On 8/31/23 7:39 AM, Ritesh Harjani (IBM) wrote:
> "Darrick J. Wong" <djwong@xxxxxxxxxx> writes:
>
>> From: Darrick J. Wong <djwong@xxxxxxxxxx>
>>
>> shrikanth hegde reports that filesystems fail shortly after mount with
>> the following failure:
>>
>> WARNING: CPU: 56 PID: 12450 at fs/xfs/xfs_inode.c:1839 xfs_iunlink_lookup+0x58/0x80 [xfs]
>>
>> This of course is the WARN_ON_ONCE in xfs_iunlink_lookup:
>>
>> ip = radix_tree_lookup(&pag->pag_ici_root, agino);
>> if (WARN_ON_ONCE(!ip || !ip->i_ino)) { ... }
>>
>> From diagnostic data collected by the bug reporters, it would appear
>> that we cleanly mounted a filesystem that contained unlinked inodes.
>> Unlinked inodes are only processed as a final step of log recovery,
>> which means that clean mounts do not process the unlinked list at all.
>>
>> Prior to the introduction of the incore unlinked lists, this wasn't a
>> problem because the unlink code would (very expensively) traverse the
>> entire ondisk metadata iunlink chain to keep things up to date.
>> However, the incore unlinked list code complains when it realizes that
>> it is out of sync with the ondisk metadata and shuts down the fs, which
>> is bad.
>>
>> Ritesh proposed to solve this problem by unconditionally parsing the
>> unlinked lists at mount time, but this imposes a mount time cost for
>> every filesystem to catch something that should be very infrequent.
>> Instead, let's target the places where we can encounter a next_unlinked
>> pointer that refers to an inode that is not in cache, and load it into
>> cache.
>>
>> Note: This patch does not address the problem of iget loading an inode
>> from the middle of the iunlink list and needing to set i_prev_unlinked
>> correctly.
>>
>> Reported-by: shrikanth hegde <sshegde@xxxxxxxxxxxxxxxxxx>
>> Triaged-by: Ritesh Harjani <ritesh.list@xxxxxxxxx>
>> Signed-off-by: Darrick J. Wong <djwong@xxxxxxxxxx>
>> ---
>> v2: log that we're doing runtime recovery, dont mess with DONTCACHE,
>> and actually return ENOLINK
>> ---
>> fs/xfs/xfs_inode.c | 75 +++++++++++++++++++++++++++++++++++++++++++++++++---
>> fs/xfs/xfs_trace.h | 25 +++++++++++++++++
>> 2 files changed, 96 insertions(+), 4 deletions(-)
>
> Hi Darrick,
>
> Thanks for taking a look at this. I tested this patch on the setup where
> Shrikanth earlier saw the crash. I still can see a problem. I saw it is
> taking the branch from
>
> + /* If this is not an unlinked inode, something is very wrong. */
> + if (VFS_I(next_ip)->i_nlink != 0) {
> + error = -EFSCORRUPTED;
> + goto rele;
> + }
>
> Here are the logs of reference -
>
> [ 21.399573] XFS (dm-0): Found unrecovered unlinked inode 0x2ec44d in AG 0x0. Initiating recovery.
> [ 21.400150] XFS (dm-0): Internal error xfs_trans_cancel at line 1104 of file fs/xfs/xfs_trans.c. Caller xfs_remove+0x1a0/0x310 [xfs]
Do you have a metadump for that filesystem, to examine that inode?
-Eric
> [ 21.400222] CPU: 0 PID: 1629 Comm: systemd-tmpfile Not tainted 6.5.0+ #2
> [ 21.400226] Hardware name: IBM,9080-HEX POWER10 (raw) 0x800200 0xf000006 of:IBM,FW1010.22 (NH1010_122) hv:phyp pSeries
> [ 21.400230] Call Trace:
> [ 21.400231] [c000000014cdbb70] [c000000000f377b8] dump_stack_lvl+0x6c/0x9c (unreliable)
> [ 21.400239] [c000000014cdbba0] [c008000000f7c204] xfs_error_report+0x5c/0x80 [xfs]
> [ 21.400303] [c000000014cdbc00] [c008000000fab320] xfs_trans_cancel+0x178/0x1b0 [xfs]
> [ 21.400371] [c000000014cdbc50] [c008000000f999d8] xfs_remove+0x1a0/0x310 [xfs]
> [ 21.400432] [c000000014cdbcc0] [c008000000f93eb0] xfs_vn_unlink+0x68/0xf0 [xfs]
> [ 21.400493] [c000000014cdbd20] [c0000000005b8038] vfs_rmdir+0x178/0x300
> [ 21.400498] [c000000014cdbd60] [c0000000005be444] do_rmdir+0x124/0x240
> [ 21.400502] [c000000014cdbdf0] [c0000000005be594] sys_rmdir+0x34/0x50
> [ 21.400506] [c000000014cdbe10] [c000000000033c38] system_call_exception+0x148/0x3a0
> [ 21.400511] [c000000014cdbe50] [c00000000000c6d4] system_call_common+0xf4/0x258
