Re: xfs_iunlink_remove: xfs_inotobp() returned error 22 -- debugging

[Brian Foster <bfoster@redhat.com>]

On 04/20/2013 06:10 AM, 符永涛 wrote:
> Dear Eric,
> I have applied your latest patch and collected the following log:
> 
> /var/log/message
> Apr 20 17:28:23 10 kernel: XFS (sdb): xfs_iunlink_remove: xfs_inotobp()
> returned error 22 for inode 0x1b20b ag 0 agino 1b20b
> Apr 20 17:28:23 10 kernel:
> Apr 20 17:28:23 10 kernel: XFS (sdb): xfs_inactive: xfs_ifree returned
> error 22
> Apr 20 17:28:23 10 kernel: XFS (sdb): xfs_do_force_shutdown(0x1) called
> from line 1184 of file fs/xfs/xfs_vnodeops.c.  Return address =
> 0xffffffffa02d4d0a
> Apr 20 17:28:23 10 kernel: XFS (sdb): I/O Error Detected. Shutting down
> filesystem
> Apr 20 17:28:23 10 kernel: XFS (sdb): Please umount the filesystem and
> rectify the problem(s)
> Apr 20 17:28:37 10 kernel: XFS (sdb): xfs_log_force: error 5 returned.
> Apr 20 17:29:07 10 kernel: XFS (sdb): xfs_log_force: error 5 returned.
> Apr 20 17:29:37 10 kernel: XFS (sdb): xfs_log_force: error 5 returned.
> Apr 20 17:30:07 10 kernel: XFS (sdb): xfs_log_force: error 5 returned.
> 
> debugfs trace:
> https://docs.google.com/file/d/0B7n2C4T5tfNCTlZGUVpnZENrZ3M/edit?usp=sharing
> 

FWIW...

<...>-6908  [001]  8739.967623: xfs_iunlink: dev 8:16 ino 0x83a8b mode
0100000, flags 0x0
<...>-6909  [001]  8739.970252: xfs_iunlink: dev 8:16 ino 0x83a8b mode
0100000, flags 0x0

0x83a8b and 0x1b20b both hash to unlinked list bucket 11.

As to the rest of the trace, there appears to be a significant amount of
link activity on (directory) inode 0x83a8a (the immediately prior inode
to the inode involved in the race). The name data in the trace suggests
activity somewhere under .glusterfs. A couple questions:

1.) Any idea what entries point to this inode right now (e.g., how many
links on this inode) and where it resides in the fs (path)?

2.) Can you associate this kind of heavy remove/link pattern on a single
inode to a higher level activity? For example, if you were to watch the
trace data live, is this a normal pattern you observe? Does it only
occur when a rebalance is in progress? Or when a rebalance finishes? Any
detailed observations you can make in that regard could be helpful.

Brian

> Thank you.
> 
> 
> 2013/4/20 符永涛 <yongtaofu@gmail.com <mailto:yongtaofu@gmail.com>>
> 
>     Hi Eric,
>     The xfs module is loaded from system kernel, it happens on our
>     production server too (I did not touch that till now) and if the xfs
>     module is mess up the systemstap may also not working but now it
>     works. As you have mentioned, strange thing is xfs shutdown always
>     happens when glusterfs rebalance completes.
> 
> 
>     2013/4/20 Eric Sandeen <sandeen@sandeen.net
>     <mailto:sandeen@sandeen.net>>
> 
>         On 4/19/13 9:03 PM, 符永涛 wrote:
>         > Hi Eric,
>         > I will enable them and run test again. I can only reproduce it
>         with
>         > glusterfs rebalance. Glusterfs uses a mechanism it called
>         syncop to
>         > unlink file. For rebalance it uses
>         > syncop_unlink(glusterfs/libglusterfs/src/syncop.c). In the
>         glusterfs
>         > sync_task framework(glusterfs/libglusterfs/src/syncop.c) it uses
>         > "makecontext/swapcontext"
>         >
>         <http://www.opengroup.org/onlinepubs/009695399/functions/makecontext.html>.
>         > Does it leads to racing unlink from different CPU core?
> 
>         Yep, I understand that it's rebalance.  It dies when rebalance
>         finishes because an
>         open but unlinked file trips over the corrupted list from
>         earlier, it seems.
> 
>         I don't know why makecontext would matter...
> 
>         Just to be sure, you are definitely loading the xfs module from
>         the kernel you built, right, and you don't have a "priority"
>         module getting loaded from elsewhere?  Seems unlikely, but just
>         to be sure.
> 
>         > Thank you.
> 
>         You could also add this patch to the xfs tracepoints to print
>         more information about the inodes - the mode & flags.
> 
>         -Eric
> 
> 
>         diff --git a/fs/xfs/linux-2.6/xfs_trace.h
>         b/fs/xfs/linux-2.6/xfs_trace.h
>         index e8ce644..c314b87 100644
>         --- a/fs/xfs/linux-2.6/xfs_trace.h
>         +++ b/fs/xfs/linux-2.6/xfs_trace.h
>         @@ -544,14 +544,18 @@ DECLARE_EVENT_CLASS(xfs_inode_class,
>                 TP_STRUCT__entry(
>                         __field(dev_t, dev)
>                         __field(xfs_ino_t, ino)
>         +               __field(__u16, mode)
>         +               __field(unsigned long, flags)
>                 ),
>                 TP_fast_assign(
>                         __entry->dev = VFS_I(ip)->i_sb->s_dev;
>                         __entry->ino = ip->i_ino;
>         +               __entry->mode = VFS_I(ip)->i_mode;
>         +               __entry->flags = ip->i_flags;
>                 ),
>         -       TP_printk("dev %d:%d ino 0x%llx",
>         +       TP_printk("dev %d:%d ino 0x%llx mode 0%o, flags 0x%lx",
>                           MAJOR(__entry->dev), MINOR(__entry->dev),
>         -                 __entry->ino)
>         +                 __entry->ino, __entry->mode, __entry->flags)
>          )
> 
>          #define DEFINE_INODE_EVENT(name) \
> 
> 
> 
> 
> 
> 
>     -- 
>     符永涛
> 
> 
> 
> 
> -- 
> 符永涛

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