6 files changed, 102 insertions, 115 deletions

diff --git a/fs/xfs/linux-2.6/xfs_super.c b/fs/xfs/linux-2.6/xfs_super.c
index 6ce828e0e17b..3b5b46b8e3b9 100644
--- a/fs/xfs/linux-2.6/xfs_super.c
+++ b/fs/xfs/linux-2.6/xfs_super.c
@@ -1064,7 +1064,7 @@ xfs_fs_write_inode(
                 xfs_ilock(ip, XFS_ILOCK_SHARED);
                 xfs_iflock(ip);
 
-                error = xfs_iflush(ip, XFS_IFLUSH_SYNC);
+                error = xfs_iflush(ip, SYNC_WAIT);
         } else {
                 error = EAGAIN;
                 if (!xfs_ilock_nowait(ip, XFS_ILOCK_SHARED))
@@ -1072,7 +1072,7 @@ xfs_fs_write_inode(
                 if (xfs_ipincount(ip) || !xfs_iflock_nowait(ip))
                         goto out_unlock;
 
-                error = xfs_iflush(ip, XFS_IFLUSH_ASYNC_NOBLOCK);
+                error = xfs_iflush(ip, 0);
         }
 
  out_unlock:
diff --git a/fs/xfs/linux-2.6/xfs_sync.c b/fs/xfs/linux-2.6/xfs_sync.c
index 525260c7617f..a9f6d20aff41 100644
--- a/fs/xfs/linux-2.6/xfs_sync.c
+++ b/fs/xfs/linux-2.6/xfs_sync.c
@@ -270,8 +270,7 @@ xfs_sync_inode_attr(
                 goto out_unlock;
         }
 
-        error = xfs_iflush(ip, (flags & SYNC_WAIT) ?
-                           XFS_IFLUSH_SYNC : XFS_IFLUSH_DELWRI);
+        error = xfs_iflush(ip, flags);
 
  out_unlock:
         xfs_iunlock(ip, XFS_ILOCK_SHARED);
@@ -460,16 +459,18 @@ xfs_quiesce_fs(
 {
         int     count = 0, pincount;
 
+        xfs_reclaim_inodes(mp, 0);
         xfs_flush_buftarg(mp->m_ddev_targp, 0);
-        xfs_reclaim_inodes(mp, XFS_IFLUSH_DELWRI_ELSE_ASYNC);
 
         /*
          * This loop must run at least twice.  The first instance of the loop
          * will flush most meta data but that will generate more meta data
          * (typically directory updates).  Which then must be flushed and
-         * logged before we can write the unmount record.
+         * logged before we can write the unmount record. We also so sync
+         * reclaim of inodes to catch any that the above delwri flush skipped.
          */
         do {
+                xfs_reclaim_inodes(mp, SYNC_WAIT);
                 xfs_sync_attr(mp, SYNC_WAIT);
                 pincount = xfs_flush_buftarg(mp->m_ddev_targp, 1);
                 if (!pincount) {
@@ -585,7 +586,7 @@ xfs_sync_worker(
 
         if (!(mp->m_flags & XFS_MOUNT_RDONLY)) {
                 xfs_log_force(mp, 0);
-                xfs_reclaim_inodes(mp, XFS_IFLUSH_DELWRI_ELSE_ASYNC);
+                xfs_reclaim_inodes(mp, 0);
                 /* dgc: errors ignored here */
                 error = xfs_qm_sync(mp, SYNC_TRYLOCK);
                 error = xfs_sync_fsdata(mp, SYNC_TRYLOCK);
@@ -719,21 +720,42 @@ __xfs_inode_clear_reclaim_tag(
  *      shutdown                EIO             unpin and reclaim
  *      clean, unpinned         0               reclaim
  *      stale, unpinned         0               reclaim
- *      clean, pinned(*)        0               unpin and reclaim
- *      stale, pinned           0               unpin and reclaim
- *      dirty, async            0               block on flush lock, reclaim
- *      dirty, sync flush       0               block on flush lock, reclaim
+ *      clean, pinned(*)        0               requeue
+ *      stale, pinned           EAGAIN          requeue
+ *      dirty, delwri ok        0               requeue
+ *      dirty, delwri blocked   EAGAIN          requeue
+ *      dirty, sync flush       0               reclaim
  *
  * (*) dgc: I don't think the clean, pinned state is possible but it gets
  * handled anyway given the order of checks implemented.
  *
+ * As can be seen from the table, the return value of xfs_iflush() is not
+ * sufficient to correctly decide the reclaim action here. The checks in
+ * xfs_iflush() might look like duplicates, but they are not.
+ *
+ * Also, because we get the flush lock first, we know that any inode that has
+ * been flushed delwri has had the flush completed by the time we check that
+ * the inode is clean. The clean inode check needs to be done before flushing
+ * the inode delwri otherwise we would loop forever requeuing clean inodes as
+ * we cannot tell apart a successful delwri flush and a clean inode from the
+ * return value of xfs_iflush().
+ *
+ * Note that because the inode is flushed delayed write by background
+ * writeback, the flush lock may already be held here and waiting on it can
+ * result in very long latencies. Hence for sync reclaims, where we wait on the
+ * flush lock, the caller should push out delayed write inodes first before
+ * trying to reclaim them to minimise the amount of time spent waiting. For
+ * background relaim, we just requeue the inode for the next pass.
+ *
  * Hence the order of actions after gaining the locks should be:
  *      bad             => reclaim
  *      shutdown        => unpin and reclaim
- *      pinned          => unpin
+ *      pinned, delwri  => requeue
+ *      pinned, sync    => unpin
  *      stale           => reclaim
  *      clean           => reclaim
- *      dirty           => flush, wait and reclaim
+ *      dirty, delwri   => flush and requeue
+ *      dirty, sync     => flush, wait and reclaim
  */
 STATIC int
 xfs_reclaim_inode(
@@ -741,7 +763,7 @@ xfs_reclaim_inode(
         struct xfs_perag        *pag,
         int                     sync_mode)
 {
-        int     error;
+        int     error = 0;
 
         /*
          * The radix tree lock here protects a thread in xfs_iget from racing
@@ -761,7 +783,11 @@ xfs_reclaim_inode(
         write_unlock(&pag->pag_ici_lock);
 
         xfs_ilock(ip, XFS_ILOCK_EXCL);
-        xfs_iflock(ip);
+        if (!xfs_iflock_nowait(ip)) {
+                if (!(sync_mode & SYNC_WAIT))
+                        goto out;
+                xfs_iflock(ip);
+        }
 
         if (is_bad_inode(VFS_I(ip)))
                 goto reclaim;
@@ -769,8 +795,13 @@ xfs_reclaim_inode(
                 xfs_iunpin_wait(ip);
                 goto reclaim;
         }
-        if (xfs_ipincount(ip))
+        if (xfs_ipincount(ip)) {
+                if (!(sync_mode & SYNC_WAIT)) {
+                        xfs_ifunlock(ip);
+                        goto out;
+                }
                 xfs_iunpin_wait(ip);
+        }
         if (xfs_iflags_test(ip, XFS_ISTALE))
                 goto reclaim;
         if (xfs_inode_clean(ip))
@@ -778,27 +809,43 @@ xfs_reclaim_inode(
 
         /* Now we have an inode that needs flushing */
         error = xfs_iflush(ip, sync_mode);
-        if (!error) {
-                switch(sync_mode) {
-                case XFS_IFLUSH_DELWRI_ELSE_ASYNC:
-                case XFS_IFLUSH_DELWRI:
-                case XFS_IFLUSH_ASYNC:
-                case XFS_IFLUSH_DELWRI_ELSE_SYNC:
-                case XFS_IFLUSH_SYNC:
-                        /* IO issued, synchronise with IO completion */
-                        xfs_iflock(ip);
-                        break;
-                default:
-                        ASSERT(0);
-                        break;
-                }
+        if (sync_mode & SYNC_WAIT) {
+                xfs_iflock(ip);
+                goto reclaim;
         }
 
+        /*
+         * When we have to flush an inode but don't have SYNC_WAIT set, we
+         * flush the inode out using a delwri buffer and wait for the next
+         * call into reclaim to find it in a clean state instead of waiting for
+         * it now. We also don't return errors here - if the error is transient
+         * then the next reclaim pass will flush the inode, and if the error
+         * is permanent then the next sync reclaim will relcaim the inode and
+         * pass on the error.
+         */
+        if (error && !XFS_FORCED_SHUTDOWN(ip->i_mount)) {
+                xfs_fs_cmn_err(CE_WARN, ip->i_mount,
+                        "inode 0x%llx background reclaim flush failed with %d",
+                        (long long)ip->i_ino, error);
+        }
+out:
+        xfs_iflags_clear(ip, XFS_IRECLAIM);
+        xfs_iunlock(ip, XFS_ILOCK_EXCL);
+        /*
+         * We could return EAGAIN here to make reclaim rescan the inode tree in
+         * a short while. However, this just burns CPU time scanning the tree
+         * waiting for IO to complete and xfssyncd never goes back to the idle
+         * state. Instead, return 0 to let the next scheduled background reclaim
+         * attempt to reclaim the inode again.
+         */
+        return 0;
+
 reclaim:
         xfs_ifunlock(ip);
         xfs_iunlock(ip, XFS_ILOCK_EXCL);
         xfs_ireclaim(ip);
-        return 0;
+        return error;
+
 }
 
 int
diff --git a/fs/xfs/xfs_inode.c b/fs/xfs/xfs_inode.c
index 8d0666dd170a..fa31360046d4 100644
--- a/fs/xfs/xfs_inode.c
+++ b/fs/xfs/xfs_inode.c
@@ -2835,8 +2835,6 @@ xfs_iflush(
         xfs_dinode_t            *dip;
         xfs_mount_t             *mp;
         int                     error;
-        int                     noblock = (flags == XFS_IFLUSH_ASYNC_NOBLOCK);
-        enum { INT_DELWRI = (1 << 0), INT_ASYNC = (1 << 1) };
 
         XFS_STATS_INC(xs_iflush_count);
 
@@ -2859,7 +2857,7 @@ xfs_iflush(
          * 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)) {
+        if (!(flags & SYNC_WAIT) && xfs_ipincount(ip)) {
                 xfs_iunpin_nowait(ip);
                 xfs_ifunlock(ip);
                 return EAGAIN;
@@ -2893,60 +2891,10 @@ xfs_iflush(
         }
 
         /*
-         * Decide how buffer will be flushed out.  This is done before
-         * the call to xfs_iflush_int because this field is zeroed by it.
-         */
-        if (iip != NULL && iip->ili_format.ilf_fields != 0) {
-                /*
-                 * Flush out the inode buffer according to the directions
-                 * of the caller.  In the cases where the caller has given
-                 * us a choice choose the non-delwri case.  This is because
-                 * the inode is in the AIL and we need to get it out soon.
-                 */
-                switch (flags) {
-                case XFS_IFLUSH_SYNC:
-                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;
-                        break;
-                case XFS_IFLUSH_DELWRI:
-                        flags = INT_DELWRI;
-                        break;
-                default:
-                        ASSERT(0);
-                        flags = 0;
-                        break;
-                }
-        } else {
-                switch (flags) {
-                case XFS_IFLUSH_DELWRI_ELSE_SYNC:
-                case XFS_IFLUSH_DELWRI_ELSE_ASYNC:
-                case XFS_IFLUSH_DELWRI:
-                        flags = INT_DELWRI;
-                        break;
-                case XFS_IFLUSH_ASYNC_NOBLOCK:
-                case XFS_IFLUSH_ASYNC:
-                        flags = INT_ASYNC;
-                        break;
-                case XFS_IFLUSH_SYNC:
-                        flags = 0;
-                        break;
-                default:
-                        ASSERT(0);
-                        flags = 0;
-                        break;
-                }
-        }
-
-        /*
          * Get the buffer containing the on-disk inode.
          */
         error = xfs_itobp(mp, NULL, ip, &dip, &bp,
-                                noblock ? XBF_TRYLOCK : XBF_LOCK);
+                                (flags & SYNC_WAIT) ? XBF_LOCK : XBF_TRYLOCK);
         if (error || !bp) {
                 xfs_ifunlock(ip);
                 return error;
@@ -2974,13 +2922,10 @@ xfs_iflush(
         if (error)
                 goto cluster_corrupt_out;
 
-        if (flags & INT_DELWRI) {
-                xfs_bdwrite(mp, bp);
-        } else if (flags & INT_ASYNC) {
-                error = xfs_bawrite(mp, bp);
-        } else {
+        if (flags & SYNC_WAIT)
                 error = xfs_bwrite(mp, bp);
-        }
+        else
+                xfs_bdwrite(mp, bp);
         return error;
 
 corrupt_out:
@@ -3015,16 +2960,6 @@ xfs_iflush_int(
         iip = ip->i_itemp;
         mp = ip->i_mount;
 
-
-        /*
-         * If the inode isn't dirty, then just release the inode
-         * flush lock and do nothing.
-         */
-        if (xfs_inode_clean(ip)) {
-                xfs_ifunlock(ip);
-                return 0;
-        }
-
         /* set *dip = inode's place in the buffer */
         dip = (xfs_dinode_t *)xfs_buf_offset(bp, ip->i_imap.im_boffset);
 
diff --git a/fs/xfs/xfs_inode.h b/fs/xfs/xfs_inode.h
index 8b618ea4d692..6c912b027596 100644
--- a/fs/xfs/xfs_inode.h
+++ b/fs/xfs/xfs_inode.h
@@ -420,16 +420,6 @@ static inline void xfs_ifunlock(xfs_inode_t *ip)
 #define XFS_ILOCK_DEP(flags)    (((flags) & XFS_ILOCK_DEP_MASK) >> XFS_ILOCK_SHIFT)
 
 /*
- * Flags for xfs_iflush()
- */
-#define XFS_IFLUSH_DELWRI_ELSE_SYNC     1
-#define XFS_IFLUSH_DELWRI_ELSE_ASYNC    2
-#define XFS_IFLUSH_SYNC                 3
-#define XFS_IFLUSH_ASYNC                4
-#define XFS_IFLUSH_DELWRI               5
-#define XFS_IFLUSH_ASYNC_NOBLOCK        6
-
-/*
  * Flags for xfs_itruncate_start().
  */
 #define XFS_ITRUNC_DEFINITE     0x1
diff --git a/fs/xfs/xfs_inode_item.c b/fs/xfs/xfs_inode_item.c
index 48ec1c0b23ce..207553e82954 100644
--- a/fs/xfs/xfs_inode_item.c
+++ b/fs/xfs/xfs_inode_item.c
@@ -866,10 +866,14 @@ xfs_inode_item_push(
                iip->ili_format.ilf_fields != 0);
 
         /*
-         * Write out the inode.  The completion routine ('iflush_done') will
-         * pull it from the AIL, mark it clean, unlock the flush lock.
+         * Push the inode to it's backing buffer. This will not remove the
+         * inode from the AIL - a further push will be required to trigger a
+         * buffer push. However, this allows all the dirty inodes to be pushed
+         * to the buffer before it is pushed to disk. THe buffer IO completion
+         * will pull th einode from the AIL, mark it clean and unlock the flush
+         * lock.
          */
-        (void) xfs_iflush(ip, XFS_IFLUSH_ASYNC);
+        (void) xfs_iflush(ip, 0);
         xfs_iunlock(ip, XFS_ILOCK_SHARED);
 
         return;
diff --git a/fs/xfs/xfs_mount.c b/fs/xfs/xfs_mount.c
index 5061149b2cc4..6afaaeb2950a 100644
--- a/fs/xfs/xfs_mount.c
+++ b/fs/xfs/xfs_mount.c
@@ -1468,7 +1468,18 @@ xfs_unmountfs(
          * need to force the log first.
          */
         xfs_log_force(mp, XFS_LOG_SYNC);
-        xfs_reclaim_inodes(mp, XFS_IFLUSH_ASYNC);
+
+        /*
+         * Do a delwri reclaim pass first so that as many dirty inodes are
+         * queued up for IO as possible. Then flush the buffers before making
+         * a synchronous path to catch all the remaining inodes are reclaimed.
+         * This makes the reclaim process as quick as possible by avoiding
+         * synchronous writeout and blocking on inodes already in the delwri
+         * state as much as possible.
+         */
+        xfs_reclaim_inodes(mp, 0);
+        XFS_bflush(mp->m_ddev_targp);
+        xfs_reclaim_inodes(mp, SYNC_WAIT);
 
         xfs_qm_unmount(mp);