1 files changed, 82 insertions, 53 deletions

diff --git a/fs/xfs/xfs_inode.c b/fs/xfs/xfs_inode.c
index 6f156faf9d46..3c3e9e3c1da8 100644
--- a/fs/xfs/xfs_inode.c
+++ b/fs/xfs/xfs_inode.c
@@ -145,11 +145,16 @@ xfs_imap_to_bp(
         xfs_buf_t       *bp;
 
         error = xfs_trans_read_buf(mp, tp, mp->m_ddev_targp, imap->im_blkno,
-                                   (int)imap->im_len, XFS_BUF_LOCK, &bp);
+                                   (int)imap->im_len, buf_flags, &bp);
         if (error) {
-                cmn_err(CE_WARN, "xfs_imap_to_bp: xfs_trans_read_buf()returned "
+                if (error != EAGAIN) {
+                        cmn_err(CE_WARN,
+                                "xfs_imap_to_bp: xfs_trans_read_buf()returned "
                                 "an error %d on %s.  Returning error.",
                                 error, mp->m_fsname);
+                } else {
+                        ASSERT(buf_flags & XFS_BUF_TRYLOCK);
+                }
                 return error;
         }
 
@@ -274,7 +279,8 @@ xfs_itobp(
         xfs_dinode_t    **dipp,
         xfs_buf_t       **bpp,
         xfs_daddr_t     bno,
-        uint            imap_flags)
+        uint            imap_flags,
+        uint            buf_flags)
 {
         xfs_imap_t      imap;
         xfs_buf_t       *bp;
@@ -305,10 +311,17 @@ xfs_itobp(
         }
         ASSERT(bno == 0 || bno == imap.im_blkno);
 
-        error = xfs_imap_to_bp(mp, tp, &imap, &bp, XFS_BUF_LOCK, imap_flags);
+        error = xfs_imap_to_bp(mp, tp, &imap, &bp, buf_flags, imap_flags);
         if (error)
                 return error;
 
+        if (!bp) {
+                ASSERT(buf_flags & XFS_BUF_TRYLOCK);
+                ASSERT(tp == NULL);
+                *bpp = NULL;
+                return EAGAIN;
+        }
+
         *dipp = (xfs_dinode_t *)xfs_buf_offset(bp, imap.im_boffset);
         *bpp = bp;
         return 0;
@@ -812,7 +825,7 @@ xfs_iread(
          * return NULL as well.  Set i_blkno to 0 so that xfs_itobp() will
          * know that this is a new incore inode.
          */
-        error = xfs_itobp(mp, tp, ip, &dip, &bp, bno, imap_flags);
+        error = xfs_itobp(mp, tp, ip, &dip, &bp, bno, imap_flags, XFS_BUF_LOCK);
         if (error) {
                 kmem_zone_free(xfs_inode_zone, ip);
                 return error;
@@ -1901,7 +1914,7 @@ xfs_iunlink(
                  * Here we put the head pointer into our next pointer,
                  * and then we fall through to point the head at us.
                  */
-                error = xfs_itobp(mp, tp, ip, &dip, &ibp, 0, 0);
+                error = xfs_itobp(mp, tp, ip, &dip, &ibp, 0, 0, XFS_BUF_LOCK);
                 if (error)
                         return error;
 
@@ -2009,7 +2022,7 @@ xfs_iunlink_remove(
                  * of dealing with the buffer when there is no need to
                  * change it.
                  */
-                error = xfs_itobp(mp, tp, ip, &dip, &ibp, 0, 0);
+                error = xfs_itobp(mp, tp, ip, &dip, &ibp, 0, 0, XFS_BUF_LOCK);
                 if (error) {
                         cmn_err(CE_WARN,
                                 "xfs_iunlink_remove: xfs_itobp()  returned an error %d on %s.  Returning error.",
@@ -2071,7 +2084,7 @@ xfs_iunlink_remove(
                  * Now last_ibp points to the buffer previous to us on
                  * the unlinked list.  Pull us from the list.
                  */
-                error = xfs_itobp(mp, tp, ip, &dip, &ibp, 0, 0);
+                error = xfs_itobp(mp, tp, ip, &dip, &ibp, 0, 0, XFS_BUF_LOCK);
                 if (error) {
                         cmn_err(CE_WARN,
                                 "xfs_iunlink_remove: xfs_itobp()  returned an error %d on %s.  Returning error.",
@@ -2334,7 +2347,7 @@ xfs_ifree(
 
         xfs_trans_log_inode(tp, ip, XFS_ILOG_CORE);
 
-        error = xfs_itobp(ip->i_mount, tp, ip, &dip, &ibp, 0, 0);
+        error = xfs_itobp(ip->i_mount, tp, ip, &dip, &ibp, 0, 0, XFS_BUF_LOCK);
         if (error)
                 return error;
 
@@ -2777,38 +2790,41 @@ xfs_iunpin(
 }
 
 /*
- * This is called to wait for the given inode to be unpinned.
- * It will sleep until this happens.  The caller must have the
- * inode locked in at least shared mode so that the buffer cannot
- * be subsequently pinned once someone is waiting for it to be
- * unpinned.
+ * This is called to unpin an inode. It can be directed to wait or to return
+ * immediately without waiting for the inode to be unpinned.  The caller must
+ * have the inode locked in at least shared mode so that the buffer cannot be
+ * subsequently pinned once someone is waiting for it to be unpinned.
  */
 STATIC void
-xfs_iunpin_wait(
-        xfs_inode_t     *ip)
+__xfs_iunpin_wait(
+        xfs_inode_t     *ip,
+        int             wait)
 {
-        xfs_inode_log_item_t    *iip;
-        xfs_lsn_t       lsn;
+        xfs_inode_log_item_t    *iip = ip->i_itemp;
 
         ASSERT(ismrlocked(&ip->i_lock, MR_UPDATE | MR_ACCESS));
-
-        if (atomic_read(&ip->i_pincount) == 0) {
+        if (atomic_read(&ip->i_pincount) == 0)
                 return;
-        }
 
-        iip = ip->i_itemp;
-        if (iip && iip->ili_last_lsn) {
-                lsn = iip->ili_last_lsn;
-        } else {
-                lsn = (xfs_lsn_t)0;
-        }
+        /* Give the log a push to start the unpinning I/O */
+        xfs_log_force(ip->i_mount, (iip && iip->ili_last_lsn) ?
+                                iip->ili_last_lsn : 0, XFS_LOG_FORCE);
+        if (wait)
+                wait_event(ip->i_ipin_wait, (atomic_read(&ip->i_pincount) == 0));
+}
 
-        /*
-         * Give the log a push so we don't wait here too long.
-         */
-        xfs_log_force(ip->i_mount, lsn, XFS_LOG_FORCE);
+static inline void
+xfs_iunpin_wait(
+        xfs_inode_t     *ip)
+{
+        __xfs_iunpin_wait(ip, 1);
+}
 
-        wait_event(ip->i_ipin_wait, (atomic_read(&ip->i_pincount) == 0));
+static inline void
+xfs_iunpin_nowait(
+        xfs_inode_t     *ip)
+{
+        __xfs_iunpin_wait(ip, 0);
 }
 
 
@@ -3003,6 +3019,7 @@ xfs_iflush(
         int                     bufwasdelwri;
         struct hlist_node       *entry;
         enum { INT_DELWRI = (1 << 0), INT_ASYNC = (1 << 1) };
+        int                     noblock = (flags == XFS_IFLUSH_ASYNC_NOBLOCK);
 
         XFS_STATS_INC(xs_iflush_count);
 
@@ -3027,11 +3044,21 @@ xfs_iflush(
         }
 
         /*
-         * We can't flush the inode until it is unpinned, so
-         * wait for it.  We know noone new can pin it, because
-         * we are holding the inode lock shared and you need
-         * to hold it exclusively to pin the inode.
+         * We can't flush the inode until it is unpinned, so wait for it if we
+         * are allowed to block.  We know noone new can pin it, because we are
+         * holding the inode lock shared and you need to hold it exclusively to
+         * pin the inode.
+         *
+         * If we are not allowed to block, force the log out asynchronously so
+         * that when we come back the inode will be unpinned. If other inodes
+         * in the same cluster are dirty, they will probably write the inode
+         * out for us if they occur after the log force completes.
          */
+        if (noblock && xfs_ipincount(ip)) {
+                xfs_iunpin_nowait(ip);
+                xfs_ifunlock(ip);
+                return EAGAIN;
+        }
         xfs_iunpin_wait(ip);
 
         /*
@@ -3048,15 +3075,6 @@ xfs_iflush(
         }
 
         /*
-         * Get the buffer containing the on-disk inode.
-         */
-        error = xfs_itobp(mp, NULL, ip, &dip, &bp, 0, 0);
-        if (error) {
-                xfs_ifunlock(ip);
-                return error;
-        }
-
-        /*
          * Decide how buffer will be flushed out.  This is done before
          * the call to xfs_iflush_int because this field is zeroed by it.
          */
@@ -3072,6 +3090,7 @@ xfs_iflush(
                 case XFS_IFLUSH_DELWRI_ELSE_SYNC:
                         flags = 0;
                         break;
+                case XFS_IFLUSH_ASYNC_NOBLOCK:
                 case XFS_IFLUSH_ASYNC:
                 case XFS_IFLUSH_DELWRI_ELSE_ASYNC:
                         flags = INT_ASYNC;
@@ -3091,6 +3110,7 @@ xfs_iflush(
                 case XFS_IFLUSH_DELWRI:
                         flags = INT_DELWRI;
                         break;
+                case XFS_IFLUSH_ASYNC_NOBLOCK:
                 case XFS_IFLUSH_ASYNC:
                         flags = INT_ASYNC;
                         break;
@@ -3105,6 +3125,16 @@ xfs_iflush(
         }
 
         /*
+         * Get the buffer containing the on-disk inode.
+         */
+        error = xfs_itobp(mp, NULL, ip, &dip, &bp, 0, 0,
+                                noblock ? XFS_BUF_TRYLOCK : XFS_BUF_LOCK);
+        if (error || !bp) {
+                xfs_ifunlock(ip);
+                return error;
+        }
+
+        /*
          * First flush out the inode that xfs_iflush was called with.
          */
         error = xfs_iflush_int(ip, bp);
@@ -3113,6 +3143,13 @@ xfs_iflush(
         }
 
         /*
+         * If the buffer is pinned then push on the log now so we won't
+         * get stuck waiting in the write for too long.
+         */
+        if (XFS_BUF_ISPINNED(bp))
+                xfs_log_force(mp, (xfs_lsn_t)0, XFS_LOG_FORCE);
+
+        /*
          * inode clustering:
          * see if other inodes can be gathered into this write
          */
@@ -3181,14 +3218,6 @@ xfs_iflush(
                 XFS_STATS_ADD(xs_icluster_flushinode, clcount);
         }
 
-        /*
-         * If the buffer is pinned then push on the log so we won't
-         * get stuck waiting in the write for too long.
-         */
-        if (XFS_BUF_ISPINNED(bp)){
-                xfs_log_force(mp, (xfs_lsn_t)0, XFS_LOG_FORCE);
-        }
-
         if (flags & INT_DELWRI) {
                 xfs_bdwrite(mp, bp);
         } else if (flags & INT_ASYNC) {