[PATCH v3 0/8] speculative preallocation inode tracking

[Brian Foster]

On 09/26/2012 11:19 AM, Ben Myers wrote:
> Hi Brian,
> 
> On Fri, Sep 14, 2012 at 08:19:47AM -0400, Brian Foster wrote:
>> This is v3 of the speculative preallocation inode tracking patchset. This
>> functionality tracks inodes with post-EOF speculative preallocation for the
>> purpose of background and on-demand trimming.
>>
>> Background scanning occurs on a longish interval (5 minutes by default) and in
>> a best-effort mode (i.e., inodes are skipped due to lock contention or dirty
>> cache). The intent is to clear up post-EOF blocks on inodes that might have
>> allocations hanging around due to open-write-close sequences (NFS).
>>
>> On demand scanning is provided via a new ioctl and supports various parameters
>> such as scan mode, filtering by quota id and minimum file size. A pending use
>> case for on demand scanning is for accurate quota accounting via the gluster
>> scale out filesystem (i.e., to free up preallocated space when near a usage
>> limit).
> 
> [33084.794491] XFS (sda2): Ending clean mount
> [33170.400045] XFS: Assertion failed: !atomic_read(&VFS_I(ip)->i_count) || xfs_isilocked(ip, XFS_IOLOCK_EXCL), file: /root/xfs/fs/xfs/xfs_inode.c, line: 1128
> [33170.41422[    0.000000] Initializing cgroup subsys cpuset
> [    0.000000] Initializing cgroup subsys cpu
> [    0.000000] Linux version 3.6.0-rc1-1.2-desktop+ (root at nfs7) (gcc version 4.6.2 (SUSE Linux) ) #26 SMP PREEMPT Fri Sep 21 18:26:16 CDT 2012
> [    0.000000] e820: BIOS-provided physical RAM map:
> [    0.000000] BIOS-e820: [mem 0x0000000000000100-0x000000000009fbff] usable
> 
> crash> bt
> PID: 1289   TASK: f38d71d0  CPU: 1   COMMAND: "kworker/1:2"
>  #0 [f17c9b88] crash_kexec at c0295045
>  #1 [f17c9be0] oops_end at c06ab2f2
>  #2 [f17c9bf8] die at c020539a
>  #3 [f17c9c10] do_trap at c06aadc1
>  #4 [f17c9c28] do_invalid_op at c0202eb1
>  #5 [f17c9cc4] error_code (via invalid_op) at c06aab7c
>     EAX: 0000008e  EBX: ec3d9400  ECX: 0000071e  EDX: 00000046  EBP: f17c9d18 
>     DS:  007b      ESI: ec3d9400  ES:  007b      EDI: ef973d00  GS:  2e30
>     CS:  0060      EIP: f9d1dbb6  ERR: ffffffff  EFLAGS: 00010292 
>  #6 [f17c9cf8] assfail at f9d1dbb6 [xfs]
>  #7 [f17c9d1c] xfs_itruncate_extents at f9d6335f [xfs]
>  #8 [f17c9d98] xfs_free_eofblocks at f9d237d9 [xfs]
>  #9 [f17c9df8] xfs_inode_free_eofblocks at f9d221b4 [xfs]
> #10 [f17c9e14] xfs_inode_ag_walk at f9d20ab9 [xfs]
> #11 [f17c9ee4] xfs_inode_ag_iterator_tag at f9d20d6b [xfs]
> #12 [f17c9f18] xfs_inodes_free_eofblocks at f9d21c95 [xfs]
> #13 [f17c9f34] xfs_eofblocks_worker at f9d21cc3 [xfs]
> #14 [f17c9f40] process_one_work at c0251ea5
> #15 [f17c9f84] worker_thread at c0252504
> #16 [f17c9fbc] kthread at c025672b
> #17 [f17c9fe8] kernel_thread_helper at c06b06f4
> 
> It seems that test 133 was running at the time of the crash in two cases.  This
> is a neat patch set but we need to resolve this before pulling it in.
> 

Indeed. It looks like I botched the need_iolock parameter to
xfs_free_eofblocks() when I migrated to rely on EAGAIN rather than a
blocking lock. Thanks for the report.

I'm surprised I didn't reproduce this. I will try and do so before I
submit an updated set so I can verify a fix. Was this a repeated 133
test or full xfstests run? Thanks again.

Brian

> Regards,
> Ben
>