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[PATCH 5/3] xfs: return unlocked dquots from xfs_qm_dqqet

To: Dave Chinner <david@xxxxxxxxxxxxx>
Subject: [PATCH 5/3] xfs: return unlocked dquots from xfs_qm_dqqet
From: Christoph Hellwig <hch@xxxxxxxxxxxxx>
Date: Fri, 13 Dec 2013 08:30:09 -0800
Cc: xfs@xxxxxxxxxxx
Delivered-to: xfs@xxxxxxxxxxx
In-reply-to: <1386841258-22183-1-git-send-email-david@xxxxxxxxxxxxx>
References: <1386841258-22183-1-git-send-email-david@xxxxxxxxxxxxx>
User-agent: Mutt/1.5.21 (2010-09-15)
We generally don't need the dquot structure locked for the fast path
operations, and we don't need the lock during lookup either.

Signed-off-by: Christoph Hellwig <hch@xxxxxx>

diff --git a/fs/xfs/xfs_dquot.c b/fs/xfs/xfs_dquot.c
index f17350d..7da4097 100644
--- a/fs/xfs/xfs_dquot.c
+++ b/fs/xfs/xfs_dquot.c
@@ -689,8 +689,9 @@ error0:
 }
 
 /*
- * Given the file system, inode OR id, and type (UDQUOT/GDQUOT), return a
- * a locked dquot, doing an allocation (if requested) as needed.
+ * Given the file system, id, type and optionally inode, return a an unlocked
+ * dquot, doing an allocation if requested and needed.
+ *
  * When both an inode and an id are given, the inode's id takes precedence.
  * That is, if the id changes while we don't hold the ilock inside this
  * function, the new dquot is returned, not necessarily the one requested
@@ -739,9 +740,7 @@ restart:
        mutex_lock(&qi->qi_tree_lock);
        dqp = radix_tree_lookup(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);
@@ -824,7 +823,6 @@ restart:
        /*
         * We return a locked, referenced dquot to the caller.
         */
-       xfs_dqlock(dqp);
        qi->qi_dquots++;
        mutex_unlock(&qi->qi_tree_lock);
 
diff --git a/fs/xfs/xfs_qm.c b/fs/xfs/xfs_qm.c
index 843ab07..985b583 100644
--- a/fs/xfs/xfs_qm.c
+++ b/fs/xfs/xfs_qm.c
@@ -395,7 +395,6 @@ xfs_qm_dqattach_one(
         * that the dquot returned is the one that should go in the inode.
         */
        *IO_idqpp = dqp;
-       xfs_dqunlock(dqp);
        return 0;
 }
 
@@ -1142,6 +1141,8 @@ xfs_qm_quotacheck_dqadjust(
 
        trace_xfs_dqadjust(dqp);
 
+       xfs_dqlock(dqp);
+
        /*
         * Adjust the inode count and the block count to reflect this inode's
         * resource usage.
@@ -1679,10 +1680,6 @@ xfs_qm_vop_dqalloc(
                                ASSERT(error != ENOENT);
                                return error;
                        }
-                       /*
-                        * Get the ilock in the right order.
-                        */
-                       xfs_dqunlock(uq);
                        lockflags = XFS_ILOCK_SHARED;
                        xfs_ilock(ip, lockflags);
                } else {
@@ -1706,7 +1703,6 @@ xfs_qm_vop_dqalloc(
                                ASSERT(error != ENOENT);
                                goto error_rele;
                        }
-                       xfs_dqunlock(gq);
                        lockflags = XFS_ILOCK_SHARED;
                        xfs_ilock(ip, lockflags);
                } else {
@@ -1726,7 +1722,6 @@ xfs_qm_vop_dqalloc(
                                ASSERT(error != ENOENT);
                                goto error_rele;
                        }
-                       xfs_dqunlock(pq);
                        lockflags = XFS_ILOCK_SHARED;
                        xfs_ilock(ip, lockflags);
                } else {
diff --git a/fs/xfs/xfs_qm_bhv.c b/fs/xfs/xfs_qm_bhv.c
index e9be63a..c8fda48 100644
--- a/fs/xfs/xfs_qm_bhv.c
+++ b/fs/xfs/xfs_qm_bhv.c
@@ -75,6 +75,7 @@ xfs_qm_statvfs(
        xfs_dquot_t             *dqp;
 
        if (!xfs_qm_dqget(mp, NULL, xfs_get_projid(ip), XFS_DQ_PROJ, 0, &dqp)) {
+               xfs_dqlock(dqp);
                xfs_fill_statvfs_from_dquot(statp, dqp);
                xfs_qm_dqput(dqp);
        }
diff --git a/fs/xfs/xfs_qm_syscalls.c b/fs/xfs/xfs_qm_syscalls.c
index 1e61cd4..94dadbe 100644
--- a/fs/xfs/xfs_qm_syscalls.c
+++ b/fs/xfs/xfs_qm_syscalls.c
@@ -617,7 +617,6 @@ xfs_qm_scall_setqlim(
                ASSERT(error != ENOENT);
                goto out_unlock;
        }
-       xfs_dqunlock(dqp);
 
        tp = xfs_trans_alloc(mp, XFS_TRANS_QM_SETQLIM);
        error = xfs_trans_reserve(tp, &M_RES(mp)->tr_qm_setqlim, 0, 0);
@@ -844,6 +843,8 @@ xfs_qm_scall_getquota(
        if (error)
                return error;
 
+       xfs_dqlock(dqp);
+
        /*
         * If everything's NULL, this dquot doesn't quite exist as far as
         * our utility programs are concerned.

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