xfs: return the dquot unlocked from xfs_qm_dqget

There is no reason to lock the dquot in xfs_qm_dqget, which just acquires
a reference.  Move the locking to the callers, or remove it in cases where
the caller instantly unlocks the dquot.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Carlos Maiolino <cem@kernel.org>

Author: Christoph Hellwig

fs/xfs/scrub/dqiterate.c

@@ -205,6 +205,7 @@ xchk_dquot_iter(
 	if (error)
 		return error;
 
+	mutex_lock(&dq->q_qlock);
 	cursor->id = dq->q_id + 1;
 	*dqpp = dq;
 	return 1;

fs/xfs/scrub/quotacheck.c

@@ -635,6 +635,7 @@ xqcheck_walk_observations(
 		if (error)
 			return error;
 
+		mutex_lock(&dq->q_qlock);
 		error = xqcheck_compare_dquot(xqc, dqtype, dq);
 		mutex_unlock(&dq->q_qlock);
 		xfs_qm_dqrele(dq);

fs/xfs/scrub/quotacheck_repair.c

@@ -187,6 +187,7 @@ xqcheck_commit_dqtype(
 		if (error)
 			return error;
 
+		mutex_lock(&dq->q_qlock);
 		error = xqcheck_commit_dquot(xqc, dqtype, dq);
 		mutex_unlock(&dq->q_qlock);
 		xfs_qm_dqrele(dq);

fs/xfs/xfs_dquot.c

@@ -895,7 +895,7 @@ xfs_qm_dqget_checks(
 
 /*
  * Given the file system, id, and type (UDQUOT/GDQUOT/PDQUOT), return a
- * locked dquot, doing an allocation (if requested) as needed.
+ * dquot, doing an allocation (if requested) as needed.
  */
 int
 xfs_qm_dqget(
@@ -940,7 +940,6 @@ xfs_qm_dqget(
 	trace_xfs_dqget_miss(dqp);
 found:
 	*O_dqpp = dqp;
-	mutex_lock(&dqp->q_qlock);
 	return 0;
 }
 
@@ -1098,6 +1097,7 @@ xfs_qm_dqget_next(
 		else if (error != 0)
 			break;
 
+		mutex_lock(&dqp->q_qlock);
 		if (!XFS_IS_DQUOT_UNINITIALIZED(dqp)) {
 			*dqpp = dqp;
 			return 0;

fs/xfs/xfs_qm.c

@@ -1268,6 +1268,7 @@ xfs_qm_quotacheck_dqadjust(
 		return error;
 	}
 
+	mutex_lock(&dqp->q_qlock);
 	error = xfs_dquot_attach_buf(NULL, dqp);
 	if (error)
 		goto out_unlock;
@@ -1907,7 +1908,6 @@ xfs_qm_vop_dqalloc(
 			/*
 			 * Get the ilock in the right order.
 			 */
-			mutex_unlock(&uq->q_qlock);
 			lockflags = XFS_ILOCK_SHARED;
 			xfs_ilock(ip, lockflags);
 		} else {
@@ -1929,7 +1929,6 @@ xfs_qm_vop_dqalloc(
 				ASSERT(error != -ENOENT);
 				goto error_rele;
 			}
-			mutex_unlock(&gq->q_qlock);
 			lockflags = XFS_ILOCK_SHARED;
 			xfs_ilock(ip, lockflags);
 		} else {
@@ -1947,7 +1946,6 @@ xfs_qm_vop_dqalloc(
 				ASSERT(error != -ENOENT);
 				goto error_rele;
 			}
-			mutex_unlock(&pq->q_qlock);
 			lockflags = XFS_ILOCK_SHARED;
 			xfs_ilock(ip, lockflags);
 		} else {

fs/xfs/xfs_qm_bhv.c

@@ -73,6 +73,7 @@ xfs_qm_statvfs(
 	struct xfs_dquot	*dqp;
 
 	if (!xfs_qm_dqget(mp, ip->i_projid, XFS_DQTYPE_PROJ, false, &dqp)) {
+		mutex_lock(&dqp->q_qlock);
 		xfs_fill_statvfs_from_dquot(statp, ip, dqp);
 		mutex_unlock(&dqp->q_qlock);
 		xfs_qm_dqrele(dqp);

fs/xfs/xfs_qm_syscalls.c

@@ -302,6 +302,7 @@ xfs_qm_scall_setqlim(
 		return error;
 	}
 
+	mutex_lock(&dqp->q_qlock);
 	defq = xfs_get_defquota(q, xfs_dquot_type(dqp));
 	mutex_unlock(&dqp->q_qlock);
 
@@ -459,6 +460,7 @@ xfs_qm_scall_getquota(
 	 * If everything's NULL, this dquot doesn't quite exist as far as
 	 * our utility programs are concerned.
 	 */
+	mutex_lock(&dqp->q_qlock);
 	if (XFS_IS_DQUOT_UNINITIALIZED(dqp)) {
 		error = -ENOENT;
 		goto out_put;