[PATCH v2 3/9] ext4: trim delalloc extent

Zhang Yi
2024-04-10T03:50:50Z

From: Zhang Yi <yi.zhang@huawei.com>

The cached delalloc or hole extent should be trimed to the map->map_len
if we map delalloc blocks in ext4_da_map_blocks(). But it doesn't
trigger any issue now because the map->m_len is always set to one and we
always insert one delayed block once a time. Fix this by trim the extent
once we get one from the cached extent tree, prearing for mapping a
extent with multiple delalloc blocks.

Signed-off-by: Zhang Yi <yi.zhang@huawei.com>
---
fs/ext4/inode.c | 14 ++++++++++----
1 file changed, 10 insertions(+), 4 deletions(-)

diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index 118b0497a954..e4043ddb07a5 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -1734,6 +1734,11 @@ static int ext4_da_map_blocks(struct inode *inode, sector_t iblock,

/* Lookup extent status tree firstly */
if (ext4_es_lookup_extent(inode, iblock, NULL, &es)) {
+ retval = es.es_len - (iblock - es.es_lblk);
+ if (retval > map->m_len)
+ retval = map->m_len;
+ map->m_len = retval;
+
if (ext4_es_is_hole(&es))
goto add_delayed;

@@ -1750,10 +1755,6 @@ static int ext4_da_map_blocks(struct inode *inode, sector_t iblock,
}

map->m_pblk = ext4_es_pblock(&es) + iblock - es.es_lblk;
- retval = es.es_len - (iblock - es.es_lblk);
- if (retval > map->m_len)
- retval = map->m_len;
- map->m_len = retval;
if (ext4_es_is_written(&es))
map->m_flags |= EXT4_MAP_MAPPED;
else if (ext4_es_is_unwritten(&es))
@@ -1788,6 +1789,11 @@ static int ext4_da_map_blocks(struct inode *inode, sector_t iblock,
* whitout holding i_rwsem and folio lock.
*/
if (ext4_es_lookup_extent(inode, iblock, NULL, &es)) {
+ retval = es.es_len - (iblock - es.es_lblk);
+ if (retval > map->m_len)
+ retval = map->m_len;
+ map->m_len = retval;
+
if (!ext4_es_is_hole(&es)) {
up_write(&EXT4_I(inode)->i_data_sem);
goto found;
--
2.39.2