On 9/11/2025 5:07 PM, wangzijie wrote:
On 9/10/25 21:58, wangzijie wrote:
When the data layout is like this:
dnode1: dnode2:
[0] A [0] NEW_ADDR
[1] A+1 [1] 0x0
... ....
[1016] A+1016
[1017] B (B!=A+1017) [1017] 0x0
We can build this kind of layout by following steps(with i_extra_isize:36):
./f2fs_io write 1 0 1881 rand dsync testfile
./f2fs_io write 1 1881 1 rand buffered testfile
./f2fs_io fallocate 0 7708672 4096 testfile
And when we map first data block in dnode2, we will get wrong extent_info data:
map->m_len = 1
ofs = start_pgofs - map->m_lblk = 1882 - 1881 = 1
ei.fofs = start_pgofs = 1882
ei.len = map->m_len - ofs = 1 - 1 = 0
Fix it by skipping updating this kind of extent info.
Signed-off-by: wangzijie <wangzij...@honor.com>
---
fs/f2fs/data.c | 3 +++
1 file changed, 3 insertions(+)
diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c
index 7961e0ddf..b8bb71852 100644
--- a/fs/f2fs/data.c
+++ b/fs/f2fs/data.c
@@ -1649,6 +1649,9 @@ int f2fs_map_blocks(struct inode *inode, struct
f2fs_map_blocks *map, int flag)
switch (flag) {
case F2FS_GET_BLOCK_PRECACHE:
+ if (__is_valid_data_blkaddr(map->m_pblk) &&
+ start_pgofs - map->m_lblk == map->m_len)
+ map->m_flags &= ~F2FS_MAP_MAPPED;
It looks we missed to reset value for map variable in f2fs_precache_extents(),
what do you think of this?
---
fs/f2fs/file.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c
index 1aae4361d0a8..2b14151d4130 100644
--- a/fs/f2fs/file.c
+++ b/fs/f2fs/file.c
@@ -3599,7 +3599,7 @@ static int f2fs_ioc_io_prio(struct file *filp, unsigned
long arg)
int f2fs_precache_extents(struct inode *inode)
{
struct f2fs_inode_info *fi = F2FS_I(inode);
- struct f2fs_map_blocks map;
+ struct f2fs_map_blocks map = { 0 };
pgoff_t m_next_extent;
loff_t end;
int err;
@@ -3617,6 +3617,8 @@ int f2fs_precache_extents(struct inode *inode)
while (map.m_lblk < end) {
map.m_len = end - map.m_lblk;
+ map.m_pblk = 0;
+ map.m_flags = 0;
f2fs_down_write(&fi->i_gc_rwsem[WRITE]);
err = f2fs_map_blocks(inode, &map, F2FS_GET_BLOCK_PRECACHE);
--
2.49.0
Thanks,
goto sync_out;
case F2FS_GET_BLOCK_BMAP:
map->m_pblk = 0;
We have already reset m_flags (map->m_flags = 0) in f2fs_map_blocks().
Zijie:
Oops, that's right, thanks for correcting me.
I think that this bug is caused by we missed to reset m_flags when we
goto next_dnode in below caseļ¼
Data layout is something like this:
dnode1: dnode2:
[0] A [0] NEW_ADDR
[1] A+1 [1] 0x0
...
[1016] A+1016
[1017] B (B!=A+1017) [1017] 0x0
we map the last block(valid blkaddr) in dnode1:
map->m_flags |= F2FS_MAP_MAPPED;
map->m_pblk = blkaddr(valid blkaddr);
map->m_len = 1;
then we goto next_dnode, meet the first block in dnode2(hole), goto sync_out:
map->m_flags & F2FS_MAP_MAPPED == true, and we make wrong blkaddr/len for
extent_info.
So, can you please add above explanation into commit message? that
should be helpful for understanding the problem more clearly.
Please take a look at this case w/ your patch:
mkfs.f2fs -O extra_attr,compression /dev/vdb -f
mount /dev/vdb /mnt/f2fs -o mode=lfs
cd /mnt/f2fs
f2fs_io write 1 0 1883 rand dsync testfile
f2fs_io fallocate 0 7712768 4096 testfile
f2fs_io write 1 1881 1 rand buffered testfile
xfs_io testfile -c "fsync"
cd /
umount /mnt/f2fs
mount /dev/vdb /mnt/f2fs
f2fs_io precache_extents /mnt/f2fs/testfile
umount /mnt/f2fs
f2fs_io-733 [010] ..... 78.134136:
f2fs_update_read_extent_tree_range: dev = (253,16), ino = 4, pgofs = 1882, len
= 0, blkaddr = 17410, c_len = 0
I suspect we need this?
@@ -1784,7 +1781,8 @@ int f2fs_map_blocks(struct inode *inode, struct
f2fs_map_blocks *map, int flag)
}
if (flag == F2FS_GET_BLOCK_PRECACHE) {
- if (map->m_flags & F2FS_MAP_MAPPED) {
+ if ((map->m_flags & F2FS_MAP_MAPPED) &&
+ (map->m_len - ofs)) {
unsigned int ofs = start_pgofs - map->m_lblk;
f2fs_update_read_extent_cache_range(&dn,
BTW, I find another bug, if one blkaddr is adjcent to previous extent,
but and it is valid, we need to set m_next_extent to pgofs rather than
pgofs + 1.
diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c
index cbf8841642c7..ac88ed68059c 100644
--- a/fs/f2fs/data.c
+++ b/fs/f2fs/data.c
@@ -1789,8 +1789,11 @@ int f2fs_map_blocks(struct inode *inode, struct
f2fs_map_blocks *map, int flag)
start_pgofs, map->m_pblk + ofs,
map->m_len - ofs);
}
- if (map->m_next_extent)
- *map->m_next_extent = pgofs + 1;
+ if (map->m_next_extent) {
+ *map->m_next_extent = pgofs;
+ if (!__is_valid_data_blkaddr(blkaddr))
+ *map->m_next_extent += 1;
+ }
}
f2fs_put_dnode(&dn);
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