* [PATCH V2] xfs: make sure sb_fdblocks is non-negative
@ 2024-05-31 18:29 Wengang Wang
2024-06-01 4:52 ` Christoph Hellwig
2024-06-01 17:46 ` Darrick J. Wong
0 siblings, 2 replies; 3+ messages in thread
From: Wengang Wang @ 2024-05-31 18:29 UTC (permalink / raw)
To: linux-xfs; +Cc: wen.gang.wang
A user with a completely full filesystem experienced an unexpected
shutdown when the filesystem tried to write the superblock during
runtime.
kernel shows the following dmesg:
[ 8.176281] XFS (dm-4): Metadata corruption detected at xfs_sb_write_verify+0x60/0x120 [xfs], xfs_sb block 0x0
[ 8.177417] XFS (dm-4): Unmount and run xfs_repair
[ 8.178016] XFS (dm-4): First 128 bytes of corrupted metadata buffer:
[ 8.178703] 00000000: 58 46 53 42 00 00 10 00 00 00 00 00 01 90 00 00 XFSB............
[ 8.179487] 00000010: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
[ 8.180312] 00000020: cf 12 dc 89 ca 26 45 29 92 e6 e3 8d 3b b8 a2 c3 .....&E)....;...
[ 8.181150] 00000030: 00 00 00 00 01 00 00 06 00 00 00 00 00 00 00 80 ................
[ 8.182003] 00000040: 00 00 00 00 00 00 00 81 00 00 00 00 00 00 00 82 ................
[ 8.182004] 00000050: 00 00 00 01 00 64 00 00 00 00 00 04 00 00 00 00 .....d..........
[ 8.182004] 00000060: 00 00 64 00 b4 a5 02 00 02 00 00 08 00 00 00 00 ..d.............
[ 8.182005] 00000070: 00 00 00 00 00 00 00 00 0c 09 09 03 17 00 00 19 ................
[ 8.182008] XFS (dm-4): Corruption of in-memory data detected. Shutting down filesystem
[ 8.182010] XFS (dm-4): Please unmount the filesystem and rectify the problem(s)
When xfs_log_sb writes super block to disk, b_fdblocks is fetched from
m_fdblocks without any lock. As m_fdblocks can experience a positive -> negative
-> positive changing when the FS reaches fullness (see xfs_mod_fdblocks)
So there is a chance that sb_fdblocks is negative, and because sb_fdblocks is
type of unsigned long long, it reads super big. And sb_fdblocks being bigger
than sb_dblocks is a problem during log recovery, xfs_validate_sb_write()
complains.
Fix:
As sb_fdblocks will be re-calculated during mount when lazysbcount is enabled,
We just need to make xfs_validate_sb_write() happy -- make sure sb_fdblocks is
not nenative.
Signed-off-by: Wengang Wang <wen.gang.wang@oracle.com>
---
V1 -> V2: add problem symptoms in patch description.
---
fs/xfs/libxfs/xfs_sb.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/fs/xfs/libxfs/xfs_sb.c b/fs/xfs/libxfs/xfs_sb.c
index 09e4bf949bf8..6dc0731e82e8 100644
--- a/fs/xfs/libxfs/xfs_sb.c
+++ b/fs/xfs/libxfs/xfs_sb.c
@@ -1042,7 +1042,7 @@ xfs_log_sb(
mp->m_sb.sb_ifree = min_t(uint64_t,
percpu_counter_sum(&mp->m_ifree),
mp->m_sb.sb_icount);
- mp->m_sb.sb_fdblocks = percpu_counter_sum(&mp->m_fdblocks);
+ mp->m_sb.sb_fdblocks = percpu_counter_sum_positive(&mp->m_fdblocks);
}
xfs_sb_to_disk(bp->b_addr, &mp->m_sb);
--
2.39.3 (Apple Git-146)
^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [PATCH V2] xfs: make sure sb_fdblocks is non-negative
2024-05-31 18:29 [PATCH V2] xfs: make sure sb_fdblocks is non-negative Wengang Wang
@ 2024-06-01 4:52 ` Christoph Hellwig
2024-06-01 17:46 ` Darrick J. Wong
1 sibling, 0 replies; 3+ messages in thread
From: Christoph Hellwig @ 2024-06-01 4:52 UTC (permalink / raw)
To: Wengang Wang; +Cc: linux-xfs
On Fri, May 31, 2024 at 11:29:18AM -0700, Wengang Wang wrote:
> - mp->m_sb.sb_fdblocks = percpu_counter_sum(&mp->m_fdblocks);
> + mp->m_sb.sb_fdblocks = percpu_counter_sum_positive(&mp->m_fdblocks);
Please break the line to ensure it isn't overly long
mp->m_sb.sb_fdblocks =
percpu_counter_sum_positive(&mp->m_fdblocks);
With that:
Reviewed-by: Christoph Hellwig <hch@lst.de>
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH V2] xfs: make sure sb_fdblocks is non-negative
2024-05-31 18:29 [PATCH V2] xfs: make sure sb_fdblocks is non-negative Wengang Wang
2024-06-01 4:52 ` Christoph Hellwig
@ 2024-06-01 17:46 ` Darrick J. Wong
1 sibling, 0 replies; 3+ messages in thread
From: Darrick J. Wong @ 2024-06-01 17:46 UTC (permalink / raw)
To: Wengang Wang; +Cc: linux-xfs
On Fri, May 31, 2024 at 11:29:18AM -0700, Wengang Wang wrote:
> A user with a completely full filesystem experienced an unexpected
> shutdown when the filesystem tried to write the superblock during
> runtime.
> kernel shows the following dmesg:
>
> [ 8.176281] XFS (dm-4): Metadata corruption detected at xfs_sb_write_verify+0x60/0x120 [xfs], xfs_sb block 0x0
> [ 8.177417] XFS (dm-4): Unmount and run xfs_repair
> [ 8.178016] XFS (dm-4): First 128 bytes of corrupted metadata buffer:
> [ 8.178703] 00000000: 58 46 53 42 00 00 10 00 00 00 00 00 01 90 00 00 XFSB............
> [ 8.179487] 00000010: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
> [ 8.180312] 00000020: cf 12 dc 89 ca 26 45 29 92 e6 e3 8d 3b b8 a2 c3 .....&E)....;...
> [ 8.181150] 00000030: 00 00 00 00 01 00 00 06 00 00 00 00 00 00 00 80 ................
> [ 8.182003] 00000040: 00 00 00 00 00 00 00 81 00 00 00 00 00 00 00 82 ................
> [ 8.182004] 00000050: 00 00 00 01 00 64 00 00 00 00 00 04 00 00 00 00 .....d..........
> [ 8.182004] 00000060: 00 00 64 00 b4 a5 02 00 02 00 00 08 00 00 00 00 ..d.............
> [ 8.182005] 00000070: 00 00 00 00 00 00 00 00 0c 09 09 03 17 00 00 19 ................
> [ 8.182008] XFS (dm-4): Corruption of in-memory data detected. Shutting down filesystem
> [ 8.182010] XFS (dm-4): Please unmount the filesystem and rectify the problem(s)
>
> When xfs_log_sb writes super block to disk, b_fdblocks is fetched from
> m_fdblocks without any lock. As m_fdblocks can experience a positive -> negative
> -> positive changing when the FS reaches fullness (see xfs_mod_fdblocks)
> So there is a chance that sb_fdblocks is negative, and because sb_fdblocks is
> type of unsigned long long, it reads super big. And sb_fdblocks being bigger
> than sb_dblocks is a problem during log recovery, xfs_validate_sb_write()
> complains.
>
> Fix:
> As sb_fdblocks will be re-calculated during mount when lazysbcount is enabled,
> We just need to make xfs_validate_sb_write() happy -- make sure sb_fdblocks is
> not nenative.
>
> Signed-off-by: Wengang Wang <wen.gang.wang@oracle.com>
With hch's comment about long lines addressed,
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
--D
> ---
> V1 -> V2: add problem symptoms in patch description.
> ---
> fs/xfs/libxfs/xfs_sb.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/fs/xfs/libxfs/xfs_sb.c b/fs/xfs/libxfs/xfs_sb.c
> index 09e4bf949bf8..6dc0731e82e8 100644
> --- a/fs/xfs/libxfs/xfs_sb.c
> +++ b/fs/xfs/libxfs/xfs_sb.c
> @@ -1042,7 +1042,7 @@ xfs_log_sb(
> mp->m_sb.sb_ifree = min_t(uint64_t,
> percpu_counter_sum(&mp->m_ifree),
> mp->m_sb.sb_icount);
> - mp->m_sb.sb_fdblocks = percpu_counter_sum(&mp->m_fdblocks);
> + mp->m_sb.sb_fdblocks = percpu_counter_sum_positive(&mp->m_fdblocks);
> }
>
> xfs_sb_to_disk(bp->b_addr, &mp->m_sb);
> --
> 2.39.3 (Apple Git-146)
>
>
^ permalink raw reply [flat|nested] 3+ messages in thread
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2024-05-31 18:29 [PATCH V2] xfs: make sure sb_fdblocks is non-negative Wengang Wang
2024-06-01 4:52 ` Christoph Hellwig
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