Jack up ext4_get_blocks() and add a new function, ext4_map_blocks()
which uses a much smaller structure, struct ext4_map_blocks which is
20 bytes, as opposed to a struct buffer_head, which nearly 5 times
bigger on an x86_64 machine. By switching things to use
ext4_map_blocks(), we can save stack space by using ext4_map_blocks()
since we can avoid allocating a struct buffer_head on the stack.
Signed-off-by: "Theodore Ts'o" <[email protected]>
---
fs/ext4/ext4.h | 30 ++++++-
fs/ext4/extents.c | 233 +++++++++++++++++++++++++---------------------------
fs/ext4/inode.c | 102 +++++++++++++----------
3 files changed, 197 insertions(+), 168 deletions(-)
diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
index bf938cf..8dfc70b 100644
--- a/fs/ext4/ext4.h
+++ b/fs/ext4/ext4.h
@@ -126,6 +126,29 @@ struct ext4_allocation_request {
};
/*
+ * Logical to physical block mapping, used by ext4_map_blocks()
+ *
+ * This structure is used to pass requests into ext4_map_blocks() as
+ * well as to store the information returned by ext4_map_blocks(). It
+ * takes less room on the stack than a struct buffer_head.
+ */
+#define EXT4_MAP_NEW (1 << BH_New)
+#define EXT4_MAP_MAPPED (1 << BH_Mapped)
+#define EXT4_MAP_UNWRITTEN (1 << BH_Unwritten)
+#define EXT4_MAP_BOUNDARY (1 << BH_Boundary)
+#define EXT4_MAP_UNINIT (1 << BH_Uninit)
+#define EXT4_MAP_FLAGS (EXT4_MAP_NEW | EXT4_MAP_MAPPED |\
+ EXT4_MAP_UNWRITTEN | EXT4_MAP_BOUNDARY |\
+ EXT4_MAP_UNINIT);
+
+struct ext4_map_blocks {
+ ext4_fsblk_t m_pblk;
+ ext4_lblk_t m_lblk;
+ unsigned int m_len;
+ unsigned int m_flags;
+};
+
+/*
* For delayed allocation tracking
*/
struct mpage_da_data {
@@ -1772,9 +1795,8 @@ extern int ext4_ext_tree_init(handle_t *handle, struct inode *);
extern int ext4_ext_writepage_trans_blocks(struct inode *, int);
extern int ext4_ext_index_trans_blocks(struct inode *inode, int nrblocks,
int chunk);
-extern int ext4_ext_get_blocks(handle_t *handle, struct inode *inode,
- ext4_lblk_t iblock, unsigned int max_blocks,
- struct buffer_head *bh_result, int flags);
+extern int ext4_ext_map_blocks(handle_t *handle, struct inode *inode,
+ struct ext4_map_blocks *map, int flags);
extern void ext4_ext_truncate(struct inode *);
extern void ext4_ext_init(struct super_block *);
extern void ext4_ext_release(struct super_block *);
@@ -1782,6 +1804,8 @@ extern long ext4_fallocate(struct inode *inode, int mode, loff_t offset,
loff_t len);
extern int ext4_convert_unwritten_extents(struct inode *inode, loff_t offset,
ssize_t len);
+extern int ext4_map_blocks(handle_t *handle, struct inode *inode,
+ struct ext4_map_blocks *map, int flags);
extern int ext4_get_blocks(handle_t *handle, struct inode *inode,
sector_t block, unsigned int max_blocks,
struct buffer_head *bh, int flags);
diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c
index ee611da..005dce9 100644
--- a/fs/ext4/extents.c
+++ b/fs/ext4/extents.c
@@ -2611,7 +2611,7 @@ static int ext4_ext_zeroout(struct inode *inode, struct ext4_extent *ex)
#define EXT4_EXT_ZERO_LEN 7
/*
- * This function is called by ext4_ext_get_blocks() if someone tries to write
+ * This function is called by ext4_ext_map_blocks() if someone tries to write
* to an uninitialized extent. It may result in splitting the uninitialized
* extent into multiple extents (upto three - one initialized and two
* uninitialized).
@@ -2621,10 +2621,9 @@ static int ext4_ext_zeroout(struct inode *inode, struct ext4_extent *ex)
* c> Splits in three extents: Somone is writing in middle of the extent
*/
static int ext4_ext_convert_to_initialized(handle_t *handle,
- struct inode *inode,
- struct ext4_ext_path *path,
- ext4_lblk_t iblock,
- unsigned int max_blocks)
+ struct inode *inode,
+ struct ext4_map_blocks *map,
+ struct ext4_ext_path *path)
{
struct ext4_extent *ex, newex, orig_ex;
struct ext4_extent *ex1 = NULL;
@@ -2640,20 +2639,20 @@ static int ext4_ext_convert_to_initialized(handle_t *handle,
ext_debug("ext4_ext_convert_to_initialized: inode %lu, logical"
"block %llu, max_blocks %u\n", inode->i_ino,
- (unsigned long long)iblock, max_blocks);
+ (unsigned long long)map->m_lblk, map->m_len);
eof_block = (inode->i_size + inode->i_sb->s_blocksize - 1) >>
inode->i_sb->s_blocksize_bits;
- if (eof_block < iblock + max_blocks)
- eof_block = iblock + max_blocks;
+ if (eof_block < map->m_lblk + map->m_len)
+ eof_block = map->m_lblk + map->m_len;
depth = ext_depth(inode);
eh = path[depth].p_hdr;
ex = path[depth].p_ext;
ee_block = le32_to_cpu(ex->ee_block);
ee_len = ext4_ext_get_actual_len(ex);
- allocated = ee_len - (iblock - ee_block);
- newblock = iblock - ee_block + ext_pblock(ex);
+ allocated = ee_len - (map->m_lblk - ee_block);
+ newblock = map->m_lblk - ee_block + ext_pblock(ex);
ex2 = ex;
orig_ex.ee_block = ex->ee_block;
@@ -2683,10 +2682,10 @@ static int ext4_ext_convert_to_initialized(handle_t *handle,
return allocated;
}
- /* ex1: ee_block to iblock - 1 : uninitialized */
- if (iblock > ee_block) {
+ /* ex1: ee_block to map->m_lblk - 1 : uninitialized */
+ if (map->m_lblk > ee_block) {
ex1 = ex;
- ex1->ee_len = cpu_to_le16(iblock - ee_block);
+ ex1->ee_len = cpu_to_le16(map->m_lblk - ee_block);
ext4_ext_mark_uninitialized(ex1);
ex2 = &newex;
}
@@ -2695,15 +2694,15 @@ static int ext4_ext_convert_to_initialized(handle_t *handle,
* we insert ex3, if ex1 is NULL. This is to avoid temporary
* overlap of blocks.
*/
- if (!ex1 && allocated > max_blocks)
- ex2->ee_len = cpu_to_le16(max_blocks);
+ if (!ex1 && allocated > map->m_len)
+ ex2->ee_len = cpu_to_le16(map->m_len);
/* ex3: to ee_block + ee_len : uninitialised */
- if (allocated > max_blocks) {
+ if (allocated > map->m_len) {
unsigned int newdepth;
/* If extent has less than EXT4_EXT_ZERO_LEN zerout directly */
if (allocated <= EXT4_EXT_ZERO_LEN && may_zeroout) {
/*
- * iblock == ee_block is handled by the zerouout
+ * map->m_lblk == ee_block is handled by the zerouout
* at the beginning.
* Mark first half uninitialized.
* Mark second half initialized and zero out the
@@ -2716,7 +2715,7 @@ static int ext4_ext_convert_to_initialized(handle_t *handle,
ext4_ext_dirty(handle, inode, path + depth);
ex3 = &newex;
- ex3->ee_block = cpu_to_le32(iblock);
+ ex3->ee_block = cpu_to_le32(map->m_lblk);
ext4_ext_store_pblock(ex3, newblock);
ex3->ee_len = cpu_to_le16(allocated);
err = ext4_ext_insert_extent(handle, inode, path,
@@ -2729,7 +2728,7 @@ static int ext4_ext_convert_to_initialized(handle_t *handle,
ex->ee_len = orig_ex.ee_len;
ext4_ext_store_pblock(ex, ext_pblock(&orig_ex));
ext4_ext_dirty(handle, inode, path + depth);
- /* blocks available from iblock */
+ /* blocks available from map->m_lblk */
return allocated;
} else if (err)
@@ -2752,7 +2751,7 @@ static int ext4_ext_convert_to_initialized(handle_t *handle,
depth = ext_depth(inode);
ext4_ext_drop_refs(path);
path = ext4_ext_find_extent(inode,
- iblock, path);
+ map->m_lblk, path);
if (IS_ERR(path)) {
err = PTR_ERR(path);
return err;
@@ -2772,9 +2771,9 @@ static int ext4_ext_convert_to_initialized(handle_t *handle,
return allocated;
}
ex3 = &newex;
- ex3->ee_block = cpu_to_le32(iblock + max_blocks);
- ext4_ext_store_pblock(ex3, newblock + max_blocks);
- ex3->ee_len = cpu_to_le16(allocated - max_blocks);
+ ex3->ee_block = cpu_to_le32(map->m_lblk + map->m_len);
+ ext4_ext_store_pblock(ex3, newblock + map->m_len);
+ ex3->ee_len = cpu_to_le16(allocated - map->m_len);
ext4_ext_mark_uninitialized(ex3);
err = ext4_ext_insert_extent(handle, inode, path, ex3, 0);
if (err == -ENOSPC && may_zeroout) {
@@ -2787,7 +2786,7 @@ static int ext4_ext_convert_to_initialized(handle_t *handle,
ext4_ext_store_pblock(ex, ext_pblock(&orig_ex));
ext4_ext_dirty(handle, inode, path + depth);
/* zeroed the full extent */
- /* blocks available from iblock */
+ /* blocks available from map->m_lblk */
return allocated;
} else if (err)
@@ -2807,7 +2806,7 @@ static int ext4_ext_convert_to_initialized(handle_t *handle,
depth = newdepth;
ext4_ext_drop_refs(path);
- path = ext4_ext_find_extent(inode, iblock, path);
+ path = ext4_ext_find_extent(inode, map->m_lblk, path);
if (IS_ERR(path)) {
err = PTR_ERR(path);
goto out;
@@ -2821,14 +2820,14 @@ static int ext4_ext_convert_to_initialized(handle_t *handle,
if (err)
goto out;
- allocated = max_blocks;
+ allocated = map->m_len;
/* If extent has less than EXT4_EXT_ZERO_LEN and we are trying
* to insert a extent in the middle zerout directly
* otherwise give the extent a chance to merge to left
*/
if (le16_to_cpu(orig_ex.ee_len) <= EXT4_EXT_ZERO_LEN &&
- iblock != ee_block && may_zeroout) {
+ map->m_lblk != ee_block && may_zeroout) {
err = ext4_ext_zeroout(inode, &orig_ex);
if (err)
goto fix_extent_len;
@@ -2838,7 +2837,7 @@ static int ext4_ext_convert_to_initialized(handle_t *handle,
ext4_ext_store_pblock(ex, ext_pblock(&orig_ex));
ext4_ext_dirty(handle, inode, path + depth);
/* zero out the first half */
- /* blocks available from iblock */
+ /* blocks available from map->m_lblk */
return allocated;
}
}
@@ -2849,12 +2848,12 @@ static int ext4_ext_convert_to_initialized(handle_t *handle,
*/
if (ex1 && ex1 != ex) {
ex1 = ex;
- ex1->ee_len = cpu_to_le16(iblock - ee_block);
+ ex1->ee_len = cpu_to_le16(map->m_lblk - ee_block);
ext4_ext_mark_uninitialized(ex1);
ex2 = &newex;
}
- /* ex2: iblock to iblock + maxblocks-1 : initialised */
- ex2->ee_block = cpu_to_le32(iblock);
+ /* ex2: map->m_lblk to map->m_lblk + maxblocks-1 : initialised */
+ ex2->ee_block = cpu_to_le32(map->m_lblk);
ext4_ext_store_pblock(ex2, newblock);
ex2->ee_len = cpu_to_le16(allocated);
if (ex2 != ex)
@@ -2924,7 +2923,7 @@ fix_extent_len:
}
/*
- * This function is called by ext4_ext_get_blocks() from
+ * This function is called by ext4_ext_map_blocks() from
* ext4_get_blocks_dio_write() when DIO to write
* to an uninitialized extent.
*
@@ -2947,9 +2946,8 @@ fix_extent_len:
*/
static int ext4_split_unwritten_extents(handle_t *handle,
struct inode *inode,
+ struct ext4_map_blocks *map,
struct ext4_ext_path *path,
- ext4_lblk_t iblock,
- unsigned int max_blocks,
int flags)
{
struct ext4_extent *ex, newex, orig_ex;
@@ -2965,20 +2963,20 @@ static int ext4_split_unwritten_extents(handle_t *handle,
ext_debug("ext4_split_unwritten_extents: inode %lu, logical"
"block %llu, max_blocks %u\n", inode->i_ino,
- (unsigned long long)iblock, max_blocks);
+ (unsigned long long)map->m_lblk, map->m_len);
eof_block = (inode->i_size + inode->i_sb->s_blocksize - 1) >>
inode->i_sb->s_blocksize_bits;
- if (eof_block < iblock + max_blocks)
- eof_block = iblock + max_blocks;
+ if (eof_block < map->m_lblk + map->m_len)
+ eof_block = map->m_lblk + map->m_len;
depth = ext_depth(inode);
eh = path[depth].p_hdr;
ex = path[depth].p_ext;
ee_block = le32_to_cpu(ex->ee_block);
ee_len = ext4_ext_get_actual_len(ex);
- allocated = ee_len - (iblock - ee_block);
- newblock = iblock - ee_block + ext_pblock(ex);
+ allocated = ee_len - (map->m_lblk - ee_block);
+ newblock = map->m_lblk - ee_block + ext_pblock(ex);
ex2 = ex;
orig_ex.ee_block = ex->ee_block;
@@ -2996,16 +2994,16 @@ static int ext4_split_unwritten_extents(handle_t *handle,
* block where the write begins, and the write completely
* covers the extent, then we don't need to split it.
*/
- if ((iblock == ee_block) && (allocated <= max_blocks))
+ if ((map->m_lblk == ee_block) && (allocated <= map->m_len))
return allocated;
err = ext4_ext_get_access(handle, inode, path + depth);
if (err)
goto out;
- /* ex1: ee_block to iblock - 1 : uninitialized */
- if (iblock > ee_block) {
+ /* ex1: ee_block to map->m_lblk - 1 : uninitialized */
+ if (map->m_lblk > ee_block) {
ex1 = ex;
- ex1->ee_len = cpu_to_le16(iblock - ee_block);
+ ex1->ee_len = cpu_to_le16(map->m_lblk - ee_block);
ext4_ext_mark_uninitialized(ex1);
ex2 = &newex;
}
@@ -3014,15 +3012,15 @@ static int ext4_split_unwritten_extents(handle_t *handle,
* we insert ex3, if ex1 is NULL. This is to avoid temporary
* overlap of blocks.
*/
- if (!ex1 && allocated > max_blocks)
- ex2->ee_len = cpu_to_le16(max_blocks);
+ if (!ex1 && allocated > map->m_len)
+ ex2->ee_len = cpu_to_le16(map->m_len);
/* ex3: to ee_block + ee_len : uninitialised */
- if (allocated > max_blocks) {
+ if (allocated > map->m_len) {
unsigned int newdepth;
ex3 = &newex;
- ex3->ee_block = cpu_to_le32(iblock + max_blocks);
- ext4_ext_store_pblock(ex3, newblock + max_blocks);
- ex3->ee_len = cpu_to_le16(allocated - max_blocks);
+ ex3->ee_block = cpu_to_le32(map->m_lblk + map->m_len);
+ ext4_ext_store_pblock(ex3, newblock + map->m_len);
+ ex3->ee_len = cpu_to_le16(allocated - map->m_len);
ext4_ext_mark_uninitialized(ex3);
err = ext4_ext_insert_extent(handle, inode, path, ex3, flags);
if (err == -ENOSPC && may_zeroout) {
@@ -3035,7 +3033,7 @@ static int ext4_split_unwritten_extents(handle_t *handle,
ext4_ext_store_pblock(ex, ext_pblock(&orig_ex));
ext4_ext_dirty(handle, inode, path + depth);
/* zeroed the full extent */
- /* blocks available from iblock */
+ /* blocks available from map->m_lblk */
return allocated;
} else if (err)
@@ -3055,7 +3053,7 @@ static int ext4_split_unwritten_extents(handle_t *handle,
depth = newdepth;
ext4_ext_drop_refs(path);
- path = ext4_ext_find_extent(inode, iblock, path);
+ path = ext4_ext_find_extent(inode, map->m_lblk, path);
if (IS_ERR(path)) {
err = PTR_ERR(path);
goto out;
@@ -3069,7 +3067,7 @@ static int ext4_split_unwritten_extents(handle_t *handle,
if (err)
goto out;
- allocated = max_blocks;
+ allocated = map->m_len;
}
/*
* If there was a change of depth as part of the
@@ -3078,15 +3076,15 @@ static int ext4_split_unwritten_extents(handle_t *handle,
*/
if (ex1 && ex1 != ex) {
ex1 = ex;
- ex1->ee_len = cpu_to_le16(iblock - ee_block);
+ ex1->ee_len = cpu_to_le16(map->m_lblk - ee_block);
ext4_ext_mark_uninitialized(ex1);
ex2 = &newex;
}
/*
- * ex2: iblock to iblock + maxblocks-1 : to be direct IO written,
+ * ex2: map->m_lblk to map->m_lblk + map->m_len-1 : to be direct IO written,
* uninitialised still.
*/
- ex2->ee_block = cpu_to_le32(iblock);
+ ex2->ee_block = cpu_to_le32(map->m_lblk);
ext4_ext_store_pblock(ex2, newblock);
ex2->ee_len = cpu_to_le16(allocated);
ext4_ext_mark_uninitialized(ex2);
@@ -3188,10 +3186,9 @@ static void unmap_underlying_metadata_blocks(struct block_device *bdev,
static int
ext4_ext_handle_uninitialized_extents(handle_t *handle, struct inode *inode,
- ext4_lblk_t iblock, unsigned int max_blocks,
+ struct ext4_map_blocks *map,
struct ext4_ext_path *path, int flags,
- unsigned int allocated, struct buffer_head *bh_result,
- ext4_fsblk_t newblock)
+ unsigned int allocated, ext4_fsblk_t newblock)
{
int ret = 0;
int err = 0;
@@ -3199,15 +3196,14 @@ ext4_ext_handle_uninitialized_extents(handle_t *handle, struct inode *inode,
ext_debug("ext4_ext_handle_uninitialized_extents: inode %lu, logical"
"block %llu, max_blocks %u, flags %d, allocated %u",
- inode->i_ino, (unsigned long long)iblock, max_blocks,
+ inode->i_ino, (unsigned long long)map->m_lblk, map->m_len,
flags, allocated);
ext4_ext_show_leaf(inode, path);
/* get_block() before submit the IO, split the extent */
if ((flags & EXT4_GET_BLOCKS_PRE_IO)) {
- ret = ext4_split_unwritten_extents(handle,
- inode, path, iblock,
- max_blocks, flags);
+ ret = ext4_split_unwritten_extents(handle, inode, map,
+ path, flags);
/*
* Flag the inode(non aio case) or end_io struct (aio case)
* that this IO needs to convertion to written when IO is
@@ -3218,7 +3214,7 @@ ext4_ext_handle_uninitialized_extents(handle_t *handle, struct inode *inode,
else
ext4_set_inode_state(inode, EXT4_STATE_DIO_UNWRITTEN);
if (ext4_should_dioread_nolock(inode))
- set_buffer_uninit(bh_result);
+ map->m_flags |= EXT4_MAP_UNINIT;
goto out;
}
/* IO end_io complete, convert the filled extent to written */
@@ -3246,14 +3242,12 @@ ext4_ext_handle_uninitialized_extents(handle_t *handle, struct inode *inode,
* the buffer head will be unmapped so that
* a read from the block returns 0s.
*/
- set_buffer_unwritten(bh_result);
+ map->m_flags |= EXT4_MAP_UNWRITTEN;
goto out1;
}
/* buffered write, writepage time, convert*/
- ret = ext4_ext_convert_to_initialized(handle, inode,
- path, iblock,
- max_blocks);
+ ret = ext4_ext_convert_to_initialized(handle, inode, map, path);
if (ret >= 0)
ext4_update_inode_fsync_trans(handle, inode, 1);
out:
@@ -3262,7 +3256,7 @@ out:
goto out2;
} else
allocated = ret;
- set_buffer_new(bh_result);
+ map->m_flags |= EXT4_MAP_NEW;
/*
* if we allocated more blocks than requested
* we need to make sure we unmap the extra block
@@ -3270,11 +3264,11 @@ out:
* unmapped later when we find the buffer_head marked
* new.
*/
- if (allocated > max_blocks) {
+ if (allocated > map->m_len) {
unmap_underlying_metadata_blocks(inode->i_sb->s_bdev,
- newblock + max_blocks,
- allocated - max_blocks);
- allocated = max_blocks;
+ newblock + map->m_len,
+ allocated - map->m_len);
+ allocated = map->m_len;
}
/*
@@ -3288,13 +3282,13 @@ out:
ext4_da_update_reserve_space(inode, allocated, 0);
map_out:
- set_buffer_mapped(bh_result);
+ map->m_flags |= EXT4_MAP_MAPPED;
out1:
- if (allocated > max_blocks)
- allocated = max_blocks;
+ if (allocated > map->m_len)
+ allocated = map->m_len;
ext4_ext_show_leaf(inode, path);
- bh_result->b_bdev = inode->i_sb->s_bdev;
- bh_result->b_blocknr = newblock;
+ map->m_pblk = newblock;
+ map->m_len = allocated;
out2:
if (path) {
ext4_ext_drop_refs(path);
@@ -3320,10 +3314,8 @@ out2:
*
* return < 0, error case.
*/
-int ext4_ext_get_blocks(handle_t *handle, struct inode *inode,
- ext4_lblk_t iblock,
- unsigned int max_blocks, struct buffer_head *bh_result,
- int flags)
+int ext4_ext_map_blocks(handle_t *handle, struct inode *inode,
+ struct ext4_map_blocks *map, int flags)
{
struct ext4_ext_path *path = NULL;
struct ext4_extent_header *eh;
@@ -3334,12 +3326,11 @@ int ext4_ext_get_blocks(handle_t *handle, struct inode *inode,
struct ext4_allocation_request ar;
ext4_io_end_t *io = EXT4_I(inode)->cur_aio_dio;
- __clear_bit(BH_New, &bh_result->b_state);
ext_debug("blocks %u/%u requested for inode %lu\n",
- iblock, max_blocks, inode->i_ino);
+ map->m_lblk, map->m_len, inode->i_ino);
/* check in cache */
- cache_type = ext4_ext_in_cache(inode, iblock, &newex);
+ cache_type = ext4_ext_in_cache(inode, map->m_lblk, &newex);
if (cache_type) {
if (cache_type == EXT4_EXT_CACHE_GAP) {
if ((flags & EXT4_GET_BLOCKS_CREATE) == 0) {
@@ -3352,12 +3343,12 @@ int ext4_ext_get_blocks(handle_t *handle, struct inode *inode,
/* we should allocate requested block */
} else if (cache_type == EXT4_EXT_CACHE_EXTENT) {
/* block is already allocated */
- newblock = iblock
+ newblock = map->m_lblk
- le32_to_cpu(newex.ee_block)
+ ext_pblock(&newex);
/* number of remaining blocks in the extent */
allocated = ext4_ext_get_actual_len(&newex) -
- (iblock - le32_to_cpu(newex.ee_block));
+ (map->m_lblk - le32_to_cpu(newex.ee_block));
goto out;
} else {
BUG();
@@ -3365,7 +3356,7 @@ int ext4_ext_get_blocks(handle_t *handle, struct inode *inode,
}
/* find extent for this block */
- path = ext4_ext_find_extent(inode, iblock, NULL);
+ path = ext4_ext_find_extent(inode, map->m_lblk, NULL);
if (IS_ERR(path)) {
err = PTR_ERR(path);
path = NULL;
@@ -3382,7 +3373,7 @@ int ext4_ext_get_blocks(handle_t *handle, struct inode *inode,
if (unlikely(path[depth].p_ext == NULL && depth != 0)) {
EXT4_ERROR_INODE(inode, "bad extent address "
"iblock: %d, depth: %d pblock %lld",
- iblock, depth, path[depth].p_block);
+ map->m_lblk, depth, path[depth].p_block);
err = -EIO;
goto out2;
}
@@ -3400,12 +3391,12 @@ int ext4_ext_get_blocks(handle_t *handle, struct inode *inode,
*/
ee_len = ext4_ext_get_actual_len(ex);
/* if found extent covers block, simply return it */
- if (in_range(iblock, ee_block, ee_len)) {
- newblock = iblock - ee_block + ee_start;
+ if (in_range(map->m_lblk, ee_block, ee_len)) {
+ newblock = map->m_lblk - ee_block + ee_start;
/* number of remaining blocks in the extent */
- allocated = ee_len - (iblock - ee_block);
- ext_debug("%u fit into %u:%d -> %llu\n", iblock,
- ee_block, ee_len, newblock);
+ allocated = ee_len - (map->m_lblk - ee_block);
+ ext_debug("%u fit into %u:%d -> %llu\n", map->m_lblk,
+ ee_block, ee_len, newblock);
/* Do not put uninitialized extent in the cache */
if (!ext4_ext_is_uninitialized(ex)) {
@@ -3415,8 +3406,8 @@ int ext4_ext_get_blocks(handle_t *handle, struct inode *inode,
goto out;
}
ret = ext4_ext_handle_uninitialized_extents(handle,
- inode, iblock, max_blocks, path,
- flags, allocated, bh_result, newblock);
+ inode, map, path, flags, allocated,
+ newblock);
return ret;
}
}
@@ -3430,7 +3421,7 @@ int ext4_ext_get_blocks(handle_t *handle, struct inode *inode,
* put just found gap into cache to speed up
* subsequent requests
*/
- ext4_ext_put_gap_in_cache(inode, path, iblock);
+ ext4_ext_put_gap_in_cache(inode, path, map->m_lblk);
goto out2;
}
/*
@@ -3438,11 +3429,11 @@ int ext4_ext_get_blocks(handle_t *handle, struct inode *inode,
*/
/* find neighbour allocated blocks */
- ar.lleft = iblock;
+ ar.lleft = map->m_lblk;
err = ext4_ext_search_left(inode, path, &ar.lleft, &ar.pleft);
if (err)
goto out2;
- ar.lright = iblock;
+ ar.lright = map->m_lblk;
err = ext4_ext_search_right(inode, path, &ar.lright, &ar.pright);
if (err)
goto out2;
@@ -3453,26 +3444,26 @@ int ext4_ext_get_blocks(handle_t *handle, struct inode *inode,
* EXT_INIT_MAX_LEN and for an uninitialized extent this limit is
* EXT_UNINIT_MAX_LEN.
*/
- if (max_blocks > EXT_INIT_MAX_LEN &&
+ if (map->m_len > EXT_INIT_MAX_LEN &&
!(flags & EXT4_GET_BLOCKS_UNINIT_EXT))
- max_blocks = EXT_INIT_MAX_LEN;
- else if (max_blocks > EXT_UNINIT_MAX_LEN &&
+ map->m_len = EXT_INIT_MAX_LEN;
+ else if (map->m_len > EXT_UNINIT_MAX_LEN &&
(flags & EXT4_GET_BLOCKS_UNINIT_EXT))
- max_blocks = EXT_UNINIT_MAX_LEN;
+ map->m_len = EXT_UNINIT_MAX_LEN;
- /* Check if we can really insert (iblock)::(iblock+max_blocks) extent */
- newex.ee_block = cpu_to_le32(iblock);
- newex.ee_len = cpu_to_le16(max_blocks);
+ /* Check if we can really insert (m_lblk)::(m_lblk + m_len) extent */
+ newex.ee_block = cpu_to_le32(map->m_lblk);
+ newex.ee_len = cpu_to_le16(map->m_len);
err = ext4_ext_check_overlap(inode, &newex, path);
if (err)
allocated = ext4_ext_get_actual_len(&newex);
else
- allocated = max_blocks;
+ allocated = map->m_len;
/* allocate new block */
ar.inode = inode;
- ar.goal = ext4_ext_find_goal(inode, path, iblock);
- ar.logical = iblock;
+ ar.goal = ext4_ext_find_goal(inode, path, map->m_lblk);
+ ar.logical = map->m_lblk;
ar.len = allocated;
if (S_ISREG(inode->i_mode))
ar.flags = EXT4_MB_HINT_DATA;
@@ -3506,7 +3497,7 @@ int ext4_ext_get_blocks(handle_t *handle, struct inode *inode,
EXT4_STATE_DIO_UNWRITTEN);
}
if (ext4_should_dioread_nolock(inode))
- set_buffer_uninit(bh_result);
+ map->m_flags |= EXT4_MAP_UNINIT;
}
if (unlikely(EXT4_I(inode)->i_flags & EXT4_EOFBLOCKS_FL)) {
@@ -3518,7 +3509,7 @@ int ext4_ext_get_blocks(handle_t *handle, struct inode *inode,
goto out2;
}
last_ex = EXT_LAST_EXTENT(eh);
- if (iblock + ar.len > le32_to_cpu(last_ex->ee_block)
+ if (map->m_lblk + ar.len > le32_to_cpu(last_ex->ee_block)
+ ext4_ext_get_actual_len(last_ex))
EXT4_I(inode)->i_flags &= ~EXT4_EOFBLOCKS_FL;
}
@@ -3536,9 +3527,9 @@ int ext4_ext_get_blocks(handle_t *handle, struct inode *inode,
/* previous routine could use block we allocated */
newblock = ext_pblock(&newex);
allocated = ext4_ext_get_actual_len(&newex);
- if (allocated > max_blocks)
- allocated = max_blocks;
- set_buffer_new(bh_result);
+ if (allocated > map->m_len)
+ allocated = map->m_len;
+ map->m_flags |= EXT4_MAP_NEW;
/*
* Update reserved blocks/metadata blocks after successful
@@ -3552,18 +3543,18 @@ int ext4_ext_get_blocks(handle_t *handle, struct inode *inode,
* when it is _not_ an uninitialized extent.
*/
if ((flags & EXT4_GET_BLOCKS_UNINIT_EXT) == 0) {
- ext4_ext_put_in_cache(inode, iblock, allocated, newblock,
+ ext4_ext_put_in_cache(inode, map->m_lblk, allocated, newblock,
EXT4_EXT_CACHE_EXTENT);
ext4_update_inode_fsync_trans(handle, inode, 1);
} else
ext4_update_inode_fsync_trans(handle, inode, 0);
out:
- if (allocated > max_blocks)
- allocated = max_blocks;
+ if (allocated > map->m_len)
+ allocated = map->m_len;
ext4_ext_show_leaf(inode, path);
- set_buffer_mapped(bh_result);
- bh_result->b_bdev = inode->i_sb->s_bdev;
- bh_result->b_blocknr = newblock;
+ map->m_flags |= EXT4_MAP_MAPPED;
+ map->m_pblk = newblock;
+ map->m_len = allocated;
out2:
if (path) {
ext4_ext_drop_refs(path);
@@ -3724,7 +3715,7 @@ retry:
if (ret <= 0) {
#ifdef EXT4FS_DEBUG
WARN_ON(ret <= 0);
- printk(KERN_ERR "%s: ext4_ext_get_blocks "
+ printk(KERN_ERR "%s: ext4_ext_map_blocks "
"returned error inode#%lu, block=%u, "
"max_blocks=%u", __func__,
inode->i_ino, block, max_blocks);
@@ -3801,7 +3792,7 @@ int ext4_convert_unwritten_extents(struct inode *inode, loff_t offset,
EXT4_GET_BLOCKS_IO_CONVERT_EXT);
if (ret <= 0) {
WARN_ON(ret <= 0);
- printk(KERN_ERR "%s: ext4_ext_get_blocks "
+ printk(KERN_ERR "%s: ext4_ext_map_blocks "
"returned error inode#%lu, block=%u, "
"max_blocks=%u", __func__,
inode->i_ino, block, max_blocks);
diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index 9c553db..0b79f46 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -148,7 +148,7 @@ int ext4_truncate_restart_trans(handle_t *handle, struct inode *inode,
int ret;
/*
- * Drop i_data_sem to avoid deadlock with ext4_get_blocks At this
+ * Drop i_data_sem to avoid deadlock with ext4_map_blocks. At this
* moment, get_block can be called only for blocks inside i_size since
* page cache has been already dropped and writes are blocked by
* i_mutex. So we can safely drop the i_data_sem here.
@@ -889,9 +889,9 @@ err_out:
}
/*
- * The ext4_ind_get_blocks() function handles non-extents inodes
+ * The ext4_ind_map_blocks() function handles non-extents inodes
* (i.e., using the traditional indirect/double-indirect i_blocks
- * scheme) for ext4_get_blocks().
+ * scheme) for ext4_map_blocks().
*
* Allocation strategy is simple: if we have to allocate something, we will
* have to go the whole way to leaf. So let's do it before attaching anything
@@ -916,9 +916,8 @@ err_out:
* down_read(&EXT4_I(inode)->i_data_sem) if not allocating file system
* blocks.
*/
-static int ext4_ind_get_blocks(handle_t *handle, struct inode *inode,
- ext4_lblk_t iblock, unsigned int maxblocks,
- struct buffer_head *bh_result,
+static int ext4_ind_map_blocks(handle_t *handle, struct inode *inode,
+ struct ext4_map_blocks *map,
int flags)
{
int err = -EIO;
@@ -934,7 +933,7 @@ static int ext4_ind_get_blocks(handle_t *handle, struct inode *inode,
J_ASSERT(!(EXT4_I(inode)->i_flags & EXT4_EXTENTS_FL));
J_ASSERT(handle != NULL || (flags & EXT4_GET_BLOCKS_CREATE) == 0);
- depth = ext4_block_to_path(inode, iblock, offsets,
+ depth = ext4_block_to_path(inode, map->m_lblk, offsets,
&blocks_to_boundary);
if (depth == 0)
@@ -945,10 +944,9 @@ static int ext4_ind_get_blocks(handle_t *handle, struct inode *inode,
/* Simplest case - block found, no allocation needed */
if (!partial) {
first_block = le32_to_cpu(chain[depth - 1].key);
- clear_buffer_new(bh_result);
count++;
/*map more blocks*/
- while (count < maxblocks && count <= blocks_to_boundary) {
+ while (count < map->m_len && count <= blocks_to_boundary) {
ext4_fsblk_t blk;
blk = le32_to_cpu(*(chain[depth-1].p + count));
@@ -968,7 +966,7 @@ static int ext4_ind_get_blocks(handle_t *handle, struct inode *inode,
/*
* Okay, we need to do block allocation.
*/
- goal = ext4_find_goal(inode, iblock, partial);
+ goal = ext4_find_goal(inode, map->m_lblk, partial);
/* the number of blocks need to allocate for [d,t]indirect blocks */
indirect_blks = (chain + depth) - partial - 1;
@@ -978,11 +976,11 @@ static int ext4_ind_get_blocks(handle_t *handle, struct inode *inode,
* direct blocks to allocate for this branch.
*/
count = ext4_blks_to_allocate(partial, indirect_blks,
- maxblocks, blocks_to_boundary);
+ map->m_len, blocks_to_boundary);
/*
* Block out ext4_truncate while we alter the tree
*/
- err = ext4_alloc_branch(handle, inode, iblock, indirect_blks,
+ err = ext4_alloc_branch(handle, inode, map->m_lblk, indirect_blks,
&count, goal,
offsets + (partial - chain), partial);
@@ -994,18 +992,20 @@ static int ext4_ind_get_blocks(handle_t *handle, struct inode *inode,
* may need to return -EAGAIN upwards in the worst case. --sct
*/
if (!err)
- err = ext4_splice_branch(handle, inode, iblock,
+ err = ext4_splice_branch(handle, inode, map->m_lblk,
partial, indirect_blks, count);
if (err)
goto cleanup;
- set_buffer_new(bh_result);
+ map->m_flags |= EXT4_MAP_NEW;
ext4_update_inode_fsync_trans(handle, inode, 1);
got_it:
- map_bh(bh_result, inode->i_sb, le32_to_cpu(chain[depth-1].key));
+ map->m_flags |= EXT4_MAP_MAPPED;
+ map->m_pblk = le32_to_cpu(chain[depth-1].key);
+ map->m_len = count;
if (count > blocks_to_boundary)
- set_buffer_boundary(bh_result);
+ map->m_flags |= EXT4_MAP_BOUNDARY;
err = count;
/* Clean up and exit */
partial = chain + depth - 1; /* the whole chain */
@@ -1015,7 +1015,6 @@ cleanup:
brelse(partial->bh);
partial--;
}
- BUFFER_TRACE(bh_result, "returned");
out:
return err;
}
@@ -1212,15 +1211,15 @@ static pgoff_t ext4_num_dirty_pages(struct inode *inode, pgoff_t idx,
}
/*
- * The ext4_get_blocks() function tries to look up the requested blocks,
+ * The ext4_map_blocks() function tries to look up the requested blocks,
* and returns if the blocks are already mapped.
*
* Otherwise it takes the write lock of the i_data_sem and allocate blocks
* and store the allocated blocks in the result buffer head and mark it
* mapped.
*
- * If file type is extents based, it will call ext4_ext_get_blocks(),
- * Otherwise, call with ext4_ind_get_blocks() to handle indirect mapping
+ * If file type is extents based, it will call ext4_ext_map_blocks(),
+ * Otherwise, call with ext4_ind_map_blocks() to handle indirect mapping
* based files
*
* On success, it returns the number of blocks being mapped or allocate.
@@ -1233,35 +1232,30 @@ static pgoff_t ext4_num_dirty_pages(struct inode *inode, pgoff_t idx,
*
* It returns the error in case of allocation failure.
*/
-int ext4_get_blocks(handle_t *handle, struct inode *inode, sector_t block,
- unsigned int max_blocks, struct buffer_head *bh,
- int flags)
+int ext4_map_blocks(handle_t *handle, struct inode *inode,
+ struct ext4_map_blocks *map, int flags)
{
int retval;
- clear_buffer_mapped(bh);
- clear_buffer_unwritten(bh);
-
- ext_debug("ext4_get_blocks(): inode %lu, flag %d, max_blocks %u,"
- "logical block %lu\n", inode->i_ino, flags, max_blocks,
- (unsigned long)block);
+ map->m_flags = 0;
+ ext_debug("ext4_map_blocks(): inode %lu, flag %d, max_blocks %u,"
+ "logical block %lu\n", inode->i_ino, flags, map->m_len,
+ (unsigned long) map->m_lblk);
/*
* Try to see if we can get the block without requesting a new
* file system block.
*/
down_read((&EXT4_I(inode)->i_data_sem));
if (EXT4_I(inode)->i_flags & EXT4_EXTENTS_FL) {
- retval = ext4_ext_get_blocks(handle, inode, block, max_blocks,
- bh, 0);
+ retval = ext4_ext_map_blocks(handle, inode, map, 0);
} else {
- retval = ext4_ind_get_blocks(handle, inode, block, max_blocks,
- bh, 0);
+ retval = ext4_ind_map_blocks(handle, inode, map, 0);
}
up_read((&EXT4_I(inode)->i_data_sem));
- if (retval > 0 && buffer_mapped(bh)) {
+ if (retval > 0 && map->m_flags & EXT4_MAP_MAPPED) {
int ret = check_block_validity(inode, "file system corruption",
- block, bh->b_blocknr, retval);
+ map->m_lblk, map->m_pblk, retval);
if (ret != 0)
return ret;
}
@@ -1277,7 +1271,7 @@ int ext4_get_blocks(handle_t *handle, struct inode *inode, sector_t block,
* ext4_ext_get_block() returns th create = 0
* with buffer head unmapped.
*/
- if (retval > 0 && buffer_mapped(bh))
+ if (retval > 0 && map->m_flags & EXT4_MAP_MAPPED)
return retval;
/*
@@ -1290,7 +1284,7 @@ int ext4_get_blocks(handle_t *handle, struct inode *inode, sector_t block,
* of BH_Unwritten and BH_Mapped flags being simultaneously
* set on the buffer_head.
*/
- clear_buffer_unwritten(bh);
+ map->m_flags &= ~EXT4_MAP_UNWRITTEN;
/*
* New blocks allocate and/or writing to uninitialized extent
@@ -1313,13 +1307,11 @@ int ext4_get_blocks(handle_t *handle, struct inode *inode, sector_t block,
* could have changed the inode type in between
*/
if (EXT4_I(inode)->i_flags & EXT4_EXTENTS_FL) {
- retval = ext4_ext_get_blocks(handle, inode, block, max_blocks,
- bh, flags);
+ retval = ext4_ext_map_blocks(handle, inode, map, flags);
} else {
- retval = ext4_ind_get_blocks(handle, inode, block,
- max_blocks, bh, flags);
+ retval = ext4_ind_map_blocks(handle, inode, map, flags);
- if (retval > 0 && buffer_new(bh)) {
+ 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
@@ -1342,16 +1334,38 @@ int ext4_get_blocks(handle_t *handle, struct inode *inode, sector_t block,
EXT4_I(inode)->i_delalloc_reserved_flag = 0;
up_write((&EXT4_I(inode)->i_data_sem));
- if (retval > 0 && buffer_mapped(bh)) {
+ if (retval > 0 && map->m_flags & EXT4_MAP_MAPPED) {
int ret = check_block_validity(inode, "file system "
"corruption after allocation",
- block, bh->b_blocknr, retval);
+ map->m_lblk, map->m_pblk,
+ retval);
if (ret != 0)
return ret;
}
return retval;
}
+int ext4_get_blocks(handle_t *handle, struct inode *inode, sector_t block,
+ unsigned int max_blocks, struct buffer_head *bh,
+ int flags)
+{
+ struct ext4_map_blocks map;
+ int ret;
+
+ map.m_lblk = block;
+ map.m_len = max_blocks;
+
+ ret = ext4_map_blocks(handle, inode, &map, flags);
+ if (ret < 0)
+ return ret;
+
+ bh->b_blocknr = map.m_pblk;
+ bh->b_size = inode->i_sb->s_blocksize * map.m_len;
+ bh->b_bdev = inode->i_sb->s_bdev;
+ bh->b_state = (bh->b_state & ~EXT4_MAP_FLAGS) | map.m_flags;
+ return ret;
+}
+
/* Maximum number of blocks we map for direct IO at once. */
#define DIO_MAX_BLOCKS 4096
--
1.6.6.1.1.g974db.dirty
This saves a huge amount of stack space by avoiding unnecesary struct
buffer_head's from being allocated on the stack.
In addition, to make the code easier to understand, collapse and
refactor ext4_get_block(), ext4_get_block_write(),
noalloc_get_block_write(), into a single function.
Signed-off-by: "Theodore Ts'o" <[email protected]>
---
fs/ext4/dir.c | 12 +-
fs/ext4/ext4.h | 2 +-
fs/ext4/extents.c | 40 +++----
fs/ext4/inode.c | 342 +++++++++++++++++++++--------------------------------
4 files changed, 158 insertions(+), 238 deletions(-)
diff --git a/fs/ext4/dir.c b/fs/ext4/dir.c
index 86cb6d8..e3f2700 100644
--- a/fs/ext4/dir.c
+++ b/fs/ext4/dir.c
@@ -128,14 +128,14 @@ static int ext4_readdir(struct file *filp,
offset = filp->f_pos & (sb->s_blocksize - 1);
while (!error && !stored && filp->f_pos < inode->i_size) {
- ext4_lblk_t blk = filp->f_pos >> EXT4_BLOCK_SIZE_BITS(sb);
- struct buffer_head map_bh;
+ struct ext4_map_blocks map;
struct buffer_head *bh = NULL;
- map_bh.b_state = 0;
- err = ext4_get_blocks(NULL, inode, blk, 1, &map_bh, 0);
+ map.m_lblk = filp->f_pos >> EXT4_BLOCK_SIZE_BITS(sb);
+ map.m_len = 1;
+ err = ext4_map_blocks(NULL, inode, &map, 0);
if (err > 0) {
- pgoff_t index = map_bh.b_blocknr >>
+ pgoff_t index = map.m_pblk >>
(PAGE_CACHE_SHIFT - inode->i_blkbits);
if (!ra_has_index(&filp->f_ra, index))
page_cache_sync_readahead(
@@ -143,7 +143,7 @@ static int ext4_readdir(struct file *filp,
&filp->f_ra, filp,
index, 1);
filp->f_ra.prev_pos = (loff_t)index << PAGE_CACHE_SHIFT;
- bh = ext4_bread(NULL, inode, blk, 0, &err);
+ bh = ext4_bread(NULL, inode, map.m_lblk, 0, &err);
}
/*
diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
index 8dfc70b..08f541b 100644
--- a/fs/ext4/ext4.h
+++ b/fs/ext4/ext4.h
@@ -139,7 +139,7 @@ struct ext4_allocation_request {
#define EXT4_MAP_UNINIT (1 << BH_Uninit)
#define EXT4_MAP_FLAGS (EXT4_MAP_NEW | EXT4_MAP_MAPPED |\
EXT4_MAP_UNWRITTEN | EXT4_MAP_BOUNDARY |\
- EXT4_MAP_UNINIT);
+ EXT4_MAP_UNINIT)
struct ext4_map_blocks {
ext4_fsblk_t m_pblk;
diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c
index 005dce9..2282f40 100644
--- a/fs/ext4/extents.c
+++ b/fs/ext4/extents.c
@@ -3667,13 +3667,12 @@ static void ext4_falloc_update_inode(struct inode *inode,
long ext4_fallocate(struct inode *inode, int mode, loff_t offset, loff_t len)
{
handle_t *handle;
- ext4_lblk_t block;
loff_t new_size;
unsigned int max_blocks;
int ret = 0;
int ret2 = 0;
int retries = 0;
- struct buffer_head map_bh;
+ struct ext4_map_blocks map;
unsigned int credits, blkbits = inode->i_blkbits;
/*
@@ -3687,13 +3686,13 @@ long ext4_fallocate(struct inode *inode, int mode, loff_t offset, loff_t len)
if (S_ISDIR(inode->i_mode))
return -ENODEV;
- block = offset >> blkbits;
+ map.m_lblk = offset >> blkbits;
/*
* We can't just convert len to max_blocks because
* If blocksize = 4096 offset = 3072 and len = 2048
*/
max_blocks = (EXT4_BLOCK_ALIGN(len + offset, blkbits) >> blkbits)
- - block;
+ - map.m_lblk;
/*
* credits to insert 1 extent into extent tree
*/
@@ -3701,16 +3700,14 @@ long ext4_fallocate(struct inode *inode, int mode, loff_t offset, loff_t len)
mutex_lock(&inode->i_mutex);
retry:
while (ret >= 0 && ret < max_blocks) {
- block = block + ret;
- max_blocks = max_blocks - ret;
+ map.m_lblk = map.m_lblk + ret;
+ map.m_len = max_blocks = max_blocks - ret;
handle = ext4_journal_start(inode, credits);
if (IS_ERR(handle)) {
ret = PTR_ERR(handle);
break;
}
- map_bh.b_state = 0;
- ret = ext4_get_blocks(handle, inode, block,
- max_blocks, &map_bh,
+ ret = ext4_map_blocks(handle, inode, &map,
EXT4_GET_BLOCKS_CREATE_UNINIT_EXT);
if (ret <= 0) {
#ifdef EXT4FS_DEBUG
@@ -3724,14 +3721,14 @@ retry:
ret2 = ext4_journal_stop(handle);
break;
}
- if ((block + ret) >= (EXT4_BLOCK_ALIGN(offset + len,
+ if ((map.m_lblk + ret) >= (EXT4_BLOCK_ALIGN(offset + len,
blkbits) >> blkbits))
new_size = offset + len;
else
- new_size = (block + ret) << blkbits;
+ new_size = (map.m_lblk + ret) << blkbits;
ext4_falloc_update_inode(inode, mode, new_size,
- buffer_new(&map_bh));
+ (map.m_flags & EXT4_MAP_NEW));
ext4_mark_inode_dirty(handle, inode);
ret2 = ext4_journal_stop(handle);
if (ret2)
@@ -3760,42 +3757,39 @@ int ext4_convert_unwritten_extents(struct inode *inode, loff_t offset,
ssize_t len)
{
handle_t *handle;
- ext4_lblk_t block;
unsigned int max_blocks;
int ret = 0;
int ret2 = 0;
- struct buffer_head map_bh;
+ struct ext4_map_blocks map;
unsigned int credits, blkbits = inode->i_blkbits;
- block = offset >> blkbits;
+ map.m_lblk = offset >> blkbits;
/*
* We can't just convert len to max_blocks because
* If blocksize = 4096 offset = 3072 and len = 2048
*/
- max_blocks = (EXT4_BLOCK_ALIGN(len + offset, blkbits) >> blkbits)
- - block;
+ max_blocks = ((EXT4_BLOCK_ALIGN(len + offset, blkbits) >> blkbits) -
+ map.m_lblk);
/*
* credits to insert 1 extent into extent tree
*/
credits = ext4_chunk_trans_blocks(inode, max_blocks);
while (ret >= 0 && ret < max_blocks) {
- block = block + ret;
- max_blocks = max_blocks - ret;
+ map.m_lblk += ret;
+ map.m_len = (max_blocks -= ret);
handle = ext4_journal_start(inode, credits);
if (IS_ERR(handle)) {
ret = PTR_ERR(handle);
break;
}
- map_bh.b_state = 0;
- ret = ext4_get_blocks(handle, inode, block,
- max_blocks, &map_bh,
+ ret = ext4_map_blocks(handle, inode, &map,
EXT4_GET_BLOCKS_IO_CONVERT_EXT);
if (ret <= 0) {
WARN_ON(ret <= 0);
printk(KERN_ERR "%s: ext4_ext_map_blocks "
"returned error inode#%lu, block=%u, "
"max_blocks=%u", __func__,
- inode->i_ino, block, max_blocks);
+ inode->i_ino, map.m_lblk, map.m_len);
}
ext4_mark_inode_dirty(handle, inode);
ret2 = ext4_journal_stop(handle);
diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index 0b79f46..9b4456f 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -1345,133 +1345,112 @@ int ext4_map_blocks(handle_t *handle, struct inode *inode,
return retval;
}
-int ext4_get_blocks(handle_t *handle, struct inode *inode, sector_t block,
- unsigned int max_blocks, struct buffer_head *bh,
- int flags)
-{
- struct ext4_map_blocks map;
- int ret;
-
- map.m_lblk = block;
- map.m_len = max_blocks;
-
- ret = ext4_map_blocks(handle, inode, &map, flags);
- if (ret < 0)
- return ret;
-
- bh->b_blocknr = map.m_pblk;
- bh->b_size = inode->i_sb->s_blocksize * map.m_len;
- bh->b_bdev = inode->i_sb->s_bdev;
- bh->b_state = (bh->b_state & ~EXT4_MAP_FLAGS) | map.m_flags;
- return ret;
-}
-
/* Maximum number of blocks we map for direct IO at once. */
#define DIO_MAX_BLOCKS 4096
-int ext4_get_block(struct inode *inode, sector_t iblock,
- struct buffer_head *bh_result, int create)
+static int _ext4_get_block(struct inode *inode, sector_t iblock,
+ struct buffer_head *bh, int flags)
{
handle_t *handle = ext4_journal_current_handle();
+ struct ext4_map_blocks map;
int ret = 0, started = 0;
- unsigned max_blocks = bh_result->b_size >> inode->i_blkbits;
int dio_credits;
- if (create && !handle) {
+ map.m_lblk = iblock;
+ map.m_len = bh->b_size >> inode->i_blkbits;
+
+ if (flags && !handle) {
/* Direct IO write... */
- if (max_blocks > DIO_MAX_BLOCKS)
- max_blocks = DIO_MAX_BLOCKS;
- dio_credits = ext4_chunk_trans_blocks(inode, max_blocks);
+ if (map.m_len > DIO_MAX_BLOCKS)
+ map.m_len = DIO_MAX_BLOCKS;
+ dio_credits = ext4_chunk_trans_blocks(inode, map.m_len);
handle = ext4_journal_start(inode, dio_credits);
if (IS_ERR(handle)) {
ret = PTR_ERR(handle);
- goto out;
+ return ret;
}
started = 1;
}
- ret = ext4_get_blocks(handle, inode, iblock, max_blocks, bh_result,
- create ? EXT4_GET_BLOCKS_CREATE : 0);
+ ret = ext4_map_blocks(handle, inode, &map, flags);
if (ret > 0) {
- bh_result->b_size = (ret << inode->i_blkbits);
+ map_bh(bh, inode->i_sb, map.m_pblk);
+ bh->b_state = (bh->b_state & ~EXT4_MAP_FLAGS) | map.m_flags;
+ bh->b_size = inode->i_sb->s_blocksize * map.m_len;
ret = 0;
}
if (started)
ext4_journal_stop(handle);
-out:
return ret;
}
+int ext4_get_block(struct inode *inode, sector_t iblock,
+ struct buffer_head *bh, int create)
+{
+ return _ext4_get_block(inode, iblock, bh,
+ create ? EXT4_GET_BLOCKS_CREATE : 0);
+}
+
/*
* `handle' can be NULL if create is zero
*/
struct buffer_head *ext4_getblk(handle_t *handle, struct inode *inode,
ext4_lblk_t block, int create, int *errp)
{
- struct buffer_head dummy;
+ struct ext4_map_blocks map;
+ struct buffer_head *bh;
int fatal = 0, err;
- int flags = 0;
J_ASSERT(handle != NULL || create == 0);
- dummy.b_state = 0;
- dummy.b_blocknr = -1000;
- buffer_trace_init(&dummy.b_history);
- if (create)
- flags |= EXT4_GET_BLOCKS_CREATE;
- err = ext4_get_blocks(handle, inode, block, 1, &dummy, flags);
- /*
- * ext4_get_blocks() returns number of blocks mapped. 0 in
- * case of a HOLE.
- */
- if (err > 0) {
- if (err > 1)
- WARN_ON(1);
- err = 0;
+ map.m_lblk = block;
+ map.m_len = 1;
+ err = ext4_map_blocks(handle, inode, &map,
+ create ? EXT4_GET_BLOCKS_CREATE : 0);
+
+ if (err < 0)
+ *errp = err;
+ if (err <= 0)
+ return NULL;
+ *errp = 0;
+
+ bh = sb_getblk(inode->i_sb, map.m_pblk);
+ if (!bh) {
+ *errp = -EIO;
+ return NULL;
}
- *errp = err;
- if (!err && buffer_mapped(&dummy)) {
- struct buffer_head *bh;
- bh = sb_getblk(inode->i_sb, dummy.b_blocknr);
- if (!bh) {
- *errp = -EIO;
- goto err;
- }
- if (buffer_new(&dummy)) {
- J_ASSERT(create != 0);
- J_ASSERT(handle != NULL);
+ if (map.m_flags & EXT4_MAP_NEW) {
+ J_ASSERT(create != 0);
+ J_ASSERT(handle != NULL);
- /*
- * Now that we do not always journal data, we should
- * keep in mind whether this should always journal the
- * new buffer as metadata. For now, regular file
- * writes use ext4_get_block instead, so it's not a
- * problem.
- */
- lock_buffer(bh);
- BUFFER_TRACE(bh, "call get_create_access");
- fatal = ext4_journal_get_create_access(handle, bh);
- if (!fatal && !buffer_uptodate(bh)) {
- memset(bh->b_data, 0, inode->i_sb->s_blocksize);
- set_buffer_uptodate(bh);
- }
- unlock_buffer(bh);
- BUFFER_TRACE(bh, "call ext4_handle_dirty_metadata");
- err = ext4_handle_dirty_metadata(handle, inode, bh);
- if (!fatal)
- fatal = err;
- } else {
- BUFFER_TRACE(bh, "not a new buffer");
- }
- if (fatal) {
- *errp = fatal;
- brelse(bh);
- bh = NULL;
+ /*
+ * Now that we do not always journal data, we should
+ * keep in mind whether this should always journal the
+ * new buffer as metadata. For now, regular file
+ * writes use ext4_get_block instead, so it's not a
+ * problem.
+ */
+ lock_buffer(bh);
+ BUFFER_TRACE(bh, "call get_create_access");
+ fatal = ext4_journal_get_create_access(handle, bh);
+ if (!fatal && !buffer_uptodate(bh)) {
+ memset(bh->b_data, 0, inode->i_sb->s_blocksize);
+ set_buffer_uptodate(bh);
}
- return bh;
+ unlock_buffer(bh);
+ BUFFER_TRACE(bh, "call ext4_handle_dirty_metadata");
+ err = ext4_handle_dirty_metadata(handle, inode, bh);
+ if (!fatal)
+ fatal = err;
+ } else {
+ BUFFER_TRACE(bh, "not a new buffer");
}
-err:
- return NULL;
+ if (fatal) {
+ *errp = fatal;
+ brelse(bh);
+ bh = NULL;
+ }
+ return bh;
}
struct buffer_head *ext4_bread(handle_t *handle, struct inode *inode,
@@ -2056,28 +2035,23 @@ static int mpage_da_submit_io(struct mpage_da_data *mpd)
/*
* mpage_put_bnr_to_bhs - walk blocks and assign them actual numbers
*
- * @mpd->inode - inode to walk through
- * @exbh->b_blocknr - first block on a disk
- * @exbh->b_size - amount of space in bytes
- * @logical - first logical block to start assignment with
- *
* 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, sector_t logical,
- struct buffer_head *exbh)
+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 = exbh->b_size >> inode->i_blkbits;
- sector_t pblock = exbh->b_blocknr, cur_logical;
+ 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 = logical >> (PAGE_CACHE_SHIFT - inode->i_blkbits);
- end = (logical + blocks - 1) >> (PAGE_CACHE_SHIFT - inode->i_blkbits);
+ 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);
@@ -2104,17 +2078,16 @@ static void mpage_put_bnr_to_bhs(struct mpage_da_data *mpd, sector_t logical,
/* skip blocks out of the range */
do {
- if (cur_logical >= logical)
+ if (cur_logical >= map->m_lblk)
break;
cur_logical++;
} while ((bh = bh->b_this_page) != head);
do {
- if (cur_logical >= logical + blocks)
+ if (cur_logical >= map->m_lblk + blocks)
break;
- if (buffer_delay(bh) ||
- buffer_unwritten(bh)) {
+ if (buffer_delay(bh) || buffer_unwritten(bh)) {
BUG_ON(bh->b_bdev != inode->i_sb->s_bdev);
@@ -2133,7 +2106,7 @@ static void mpage_put_bnr_to_bhs(struct mpage_da_data *mpd, sector_t logical,
} else if (buffer_mapped(bh))
BUG_ON(bh->b_blocknr != pblock);
- if (buffer_uninit(exbh))
+ if (map->m_flags & EXT4_MAP_UNINIT)
set_buffer_uninit(bh);
cur_logical++;
pblock++;
@@ -2144,21 +2117,6 @@ static void mpage_put_bnr_to_bhs(struct mpage_da_data *mpd, sector_t logical,
}
-/*
- * __unmap_underlying_blocks - just a helper function to unmap
- * set of blocks described by @bh
- */
-static inline void __unmap_underlying_blocks(struct inode *inode,
- struct buffer_head *bh)
-{
- struct block_device *bdev = inode->i_sb->s_bdev;
- int blocks, i;
-
- blocks = bh->b_size >> inode->i_blkbits;
- for (i = 0; i < blocks; i++)
- unmap_underlying_metadata(bdev, bh->b_blocknr + i);
-}
-
static void ext4_da_block_invalidatepages(struct mpage_da_data *mpd,
sector_t logical, long blk_cnt)
{
@@ -2220,7 +2178,7 @@ static void ext4_print_free_blocks(struct inode *inode)
static int mpage_da_map_blocks(struct mpage_da_data *mpd)
{
int err, blks, get_blocks_flags;
- struct buffer_head new;
+ struct ext4_map_blocks map;
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;
@@ -2261,15 +2219,15 @@ static int mpage_da_map_blocks(struct mpage_da_data *mpd)
* EXT4_GET_BLOCKS_DELALLOC_RESERVE so the delalloc accounting
* variables are updated after the blocks have been allocated.
*/
- new.b_state = 0;
+ map.m_lblk = next;
+ map.m_len = max_blocks;
get_blocks_flags = EXT4_GET_BLOCKS_CREATE;
if (ext4_should_dioread_nolock(mpd->inode))
get_blocks_flags |= EXT4_GET_BLOCKS_IO_CREATE_EXT;
if (mpd->b_state & (1 << BH_Delay))
get_blocks_flags |= EXT4_GET_BLOCKS_DELALLOC_RESERVE;
- blks = ext4_get_blocks(handle, mpd->inode, next, max_blocks,
- &new, get_blocks_flags);
+ blks = ext4_map_blocks(handle, mpd->inode, &map, get_blocks_flags);
if (blks < 0) {
err = blks;
/*
@@ -2311,10 +2269,13 @@ static int mpage_da_map_blocks(struct mpage_da_data *mpd)
}
BUG_ON(blks == 0);
- new.b_size = (blks << mpd->inode->i_blkbits);
+ if (map.m_flags & EXT4_MAP_NEW) {
+ struct block_device *bdev = mpd->inode->i_sb->s_bdev;
+ int i;
- if (buffer_new(&new))
- __unmap_underlying_blocks(mpd->inode, &new);
+ for (i = 0; i < map.m_len; i++)
+ unmap_underlying_metadata(bdev, map.m_pblk + i);
+ }
/*
* If blocks are delayed marked, we need to
@@ -2322,7 +2283,7 @@ static int mpage_da_map_blocks(struct mpage_da_data *mpd)
*/
if ((mpd->b_state & (1 << BH_Delay)) ||
(mpd->b_state & (1 << BH_Unwritten)))
- mpage_put_bnr_to_bhs(mpd, next, &new);
+ mpage_put_bnr_to_bhs(mpd, &map);
if (ext4_should_order_data(mpd->inode)) {
err = ext4_jbd2_file_inode(handle, mpd->inode);
@@ -2551,8 +2512,9 @@ static int __mpage_da_writepage(struct page *page,
* initialized properly.
*/
static int ext4_da_get_block_prep(struct inode *inode, sector_t iblock,
- struct buffer_head *bh_result, int create)
+ struct buffer_head *bh, int create)
{
+ struct ext4_map_blocks map;
int ret = 0;
sector_t invalid_block = ~((sector_t) 0xffff);
@@ -2560,45 +2522,50 @@ static int ext4_da_get_block_prep(struct inode *inode, sector_t iblock,
invalid_block = ~0;
BUG_ON(create == 0);
- BUG_ON(bh_result->b_size != inode->i_sb->s_blocksize);
+ BUG_ON(bh->b_size != inode->i_sb->s_blocksize);
+
+ map.m_lblk = iblock;
+ map.m_len = 1;
/*
* first, we need to know whether the block is allocated already
* preallocated blocks are unmapped but should treated
* the same as allocated blocks.
*/
- ret = ext4_get_blocks(NULL, inode, iblock, 1, bh_result, 0);
- if ((ret == 0) && !buffer_delay(bh_result)) {
- /* the block isn't (pre)allocated yet, let's reserve space */
- /*
- * XXX: __block_prepare_write() unmaps passed block,
- * is it OK?
- */
- ret = ext4_da_reserve_space(inode, iblock);
- if (ret)
- /* not enough space to reserve */
- return ret;
-
- map_bh(bh_result, inode->i_sb, invalid_block);
- set_buffer_new(bh_result);
- set_buffer_delay(bh_result);
- } else if (ret > 0) {
- bh_result->b_size = (ret << inode->i_blkbits);
- if (buffer_unwritten(bh_result)) {
- /* A delayed write to unwritten bh should
- * be marked new and mapped. Mapped ensures
- * that we don't do get_block multiple times
- * when we write to the same offset and new
- * ensures that we do proper zero out for
- * partial write.
+ ret = ext4_map_blocks(NULL, inode, &map, 0);
+ if (ret < 0)
+ return ret;
+ if (ret == 0) {
+ if (!buffer_delay(bh)) {
+ /*
+ * XXX: __block_prepare_write() unmaps passed
+ * block, is it OK?
*/
- set_buffer_new(bh_result);
- set_buffer_mapped(bh_result);
+ ret = ext4_da_reserve_space(inode, iblock);
+ if (ret)
+ return ret; /* not enough space to reserve */
+
+ map_bh(bh, inode->i_sb, invalid_block);
+ set_buffer_new(bh);
+ set_buffer_delay(bh);
}
- ret = 0;
+ return 0;
}
- return ret;
+ map_bh(bh, inode->i_sb, map.m_pblk);
+ bh->b_state = (bh->b_state & ~EXT4_MAP_FLAGS) | map.m_flags;
+
+ if (buffer_unwritten(bh)) {
+ /* A delayed write to unwritten bh should be marked
+ * new and mapped. Mapped ensures that we don't do
+ * get_block multiple times when we write to the same
+ * offset and new ensures that we do proper zero out
+ * for partial write.
+ */
+ set_buffer_new(bh);
+ set_buffer_mapped(bh);
+ }
+ return 0;
}
/*
@@ -2620,21 +2587,8 @@ static int ext4_da_get_block_prep(struct inode *inode, sector_t iblock,
static int noalloc_get_block_write(struct inode *inode, sector_t iblock,
struct buffer_head *bh_result, int create)
{
- int ret = 0;
- unsigned max_blocks = bh_result->b_size >> inode->i_blkbits;
-
BUG_ON(bh_result->b_size != inode->i_sb->s_blocksize);
-
- /*
- * we don't want to do block allocation in writepage
- * so call get_block_wrap with create = 0
- */
- ret = ext4_get_blocks(NULL, inode, iblock, max_blocks, bh_result, 0);
- if (ret > 0) {
- bh_result->b_size = (ret << inode->i_blkbits);
- ret = 0;
- }
- return ret;
+ return _ext4_get_block(inode, iblock, bh_result, 0);
}
static int bget_one(handle_t *handle, struct buffer_head *bh)
@@ -3569,46 +3523,18 @@ out:
return ret;
}
+/*
+ * ext4_get_block used when preparing for a DIO write or buffer write.
+ * We allocate an uinitialized extent if blocks haven't been allocated.
+ * The extent will be converted to initialized after the IO is complete.
+ */
static int ext4_get_block_write(struct inode *inode, sector_t iblock,
struct buffer_head *bh_result, int create)
{
- handle_t *handle = ext4_journal_current_handle();
- int ret = 0;
- unsigned max_blocks = bh_result->b_size >> inode->i_blkbits;
- int dio_credits;
- int started = 0;
-
ext4_debug("ext4_get_block_write: inode %lu, create flag %d\n",
inode->i_ino, create);
- /*
- * ext4_get_block in prepare for a DIO write or buffer write.
- * We allocate an uinitialized extent if blocks haven't been allocated.
- * The extent will be converted to initialized after IO complete.
- */
- create = EXT4_GET_BLOCKS_IO_CREATE_EXT;
-
- if (!handle) {
- if (max_blocks > DIO_MAX_BLOCKS)
- max_blocks = DIO_MAX_BLOCKS;
- dio_credits = ext4_chunk_trans_blocks(inode, max_blocks);
- handle = ext4_journal_start(inode, dio_credits);
- if (IS_ERR(handle)) {
- ret = PTR_ERR(handle);
- goto out;
- }
- started = 1;
- }
On Mon, 3 May 2010 18:51:21 -0400, "Theodore Ts'o" <[email protected]> wrote:
> @@ -2560,45 +2522,50 @@ static int ext4_da_get_block_prep(struct inode *inode, sector_t iblock,
> invalid_block = ~0;
>
> BUG_ON(create == 0);
> - BUG_ON(bh_result->b_size != inode->i_sb->s_blocksize);
> + BUG_ON(bh->b_size != inode->i_sb->s_blocksize);
> +
> + map.m_lblk = iblock;
> + map.m_len = 1;
>
> /*
> * first, we need to know whether the block is allocated already
> * preallocated blocks are unmapped but should treated
> * the same as allocated blocks.
> */
> - ret = ext4_get_blocks(NULL, inode, iblock, 1, bh_result, 0);
> - if ((ret == 0) && !buffer_delay(bh_result)) {
> - /* the block isn't (pre)allocated yet, let's reserve space */
> - /*
> - * XXX: __block_prepare_write() unmaps passed block,
> - * is it OK?
> - */
> - ret = ext4_da_reserve_space(inode, iblock);
> - if (ret)
> - /* not enough space to reserve */
> - return ret;
> -
> - map_bh(bh_result, inode->i_sb, invalid_block);
> - set_buffer_new(bh_result);
> - set_buffer_delay(bh_result);
> - } else if (ret > 0) {
> - bh_result->b_size = (ret << inode->i_blkbits);
> - if (buffer_unwritten(bh_result)) {
> - /* A delayed write to unwritten bh should
> - * be marked new and mapped. Mapped ensures
> - * that we don't do get_block multiple times
> - * when we write to the same offset and new
> - * ensures that we do proper zero out for
> - * partial write.
> + ret = ext4_map_blocks(NULL, inode, &map, 0);
> + if (ret < 0)
> + return ret;
> + if (ret == 0) {
> + if (!buffer_delay(bh)) {
bh flags are not set here. This check should be based on map.m_flags.
> + /*
> + * XXX: __block_prepare_write() unmaps passed
> + * block, is it OK?
> */
> - set_buffer_new(bh_result);
> - set_buffer_mapped(bh_result);
> + ret = ext4_da_reserve_space(inode, iblock);
> + if (ret)
> + return ret; /* not enough space to reserve */
> +
> + map_bh(bh, inode->i_sb, invalid_block);
> + set_buffer_new(bh);
> + set_buffer_delay(bh);
> }
> - ret = 0;
> + return 0;
> }
>
Only thing i am worried about is we were modifying bh_flags in all
possible confusing ways. We may want to make sure we get the update
correct. I am still going through the patch after applying it to the
tree. So may take more time to look at the full changeset.
-aneesh
On Tue, May 04, 2010 at 03:34:59PM +0530, Aneesh Kumar K. V wrote:
>
> bh flags are not set here. This check should be based on map.m_flags.
Good catch, thanks.
> Only thing i am worried about is we were modifying bh_flags in all
> possible confusing ways. We may want to make sure we get the update
> correct. I am still going through the patch after applying it to the
> tree. So may take more time to look at the full changeset.
I'm concerned about that as well; in fact I'm not sure what we had
before was completely correct, and I *still* have trouble reasoning
about how all the flags work and why we do some of the things that we
do based on how the flags are set --- and that scares me.
XFS doesn't jump through *nearly* as many hoops as we do --- and given
XFS's reputation for complexity, that's saying a lot! --- and I
suspect some of the things we do are mandated by the fs/buffer.c and
fs/direct_io.c, the latter of which does some very strange and
unnatural things with buffer_heads --- and some of the things we do
are based on our own, ext4-specific logic and how we route state
through the many layers of callback functions. I think I've figured
some of this out, but it's gotten very crufty over the course of
ext4's development.
One of the reasons I had for doing this cleanup, in addition to
reducing stack usage (which I have measured as around 120 bytes or so
on an 32-bit system, and I'm sure it's got to be more on a 64-bit
system) was to make explicit how we were modifying the bh_flags. At
least now we can grep for EXT4_MAP_* and see on the places where we
were mucking with things.
- Ted
On Tue, May 04, 2010 at 03:34:59PM +0530, Aneesh Kumar K. V wrote:
> > + ret = ext4_map_blocks(NULL, inode, &map, 0);
> > + if (ret < 0)
> > + return ret;
> > + if (ret == 0) {
> > + if (!buffer_delay(bh)) {
>
> bh flags are not set here. This check should be based on map.m_flags.
Actually, I looked more closely at this again today.
ext4_get_blocks() never messed with BH_DELAY, so this flag would only
be set or not set if it was originally set in the buffer_head before
it had been passed into ext4_get_blocks().
BTW, this is one of the reasons why I really hated the old system. It
was never clear which flags were set by whom, and whether the flags
that had been in the struct bh before it had been passed into
ext4_get_blocks() was random stack garbage, or whether it had meaning,
etc.
I'm still not sure we have it all right, but it's clearly better to
use !buffer_delay(bh), since the buffer_delay flag is one that had
been never touched by ext4_get_blocks().
- Ted