xfs: do not write the buffer from xfs_qm_dqflush

Instead of writing the buffer directly from inside xfs_qm_dqflush return it
to the caller and let the caller decide what to do with the buffer.  Also
remove the pincount check in xfs_qm_dqflush that all non-blocking callers
already implement and the now unused flags parameter and the XFS_DQ_IS_DIRTY
check that all callers already perform.

[ Dave Chinner: fixed build error cause by missing '{'. ]

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Mark Tinguely <tinguely@sgi.com>
Signed-off-by: Ben Myers <bpm@sgi.com>

4 files changed, 53 insertions, 38 deletions

diff --git a/fs/xfs/xfs_dquot.c b/fs/xfs/xfs_dquot.c
index 786a61e1cccd..53757d83e4f6 100644
--- a/fs/xfs/xfs_dquot.c
+++ b/fs/xfs/xfs_dquot.c
@@ -878,8 +878,8 @@ xfs_qm_dqflush_done(
  */
 int
 xfs_qm_dqflush(
-        xfs_dquot_t             *dqp,
-        uint                    flags)
+        struct xfs_dquot        *dqp,
+        struct xfs_buf          **bpp)
 {
         struct xfs_mount        *mp = dqp->q_mount;
         struct xfs_buf          *bp;
@@ -891,14 +891,8 @@ xfs_qm_dqflush(
 
         trace_xfs_dqflush(dqp);
 
-        /*
-         * If not dirty, or it's pinned and we are not supposed to block, nada.
-         */
-        if (!XFS_DQ_IS_DIRTY(dqp) ||
-            ((flags & SYNC_TRYLOCK) && atomic_read(&dqp->q_pincount) > 0)) {
-                xfs_dqfunlock(dqp);
-                return 0;
-        }
+        *bpp = NULL;
+
         xfs_qm_dqunpin_wait(dqp);
 
         /*
@@ -918,9 +912,8 @@ xfs_qm_dqflush(
                         xfs_trans_ail_delete(mp->m_ail, lip);
                 else
                         spin_unlock(&mp->m_ail->xa_lock);
-
-                xfs_dqfunlock(dqp);
-                return XFS_ERROR(EIO);
+                error = XFS_ERROR(EIO);
+                goto out_unlock;
         }
 
         /*
@@ -928,11 +921,8 @@ xfs_qm_dqflush(
          */
         error = xfs_trans_read_buf(mp, NULL, mp->m_ddev_targp, dqp->q_blkno,
                                    mp->m_quotainfo->qi_dqchunklen, 0, &bp);
-        if (error) {
-                ASSERT(error != ENOENT);
-                xfs_dqfunlock(dqp);
-                return error;
-        }
+        if (error)
+                goto out_unlock;
 
         /*
          * Calculate the location of the dquot inside the buffer.
@@ -978,20 +968,13 @@ xfs_qm_dqflush(
                 xfs_log_force(mp, 0);
         }
 
-        if (flags & SYNC_WAIT)
-                error = xfs_bwrite(bp);
-        else
-                xfs_buf_delwri_queue(bp);
-
-        xfs_buf_relse(bp);
-
         trace_xfs_dqflush_done(dqp);
+        *bpp = bp;
+        return 0;
 
-        /*
-         * dqp is still locked, but caller is free to unlock it now.
-         */
-        return error;
-
+out_unlock:
+        xfs_dqfunlock(dqp);
+        return XFS_ERROR(EIO);
 }
 
 /*
diff --git a/fs/xfs/xfs_dquot.h b/fs/xfs/xfs_dquot.h
index ef9190bd8b30..5f2a2f2c0c5b 100644
--- a/fs/xfs/xfs_dquot.h
+++ b/fs/xfs/xfs_dquot.h
@@ -141,7 +141,7 @@ static inline xfs_dquot_t *xfs_inode_dquot(struct xfs_inode *ip, int type)
 extern int              xfs_qm_dqread(struct xfs_mount *, xfs_dqid_t, uint,
                                         uint, struct xfs_dquot  **);
 extern void             xfs_qm_dqdestroy(xfs_dquot_t *);
-extern int              xfs_qm_dqflush(xfs_dquot_t *, uint);
+extern int              xfs_qm_dqflush(struct xfs_dquot *, struct xfs_buf **);
 extern void             xfs_qm_dqunpin_wait(xfs_dquot_t *);
 extern void             xfs_qm_adjust_dqtimers(xfs_mount_t *,
                                         xfs_disk_dquot_t *);
diff --git a/fs/xfs/xfs_dquot_item.c b/fs/xfs/xfs_dquot_item.c
index 34baeae45265..8d8295814272 100644
--- a/fs/xfs/xfs_dquot_item.c
+++ b/fs/xfs/xfs_dquot_item.c
@@ -119,10 +119,12 @@ xfs_qm_dquot_logitem_push(
         struct xfs_log_item     *lip)
 {
         struct xfs_dquot        *dqp = DQUOT_ITEM(lip)->qli_dquot;
+        struct xfs_buf          *bp = NULL;
         int                     error;
 
         ASSERT(XFS_DQ_IS_LOCKED(dqp));
         ASSERT(!completion_done(&dqp->q_flush));
+        ASSERT(atomic_read(&dqp->q_pincount) == 0);
 
         /*
          * Since we were able to lock the dquot's flush lock and
@@ -133,10 +135,16 @@ xfs_qm_dquot_logitem_push(
          * lock without sleeping, then there must not have been
          * anyone in the process of flushing the dquot.
          */
-        error = xfs_qm_dqflush(dqp, SYNC_TRYLOCK);
-        if (error)
+        error = xfs_qm_dqflush(dqp, &bp);
+        if (error) {
                 xfs_warn(dqp->q_mount, "%s: push error %d on dqp %p",
                         __func__, error, dqp);
+                goto out_unlock;
+        }
+
+        xfs_buf_delwri_queue(bp);
+        xfs_buf_relse(bp);
+out_unlock:
         xfs_dqunlock(dqp);
 }
 
@@ -239,6 +247,15 @@ xfs_qm_dquot_logitem_trylock(
         if (!xfs_dqlock_nowait(dqp))
                 return XFS_ITEM_LOCKED;
 
+        /*
+         * Re-check the pincount now that we stabilized the value by
+         * taking the quota lock.
+         */
+        if (atomic_read(&dqp->q_pincount) > 0) {
+                xfs_dqunlock(dqp);
+                return XFS_ITEM_PINNED;
+        }
+
         if (!xfs_dqflock_nowait(dqp)) {
                 /*
                  * dquot has already been flushed to the backing buffer,
diff --git a/fs/xfs/xfs_qm.c b/fs/xfs/xfs_qm.c
index 18ba438386ab..95aecf52475d 100644
--- a/fs/xfs/xfs_qm.c
+++ b/fs/xfs/xfs_qm.c
@@ -175,16 +175,21 @@ xfs_qm_dqpurge(
          * we're unmounting, we do care, so we flush it and wait.
          */
         if (XFS_DQ_IS_DIRTY(dqp)) {
-                int     error;
+                struct xfs_buf  *bp = NULL;
+                int             error;
 
                 /*
                  * We don't care about getting disk errors here. We need
                  * to purge this dquot anyway, so we go ahead regardless.
                  */
-                error = xfs_qm_dqflush(dqp, SYNC_WAIT);
-                if (error)
+                error = xfs_qm_dqflush(dqp, &bp);
+                if (error) {
                         xfs_warn(mp, "%s: dquot %p flush failed",
                                 __func__, dqp);
+                } else {
+                        error = xfs_bwrite(bp);
+                        xfs_buf_relse(bp);
+                }
                 xfs_dqflock(dqp);
         }
 
@@ -1200,6 +1205,7 @@ STATIC int
 xfs_qm_flush_one(
         struct xfs_dquot        *dqp)
 {
+        struct xfs_buf          *bp = NULL;
         int                     error = 0;
 
         xfs_dqlock(dqp);
@@ -1211,8 +1217,12 @@ xfs_qm_flush_one(
         if (!xfs_dqflock_nowait(dqp))
                 xfs_dqflock_pushbuf_wait(dqp);
 
-        error = xfs_qm_dqflush(dqp, 0);
+        error = xfs_qm_dqflush(dqp, &bp);
+        if (error)
+                goto out_unlock;
 
+        xfs_buf_delwri_queue(bp);
+        xfs_buf_relse(bp);
 out_unlock:
         xfs_dqunlock(dqp);
         return error;
@@ -1479,18 +1489,23 @@ xfs_qm_dqreclaim_one(
          * dirty dquots.
          */
         if (XFS_DQ_IS_DIRTY(dqp)) {
+                struct xfs_buf  *bp = NULL;
+
                 trace_xfs_dqreclaim_dirty(dqp);
 
                 /*
                  * We flush it delayed write, so don't bother releasing the
                  * freelist lock.
                  */
-                error = xfs_qm_dqflush(dqp, 0);
+                error = xfs_qm_dqflush(dqp, &bp);
                 if (error) {
                         xfs_warn(mp, "%s: dquot %p flush failed",
                                  __func__, dqp);
+                        goto out_busy;
                 }
 
+                xfs_buf_delwri_queue(bp);
+                xfs_buf_relse(bp);
                 /*
                  * Give the dquot another try on the freelist, as the
                  * flushing will take some time.