Re: ZFS: Listable but un-stat():able snapshot

If memory serves me right, Peter Schuller wrote:
> Hello,
> 
> first off, this is on a machine running CURRENT from ~ 2007-05-08, so perhaps 
> this is no longer an issue. But I don't remember reading about it anywhere.
> 
> zfs list contains among other things (full path obscured, but otherwise 
> exactly as-is):
> 
> XXX_at_rsync                      0      -   146G  -
> XXX_at_200708181011               0      -   146G  -
> XXX_at_rsync2                  126K      -   146G  -
> 
> I took the first two snapshots rapidly in succession after each other - I 
> believe without any I/O to the fs in between. After I could not "cd" into the 
> rsync snapshot, I took another one (rsync2) for testing.
> 
> ls XXX/.zfs/snapshot:
> 
> 200708122313    200708180037    200708181011    rsync           rsync2
> 
> ls -l XXX/.zfs/snapshot (username obscured):
> 
> ls: rsync: No such file or directory
> drwx------  12 YYY YYY  43 Aug 12 22:31 200708122313
> drwx------  12 YYY YYY  43 Aug 18 00:30 200708180037
> drwx------  12 YYY YYY  43 Aug 18 09:30 200708181011
> drwx------  12 YYY YYY  43 Aug 18 09:30 rsync2
> 
> cd XXX/.zfs/snapshot/rsync:
> 
> cd: no such file or directory: XXX/.zfs/snapshot/rsync

I've seen something similar to this (several months ago?).  But I wasn't
able to do much more investigation, nor was I able to reproduce the
problem reliably.  pjd_at_ and I talked about it briefly and while we
agreed there was a problem, it wasn't obvious what it was.  I think I
made the problem go away with a reboot.

Bruce.

> Excerpt of kdump after ktrace ls -l:
> 
>  55508 ls       CALL  getdirentries(0x5,0x28214000,0x1000,0x28213054)
>  55508 ls       RET   getdirentries 128/0x80
>  55508 ls       CALL  lstat(0x28216168,0x28216108)
>  55508 ls       NAMI  "200708181011"
>  55508 ls       RET   lstat 0
>  55508 ls       CALL  lstat(0x28216228,0x282161c8)
>  55508 ls       NAMI  "200708180037"
>  55508 ls       RET   lstat 0
>  55508 ls       CALL  lstat(0x282162e8,0x28216288)
>  55508 ls       NAMI  "200708122313"
>  55508 ls       RET   lstat 0
>  55508 ls       CALL  lstat(0x28211268,0x28211208)
>  55508 ls       NAMI  "rsync2"
>  55508 ls       RET   lstat 0
>  55508 ls       CALL  lstat(0x28211318,0x282112b8)
>  55508 ls       NAMI  "rsync"
>  55508 ls       RET   lstat -1 errno 2 No such file or directory
> 
> I still have the snapshot on the machine and such if anybody wants me to run 
> some diagnostic commands.
>