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Commit cc2047c4 authored by Darrick J. Wong's avatar Darrick J. Wong
Browse files

xfs: refactor dquot cache handling 



Delegate the dquot cache handling (radix tree lookup and insertion) to
separate helper functions so that we can continue to simplify the body
of dqget.

Signed-off-by: default avatarDarrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: default avatarBrian Foster <bfoster@redhat.com>
Reviewed-by: default avatarChristoph Hellwig <hch@lst.de>
parent 2e330e76

fs/xfs/xfs_dquot.c

+78 −34
Original line number Diff line number Diff line
@@ -686,6 +686,81 @@ xfs_dq_get_next_id( 
	return error;

}



/*

 * Look up the dquot in the in-core cache.  If found, the dquot is returned

 * locked and ready to go.

 */

static struct xfs_dquot *

xfs_qm_dqget_cache_lookup(

	struct xfs_mount	*mp,

	struct xfs_quotainfo	*qi,

	struct radix_tree_root	*tree,

	xfs_dqid_t		id)

{

	struct xfs_dquot	*dqp;



restart:

	mutex_lock(&qi->qi_tree_lock);

	dqp = radix_tree_lookup(tree, id);

	if (!dqp) {

		mutex_unlock(&qi->qi_tree_lock);

		XFS_STATS_INC(mp, xs_qm_dqcachemisses);

		return NULL;

	}



	xfs_dqlock(dqp);

	if (dqp->dq_flags & XFS_DQ_FREEING) {

		xfs_dqunlock(dqp);

		mutex_unlock(&qi->qi_tree_lock);

		trace_xfs_dqget_freeing(dqp);

		delay(1);

		goto restart;

	}



	dqp->q_nrefs++;

	mutex_unlock(&qi->qi_tree_lock);



	trace_xfs_dqget_hit(dqp);

	XFS_STATS_INC(mp, xs_qm_dqcachehits);

	return dqp;

}



/*

 * Try to insert a new dquot into the in-core cache.  If an error occurs the

 * caller should throw away the dquot and start over.  Otherwise, the dquot

 * is returned locked (and held by the cache) as if there had been a cache

 * hit.

 */

static int

xfs_qm_dqget_cache_insert(

	struct xfs_mount	*mp,

	struct xfs_quotainfo	*qi,

	struct radix_tree_root	*tree,

	xfs_dqid_t		id,

	struct xfs_dquot	*dqp)

{

	int			error;



	mutex_lock(&qi->qi_tree_lock);

	error = radix_tree_insert(tree, id, dqp);

	if (unlikely(error)) {

		/* Duplicate found!  Caller must try again. */

		WARN_ON(error != -EEXIST);

		mutex_unlock(&qi->qi_tree_lock);

		trace_xfs_dqget_dup(dqp);

		return error;

	}



	/* Return a locked dquot to the caller, with a reference taken. */

	xfs_dqlock(dqp);

	dqp->q_nrefs = 1;



	qi->qi_dquots++;

	mutex_unlock(&qi->qi_tree_lock);



	return 0;

}



/*

 * Given the file system, inode OR id, and type (UDQUOT/GDQUOT), return a

 * a locked dquot, doing an allocation (if requested) as needed.
@@ -724,28 +799,11 @@ xfs_qm_dqget( 
	}



restart:

	mutex_lock(&qi->qi_tree_lock);

	dqp = radix_tree_lookup(tree, id);

	dqp = xfs_qm_dqget_cache_lookup(mp, qi, tree, id);

	if (dqp) {

		xfs_dqlock(dqp);

		if (dqp->dq_flags & XFS_DQ_FREEING) {

			xfs_dqunlock(dqp);

			mutex_unlock(&qi->qi_tree_lock);

			trace_xfs_dqget_freeing(dqp);

			delay(1);

			goto restart;

		}



		dqp->q_nrefs++;

		mutex_unlock(&qi->qi_tree_lock);



		trace_xfs_dqget_hit(dqp);

		XFS_STATS_INC(mp, xs_qm_dqcachehits);

		*O_dqpp = dqp;

		return 0;

	}

	mutex_unlock(&qi->qi_tree_lock);

	XFS_STATS_INC(mp, xs_qm_dqcachemisses);



	/*

	 * Dquot cache miss. We don't want to keep the inode lock across
@@ -787,31 +845,17 @@ xfs_qm_dqget( 
		}

	}



	mutex_lock(&qi->qi_tree_lock);

	error = radix_tree_insert(tree, id, dqp);

	if (unlikely(error)) {

		WARN_ON(error != -EEXIST);



	error = xfs_qm_dqget_cache_insert(mp, qi, tree, id, dqp);

	if (error) {

		/*

		 * Duplicate found. Just throw away the new dquot and start

		 * over.

		 */

		mutex_unlock(&qi->qi_tree_lock);

		trace_xfs_dqget_dup(dqp);

		xfs_qm_dqdestroy(dqp);

		XFS_STATS_INC(mp, xs_qm_dquot_dups);

		goto restart;

	}



	/*

	 * We return a locked dquot to the caller, with a reference taken

	 */

	xfs_dqlock(dqp);

	dqp->q_nrefs = 1;



	qi->qi_dquots++;

	mutex_unlock(&qi->qi_tree_lock);



 dqret:

	ASSERT((ip == NULL) || xfs_isilocked(ip, XFS_ILOCK_EXCL));

	trace_xfs_dqget_miss(dqp);