4/Makefile
index 8867b2a..c947e36 100644
--- a/fs/ext4/Makefile
+++ b/fs/ext4/Makefile
@@ -4,7 +4,7 @@
obj-$(CONFIG_EXT4_FS) += ext4.o
-ext4-y := balloc.o bitmap.o dir.o file.o fsync.o ialloc.o inode.o \
+ext4-y := balloc.o bitmap.o dir.o file.o fsync.o ialloc.o inode.o page-io.o \
ioctl.o namei.o super.o symlink.o hash.o resize.o extents.o \
ext4_jbd2.o migrate.o mballoc.o block_validity.o move_extent.o
diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
index 2283369..bc1962f 100644
--- a/fs/ext4/ext4.h
+++ b/fs/ext4/ext4.h
@@ -168,7 +168,18 @@ struct mpage_da_data {
int pages_written;
int retval;
};
-#define EXT4_IO_UNWRITTEN 0x1
+
+/*
+ * Flags for ext4_io_end->flags
+ */
+#define EXT4_IO_END_UNWRITTEN 0x0001
+#define EXT4_IO_END_ERROR 0x0002
+
+struct ext4_io_page {
+ struct page *p_page;
+ struct ext4_io_page *p_next;
+};
+
typedef struct ext4_io_end {
struct list_head list; /* per-file finished IO list */
struct inode *inode; /* file being written to */
@@ -179,8 +190,17 @@ typedef struct ext4_io_end {
struct work_struct work; /* data work queue */
struct kiocb *iocb; /* iocb struct for AIO */
int result; /* error value for AIO */
+ struct ext4_io_page *io_page;
} ext4_io_end_t;
+struct ext4_io_submit {
+ int io_op;
+ struct bio *io_bio;
+ ext4_io_end_t *io_end;
+ struct ext4_io_page *io_page;
+ sector_t io_next_block;
+};
+
/*
* Special inodes numbers
*/
@@ -2044,6 +2064,17 @@ extern int ext4_move_extents(struct file *o_filp, struct file *d_filp,
__u64 start_orig, __u64 start_donor,
__u64 len, __u64 *moved_len);
+/* page_io.c */
+extern int __init init_ext4_pageio(void);
+extern void exit_ext4_pageio(void);
+extern void ext4_free_io_end(ext4_io_end_t *io);
+extern ext4_io_end_t *ext4_init_io_end(struct inode *inode, gfp_t flags);
+extern int ext4_end_io_nolock(ext4_io_end_t *io);
+extern void ext4_io_submit(struct ext4_io_submit *io);
+extern int ext4_bio_write_page(struct ext4_io_submit *io,
+ struct page *page,
+ int len,
+ struct writeback_control *wbc);
/* BH_Uninit flag: blocks are allocated but uninitialized on disk */
enum ext4_state_bits {
diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c
index a0e6230..a1e20c8 100644
--- a/fs/ext4/extents.c
+++ b/fs/ext4/extents.c
@@ -3202,7 +3202,7 @@ ext4_ext_handle_uninitialized_extents(handle_t *handle, struct inode *inode,
* completed
*/
if (io)
- io->flag = EXT4_IO_UNWRITTEN;
+ io->flag = EXT4_IO_END_UNWRITTEN;
else
ext4_set_inode_state(inode, EXT4_STATE_DIO_UNWRITTEN);
if (ext4_should_dioread_nolock(inode))
@@ -3494,7 +3494,7 @@ int ext4_ext_map_blocks(handle_t *handle, struct inode *inode,
*/
if ((flags & EXT4_GET_BLOCKS_PRE_IO)) {
if (io)
- io->flag = EXT4_IO_UNWRITTEN;
+ io->flag = EXT4_IO_END_UNWRITTEN;
else
ext4_set_inode_state(inode,
EXT4_STATE_DIO_UNWRITTEN);
diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index 93668ca..79fdace 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -2016,8 +2016,10 @@ static int mpage_da_submit_io(struct mpage_da_data *mpd,
struct buffer_head *bh, *page_bufs = NULL;
int journal_data = ext4_should_journal_data(inode);
sector_t pblock = 0, cur_logical = 0;
+ struct ext4_io_submit io_submit;
BUG_ON(mpd->next_page <= mpd->first_page);
+ memset(&io_submit, 0, sizeof(io_submit));
/*
* We need to start from the first_page to the next_page - 1
* to make sure we also write the mapped dirty buffer_heads.
@@ -2109,16 +2111,16 @@ static int mpage_da_submit_io(struct mpage_da_data *mpd,
/* mark the buffer_heads as dirty & uptodate */
block_commit_write(page, 0, len);
- if (journal_data && PageChecked(page))
+ /*
+ * Delalloc doesn't support data journalling,
+ * but eventually maybe we'll lift this
+ * restriction.
+ */
+ if (unlikely(journal_data && PageChecked(page)))
err = __ext4_journalled_writepage(page, len);
- else if (buffer_uninit(page_bufs)) {
- ext4_set_bh_endio(page_bufs, inode);
- err = block_write_full_page_endio(page,
- noalloc_get_block_write,
- mpd->wbc, ext4_end_io_buffer_write);
- } else
- err = block_write_full_page(page,
- noalloc_get_block_write, mpd->wbc);
+ else
+ err = ext4_bio_write_page(&io_submit, page,
+ len, mpd->wbc);
if (!err)
mpd->pages_written++;
@@ -2131,6 +2133,7 @@ static int mpage_da_submit_io(struct mpage_da_data *mpd,
}
pagevec_release(&pvec);
}
+ ext4_io_submit(&io_submit);
return ret;
}
@@ -3423,15 +3426,6 @@ ext4_readpages(struct file *file, struct address_space *mapping,
return mpage_readpages(mapping, pages, nr_pages, ext4_get_block);
}
-static void ext4_free_io_end(ext4_io_end_t *io)
-{
- BUG_ON(!io);
- if (io->page)
- put_page(io->page);
- iput(io->inode);
- kfree(io);
-}
-
static void ext4_invalidatepage_free_endio(struct page *page, unsigned long offset)
{
struct buffer_head *head, *bh;
@@ -3637,68 +3631,6 @@ static void dump_completed_IO(struct inode * inode)
}
/*
- * check a range of space and convert unwritten extents to written.
- */
-static int ext4_end_io_nolock(ext4_io_end_t *io)
-{
- struct inode *inode = io->inode;
- loff_t offset = io->offset;
- ssize_t size = io->size;
- int ret = 0;
-
- ext4_debug("ext4_end_io_nolock: io 0x%p from inode %lu,list->next 0x%p,"
- "list->prev 0x%p\n",
- io, inode->i_ino, io->list.next, io->list.prev);
-
- if (list_empty(&io->list))
- return ret;
-
- if (io->flag != EXT4_IO_UNWRITTEN)
- return ret;
-
- ret = ext4_convert_unwritten_extents(inode, offset, size);
- if (ret < 0) {
- printk(KERN_EMERG "%s: failed to convert unwritten"
- "extents to written extents, error is %d"
- " io is still on inode %lu aio dio list\n",
- __func__, ret, inode->i_ino);
- return ret;
- }
-
- if (io->iocb)
- aio_complete(io->iocb, io->result, 0);
- /* clear the DIO AIO unwritten flag */
- io->flag = 0;
- return ret;
-}
-
-/*
- * work on completed aio dio IO, to convert unwritten extents to extents
- */
-static void ext4_end_io_work(struct work_struct *work)
-{
- ext4_io_end_t *io = container_of(work, ext4_io_end_t, work);
- struct inode *inode = io->inode;
- struct ext4_inode_info *ei = EXT4_I(inode);
- unsigned long flags;
- int ret;
-
- mutex_lock(&inode->i_mutex);
- ret = ext4_end_io_nolock(io);
- if (ret < 0) {
- mutex_unlock(&inode->i_mutex);
- return;
- }
-
- spin_lock_irqsave(&ei->i_completed_io_lock, flags);
- if (!list_empty(&io->list))
- list_del_init(&io->list);
- spin_unlock_irqrestore(&ei->i_completed_io_lock, flags);
- mutex_unlock(&inode->i_mutex);
- ext4_free_io_end(io);
-}
-
-/*
* This function is called from ext4_sync_file().
*
* When IO is completed, the work to convert unwritten extents to
@@ -3753,28 +3685,6 @@ int flush_completed_IO(struct inode *inode)
return (ret2 < 0) ? ret2 : 0;
}
-static ext4_io_end_t *ext4_init_io_end (struct inode *inode, gfp_t flags)
-{
- ext4_io_end_t *io = NULL;
-
- io = kmalloc(sizeof(*io), flags);
-
- if (io) {
- igrab(inode);
- io->inode = inode;
- io->flag = 0;
- io->offset = 0;
- io->size = 0;
- io->page = NULL;
- io->iocb = NULL;
- io->result = 0;
- INIT_WORK(&io->work, ext4_end_io_work);
- INIT_LIST_HEAD(&io->list);
- }
-
- return io;
-}
-
static void ext4_end_io_dio(struct kiocb *iocb, loff_t offset,
ssize_t size, void *private, int ret,
bool is_async)
@@ -3794,7 +3704,7 @@ static void ext4_end_io_dio(struct kiocb *iocb, loff_t offset,
size);
/* if not aio dio with unwritten extents, just free io and return */
- if (io_end->flag != EXT4_IO_UNWRITTEN){
+ if (!(io_end->flag & EXT4_IO_END_UNWRITTEN)) {
ext4_free_io_end(io_end);
iocb->private = NULL;
out:
@@ -3839,7 +3749,7 @@ static void ext4_end_io_buffer_write(struct buffer_head *bh, int uptodate)
goto out;
}
- io_end->flag = EXT4_IO_UNWRITTEN;
+ io_end->flag = EXT4_IO_END_UNWRITTEN;
inode = io_end->inode;
/* Add the io_end to per-inode completed io list*/
diff --git a/fs/ext4/page-io.c b/fs/ext4/page-io.c
new file mode 100644
index 0000000..affd6cc
--- /dev/null
+++ b/fs/ext4/page-io.c
@@ -0,0 +1,363 @@
+/*
+ * linux/fs/ext4/page-io.c
+ *
+ * This contains the new page_io functions for ext4
+ *
+ * Written by Theodore Ts'o, 2010.
+ */
+
+#include <linux/module.h>
+#include <linux/fs.h>
+#include <linux/time.h>
+#include <linux/jbd2.h>
+#include <linux/highuid.h>
+#include <linux/pagemap.h>
+#include <linux/quotaops.h>
+#include <linux/string.h>
+#include <linux/buffer_head.h>
+#include <linux/writeback.h>
+#include <linux/pagevec.h>
+#include <linux/mpage.h>
+#include <linux/namei.h>
+#include <linux/uio.h>
+#include <linux/bio.h>
+#include <linux/workqueue.h>
+#include <linux/kernel.h>
+#include <linux/slab.h>
+
+#include "ext4_jbd2.h"
+#include "xattr.h"
+#include "acl.h"
+#include "ext4_extents.h"
+
+static struct kmem_cache *io_page_cachep;
+
+int __init init_ext4_pageio(void)
+{
+ io_page_cachep = KMEM_CACHE(ext4_io_page, SLAB_RECLAIM_ACCOUNT);
+ if (io_page_cachep == NULL)
+ return -ENOMEM;
+
+ return 0;
+}
+
+void exit_ext4_pageio(void)
+{
+ kmem_cache_destroy(io_page_cachep);
+}
+
+void ext4_free_io_end(ext4_io_end_t *io)
+{
+ struct ext4_io_page *io_page, *next;
+
+ BUG_ON(!io);
+ if (io->page)
+ put_page(io->page);
+ iput(io->inode);
+ for (io_page = io->io_page; io_page; io_page = next) {
+ put_page(io_page->p_page);
+ next = io_page->p_next;
+ kmem_cache_free(io_page_cachep, io_page);
+ }
+ kfree(io);
+}
+
+/*
+ * check a range of space and convert unwritten extents to written.
+ */
+int ext4_end_io_nolock(ext4_io_end_t *io)
+{
+ struct inode *inode = io->inode;
+ loff_t offset = io->offset;
+ ssize_t size = io->size;
+ int ret = 0;
+
+ ext4_debug("ext4_end_io_nolock: io 0x%p from inode %lu,list->next 0x%p,"
+ "list->prev 0x%p\n",
+ io, inode->i_ino, io->list.next, io->list.prev);
+
+ if (list_empty(&io->list))
+ return ret;
+
+ if (!(io->flag & EXT4_IO_END_UNWRITTEN))
+ return ret;
+
+ ret = ext4_convert_unwritten_extents(inode, offset, size);
+ if (ret < 0) {
+ printk(KERN_EMERG "%s: failed to convert unwritten"
+ "extents to written extents, error is %d"
+ " io is still on inode %lu aio dio list\n",
+ __func__, ret, inode->i_ino);
+ return ret;
+ }
+
+ if (io->iocb)
+ aio_complete(io->iocb, io->result, 0);
+ /* clear the DIO AIO unwritten flag */
+ io->flag &= ~EXT4_IO_END_UNWRITTEN;
+ return ret;
+}
+
+/*
+ * work on completed aio dio IO, to convert unwritten extents to extents
+ */
+static void ext4_end_io_work(struct work_struct *work)
+{
+ ext4_io_end_t *io = container_of(work, ext4_io_end_t, work);
+ struct inode *inode = io->inode;
+ struct ext4_inode_info *ei = EXT4_I(inode);
+ unsigned long flags;
+ int ret;
+
+ mutex_lock(&inode->i_mutex);
+ ret = ext4_end_io_nolock(io);
+ if (ret < 0) {
+ mutex_unlock(&inode->i_mutex);
+ return;
+ }
+
+ spin_lock_irqsave(&ei->i_completed_io_lock, flags);
+ if (!list_empty(&io->list))
+ list_del_init(&io->list);
+ spin_unlock_irqrestore(&ei->i_completed_io_lock, flags);
+ mutex_unlock(&inode->i_mutex);
+ ext4_free_io_end(io);
+}
+
+ext4_io_end_t *ext4_init_io_end(struct inode *inode, gfp_t flags)
+{
+ ext4_io_end_t *io = NULL;
+
+ io = kmalloc(sizeof(*io), flags);
+
+ if (io) {
+ memset(io, 0, sizeof(*io));
+ igrab(inode);
+ io->inode = inode;
+ INIT_WORK(&io->work, ext4_end_io_work);
+ INIT_LIST_HEAD(&io->list);
+ }
+
+ return io;
+}
+
+static void ext4_end_bio(struct bio *bio, int error)
+{
+ ext4_io_end_t *io_end = bio->bi_private;
+ struct workqueue_struct *wq;
+ struct inode *inode;
+ unsigned long flags;
+ struct ext4_io_page *io_page;
+
+ BUG_ON(!io_end);
+ inode = io_end->inode;
+ bio->bi_private = NULL;
+ bio->bi_end_io = NULL;
+ if (test_bit(BIO_UPTODATE, &bio->bi_flags))
+ error = 0;
+ bio_put(bio);
+
+ if (!(inode->i_sb->s_flags & MS_ACTIVE)) {
+ printk("sb umounted, discard end_io request for inode %lu\n",
+ io_end->inode->i_ino);
+ ext4_free_io_end(io_end);
+ return;
+ }
+
+ if (error)
+ io_end->flag |= EXT4_IO_END_ERROR;
+
+ for (io_page = io_end->io_page; io_page; io_page = io_page->p_next) {
+ struct page *page = io_page->p_page;
+ struct buffer_head *bh, *head = page_buffers(io_page->p_page);
+
+ if (error)
+ SetPageError(page);
+ BUG_ON(!head);
+ if (head->b_size == PAGE_CACHE_SIZE)
+ clear_buffer_dirty(head);
+ else {
+ /*
+ * If block_size < page_size we need to worry
+ * about partial writes.
+ */
+ loff_t offset;
+ loff_t io_end_offset = io_end->offset + io_end->size;
+ int partial = 0;
+
+ offset = (sector_t) page->index << PAGE_CACHE_SHIFT;
+ bh = head;
+ do {
+ if ((offset >= io_end->offset) &&
+ (offset+bh->b_size <= io_end_offset))
+ clear_buffer_dirty(bh);
+ if (buffer_dirty(bh))
+ partial = 1;
+ offset += bh->b_size;
+ bh = bh->b_this_page;
+ } while (bh != head);
+ if (partial)
+ continue;
+ }
+ end_page_writeback(page);
+ }
+
+ /* Add the io_end to per-inode completed io list*/
+ spin_lock_irqsave(&EXT4_I(inode)->i_completed_io_lock, flags);
+ list_add_tail(&io_end->list, &EXT4_I(inode)->i_completed_io_list);
+ spin_unlock_irqrestore(&EXT4_I(inode)->i_completed_io_lock, flags);
+
+ wq = EXT4_SB(inode->i_sb)->dio_unwritten_wq;
+ /* queue the work to convert unwritten extents to written */
+ queue_work(wq, &io_end->work);
+}
+
+void ext4_io_submit(struct ext4_io_submit *io)
+{
+ struct bio *bio = io->io_bio;
+
+ if (bio) {
+ bio_get(io->io_bio);
+ submit_bio(io->io_op, io->io_bio);
+ BUG_ON(bio_flagged(io->io_bio, BIO_EOPNOTSUPP));
+ bio_put(io->io_bio);
+ }
+ io->io_bio = 0;
+ io->io_op = 0;
+ io->io_end = 0;
+}
+
+static int io_submit_init(struct ext4_io_submit *io,
+ struct inode *inode,
+ struct writeback_control *wbc,
+ struct buffer_head *bh)
+{
+ ext4_io_end_t *io_end;
+ struct page *page = bh->b_page;
+ int nvecs = bio_get_nr_vecs(bh->b_bdev);
+ struct bio *bio;
+
+ io_end = ext4_init_io_end(inode, GFP_NOFS);
+ if (!io_end)
+ return -ENOMEM;
+ do {
+
+ bio = bio_alloc(GFP_NOIO, nvecs);
+ nvecs >>= 1;
+ } while (bio == NULL);
+
+ bio->bi_sector = bh->b_blocknr * (bh->b_size >> 9);
+ bio->bi_bdev = bh->b_bdev;
+ bio->bi_private = io->io_end = io_end;
+ bio->bi_end_io = ext4_end_bio;
+
+ io_end->inode = inode;
+ io_end->offset = (page->index << PAGE_CACHE_SHIFT) + bh_offset(bh);
+
+ io->io_bio = bio;
+ io->io_op = (wbc->sync_mode == WB_SYNC_ALL ?
+ WRITE_SYNC_PLUG : WRITE);
+ io->io_next_block = bh->b_blocknr;
+ return 0;
+}
+
+static int io_submit_add_bh(struct ext4_io_submit *io,
+ struct inode *inode,
+ struct writeback_control *wbc,
+ struct buffer_head *bh)
+{
+ struct ext4_io_page *new_io_page;
+ int ret;
+
+ if (buffer_new(bh)) {
+ clear_buffer_new(bh);
+ unmap_underlying_metadata(bh->b_bdev, bh->b_blocknr);
+ }
+
+ if (!buffer_mapped(bh)) {
+ clear_buffer_dirty(bh);
+ if (io->io_bio)
+ ext4_io_submit(io);
+ return 0;
+ }
+
+retry:
+ if (io->io_bio && bh->b_blocknr != io->io_next_block)
+ ext4_io_submit(io);
+ if (io->io_bio == NULL) {
+ ret = io_submit_init(io, inode, wbc, bh);
+ if (ret)
+ return ret;
+ }
+ if (buffer_uninit(bh))
+ io->io_end->flag |= EXT4_IO_END_UNWRITTEN;
+ io->io_end->size += bh->b_size;
+ io->io_next_block++;
+ ret = bio_add_page(io->io_bio, bh->b_page, bh->b_size, bh_offset(bh));
+ if (ret != bh->b_size) {
+ submit_and_retry:
+ ext4_io_submit(io);
+ goto retry;
+ }
+ if (!io->io_end->io_page || io->io_end->io_page->p_page != bh->b_page) {
+ new_io_page = kmem_cache_alloc(io_page_cachep, GFP_NOFS);
+ if (!new_io_page)
+ goto submit_and_retry;
+ get_page(bh->b_page);
+ new_io_page->p_page = bh->b_page;
+ new_io_page->p_next = io->io_end->io_page;
+ io->io_end->io_page = new_io_page;
+ }
+ return 0;
+}
+
+int ext4_bio_write_page(struct ext4_io_submit *io,
+ struct page *page,
+ int len,
+ struct writeback_control *wbc)
+{
+ struct inode *inode = page->mapping->host;
+ unsigned block_start, block_end, blocksize;
+ struct buffer_head *bh, *head;
+ int ret = 0, written = 0;
+
+ blocksize = 1 << inode->i_blkbits;
+
+ BUG_ON(PageWriteback(page));
+ set_page_writeback(page);
+ ClearPageError(page);
+
+ for (bh = head = page_buffers(page), block_start = 0;
+ bh != head || !block_start;
+ block_start=block_end, bh = bh->b_this_page) {
+ block_end = block_start + blocksize;
+ if (block_start >= len) {
+ clear_buffer_dirty(bh);
+ set_buffer_uptodate(bh);
+ continue;
+ }
+ ret = io_submit_add_bh(io, inode, wbc, bh);
+ if (ret) {
+ /*
+ * We only get here on ENOMEM. Not much else
+ * we can do but mark the page as dirty, and
+ * better luck next time.
+ */
+ set_page_dirty(page);
+ break;
+ }
+ written++;
+ }
+ unlock_page(page);
+ /*
+ * If the page was truncated before we could do the writeback,
+ * or we had a memory allocation error while trying to write
+ * the first buffer head, we won't have submitted any pages for
+ * I/O. In that case we need to make sure we've cleared the
+ * PageWriteback bit from the page to prevent the system from
+ * wedging later on.
+ */
+ if (written == 0)
+ end_page_writeback(page);
+ return ret;
+}
diff --git a/fs/ext4/super.c b/fs/ext4/super.c
index 16002ec..9f602c2 100644
--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -4768,9 +4768,12 @@ static int __init init_ext4_fs(void)
int err;
ext4_check_flag_values();
- err = init_ext4_system_zone();
+ err = init_ext4_pageio();
if (err)
return err;
+ err = init_ext4_system_zone();
+ if (err)
+ goto out5;
ext4_kset = kset_create_and_add("ext4", NULL, fs_kobj);
if (!ext4_kset)
goto out4;
@@ -4811,6 +4814,8 @@ out3:
kset_unregister(ext4_kset);
out4:
exit_ext4_system_zone();
+out5:
+ exit_ext4_pageio();
return err;
}
@@ -4826,6 +4831,7 @@ static void __exit exit_ext4_fs(void)
remove_proc_entry("fs/ext4", NULL);
kset_unregister(ext4_kset);
exit_ext4_system_zone();
+ exit_ext4_pageio();
}
MODULE_AUTHOR("Remy Card, Stephen Tweedie, Andrew Morton, Andreas Dilger, Theodore Ts'o and others");
--
1.7.1
Expand the call:
if (walk_page_buffers(NULL, page_bufs, 0, len, NULL,
ext4_bh_delay_or_unwritten))
goto redirty_page
into mpage_da_submit_io().
This will allow us to merge in mpage_put_bnr_to_bhs() in the next
patch.
Signed-off-by: "Theodore Ts'o" <[email protected]>
---
fs/ext4/inode.c | 24 +++++++++++++-----------
1 files changed, 13 insertions(+), 11 deletions(-)
diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index f97fc46..9fda16c 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -2011,8 +2011,8 @@ static int mpage_da_submit_io(struct mpage_da_data *mpd)
struct inode *inode = mpd->inode;
struct address_space *mapping = inode->i_mapping;
loff_t size = i_size_read(inode);
- unsigned int len;
- struct buffer_head *page_bufs = NULL;
+ unsigned int len, block_start;
+ struct buffer_head *bh, *page_bufs = NULL;
int journal_data = ext4_should_journal_data(inode);
BUG_ON(mpd->next_page <= mpd->first_page);
@@ -2064,15 +2064,17 @@ static int mpage_da_submit_io(struct mpage_da_data *mpd)
}
commit_write = 1;
}
- page_bufs = page_buffers(page);
- if (walk_page_buffers(NULL, page_bufs, 0, len, NULL,
- ext4_bh_delay_or_unwritten)) {
- /*
- * We couldn't do block allocation for
- * some reason.
- */
- goto redirty_page;
- }
+
+ bh = page_bufs = page_buffers(page);
+ block_start = 0;
+ do {
+ /* redirty page if block allocation undone */
+ if (!bh || buffer_delay(bh) ||
+ buffer_unwritten(bh))
+ goto redirty_page;
+ bh = bh->b_this_page;
+ block_start += bh->b_size;
+ } while ((bh != page_bufs) && (block_start < len));
if (commit_write)
/* mark the buffer_heads as dirty & uptodate */
--
1.7.1
Eventually we need to completely reorganize the ext4 writepage
callpath, but for now, we simplify things a little by calling
mpage_da_submit_io() from mpage_da_map_blocks(), since all of the
places where we call mpage_da_map_blocks() it is followed up by a call
to mpage_da_submit_io().
We're also a wee bit better with respect to error handling, but there
are still a number of issues where it's not clear what the right thing
is to do with ext4 functions deep in the writeback codepath fails.
Signed-off-by: "Theodore Ts'o" <[email protected]>
---
fs/ext4/inode.c | 63 ++++++++++++++++++++++++++----------------------------
1 files changed, 30 insertions(+), 33 deletions(-)
diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index 670ab15..c3cc036 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -60,6 +60,7 @@ static inline int ext4_begin_ordered_truncate(struct inode *inode,
}
static void ext4_invalidatepage(struct page *page, unsigned long offset);
+static int ext4_writepage(struct page *page, struct writeback_control *wbc);
/*
* Test whether an inode is a fast symlink.
@@ -2033,7 +2034,7 @@ static int mpage_da_submit_io(struct mpage_da_data *mpd)
BUG_ON(PageWriteback(page));
pages_skipped = mpd->wbc->pages_skipped;
- err = mapping->a_ops->writepage(page, mpd->wbc);
+ err = ext4_writepage(page, mpd->wbc);
if (!err && (pages_skipped == mpd->wbc->pages_skipped))
/*
* have successfully written the page
@@ -2189,14 +2190,15 @@ static void ext4_print_free_blocks(struct inode *inode)
}
/*
- * mpage_da_map_blocks - go through given space
+ * mpage_da_map_and_submit - go through given space, map them
+ * if necessary, and then submit them for I/O
*
* @mpd - bh describing space
*
* The function skips space we know is already mapped to disk blocks.
*
*/
-static int mpage_da_map_blocks(struct mpage_da_data *mpd)
+static void mpage_da_map_and_submit(struct mpage_da_data *mpd)
{
int err, blks, get_blocks_flags;
struct ext4_map_blocks map;
@@ -2206,18 +2208,14 @@ static int mpage_da_map_blocks(struct mpage_da_data *mpd)
handle_t *handle = NULL;
/*
- * We consider only non-mapped and non-allocated blocks
+ * If the blocks are mapped already, or we couldn't accumulate
+ * any blocks, then proceed immediately to the submission stage.
*/
- if ((mpd->b_state & (1 << BH_Mapped)) &&
- !(mpd->b_state & (1 << BH_Delay)) &&
- !(mpd->b_state & (1 << BH_Unwritten)))
- return 0;
-
- /*
- * If we didn't accumulate anything to write simply return
- */
- if (!mpd->b_size)
- return 0;
+ if ((mpd->b_size == 0) ||
+ ((mpd->b_state & (1 << BH_Mapped)) &&
+ !(mpd->b_state & (1 << BH_Delay)) &&
+ !(mpd->b_state & (1 << BH_Unwritten))))
+ goto submit_io;
handle = ext4_journal_current_handle();
BUG_ON(!handle);
@@ -2254,17 +2252,18 @@ static int mpage_da_map_blocks(struct mpage_da_data *mpd)
err = blks;
/*
- * If get block returns with error we simply
- * return. Later writepage will redirty the page and
- * writepages will find the dirty page again
+ * If get block returns EAGAIN or ENOSPC and there
+ * appears to be free blocks we will call
+ * ext4_writepage() for all of the pages which will
+ * just redirty the pages.
*/
if (err == -EAGAIN)
- return 0;
+ goto submit_io;
if (err == -ENOSPC &&
ext4_count_free_blocks(sb)) {
mpd->retval = err;
- return 0;
+ goto submit_io;
}
/*
@@ -2289,7 +2288,7 @@ static int mpage_da_map_blocks(struct mpage_da_data *mpd)
/* invalidate all the pages */
ext4_da_block_invalidatepages(mpd, next,
mpd->b_size >> mpd->inode->i_blkbits);
- return err;
+ return;
}
BUG_ON(blks == 0);
@@ -2312,7 +2311,8 @@ static int mpage_da_map_blocks(struct mpage_da_data *mpd)
if (ext4_should_order_data(mpd->inode)) {
err = ext4_jbd2_file_inode(handle, mpd->inode);
if (err)
- return err;
+ /* This only happens if the journal is aborted */
+ return;
}
/*
@@ -2323,10 +2323,13 @@ static int mpage_da_map_blocks(struct mpage_da_data *mpd)
disksize = i_size_read(mpd->inode);
if (disksize > EXT4_I(mpd->inode)->i_disksize) {
ext4_update_i_disksize(mpd->inode, disksize);
- return ext4_mark_inode_dirty(handle, mpd->inode);
+ err = ext4_mark_inode_dirty(handle, mpd->inode);
+ /* XXX not sure what our error handling straegy is here */
}
- return 0;
+submit_io:
+ mpage_da_submit_io(mpd);
+ mpd->io_done = 1;
}
#define BH_FLAGS ((1 << BH_Uptodate) | (1 << BH_Mapped) | \
@@ -2403,9 +2406,7 @@ flush_it:
* We couldn't merge the block to our extent, so we
* need to flush current extent and start new one
*/
- if (mpage_da_map_blocks(mpd) == 0)
- mpage_da_submit_io(mpd);
- mpd->io_done = 1;
+ mpage_da_map_and_submit(mpd);
return;
}
@@ -2437,15 +2438,13 @@ static int __mpage_da_writepage(struct page *page,
if (mpd->next_page != page->index) {
/*
* Nope, we can't. So, we map non-allocated blocks
- * and start IO on them using writepage()
+ * and start IO on them
*/
if (mpd->next_page != mpd->first_page) {
- if (mpage_da_map_blocks(mpd) == 0)
- mpage_da_submit_io(mpd);
+ mpage_da_map_and_submit(mpd);
/*
* skip rest of the page in the page_vec
*/
- mpd->io_done = 1;
redirty_page_for_writepage(wbc, page);
unlock_page(page);
return MPAGE_DA_EXTENT_TAIL;
@@ -3071,9 +3070,7 @@ retry:
* them for I/O.
*/
if (!mpd.io_done && mpd.next_page != mpd.first_page) {
- if (mpage_da_map_blocks(&mpd) == 0)
- mpage_da_submit_io(&mpd);
- mpd.io_done = 1;
+ mpage_da_map_and_submit(&mpd);
ret = MPAGE_DA_EXTENT_TAIL;
}
trace_ext4_da_write_pages(inode, &mpd);
--
1.7.1
On 2010-10-22, at 09:29, Theodore Ts'o wrote:
> @@ -2323,10 +2323,13 @@ static int mpage_da_map_blocks(struct mpage_da_data *mpd)
> disksize = i_size_read(mpd->inode);
> if (disksize > EXT4_I(mpd->inode)->i_disksize) {
> ext4_update_i_disksize(mpd->inode, disksize);
> - return ext4_mark_inode_dirty(handle, mpd->inode);
> + err = ext4_mark_inode_dirty(handle, mpd->inode);
> + /* XXX not sure what our error handling straegy is here */
(typo) s/straegy/strategy/
I don't think this is necessarily fatal. It looks like the only time we can fail from ext4_mark_inode_dirty() is cases of IO errors or bad inode numbers and such (which should have been caught already). At worst, if the blocks are newly mapped (and referenced directly from the inode) then the new blocks would be leaked and the data would be unreachable. These should already have marked the filesystem in error, so it may be any error here is irrelevant.
Cheers, Andreas