On Mon, Mar 30, 2020 at 09:46:02AM +1100, Dave Chinner wrote: > On Thu, Mar 26, 2020 at 09:17:02AM -0400, Brian Foster wrote: > > A dquot flush currently blocks on the buffer lock for the underlying > > dquot buffer. In turn, this causes xfsaild to block rather than > > continue processing other items in the meantime. Update > > xfs_qm_dqflush() to trylock the buffer, similar to how inode buffers > > are handled, and return -EAGAIN if the lock fails. Fix up any > > callers that don't currently handle the error properly. > > > > Signed-off-by: Brian Foster <bfoster@xxxxxxxxxx> > > --- > > fs/xfs/xfs_dquot.c | 6 +++--- > > fs/xfs/xfs_dquot_item.c | 3 ++- > > fs/xfs/xfs_qm.c | 14 +++++++++----- > > 3 files changed, 14 insertions(+), 9 deletions(-) > > > > diff --git a/fs/xfs/xfs_dquot.c b/fs/xfs/xfs_dquot.c > > index 711376ca269f..af2c8e5ceea0 100644 > > --- a/fs/xfs/xfs_dquot.c > > +++ b/fs/xfs/xfs_dquot.c > > @@ -1105,8 +1105,8 @@ xfs_qm_dqflush( > > * Get the buffer containing the on-disk dquot > > */ > > error = xfs_trans_read_buf(mp, NULL, mp->m_ddev_targp, dqp->q_blkno, > > - mp->m_quotainfo->qi_dqchunklen, 0, &bp, > > - &xfs_dquot_buf_ops); > > + mp->m_quotainfo->qi_dqchunklen, XBF_TRYLOCK, > > + &bp, &xfs_dquot_buf_ops); > > if (error) > > goto out_unlock; > > > > @@ -1177,7 +1177,7 @@ xfs_qm_dqflush( > > > > out_unlock: > > xfs_dqfunlock(dqp); > > - return -EIO; > > + return error; > > } > > > > /* > > diff --git a/fs/xfs/xfs_dquot_item.c b/fs/xfs/xfs_dquot_item.c > > index cf65e2e43c6e..baad1748d0d1 100644 > > --- a/fs/xfs/xfs_dquot_item.c > > +++ b/fs/xfs/xfs_dquot_item.c > > @@ -189,7 +189,8 @@ xfs_qm_dquot_logitem_push( > > if (!xfs_buf_delwri_queue(bp, buffer_list)) > > rval = XFS_ITEM_FLUSHING; > > xfs_buf_relse(bp); > > - } > > + } else if (error == -EAGAIN) > > + rval = XFS_ITEM_LOCKED; > > Doesn't xfs_inode_item_push() also have this problem in that it > doesn't handle -EAGAIN properly? > > Also, we can get -EIO, -EFSCORRUPTED, etc here. They probably > shouldn't return XFS_ITEM_SUCCESS, either.... > Good point. I'm actually not sure what we should return in that case given the item return codes all seem to assume a valid state. We could define an XFS_ITEM_ERROR return, but I'm not sure it's worth it for what is currently stat/tracepoint logic in the caller. Perhaps a broader rework of error handling in this context is in order that would lift generic (fatal) error handling into xfsaild. E.g., I see that xfs_qm_dqflush() is inconsistent by itself in that the item is removed from the AIL if we're already shut down, but not if that function invokes the shutdown; we shutdown if the direct xfs_dqblk_verify() call fails but not if the read verifier (which also looks like it calls xfs_dqblk_verify() on every on-disk dquot) returns -EFSCORRUPTED, etc. It might make some sense to let iop_push() return negative error codes if that facilitates consistent error handling... Brian > Otherwise seems OK. > > Cheers, > > Dave. > -- > Dave Chinner > david@xxxxxxxxxxxxx >
