On Mon, May 31, 2021 at 03:41:13PM -0700, Darrick J. Wong wrote:
> From: Darrick J. Wong <djwong@xxxxxxxxxx>
>
> During quotaoff, the incore inode scan to detach dquots from inodes
> won't touch inodes that have lost their VFS state but haven't yet been
> queued for reclaim. This isn't strictly a problem because we drop the
> dquots at the end of inactivation, but if we detect this situation
> before starting inactivation, we can drop the inactive dquots early to
> avoid delaying quotaoff further.
>
> Signed-off-by: Darrick J. Wong <djwong@xxxxxxxxxx>
> ---
> fs/xfs/xfs_super.c | 32 ++++++++++++++++++++++++++++----
> 1 file changed, 28 insertions(+), 4 deletions(-)
>
>
> diff --git a/fs/xfs/xfs_super.c b/fs/xfs/xfs_super.c
> index a2dab05332ac..79f1cd1a0221 100644
> --- a/fs/xfs/xfs_super.c
> +++ b/fs/xfs/xfs_super.c
> @@ -637,22 +637,46 @@ xfs_fs_destroy_inode(
> struct inode *inode)
> {
> struct xfs_inode *ip = XFS_I(inode);
> + struct xfs_mount *mp = ip->i_mount;
>
> trace_xfs_destroy_inode(ip);
>
> ASSERT(!rwsem_is_locked(&inode->i_rwsem));
> - XFS_STATS_INC(ip->i_mount, vn_rele);
> - XFS_STATS_INC(ip->i_mount, vn_remove);
> + XFS_STATS_INC(mp, vn_rele);
> + XFS_STATS_INC(mp, vn_remove);
> +
> + /*
> + * If a quota type is turned off but we still have a dquot attached to
> + * the inode, detach it before processing this inode to avoid delaying
> + * quotaoff for longer than is necessary.
> + *
> + * The inode has no VFS state and hasn't been tagged for any kind of
> + * reclamation, which means that iget, quotaoff, blockgc, and reclaim
> + * will not touch it. It is therefore safe to do this locklessly
> + * because we have the only reference here.
> + */
> + if (!XFS_IS_UQUOTA_ON(mp)) {
> + xfs_qm_dqrele(ip->i_udquot);
> + ip->i_udquot = NULL;
> + }
> + if (!XFS_IS_GQUOTA_ON(mp)) {
> + xfs_qm_dqrele(ip->i_gdquot);
> + ip->i_gdquot = NULL;
> + }
> + if (!XFS_IS_PQUOTA_ON(mp)) {
> + xfs_qm_dqrele(ip->i_pdquot);
> + ip->i_pdquot = NULL;
> + }
>
> xfs_inactive(ip);
Shouldn't we just make xfs_inactive() unconditionally detatch dquots
rather than just in the conditional case it does now after attaching
dquots because it has to make modifications? For inodes that don't
require any inactivation work, we get the same thing, and for those
that do running a few extra transactions before dropping the dquots
isn't going to make a huge difference to the quotaoff latency....
Cheers,
Dave.
--
Dave Chinner
david@xxxxxxxxxxxxx
