1 files changed, 135 insertions, 51 deletions

diff --git a/fs/xfs/linux-2.6/xfs_sync.c b/fs/xfs/linux-2.6/xfs_sync.c
index 1f5e4bb5e970..a9f6d20aff41 100644
--- a/fs/xfs/linux-2.6/xfs_sync.c
+++ b/fs/xfs/linux-2.6/xfs_sync.c
@@ -90,14 +90,13 @@ xfs_inode_ag_lookup(
 STATIC int
 xfs_inode_ag_walk(
         struct xfs_mount        *mp,
-        xfs_agnumber_t          ag,
+        struct xfs_perag        *pag,
         int                     (*execute)(struct xfs_inode *ip,
                                            struct xfs_perag *pag, int flags),
         int                     flags,
         int                     tag,
         int                     exclusive)
 {
-        struct xfs_perag        *pag = &mp->m_perag[ag];
         uint32_t                first_index;
         int                     last_error = 0;
         int                     skipped;
@@ -141,8 +140,6 @@ restart:
                 delay(1);
                 goto restart;
         }
-
-        xfs_put_perag(mp, pag);
         return last_error;
 }
 
@@ -160,10 +157,16 @@ xfs_inode_ag_iterator(
         xfs_agnumber_t          ag;
 
         for (ag = 0; ag < mp->m_sb.sb_agcount; ag++) {
-                if (!mp->m_perag[ag].pag_ici_init)
+                struct xfs_perag        *pag;
+
+                pag = xfs_perag_get(mp, ag);
+                if (!pag->pag_ici_init) {
+                        xfs_perag_put(pag);
                         continue;
-                error = xfs_inode_ag_walk(mp, ag, execute, flags, tag,
+                }
+                error = xfs_inode_ag_walk(mp, pag, execute, flags, tag,
                                                 exclusive);
+                xfs_perag_put(pag);
                 if (error) {
                         last_error = error;
                         if (error == EFSCORRUPTED)
@@ -231,7 +234,7 @@ xfs_sync_inode_data(
         }
 
         error = xfs_flush_pages(ip, 0, -1, (flags & SYNC_WAIT) ?
-                                0 : XFS_B_ASYNC, FI_NONE);
+                                0 : XBF_ASYNC, FI_NONE);
         xfs_iunlock(ip, XFS_IOLOCK_SHARED);
 
  out_wait:
@@ -267,8 +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);
@@ -293,10 +295,7 @@ xfs_sync_data(
         if (error)
                 return XFS_ERROR(error);
 
-        xfs_log_force(mp, 0,
-                      (flags & SYNC_WAIT) ?
-                       XFS_LOG_FORCE | XFS_LOG_SYNC :
-                       XFS_LOG_FORCE);
+        xfs_log_force(mp, (flags & SYNC_WAIT) ? XFS_LOG_SYNC : 0);
         return 0;
 }
 
@@ -322,10 +321,6 @@ xfs_commit_dummy_trans(
         struct xfs_inode        *ip = mp->m_rootip;
         struct xfs_trans        *tp;
         int                     error;
-        int                     log_flags = XFS_LOG_FORCE;
-
-        if (flags & SYNC_WAIT)
-                log_flags |= XFS_LOG_SYNC;
 
         /*
          * Put a dummy transaction in the log to tell recovery
@@ -347,11 +342,11 @@ xfs_commit_dummy_trans(
         xfs_iunlock(ip, XFS_ILOCK_EXCL);
 
         /* the log force ensures this transaction is pushed to disk */
-        xfs_log_force(mp, 0, log_flags);
+        xfs_log_force(mp, (flags & SYNC_WAIT) ? XFS_LOG_SYNC : 0);
         return error;
 }
 
-int
+STATIC int
 xfs_sync_fsdata(
         struct xfs_mount        *mp,
         int                     flags)
@@ -367,7 +362,7 @@ xfs_sync_fsdata(
         if (flags & SYNC_TRYLOCK) {
                 ASSERT(!(flags & SYNC_WAIT));
 
-                bp = xfs_getsb(mp, XFS_BUF_TRYLOCK);
+                bp = xfs_getsb(mp, XBF_TRYLOCK);
                 if (!bp)
                         goto out;
 
@@ -387,7 +382,7 @@ xfs_sync_fsdata(
                  * become pinned in between there and here.
                  */
                 if (XFS_BUF_ISPINNED(bp))
-                        xfs_log_force(mp, 0, XFS_LOG_FORCE);
+                        xfs_log_force(mp, 0);
         }
 
 
@@ -448,9 +443,6 @@ xfs_quiesce_data(
         xfs_sync_data(mp, SYNC_WAIT);
         xfs_qm_sync(mp, SYNC_WAIT);
 
-        /* drop inode references pinned by filestreams */
-        xfs_filestream_flush(mp);
-
         /* write superblock and hoover up shutdown errors */
         error = xfs_sync_fsdata(mp, SYNC_WAIT);
 
@@ -467,16 +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) {
@@ -575,7 +569,7 @@ xfs_flush_inodes(
         igrab(inode);
         xfs_syncd_queue_work(ip->i_mount, inode, xfs_flush_inodes_work, &completion);
         wait_for_completion(&completion);
-        xfs_log_force(ip->i_mount, (xfs_lsn_t)0, XFS_LOG_FORCE|XFS_LOG_SYNC);
+        xfs_log_force(ip->i_mount, XFS_LOG_SYNC);
 }
 
 /*
@@ -591,8 +585,8 @@ xfs_sync_worker(
         int             error;
 
         if (!(mp->m_flags & XFS_MOUNT_RDONLY)) {
-                xfs_log_force(mp, (xfs_lsn_t)0, XFS_LOG_FORCE);
-                xfs_reclaim_inodes(mp, XFS_IFLUSH_DELWRI_ELSE_ASYNC);
+                xfs_log_force(mp, 0);
+                xfs_reclaim_inodes(mp, 0);
                 /* dgc: errors ignored here */
                 error = xfs_qm_sync(mp, SYNC_TRYLOCK);
                 error = xfs_sync_fsdata(mp, SYNC_TRYLOCK);
@@ -690,16 +684,17 @@ void
 xfs_inode_set_reclaim_tag(
         xfs_inode_t     *ip)
 {
-        xfs_mount_t     *mp = ip->i_mount;
-        xfs_perag_t     *pag = xfs_get_perag(mp, ip->i_ino);
+        struct xfs_mount *mp = ip->i_mount;
+        struct xfs_perag *pag;
 
+        pag = xfs_perag_get(mp, XFS_INO_TO_AGNO(mp, ip->i_ino));
         read_lock(&pag->pag_ici_lock);
         spin_lock(&ip->i_flags_lock);
         __xfs_inode_set_reclaim_tag(pag, ip);
         __xfs_iflags_set(ip, XFS_IRECLAIMABLE);
         spin_unlock(&ip->i_flags_lock);
         read_unlock(&pag->pag_ici_lock);
-        xfs_put_perag(mp, pag);
+        xfs_perag_put(pag);
 }
 
 void
@@ -712,12 +707,64 @@ __xfs_inode_clear_reclaim_tag(
                         XFS_INO_TO_AGINO(mp, ip->i_ino), XFS_ICI_RECLAIM_TAG);
 }
 
+/*
+ * Inodes in different states need to be treated differently, and the return
+ * value of xfs_iflush is not sufficient to get this right. The following table
+ * lists the inode states and the reclaim actions necessary for non-blocking
+ * reclaim:
+ *
+ *
+ *      inode state          iflush ret         required action
+ *      ---------------      ----------         ---------------
+ *      bad                     -               reclaim
+ *      shutdown                EIO             unpin and reclaim
+ *      clean, unpinned         0               reclaim
+ *      stale, unpinned         0               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, delwri  => requeue
+ *      pinned, sync    => unpin
+ *      stale           => reclaim
+ *      clean           => reclaim
+ *      dirty, delwri   => flush and requeue
+ *      dirty, sync     => flush, wait and reclaim
+ */
 STATIC int
 xfs_reclaim_inode(
         struct xfs_inode        *ip,
         struct xfs_perag        *pag,
         int                     sync_mode)
 {
+        int     error = 0;
+
         /*
          * The radix tree lock here protects a thread in xfs_iget from racing
          * with us starting reclaim on the inode.  Once we have the
@@ -735,33 +782,70 @@ xfs_reclaim_inode(
         spin_unlock(&ip->i_flags_lock);
         write_unlock(&pag->pag_ici_lock);
 
-        /*
-         * If the inode is still dirty, then flush it out.  If the inode
-         * is not in the AIL, then it will be OK to flush it delwri as
-         * long as xfs_iflush() does not keep any references to the inode.
-         * We leave that decision up to xfs_iflush() since it has the
-         * knowledge of whether it's OK to simply do a delwri flush of
-         * the inode or whether we need to wait until the inode is
-         * pulled from the AIL.
-         * We get the flush lock regardless, though, just to make sure
-         * we don't free it while it is being flushed.
-         */
         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;
+        if (XFS_FORCED_SHUTDOWN(ip->i_mount)) {
+                xfs_iunpin_wait(ip);
+                goto reclaim;
+        }
+        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))
+                goto reclaim;
+
+        /* Now we have an inode that needs flushing */
+        error = xfs_iflush(ip, sync_mode);
+        if (sync_mode & SYNC_WAIT) {
+                xfs_iflock(ip);
+                goto reclaim;
+        }
 
         /*
-         * In the case of a forced shutdown we rely on xfs_iflush() to
-         * wait for the inode to be unpinned before returning an error.
+         * 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 (!is_bad_inode(VFS_I(ip)) && xfs_iflush(ip, sync_mode) == 0) {
-                /* synchronize with xfs_iflush_done */
-                xfs_iflock(ip);
-                xfs_ifunlock(ip);
+        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