f2fs: fix summary info corruption
Sometimes, after running generic/270 of fstest, fsck reports summary
info and actual position of block address in direct node becoming
inconsistent.
The root cause is race in between __f2fs_replace_block and change_curseg
as below:
Thread A Thread B
- __clone_blkaddrs
- f2fs_replace_block
- __f2fs_replace_block
- segnoA = GET_SEGNO(sbi, blkaddrA);
- type = se->type:=CURSEG_HOT_DATA
- if (!IS_CURSEG(sbi, segnoA))
type = CURSEG_WARM_DATA
- allocate_data_block
- allocate_segment
- get_ssr_segment
- change_curseg(segnoA, CURSEG_HOT_DATA)
- change_curseg(segnoA, CURSEG_WARM_DATA)
- reset_curseg
- __set_sit_entry_type
- change se->type from CURSEG_HOT_DATA to CURSEG_WARM_DATA
So finally, hot curseg locates in segnoA, but type of segnoA becomes
CURSEG_WARM_DATA.
Then if we invoke __f2fs_replace_block(blkaddrB, blkaddrA, true, false),
as blkaddrA locates in segnoA, so we will move warm type curseg to segnoA,
then change its summary cache and writeback it to summary block.
But segnoA is used by hot type curseg too, once it moves or persist, it
will cover summary block content with inner old summary cache, result in
inconsistent status.
This patch tries to fix this issue by introduce global curseg lock to avoid
race in between __f2fs_replace_block and change_curseg.
Signed-off-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
index aadf553..866d749 100644
--- a/fs/f2fs/f2fs.h
+++ b/fs/f2fs/f2fs.h
@@ -818,6 +818,8 @@
struct dirty_seglist_info *dirty_info; /* dirty segment information */
struct curseg_info *curseg_array; /* active segment information */
+ struct rw_semaphore curseg_lock; /* for preventing curseg change */
+
block_t seg0_blkaddr; /* block address of 0'th segment */
block_t main_blkaddr; /* start block address of main area */
block_t ssa_blkaddr; /* start block address of SSA area */