From: Darrick J. Wong darrick.wong@oracle.com
[ Upstream commit c97738a960a86081a147e7d436138e6481757445 ]
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.
(copy-pasting from Dave Chinner's identical patch)
This was found by inspection after having xfs/305 hang 1 in ~50 iterations in a quotaoff operation:
[ 8872.301115] xfs_quota D13888 92262 91813 0x00004002 [ 8872.302538] Call Trace: [ 8872.303193] __schedule+0x2d2/0x780 [ 8872.304108] ? do_raw_spin_unlock+0x57/0xd0 [ 8872.305198] schedule+0x6e/0xe0 [ 8872.306021] schedule_timeout+0x14d/0x300 [ 8872.307060] ? __next_timer_interrupt+0xe0/0xe0 [ 8872.308231] ? xfs_qm_dqusage_adjust+0x200/0x200 [ 8872.309422] schedule_timeout_uninterruptible+0x2a/0x30 [ 8872.310759] xfs_qm_dquot_walk.isra.0+0x15a/0x1b0 [ 8872.311971] xfs_qm_dqpurge_all+0x7f/0x90 [ 8872.313022] xfs_qm_scall_quotaoff+0x18d/0x2b0 [ 8872.314163] xfs_quota_disable+0x3a/0x60 [ 8872.315179] kernel_quotactl+0x7e2/0x8d0 [ 8872.316196] ? __do_sys_newstat+0x51/0x80 [ 8872.317238] __x64_sys_quotactl+0x1e/0x30 [ 8872.318266] do_syscall_64+0x46/0x90 [ 8872.319193] entry_SYSCALL_64_after_hwframe+0x44/0xa9 [ 8872.320490] RIP: 0033:0x7f46b5490f2a [ 8872.321414] Code: Bad RIP value.
Returning -EAGAIN from xfs_qm_dqpurge() without clearing the XFS_DQ_FREEING flag means the xfs_qm_dqpurge_all() code can never free the dquot, and we loop forever waiting for the XFS_DQ_FREEING flag to go away on the dquot that leaked it via -EAGAIN.
Fixes: 8d3d7e2b35ea ("xfs: trylock underlying buffer on dquot flush") Signed-off-by: Darrick J. Wong darrick.wong@oracle.com Reviewed-by: Allison Collins allison.henderson@oracle.com Reviewed-by: Chandan Babu R chandanrlinux@gmail.com Reviewed-by: Christoph Hellwig hch@lst.de Reviewed-by: Brian Foster bfoster@redhat.com Signed-off-by: Dave Chinner dchinner@redhat.com Reviewed-by: Dave Chinner dchinner@redhat.com Signed-off-by: Sasha Levin sashal@kernel.org --- 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 c225691fad156..2a0cdca80f861 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);