[Linux-cluster] GFS2/DLM deadlock

Jason Henderson sonredhen at gmail.com
Sun Sep 9 21:31:58 UTC 2012

On Sep 8, 2012 9:44 AM, "Bob Peterson" <rpeterso at redhat.com> wrote:
> ----- Original Message -----
> | A question on the inode numbers in the hangalyzer output.
> |
> | In the glock dump for node2 you have these lines:
> | G:  s:SH n:2/81523 f:dq t:SH d:UN/0 l:0 a:0 r:4 m:100
> |     I: n:126/529699 t:4 f:0x10 d:0x00000001 s:3864/3864
> |
> | >From docs I've read I understand that the glock field 'n:2/81523'
> | tells me that 81523 is the inode number in hex (if then type is 2 or
> | 5).
> | What are the fields in the inode line following the glock mean (at
> | least the n: field)?
> The numbers after the n: are the glock identifier. It consists of
> the glock type (2 for inode, 3 for rgrp, 5 for i_open, and a bunch
> of special ones) followed by "/" followed by the inode number
> (disk inode's block address) in hex.
> After f: are the glock flags. For example, "q" means the glock is
> queued. There are a bunch of flags with a bunch of meanings.
> t: is the target glock state; the lock state it's trying to achieve.
> SH is for a shared lock, EX is exclusive, UN is unlocked, etc.
> d: is the demote glock state; the lock state it needs to transition
> to when the lock is demoted. In this case, demote to UNlocked.
> The number after the slash is the demote time.
> a: is active items count, or the number of "live" buffers to be written.
> r: is the revoke count, or the number of journal items needing to be
>    revoked due to delete, etc.
> m: is the minimum hold time for the glock, in milliseconds.
> On the next line, I: indicates this glock is for an inode.
> n:126 is a formal inode number (can be ignored). The number after the
> slash, 529699, is the inode disk address in decimal.
> t: is the mode, f: are the inode flags, d: are the disk flags, and
> s: is the inode's size in decimal. Before the slash is the size stored
> in one of our internal structures. After the slash is the size
> according to the vfs inode. In almost all cases they should be the same.
> Note that the format of these fields, the flags, and everything
> differs from release to release. For example, newer versions of GFS2
> don't have two different numbers for inode size.

I'm not clear on the two different inode numbers in the two lines above:
Which n: number do I use to locate the file the lock is for? The one in the
glock line or the one in the I: line? From RedHat docs I have read, I
should convert the 81523 (from the '2/ 81523') to decimal, which is  533795,
and then use 'find -inum 533795' to locate the file after the filesystem
has been unfrozen.

I guess my confusion is the definition of a "disk inode's block address"
versus an "inode disk address". Could you clarify the difference for me?
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