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![]() [ Upstream commit 8175c864391753b210f3dcfae1aeed686a226ebb ]
Script to reproduce:
f2fs_io write 1 0 1881 rand dsync testfile
f2fs_io fallocate 0 7708672 4096 testfile
f2fs_io write 1 1881 1 rand buffered testfile
fsync testfile
umount
mount
f2fs_io precache_extents testfile
When the 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
During precache_extents, 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 zero-sized extent:
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
Rebased on patch[1], this patch can cover these cases to avoid zero-sized extent:
A,B,C is valid blkaddr
case1:
dnode1: dnode2:
[0] A [0] NEW_ADDR
[1] A+1 [1] 0x0
... ....
[1016] A+1016
[1017] B (B!=A+1017) [1017] 0x0
case2:
dnode1: dnode2:
[0] A [0] C (C!=B+1)
[1] A+1 [1] C+1
... ....
[1016] A+1016
[1017] B (B!=A+1017) [1017] 0x0
case3:
dnode1: dnode2:
[0] A [0] C (C!=B+2)
[1] A+1 [1] C+1
... ....
[1015] A+1015
[1016] B (B!=A+1016)
[1017] B+1 [1017] 0x0
[1] https://lore.kernel.org/linux-f2fs-devel/20250912081250.44383-1-chao@kernel.org/
Fixes:
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.. | ||
acl.c | ||
acl.h | ||
checkpoint.c | ||
compress.c | ||
data.c | ||
debug.c | ||
dir.c | ||
extent_cache.c | ||
f2fs.h | ||
file.c | ||
gc.c | ||
gc.h | ||
hash.c | ||
inline.c | ||
inode.c | ||
iostat.c | ||
iostat.h | ||
Kconfig | ||
Makefile | ||
namei.c | ||
node.c | ||
node.h | ||
recovery.c | ||
segment.c | ||
segment.h | ||
shrinker.c | ||
super.c | ||
sysfs.c | ||
verity.c | ||
xattr.c | ||
xattr.h |