[PATCH 6.6 004/105] f2fs: fix wrong block mapping for multi-devices

Greg Kroah-Hartman
2025-10-21T19:52:43Z

From: Jaegeuk Kim <jaegeuk@kernel.org>

commit 9d5c4f5c7a2c7677e1b3942772122b032c265aae upstream.

Assuming the disk layout as below,

disk0: 0 --- 0x00035abfff
disk1: 0x00035ac000 --- 0x00037abfff
disk2: 0x00037ac000 --- 0x00037ebfff

and we want to read data from offset=13568 having len=128 across the block
devices, we can illustrate the block addresses like below.

0 .. 0x00037ac000 ------------------- 0x00037ebfff, 0x00037ec000 -------
| ^ ^ ^
| fofs 0 13568 13568+128
| ------------------------------------------------------
| LBA 0x37e8aa9 0x37ebfa9 0x37ec029
--- map 0x3caa9 0x3ffa9

In this example, we should give the relative map of the target block device
ranging from 0x3caa9 to 0x3ffa9 where the length should be calculated by
0x37ebfff + 1 - 0x37ebfa9.

In the below equation, however, map->m_pblk was supposed to be the original
address instead of the one from the target block address.

- map->m_len = min(map->m_len, dev->end_blk + 1 - map->m_pblk);

Cc: stable@vger.kernel.org
Fixes: 71f2c8206202 ("f2fs: multidevice: support direct IO")
Reviewed-by: Chao Yu <chao@kernel.org>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
fs/f2fs/data.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

--- a/fs/f2fs/data.c
+++ b/fs/f2fs/data.c
@@ -1506,8 +1506,8 @@ static bool f2fs_map_blocks_cached(struc
struct f2fs_dev_info *dev = &sbi->devs[bidx];

map->m_bdev = dev->bdev;
- map->m_pblk -= dev->start_blk;
map->m_len = min(map->m_len, dev->end_blk + 1 - map->m_pblk);
+ map->m_pblk -= dev->start_blk;
} else {
map->m_bdev = inode->i_sb->s_bdev;
}