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From: Chandan Babu R <chandanrlinux@gmail.com>
To: "Darrick J. Wong" <darrick.wong@oracle.com>
Cc: linux-xfs@vger.kernel.org
Subject: Re: [PATCH 01/18] xfs: clear XFS_DQ_FREEING if we can't lock the dquot buffer to flush
Date: Wed, 01 Jul 2020 14:02:15 +0530
Message-ID: <5478435.i7RmhvRWad@garuda> (raw)
In-Reply-To: <159353171640.2864738.7967439700762859129.stgit@magnolia>

On Tuesday 30 June 2020 9:11:56 PM IST Darrick J. Wong wrote:
> From: Darrick J. Wong <darrick.wong@oracle.com>
> 
> In commit 8d3d7e2b35ea, we changed xfs_qm_dqpurge to bail out if we
> can't lock the dquot buf to flush the dquot.  This prevents the AIL from
> blocking on the dquot, but it also forgets to clear the FREEING flag on
> its way out.  A subsequent purge attempt will see the FREEING flag is
> set and bail out, which leads to dqpurge_all failing to purge all the
> dquots.  This causes unmounts and quotaoff operations to hang.
>

xfs_qm_dqpurge() checks for the presence of XFS_DQ_FREEING. If it is set, it
indicates that another task is freeing this dquot.

A failed read operation could return -EAGAIN and hence xfs_qm_dqpurge()
returning without clearing XFS_DQ_FREEING would mean that future invocations
of this function would turn out to be a nop and hence the corresponding dquot
would linger around forever. Hence the fix is correct.

Reviewed-by: Chandan Babu R <chandanrlinux@gmail.com>

> Fixes: 8d3d7e2b35ea ("xfs: trylock underlying buffer on dquot flush")
> Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
> ---
>  fs/xfs/xfs_qm.c |    1 +
>  1 file changed, 1 insertion(+)
> 
> 
> diff --git a/fs/xfs/xfs_qm.c b/fs/xfs/xfs_qm.c
> index d6cd83317344..938023dd8ce5 100644
> --- a/fs/xfs/xfs_qm.c
> +++ b/fs/xfs/xfs_qm.c
> @@ -148,6 +148,7 @@ xfs_qm_dqpurge(
>  			error = xfs_bwrite(bp);
>  			xfs_buf_relse(bp);
>  		} else if (error == -EAGAIN) {
> +			dqp->dq_flags &= ~XFS_DQ_FREEING;
>  			goto out_unlock;
>  		}
>  		xfs_dqflock(dqp);
> 
> 


-- 
chandan




  parent reply index

Thread overview: 87+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-06-30 15:41 [PATCH 00/18] xfs: remove xfs_disk_quot from incore dquot Darrick J. Wong
2020-06-30 15:41 ` [PATCH 01/18] xfs: clear XFS_DQ_FREEING if we can't lock the dquot buffer to flush Darrick J. Wong
2020-06-30 21:35   ` Allison Collins
2020-07-01  8:32   ` Chandan Babu R [this message]
2020-07-01  8:33   ` Christoph Hellwig
2020-07-01 22:42     ` Dave Chinner
2020-06-30 15:42 ` [PATCH 02/18] xfs: fix inode quota reservation checks Darrick J. Wong
2020-06-30 21:35   ` Allison Collins
2020-07-01  8:33   ` Chandan Babu R
2020-07-01  8:34   ` Christoph Hellwig
2020-06-30 15:42 ` [PATCH 03/18] xfs: validate ondisk/incore dquot flags Darrick J. Wong
2020-06-30 21:35   ` Allison Collins
2020-07-01  8:33   ` Chandan Babu R
2020-07-01  8:42   ` Christoph Hellwig
2020-07-01 18:25     ` Darrick J. Wong
2020-07-02  6:30       ` Christoph Hellwig
2020-07-02 15:13         ` Darrick J. Wong
2020-07-01 22:41   ` Dave Chinner
2020-07-01 23:16     ` Darrick J. Wong
2020-06-30 15:42 ` [PATCH 04/18] xfs: stop using q_core.d_flags in the quota code Darrick J. Wong
2020-07-01  8:34   ` Chandan Babu R
2020-07-01  8:47   ` Christoph Hellwig
2020-07-01 19:02     ` Darrick J. Wong
2020-07-01 20:15   ` Allison Collins
2020-07-01 22:50   ` Dave Chinner
2020-07-01 23:19     ` Darrick J. Wong
2020-07-01 23:44       ` Dave Chinner
2020-07-01 23:50         ` Darrick J. Wong
2020-07-03  0:58           ` Dave Chinner
2020-06-30 15:42 ` [PATCH 05/18] xfs: stop using q_core.d_id " Darrick J. Wong
2020-07-01  8:33   ` Chandan Babu R
2020-07-01  8:48   ` Christoph Hellwig
2020-07-01 20:16   ` Allison Collins
2020-06-30 15:42 ` [PATCH 06/18] xfs: use a per-resource struct for incore dquot data Darrick J. Wong
2020-07-01  8:33   ` Chandan Babu R
2020-07-01  8:49   ` Christoph Hellwig
2020-07-01 20:16   ` Allison Collins
2020-06-30 15:42 ` [PATCH 07/18] xfs: stop using q_core limits in the quota code Darrick J. Wong
2020-07-01  8:33   ` Chandan Babu R
2020-07-01  8:50   ` Christoph Hellwig
2020-07-01 20:16   ` Allison Collins
2020-07-01 23:01   ` Dave Chinner
2020-07-01 23:13     ` Darrick J. Wong
2020-07-01 23:33       ` Darrick J. Wong
2020-07-01 23:45         ` Dave Chinner
2020-06-30 15:42 ` [PATCH 08/18] xfs: stop using q_core counters " Darrick J. Wong
2020-07-01  8:33   ` Chandan Babu R
2020-07-01  8:51   ` Christoph Hellwig
2020-07-01 23:20   ` Allison Collins
2020-06-30 15:42 ` [PATCH 09/18] xfs: stop using q_core warning " Darrick J. Wong
2020-07-01  8:33   ` Chandan Babu R
2020-07-01  8:51   ` Christoph Hellwig
2020-07-01 23:20   ` Allison Collins
2020-06-30 15:42 ` [PATCH 10/18] xfs: stop using q_core timers " Darrick J. Wong
2020-07-01  8:34   ` Chandan Babu R
2020-07-01  8:51   ` Christoph Hellwig
2020-07-01 23:20   ` Allison Collins
2020-06-30 15:43 ` [PATCH 11/18] xfs: remove qcore from incore dquots Darrick J. Wong
2020-07-01  8:34   ` Chandan Babu R
2020-07-01  8:52   ` Christoph Hellwig
2020-07-01 23:07   ` Dave Chinner
2020-07-01 23:14     ` Darrick J. Wong
2020-07-02  2:06   ` Allison Collins
2020-06-30 15:43 ` [PATCH 12/18] xfs: refactor default quota limits by resource Darrick J. Wong
2020-07-01  8:52   ` Chandan Babu R
2020-07-01  8:53   ` Christoph Hellwig
2020-07-01 23:30   ` Dave Chinner
2020-07-02  0:07     ` Darrick J. Wong
2020-07-02  2:06   ` Allison Collins
2020-06-30 15:43 ` [PATCH 13/18] xfs: remove unnecessary arguments from quota adjust functions Darrick J. Wong
2020-07-01  8:53   ` Christoph Hellwig
2020-07-01  8:58   ` Chandan Babu R
2020-07-02  2:06   ` Allison Collins
2020-06-30 15:43 ` [PATCH 14/18] xfs: refactor quota exceeded test Darrick J. Wong
2020-07-01  8:56   ` Christoph Hellwig
2020-07-01 17:51     ` Darrick J. Wong
2020-07-01 18:48       ` Eric Sandeen
2020-07-01 23:34       ` Dave Chinner
2020-07-01 10:19   ` Chandan Babu R
2020-07-02 18:57   ` Allison Collins
2020-06-30 15:43 ` [PATCH 15/18] xfs: refactor xfs_qm_scall_setqlim Darrick J. Wong
2020-07-01  8:56   ` Christoph Hellwig
2020-07-03  4:11   ` Allison Collins
2020-06-30 15:43 ` [PATCH 16/18] xfs: refactor xfs_trans_dqresv Darrick J. Wong
2020-07-03  4:11   ` Allison Collins
2020-06-30 15:43 ` [PATCH 17/18] xfs: refactor xfs_trans_apply_dquot_deltas Darrick J. Wong
2020-06-30 15:43 ` [PATCH 18/18] xfs: add more dquot tracepoints Darrick J. Wong

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