1 files changed, 165 insertions, 30 deletions

diff --git a/fs/xfs/xfs_dquot.c b/fs/xfs/xfs_dquot.c
index ff982d983989..f11d475898f2 100644
--- a/fs/xfs/xfs_dquot.c
+++ b/fs/xfs/xfs_dquot.c
@@ -69,6 +69,30 @@ xfs_dquot_mark_sick(
 }
 
 /*
+ * Detach the dquot buffer if it's still attached, because we can get called
+ * through dqpurge after a log shutdown.  Caller must hold the dqflock or have
+ * otherwise isolated the dquot.
+ */
+void
+xfs_dquot_detach_buf(
+	struct xfs_dquot	*dqp)
+{
+	struct xfs_dq_logitem	*qlip = &dqp->q_logitem;
+	struct xfs_buf		*bp = NULL;
+
+	spin_lock(&qlip->qli_lock);
+	if (qlip->qli_item.li_buf) {
+		bp = qlip->qli_item.li_buf;
+		qlip->qli_item.li_buf = NULL;
+	}
+	spin_unlock(&qlip->qli_lock);
+	if (bp) {
+		list_del_init(&qlip->qli_item.li_bio_list);
+		xfs_buf_rele(bp);
+	}
+}
+
+/*
  * This is called to free all the memory associated with a dquot
  */
 void
@@ -76,6 +100,7 @@ xfs_qm_dqdestroy(
 	struct xfs_dquot	*dqp)
 {
 	ASSERT(list_empty(&dqp->q_lru));
+	ASSERT(dqp->q_logitem.qli_item.li_buf == NULL);
 
 	kvfree(dqp->q_logitem.qli_item.li_lv_shadow);
 	mutex_destroy(&dqp->q_qlock);
@@ -1142,9 +1167,11 @@ static void
 xfs_qm_dqflush_done(
 	struct xfs_log_item	*lip)
 {
-	struct xfs_dq_logitem	*qip = (struct xfs_dq_logitem *)lip;
-	struct xfs_dquot	*dqp = qip->qli_dquot;
+	struct xfs_dq_logitem	*qlip =
+			container_of(lip, struct xfs_dq_logitem, qli_item);
+	struct xfs_dquot	*dqp = qlip->qli_dquot;
 	struct xfs_ail		*ailp = lip->li_ailp;
+	struct xfs_buf		*bp = NULL;
 	xfs_lsn_t		tail_lsn;
 
 	/*
@@ -1156,12 +1183,12 @@ xfs_qm_dqflush_done(
 	 * holding the lock before removing the dquot from the AIL.
 	 */
 	if (test_bit(XFS_LI_IN_AIL, &lip->li_flags) &&
-	    ((lip->li_lsn == qip->qli_flush_lsn) ||
+	    (lip->li_lsn == qlip->qli_flush_lsn ||
 	     test_bit(XFS_LI_FAILED, &lip->li_flags))) {
 
 		spin_lock(&ailp->ail_lock);
 		xfs_clear_li_failed(lip);
-		if (lip->li_lsn == qip->qli_flush_lsn) {
+		if (lip->li_lsn == qlip->qli_flush_lsn) {
 			/* xfs_ail_update_finish() drops the AIL lock */
 			tail_lsn = xfs_ail_delete_one(ailp, lip);
 			xfs_ail_update_finish(ailp, tail_lsn);
@@ -1171,6 +1198,20 @@ xfs_qm_dqflush_done(
 	}
 
 	/*
+	 * If this dquot hasn't been dirtied since initiating the last dqflush,
+	 * release the buffer reference.  We already unlinked this dquot item
+	 * from the buffer.
+	 */
+	spin_lock(&qlip->qli_lock);
+	if (!qlip->qli_dirty) {
+		bp = lip->li_buf;
+		lip->li_buf = NULL;
+	}
+	spin_unlock(&qlip->qli_lock);
+	if (bp)
+		xfs_buf_rele(bp);
+
+	/*
 	 * Release the dq's flush lock since we're done with it.
 	 */
 	xfs_dqfunlock(dqp);
@@ -1196,7 +1237,7 @@ xfs_buf_dquot_io_fail(
 
 	spin_lock(&bp->b_mount->m_ail->ail_lock);
 	list_for_each_entry(lip, &bp->b_li_list, li_bio_list)
-		xfs_set_li_failed(lip, bp);
+		set_bit(XFS_LI_FAILED, &lip->li_flags);
 	spin_unlock(&bp->b_mount->m_ail->ail_lock);
 }
 
@@ -1239,6 +1280,111 @@ xfs_qm_dqflush_check(
 }
 
 /*
+ * Get the buffer containing the on-disk dquot.
+ *
+ * Requires dquot flush lock, will clear the dirty flag, delete the quota log
+ * item from the AIL, and shut down the system if something goes wrong.
+ */
+static int
+xfs_dquot_read_buf(
+	struct xfs_trans	*tp,
+	struct xfs_dquot	*dqp,
+	struct xfs_buf		**bpp)
+{
+	struct xfs_mount	*mp = dqp->q_mount;
+	struct xfs_buf		*bp = NULL;
+	int			error;
+
+	error = xfs_trans_read_buf(mp, tp, mp->m_ddev_targp, dqp->q_blkno,
+				   mp->m_quotainfo->qi_dqchunklen, 0,
+				   &bp, &xfs_dquot_buf_ops);
+	if (xfs_metadata_is_sick(error))
+		xfs_dquot_mark_sick(dqp);
+	if (error)
+		goto out_abort;
+
+	*bpp = bp;
+	return 0;
+
+out_abort:
+	dqp->q_flags &= ~XFS_DQFLAG_DIRTY;
+	xfs_trans_ail_delete(&dqp->q_logitem.qli_item, 0);
+	xfs_force_shutdown(mp, SHUTDOWN_CORRUPT_INCORE);
+	return error;
+}
+
+/*
+ * Attach a dquot buffer to this dquot to avoid allocating a buffer during a
+ * dqflush, since dqflush can be called from reclaim context.
+ */
+int
+xfs_dquot_attach_buf(
+	struct xfs_trans	*tp,
+	struct xfs_dquot	*dqp)
+{
+	struct xfs_dq_logitem	*qlip = &dqp->q_logitem;
+	struct xfs_log_item	*lip = &qlip->qli_item;
+	int			error;
+
+	spin_lock(&qlip->qli_lock);
+	if (!lip->li_buf) {
+		struct xfs_buf	*bp = NULL;
+
+		spin_unlock(&qlip->qli_lock);
+		error = xfs_dquot_read_buf(tp, dqp, &bp);
+		if (error)
+			return error;
+
+		/*
+		 * Attach the dquot to the buffer so that the AIL does not have
+		 * to read the dquot buffer to push this item.
+		 */
+		xfs_buf_hold(bp);
+		spin_lock(&qlip->qli_lock);
+		lip->li_buf = bp;
+		xfs_trans_brelse(tp, bp);
+	}
+	qlip->qli_dirty = true;
+	spin_unlock(&qlip->qli_lock);
+
+	return 0;
+}
+
+/*
+ * Get a new reference the dquot buffer attached to this dquot for a dqflush
+ * operation.
+ *
+ * Returns 0 and a NULL bp if none was attached to the dquot; 0 and a locked
+ * bp; or -EAGAIN if the buffer could not be locked.
+ */
+int
+xfs_dquot_use_attached_buf(
+	struct xfs_dquot	*dqp,
+	struct xfs_buf		**bpp)
+{
+	struct xfs_buf		*bp = dqp->q_logitem.qli_item.li_buf;
+
+	/*
+	 * A NULL buffer can happen if the dquot dirty flag was set but the
+	 * filesystem shut down before transaction commit happened.  In that
+	 * case we're not going to flush anyway.
+	 */
+	if (!bp) {
+		ASSERT(xfs_is_shutdown(dqp->q_mount));
+
+		*bpp = NULL;
+		return 0;
+	}
+
+	if (!xfs_buf_trylock(bp))
+		return -EAGAIN;
+
+	xfs_buf_hold(bp);
+	*bpp = bp;
+	return 0;
+}
+
+/*
  * Write a modified dquot to disk.
  * The dquot must be locked and the flush lock too taken by caller.
  * The flush lock will not be unlocked until the dquot reaches the disk,
@@ -1249,11 +1395,11 @@ xfs_qm_dqflush_check(
 int
 xfs_qm_dqflush(
 	struct xfs_dquot	*dqp,
-	struct xfs_buf		**bpp)
+	struct xfs_buf		*bp)
 {
 	struct xfs_mount	*mp = dqp->q_mount;
-	struct xfs_log_item	*lip = &dqp->q_logitem.qli_item;
-	struct xfs_buf		*bp;
+	struct xfs_dq_logitem	*qlip = &dqp->q_logitem;
+	struct xfs_log_item	*lip = &qlip->qli_item;
 	struct xfs_dqblk	*dqblk;
 	xfs_failaddr_t		fa;
 	int			error;
@@ -1263,28 +1409,12 @@ xfs_qm_dqflush(
 
 	trace_xfs_dqflush(dqp);
 
-	*bpp = NULL;
-
 	xfs_qm_dqunpin_wait(dqp);
 
-	/*
-	 * Get the buffer containing the on-disk dquot
-	 */
-	error = xfs_trans_read_buf(mp, NULL, mp->m_ddev_targp, dqp->q_blkno,
-				   mp->m_quotainfo->qi_dqchunklen, XBF_TRYLOCK,
-				   &bp, &xfs_dquot_buf_ops);
-	if (error == -EAGAIN)
-		goto out_unlock;
-	if (xfs_metadata_is_sick(error))
-		xfs_dquot_mark_sick(dqp);
-	if (error)
-		goto out_abort;
-
 	fa = xfs_qm_dqflush_check(dqp);
 	if (fa) {
 		xfs_alert(mp, "corrupt dquot ID 0x%x in memory at %pS",
 				dqp->q_id, fa);
-		xfs_buf_relse(bp);
 		xfs_dquot_mark_sick(dqp);
 		error = -EFSCORRUPTED;
 		goto out_abort;
@@ -1299,8 +1429,15 @@ xfs_qm_dqflush(
 	 */
 	dqp->q_flags &= ~XFS_DQFLAG_DIRTY;
 
-	xfs_trans_ail_copy_lsn(mp->m_ail, &dqp->q_logitem.qli_flush_lsn,
-					&dqp->q_logitem.qli_item.li_lsn);
+	/*
+	 * We hold the dquot lock, so nobody can dirty it while we're
+	 * scheduling the write out.  Clear the dirty-since-flush flag.
+	 */
+	spin_lock(&qlip->qli_lock);
+	qlip->qli_dirty = false;
+	spin_unlock(&qlip->qli_lock);
+
+	xfs_trans_ail_copy_lsn(mp->m_ail, &qlip->qli_flush_lsn, &lip->li_lsn);
 
 	/*
 	 * copy the lsn into the on-disk dquot now while we have the in memory
@@ -1312,7 +1449,7 @@ xfs_qm_dqflush(
 	 * of a dquot without an up-to-date CRC getting to disk.
 	 */
 	if (xfs_has_crc(mp)) {
-		dqblk->dd_lsn = cpu_to_be64(dqp->q_logitem.qli_item.li_lsn);
+		dqblk->dd_lsn = cpu_to_be64(lip->li_lsn);
 		xfs_update_cksum((char *)dqblk, sizeof(struct xfs_dqblk),
 				 XFS_DQUOT_CRC_OFF);
 	}
@@ -1322,7 +1459,7 @@ xfs_qm_dqflush(
 	 * the AIL and release the flush lock once the dquot is synced to disk.
 	 */
 	bp->b_flags |= _XBF_DQUOTS;
-	list_add_tail(&dqp->q_logitem.qli_item.li_bio_list, &bp->b_li_list);
+	list_add_tail(&lip->li_bio_list, &bp->b_li_list);
 
 	/*
 	 * If the buffer is pinned then push on the log so we won't
@@ -1334,14 +1471,12 @@ xfs_qm_dqflush(
 	}
 
 	trace_xfs_dqflush_done(dqp);
-	*bpp = bp;
 	return 0;
 
 out_abort:
 	dqp->q_flags &= ~XFS_DQFLAG_DIRTY;
 	xfs_trans_ail_delete(lip, 0);
 	xfs_force_shutdown(mp, SHUTDOWN_CORRUPT_INCORE);
-out_unlock:
 	xfs_dqfunlock(dqp);
 	return error;
 }