linux-kernel - [PATCH v2] f2fs: fix to update map->m_next_extent correctly in f2fs_map

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Message-Id: <20250912081250.44383-1-chao@kernel.org>
Date: Fri, 12 Sep 2025 16:12:50 +0800
From: Chao Yu <chao@...nel.org>
To: jaegeuk@...nel.org
Cc: linux-f2fs-devel@...ts.sourceforge.net,
	linux-kernel@...r.kernel.org,
	Chao Yu <chao@...nel.org>
Subject: [PATCH v2] f2fs: fix to update map->m_next_extent correctly in f2fs_map_blocks()

Script to reproduce:
mkfs.f2fs -O extra_attr,compression /dev/vdb -f
mount /dev/vdb /mnt/f2fs -o mode=lfs,noextent_cache
cd /mnt/f2fs
f2fs_io write 1 0 1024 rand dsync testfile
xfs_io testfile -c "fsync"
f2fs_io write 1 0 512 rand dsync 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

Tracepoint output:
f2fs_update_read_extent_tree_range: dev = (253,16), ino = 4, pgofs = 0, len = 512, blkaddr = 1055744, c_len = 0
f2fs_update_read_extent_tree_range: dev = (253,16), ino = 4, pgofs = 513, len = 351, blkaddr = 17921, c_len = 0
f2fs_update_read_extent_tree_range: dev = (253,16), ino = 4, pgofs = 864, len = 160, blkaddr = 18272, c_len = 0

During precache_extents, there is off-by-one issue, we should update
map->m_next_extent to pgofs rather than pgofs + 1, if last blkaddr is
valid and not contiguous to previous extent.

Fixes: c4020b2da4c9 ("f2fs: support F2FS_IOC_PRECACHE_EXTENTS")
Signed-off-by: Chao Yu <chao@...nel.org>
---
v2:
- clean up codes
 fs/f2fs/data.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c
index 6bb03add93fe..d747850e765f 100644
--- a/fs/f2fs/data.c
+++ b/fs/f2fs/data.c
@@ -1782,7 +1782,7 @@ int f2fs_map_blocks(struct inode *inode, struct f2fs_map_blocks *map, int flag)
 				map->m_len - ofs);
 		}
 		if (map->m_next_extent)
-			*map->m_next_extent = pgofs + 1;
+			*map->m_next_extent = is_hole ? pgofs + 1 : pgofs;
 	}
 	f2fs_put_dnode(&dn);
 unlock_out:
-- 
2.40.1