Merge branch '2.6.36-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/dgc/xfsdev

* '2.6.36-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/dgc/xfsdev:
  xfs: do not discard page cache data on EAGAIN
  xfs: don't do memory allocation under the CIL context lock
  xfs: Reduce log force overhead for delayed logging
  xfs: dummy transactions should not dirty VFS state
  xfs: ensure f_ffree returned by statfs() is non-negative
  xfs: handle negative wbc->nr_to_write during sync writeback
  writeback: write_cache_pages doesn't terminate at nr_to_write <= 0
  xfs: fix untrusted inode number lookup
  xfs: ensure we mark all inodes in a freed cluster XFS_ISTALE
  xfs: unlock items before allowing the CIL to commit

13 files changed, 261 insertions, 218 deletions

diff --git a/fs/xfs/linux-2.6/xfs_aops.c b/fs/xfs/linux-2.6/xfs_aops.c
index 15412fe15c3a..b552f816de15 100644
--- a/fs/xfs/linux-2.6/xfs_aops.c
+++ b/fs/xfs/linux-2.6/xfs_aops.c
@@ -852,8 +852,8 @@ xfs_convert_page(
                 SetPageUptodate(page);
 
         if (count) {
-                wbc->nr_to_write--;
-                if (wbc->nr_to_write <= 0)
+                if (--wbc->nr_to_write <= 0 &&
+                    wbc->sync_mode == WB_SYNC_NONE)
                         done = 1;
         }
         xfs_start_page_writeback(page, !page_dirty, count);
@@ -1068,7 +1068,7 @@ xfs_vm_writepage(
          * by themselves.
          */
         if ((current->flags & (PF_MEMALLOC|PF_KSWAPD)) == PF_MEMALLOC)
-                goto out_fail;
+                goto redirty;
 
         /*
          * We need a transaction if there are delalloc or unwritten buffers
@@ -1080,7 +1080,7 @@ xfs_vm_writepage(
          */
         xfs_count_page_state(page, &delalloc, &unwritten);
         if ((current->flags & PF_FSTRANS) && (delalloc || unwritten))
-                goto out_fail;
+                goto redirty;
 
         /* Is this page beyond the end of the file? */
         offset = i_size_read(inode);
@@ -1245,12 +1245,15 @@ error:
         if (iohead)
                 xfs_cancel_ioend(iohead);
 
+        if (err == -EAGAIN)
+                goto redirty;
+
         xfs_aops_discard_page(page);
         ClearPageUptodate(page);
         unlock_page(page);
         return err;
 
-out_fail:
+redirty:
         redirty_page_for_writepage(wbc, page);
         unlock_page(page);
         return 0;
diff --git a/fs/xfs/linux-2.6/xfs_super.c b/fs/xfs/linux-2.6/xfs_super.c
index 15c35b62ff14..a4e07974955b 100644
--- a/fs/xfs/linux-2.6/xfs_super.c
+++ b/fs/xfs/linux-2.6/xfs_super.c
@@ -1226,6 +1226,7 @@ xfs_fs_statfs(
         struct xfs_inode        *ip = XFS_I(dentry->d_inode);
         __uint64_t              fakeinos, id;
         xfs_extlen_t            lsize;
+        __int64_t               ffree;
 
         statp->f_type = XFS_SB_MAGIC;
         statp->f_namelen = MAXNAMELEN - 1;
@@ -1249,7 +1250,11 @@ xfs_fs_statfs(
                 statp->f_files = min_t(typeof(statp->f_files),
                                         statp->f_files,
                                         mp->m_maxicount);
-        statp->f_ffree = statp->f_files - (sbp->sb_icount - sbp->sb_ifree);
+
+        /* make sure statp->f_ffree does not underflow */
+        ffree = statp->f_files - (sbp->sb_icount - sbp->sb_ifree);
+        statp->f_ffree = max_t(__int64_t, ffree, 0);
+
         spin_unlock(&mp->m_sb_lock);
 
         if ((ip->i_d.di_flags & XFS_DIFLAG_PROJINHERIT) ||
@@ -1402,7 +1407,7 @@ xfs_fs_freeze(
 
         xfs_save_resvblks(mp);
         xfs_quiesce_attr(mp);
-        return -xfs_fs_log_dummy(mp);
+        return -xfs_fs_log_dummy(mp, SYNC_WAIT);
 }
 
 STATIC int
diff --git a/fs/xfs/linux-2.6/xfs_sync.c b/fs/xfs/linux-2.6/xfs_sync.c
index dfcbd98d1599..d59c4a65d492 100644
--- a/fs/xfs/linux-2.6/xfs_sync.c
+++ b/fs/xfs/linux-2.6/xfs_sync.c
@@ -34,6 +34,7 @@
 #include "xfs_inode_item.h"
 #include "xfs_quota.h"
 #include "xfs_trace.h"
+#include "xfs_fsops.h"
 
 #include <linux/kthread.h>
 #include <linux/freezer.h>
@@ -341,38 +342,6 @@ xfs_sync_attr(
 }
 
 STATIC int
-xfs_commit_dummy_trans(
-        struct xfs_mount        *mp,
-        uint                    flags)
-{
-        struct xfs_inode        *ip = mp->m_rootip;
-        struct xfs_trans        *tp;
-        int                     error;
-
-        /*
-         * Put a dummy transaction in the log to tell recovery
-         * that all others are OK.
-         */
-        tp = xfs_trans_alloc(mp, XFS_TRANS_DUMMY1);
-        error = xfs_trans_reserve(tp, 0, XFS_ICHANGE_LOG_RES(mp), 0, 0, 0);
-        if (error) {
-                xfs_trans_cancel(tp, 0);
-                return error;
-        }
-
-        xfs_ilock(ip, XFS_ILOCK_EXCL);
-
-        xfs_trans_ijoin(tp, ip);
-        xfs_trans_log_inode(tp, ip, XFS_ILOG_CORE);
-        error = xfs_trans_commit(tp, 0);
-        xfs_iunlock(ip, XFS_ILOCK_EXCL);
-
-        /* the log force ensures this transaction is pushed to disk */
-        xfs_log_force(mp, (flags & SYNC_WAIT) ? XFS_LOG_SYNC : 0);
-        return error;
-}
-
-STATIC int
 xfs_sync_fsdata(
         struct xfs_mount        *mp)
 {
@@ -432,7 +401,7 @@ xfs_quiesce_data(
 
         /* mark the log as covered if needed */
         if (xfs_log_need_covered(mp))
-                error2 = xfs_commit_dummy_trans(mp, SYNC_WAIT);
+                error2 = xfs_fs_log_dummy(mp, SYNC_WAIT);
 
         /* flush data-only devices */
         if (mp->m_rtdev_targp)
@@ -563,7 +532,7 @@ xfs_flush_inodes(
 /*
  * Every sync period we need to unpin all items, reclaim inodes and sync
  * disk quotas.  We might need to cover the log to indicate that the
- * filesystem is idle.
+ * filesystem is idle and not frozen.
  */
 STATIC void
 xfs_sync_worker(
@@ -577,8 +546,9 @@ xfs_sync_worker(
                 xfs_reclaim_inodes(mp, 0);
                 /* dgc: errors ignored here */
                 error = xfs_qm_sync(mp, SYNC_TRYLOCK);
-                if (xfs_log_need_covered(mp))
-                        error = xfs_commit_dummy_trans(mp, 0);
+                if (mp->m_super->s_frozen == SB_UNFROZEN &&
+                    xfs_log_need_covered(mp))
+                        error = xfs_fs_log_dummy(mp, 0);
         }
         mp->m_sync_seq++;
         wake_up(&mp->m_wait_single_sync_task);
diff --git a/fs/xfs/xfs_fsops.c b/fs/xfs/xfs_fsops.c
index dbca5f5c37ba..43b1d5699335 100644
--- a/fs/xfs/xfs_fsops.c
+++ b/fs/xfs/xfs_fsops.c
@@ -604,31 +604,36 @@ out:
         return 0;
 }
 
+/*
+ * Dump a transaction into the log that contains no real change. This is needed
+ * to be able to make the log dirty or stamp the current tail LSN into the log
+ * during the covering operation.
+ *
+ * We cannot use an inode here for this - that will push dirty state back up
+ * into the VFS and then periodic inode flushing will prevent log covering from
+ * making progress. Hence we log a field in the superblock instead.
+ */
 int
 xfs_fs_log_dummy(
-        xfs_mount_t     *mp)
+        xfs_mount_t     *mp,
+        int             flags)
 {
         xfs_trans_t     *tp;
-        xfs_inode_t     *ip;
         int             error;
 
         tp = _xfs_trans_alloc(mp, XFS_TRANS_DUMMY1, KM_SLEEP);
-        error = xfs_trans_reserve(tp, 0, XFS_ICHANGE_LOG_RES(mp), 0, 0, 0);
+        error = xfs_trans_reserve(tp, 0, mp->m_sb.sb_sectsize + 128, 0, 0,
+                                        XFS_DEFAULT_LOG_COUNT);
         if (error) {
                 xfs_trans_cancel(tp, 0);
                 return error;
         }
 
-        ip = mp->m_rootip;
-        xfs_ilock(ip, XFS_ILOCK_EXCL);
-
-        xfs_trans_ijoin(tp, ip);
-        xfs_trans_log_inode(tp, ip, XFS_ILOG_CORE);
-        xfs_trans_set_sync(tp);
-        error = xfs_trans_commit(tp, 0);
-
-        xfs_iunlock(ip, XFS_ILOCK_EXCL);
-        return error;
+        /* log the UUID because it is an unchanging field */
+        xfs_mod_sb(tp, XFS_SB_UUID);
+        if (flags & SYNC_WAIT)
+                xfs_trans_set_sync(tp);
+        return xfs_trans_commit(tp, 0);
 }
 
 int
diff --git a/fs/xfs/xfs_fsops.h b/fs/xfs/xfs_fsops.h
index 88435e0a77c9..a786c5212c1e 100644
--- a/fs/xfs/xfs_fsops.h
+++ b/fs/xfs/xfs_fsops.h
@@ -25,6 +25,6 @@ extern int xfs_fs_counts(xfs_mount_t *mp, xfs_fsop_counts_t *cnt);
 extern int xfs_reserve_blocks(xfs_mount_t *mp, __uint64_t *inval,
                                 xfs_fsop_resblks_t *outval);
 extern int xfs_fs_goingdown(xfs_mount_t *mp, __uint32_t inflags);
-extern int xfs_fs_log_dummy(xfs_mount_t *mp);
+extern int xfs_fs_log_dummy(xfs_mount_t *mp, int flags);
 
 #endif  /* __XFS_FSOPS_H__ */
diff --git a/fs/xfs/xfs_ialloc.c b/fs/xfs/xfs_ialloc.c
index abf80ae1e95b..5371d2dc360e 100644
--- a/fs/xfs/xfs_ialloc.c
+++ b/fs/xfs/xfs_ialloc.c
@@ -1213,7 +1213,6 @@ xfs_imap_lookup(
         struct xfs_inobt_rec_incore rec;
         struct xfs_btree_cur    *cur;
         struct xfs_buf          *agbp;
-        xfs_agino_t             startino;
         int                     error;
         int                     i;
 
@@ -1227,13 +1226,13 @@ xfs_imap_lookup(
         }
 
         /*
-         * derive and lookup the exact inode record for the given agino. If the
-         * record cannot be found, then it's an invalid inode number and we
-         * should abort.
+         * Lookup the inode record for the given agino. If the record cannot be
+         * found, then it's an invalid inode number and we should abort. Once
+         * we have a record, we need to ensure it contains the inode number
+         * we are looking up.
          */
         cur = xfs_inobt_init_cursor(mp, tp, agbp, agno);
-        startino = agino & ~(XFS_IALLOC_INODES(mp) - 1);
-        error = xfs_inobt_lookup(cur, startino, XFS_LOOKUP_EQ, &i);
+        error = xfs_inobt_lookup(cur, agino, XFS_LOOKUP_LE, &i);
         if (!error) {
                 if (i)
                         error = xfs_inobt_get_rec(cur, &rec, &i);
@@ -1246,6 +1245,11 @@ xfs_imap_lookup(
         if (error)
                 return error;
 
+        /* check that the returned record contains the required inode */
+        if (rec.ir_startino > agino ||
+            rec.ir_startino + XFS_IALLOC_INODES(mp) <= agino)
+                return EINVAL;
+
         /* for untrusted inodes check it is allocated first */
         if ((flags & XFS_IGET_UNTRUSTED) &&
             (rec.ir_free & XFS_INOBT_MASK(agino - rec.ir_startino)))
diff --git a/fs/xfs/xfs_inode.c b/fs/xfs/xfs_inode.c
index 68415cb4f23c..34798f391c49 100644
--- a/fs/xfs/xfs_inode.c
+++ b/fs/xfs/xfs_inode.c
@@ -1914,6 +1914,11 @@ xfs_iunlink_remove(
         return 0;
 }
 
+/*
+ * A big issue when freeing the inode cluster is is that we _cannot_ skip any
+ * inodes that are in memory - they all must be marked stale and attached to
+ * the cluster buffer.
+ */
 STATIC void
 xfs_ifree_cluster(
         xfs_inode_t     *free_ip,
@@ -1945,8 +1950,6 @@ xfs_ifree_cluster(
         }
 
         for (j = 0; j < nbufs; j++, inum += ninodes) {
-                int     found = 0;
-
                 blkno = XFS_AGB_TO_DADDR(mp, XFS_INO_TO_AGNO(mp, inum),
                                          XFS_INO_TO_AGBNO(mp, inum));
 
@@ -1965,7 +1968,9 @@ xfs_ifree_cluster(
                 /*
                  * Walk the inodes already attached to the buffer and mark them
                  * stale. These will all have the flush locks held, so an
-                 * in-memory inode walk can't lock them.
+                 * in-memory inode walk can't lock them. By marking them all
+                 * stale first, we will not attempt to lock them in the loop
+                 * below as the XFS_ISTALE flag will be set.
                  */
                 lip = XFS_BUF_FSPRIVATE(bp, xfs_log_item_t *);
                 while (lip) {
@@ -1977,11 +1982,11 @@ xfs_ifree_cluster(
                                                         &iip->ili_flush_lsn,
                                                         &iip->ili_item.li_lsn);
                                 xfs_iflags_set(iip->ili_inode, XFS_ISTALE);
-                                found++;
                         }
                         lip = lip->li_bio_list;
                 }
 
+
                 /*
                  * For each inode in memory attempt to add it to the inode
                  * buffer and set it up for being staled on buffer IO
@@ -1993,6 +1998,7 @@ xfs_ifree_cluster(
                  * even trying to lock them.
                  */
                 for (i = 0; i < ninodes; i++) {
+retry:
                         read_lock(&pag->pag_ici_lock);
                         ip = radix_tree_lookup(&pag->pag_ici_root,
                                         XFS_INO_TO_AGINO(mp, (inum + i)));
@@ -2003,38 +2009,36 @@ xfs_ifree_cluster(
                                 continue;
                         }
 
-                        /* don't try to lock/unlock the current inode */
+                        /*
+                         * Don't try to lock/unlock the current inode, but we
+                         * _cannot_ skip the other inodes that we did not find
+                         * in the list attached to the buffer and are not
+                         * already marked stale. If we can't lock it, back off
+                         * and retry.
+                         */
                         if (ip != free_ip &&
                             !xfs_ilock_nowait(ip, XFS_ILOCK_EXCL)) {
                                 read_unlock(&pag->pag_ici_lock);
-                                continue;
+                                delay(1);
+                                goto retry;
                         }
                         read_unlock(&pag->pag_ici_lock);
 
-                        if (!xfs_iflock_nowait(ip)) {
-                                if (ip != free_ip)
-                                        xfs_iunlock(ip, XFS_ILOCK_EXCL);
-                                continue;
-                        }
-
+                        xfs_iflock(ip);
                         xfs_iflags_set(ip, XFS_ISTALE);
-                        if (xfs_inode_clean(ip)) {
-                                ASSERT(ip != free_ip);
-                                xfs_ifunlock(ip);
-                                xfs_iunlock(ip, XFS_ILOCK_EXCL);
-                                continue;
-                        }
 
+                        /*
+                         * we don't need to attach clean inodes or those only
+                         * with unlogged changes (which we throw away, anyway).
+                         */
                         iip = ip->i_itemp;
-                        if (!iip) {
-                                /* inode with unlogged changes only */
+                        if (!iip || xfs_inode_clean(ip)) {
                                 ASSERT(ip != free_ip);
                                 ip->i_update_core = 0;
                                 xfs_ifunlock(ip);
                                 xfs_iunlock(ip, XFS_ILOCK_EXCL);
                                 continue;
                         }
-                        found++;
 
                         iip->ili_last_fields = iip->ili_format.ilf_fields;
                         iip->ili_format.ilf_fields = 0;
@@ -2049,8 +2053,7 @@ xfs_ifree_cluster(
                                 xfs_iunlock(ip, XFS_ILOCK_EXCL);
                 }
 
-                if (found)
-                        xfs_trans_stale_inode_buf(tp, bp);
+                xfs_trans_stale_inode_buf(tp, bp);
                 xfs_trans_binval(tp, bp);
         }
 
diff --git a/fs/xfs/xfs_log.c b/fs/xfs/xfs_log.c
index 925d572bf0f4..33f718f92a48 100644
--- a/fs/xfs/xfs_log.c
+++ b/fs/xfs/xfs_log.c
@@ -3015,7 +3015,8 @@ _xfs_log_force(
 
         XFS_STATS_INC(xs_log_force);
 
-        xlog_cil_push(log, 1);
+        if (log->l_cilp)
+                xlog_cil_force(log);
 
         spin_lock(&log->l_icloglock);
 
@@ -3167,7 +3168,7 @@ _xfs_log_force_lsn(
         XFS_STATS_INC(xs_log_force);
 
         if (log->l_cilp) {
-                lsn = xlog_cil_push_lsn(log, lsn);
+                lsn = xlog_cil_force_lsn(log, lsn);
                 if (lsn == NULLCOMMITLSN)
                         return 0;
         }
@@ -3724,7 +3725,7 @@ xfs_log_force_umount(
          * call below.
          */
         if (!logerror && (mp->m_flags & XFS_MOUNT_DELAYLOG))
-                xlog_cil_push(log, 1);
+                xlog_cil_force(log);
 
         /*
          * We must hold both the GRANT lock and the LOG lock,
diff --git a/fs/xfs/xfs_log_cil.c b/fs/xfs/xfs_log_cil.c
index 31e4ea2d19ac..ed575fb4b495 100644
--- a/fs/xfs/xfs_log_cil.c
+++ b/fs/xfs/xfs_log_cil.c
@@ -68,6 +68,7 @@ xlog_cil_init(
         ctx->sequence = 1;
         ctx->cil = cil;
         cil->xc_ctx = ctx;
+        cil->xc_current_sequence = ctx->sequence;
 
         cil->xc_log = log;
         log->l_cilp = cil;
@@ -269,15 +270,10 @@ xlog_cil_insert(
 static void
 xlog_cil_format_items(
         struct log              *log,
-        struct xfs_log_vec      *log_vector,
-        struct xlog_ticket      *ticket,
-        xfs_lsn_t               *start_lsn)
+        struct xfs_log_vec      *log_vector)
 {
         struct xfs_log_vec *lv;
 
-        if (start_lsn)
-                *start_lsn = log->l_cilp->xc_ctx->sequence;
-
         ASSERT(log_vector);
         for (lv = log_vector; lv; lv = lv->lv_next) {
                 void    *ptr;
@@ -301,9 +297,24 @@ xlog_cil_format_items(
                         ptr += vec->i_len;
                 }
                 ASSERT(ptr == lv->lv_buf + lv->lv_buf_len);
+        }
+}
+
+static void
+xlog_cil_insert_items(
+        struct log              *log,
+        struct xfs_log_vec      *log_vector,
+        struct xlog_ticket      *ticket,
+        xfs_lsn_t               *start_lsn)
+{
+        struct xfs_log_vec *lv;
+
+        if (start_lsn)
+                *start_lsn = log->l_cilp->xc_ctx->sequence;
 
+        ASSERT(log_vector);
+        for (lv = log_vector; lv; lv = lv->lv_next)
                 xlog_cil_insert(log, ticket, lv->lv_item, lv);
-        }
 }
 
 static void
@@ -321,80 +332,6 @@ xlog_cil_free_logvec(
 }
 
 /*
- * Commit a transaction with the given vector to the Committed Item List.
- *
- * To do this, we need to format the item, pin it in memory if required and
- * account for the space used by the transaction. Once we have done that we
- * need to release the unused reservation for the transaction, attach the
- * transaction to the checkpoint context so we carry the busy extents through
- * to checkpoint completion, and then unlock all the items in the transaction.
- *
- * For more specific information about the order of operations in
- * xfs_log_commit_cil() please refer to the comments in
- * xfs_trans_commit_iclog().
- *
- * Called with the context lock already held in read mode to lock out
- * background commit, returns without it held once background commits are
- * allowed again.
- */
-int
-xfs_log_commit_cil(
-        struct xfs_mount        *mp,
-        struct xfs_trans        *tp,
-        struct xfs_log_vec      *log_vector,
-        xfs_lsn_t               *commit_lsn,
-        int                     flags)
-{
-        struct log              *log = mp->m_log;
-        int                     log_flags = 0;
-        int                     push = 0;
-
-        if (flags & XFS_TRANS_RELEASE_LOG_RES)
-                log_flags = XFS_LOG_REL_PERM_RESERV;
-
-        if (XLOG_FORCED_SHUTDOWN(log)) {
-                xlog_cil_free_logvec(log_vector);
-                return XFS_ERROR(EIO);
-        }
-
-        /* lock out background commit */
-        down_read(&log->l_cilp->xc_ctx_lock);
-        xlog_cil_format_items(log, log_vector, tp->t_ticket, commit_lsn);
-
-        /* check we didn't blow the reservation */
-        if (tp->t_ticket->t_curr_res < 0)
-                xlog_print_tic_res(log->l_mp, tp->t_ticket);
-
-        /* attach the transaction to the CIL if it has any busy extents */
-        if (!list_empty(&tp->t_busy)) {
-                spin_lock(&log->l_cilp->xc_cil_lock);
-                list_splice_init(&tp->t_busy,
-                                        &log->l_cilp->xc_ctx->busy_extents);
-                spin_unlock(&log->l_cilp->xc_cil_lock);
-        }
-
-        tp->t_commit_lsn = *commit_lsn;
-        xfs_log_done(mp, tp->t_ticket, NULL, log_flags);
-        xfs_trans_unreserve_and_mod_sb(tp);
-
-        /* check for background commit before unlock */
-        if (log->l_cilp->xc_ctx->space_used > XLOG_CIL_SPACE_LIMIT(log))
-                push = 1;
-        up_read(&log->l_cilp->xc_ctx_lock);
-
-        /*
-         * We need to push CIL every so often so we don't cache more than we
-         * can fit in the log. The limit really is that a checkpoint can't be
-         * more than half the log (the current checkpoint is not allowed to
-         * overwrite the previous checkpoint), but commit latency and memory
-         * usage limit this to a smaller size in most cases.
-         */
-        if (push)
-                xlog_cil_push(log, 0);
-        return 0;
-}
-
-/*
  * Mark all items committed and clear busy extents. We free the log vector
  * chains in a separate pass so that we unpin the log items as quickly as
  * possible.
@@ -427,13 +364,23 @@ xlog_cil_committed(
 }
 
 /*
- * Push the Committed Item List to the log. If the push_now flag is not set,
- * then it is a background flush and so we can chose to ignore it.
+ * Push the Committed Item List to the log. If @push_seq flag is zero, then it
+ * is a background flush and so we can chose to ignore it. Otherwise, if the
+ * current sequence is the same as @push_seq we need to do a flush. If
+ * @push_seq is less than the current sequence, then it has already been
+ * flushed and we don't need to do anything - the caller will wait for it to
+ * complete if necessary.
+ *
+ * @push_seq is a value rather than a flag because that allows us to do an
+ * unlocked check of the sequence number for a match. Hence we can allows log
+ * forces to run racily and not issue pushes for the same sequence twice. If we
+ * get a race between multiple pushes for the same sequence they will block on
+ * the first one and then abort, hence avoiding needless pushes.
  */
-int
+STATIC int
 xlog_cil_push(
         struct log              *log,
-        int                     push_now)
+        xfs_lsn_t               push_seq)
 {
         struct xfs_cil          *cil = log->l_cilp;
         struct xfs_log_vec      *lv;
@@ -453,12 +400,14 @@ xlog_cil_push(
         if (!cil)
                 return 0;
 
+        ASSERT(!push_seq || push_seq <= cil->xc_ctx->sequence);
+
         new_ctx = kmem_zalloc(sizeof(*new_ctx), KM_SLEEP|KM_NOFS);
         new_ctx->ticket = xlog_cil_ticket_alloc(log);
 
         /* lock out transaction commit, but don't block on background push */
         if (!down_write_trylock(&cil->xc_ctx_lock)) {
-                if (!push_now)
+                if (!push_seq)
                         goto out_free_ticket;
                 down_write(&cil->xc_ctx_lock);
         }
@@ -469,7 +418,11 @@ xlog_cil_push(
                 goto out_skip;
 
         /* check for spurious background flush */
-        if (!push_now && cil->xc_ctx->space_used < XLOG_CIL_SPACE_LIMIT(log))
+        if (!push_seq && cil->xc_ctx->space_used < XLOG_CIL_SPACE_LIMIT(log))
+                goto out_skip;
+
+        /* check for a previously pushed seqeunce */
+        if (push_seq < cil->xc_ctx->sequence)
                 goto out_skip;
 
         /*
@@ -515,6 +468,13 @@ xlog_cil_push(
         cil->xc_ctx = new_ctx;
 
         /*
+         * mirror the new sequence into the cil structure so that we can do
+         * unlocked checks against the current sequence in log forces without
+         * risking deferencing a freed context pointer.
+         */
+        cil->xc_current_sequence = new_ctx->sequence;
+
+        /*
          * The switch is now done, so we can drop the context lock and move out
          * of a shared context. We can't just go straight to the commit record,
          * though - we need to synchronise with previous and future commits so
@@ -626,6 +586,102 @@ out_abort:
 }
 
 /*
+ * Commit a transaction with the given vector to the Committed Item List.
+ *
+ * To do this, we need to format the item, pin it in memory if required and
+ * account for the space used by the transaction. Once we have done that we
+ * need to release the unused reservation for the transaction, attach the
+ * transaction to the checkpoint context so we carry the busy extents through
+ * to checkpoint completion, and then unlock all the items in the transaction.
+ *
+ * For more specific information about the order of operations in
+ * xfs_log_commit_cil() please refer to the comments in
+ * xfs_trans_commit_iclog().
+ *
+ * Called with the context lock already held in read mode to lock out
+ * background commit, returns without it held once background commits are
+ * allowed again.
+ */
+int
+xfs_log_commit_cil(
+        struct xfs_mount        *mp,
+        struct xfs_trans        *tp,
+        struct xfs_log_vec      *log_vector,
+        xfs_lsn_t               *commit_lsn,
+        int                     flags)
+{
+        struct log              *log = mp->m_log;
+        int                     log_flags = 0;
+        int                     push = 0;
+
+        if (flags & XFS_TRANS_RELEASE_LOG_RES)
+                log_flags = XFS_LOG_REL_PERM_RESERV;
+
+        if (XLOG_FORCED_SHUTDOWN(log)) {
+                xlog_cil_free_logvec(log_vector);
+                return XFS_ERROR(EIO);
+        }
+
+        /*
+         * do all the hard work of formatting items (including memory
+         * allocation) outside the CIL context lock. This prevents stalling CIL
+         * pushes when we are low on memory and a transaction commit spends a
+         * lot of time in memory reclaim.
+         */
+        xlog_cil_format_items(log, log_vector);
+
+        /* lock out background commit */
+        down_read(&log->l_cilp->xc_ctx_lock);
+        xlog_cil_insert_items(log, log_vector, tp->t_ticket, commit_lsn);
+
+        /* check we didn't blow the reservation */
+        if (tp->t_ticket->t_curr_res < 0)
+                xlog_print_tic_res(log->l_mp, tp->t_ticket);
+
+        /* attach the transaction to the CIL if it has any busy extents */
+        if (!list_empty(&tp->t_busy)) {
+                spin_lock(&log->l_cilp->xc_cil_lock);
+                list_splice_init(&tp->t_busy,
+                                        &log->l_cilp->xc_ctx->busy_extents);
+                spin_unlock(&log->l_cilp->xc_cil_lock);
+        }
+
+        tp->t_commit_lsn = *commit_lsn;
+        xfs_log_done(mp, tp->t_ticket, NULL, log_flags);
+        xfs_trans_unreserve_and_mod_sb(tp);
+
+        /*
+         * Once all the items of the transaction have been copied to the CIL,
+         * the items can be unlocked and freed.
+         *
+         * This needs to be done before we drop the CIL context lock because we
+         * have to update state in the log items and unlock them before they go
+         * to disk. If we don't, then the CIL checkpoint can race with us and
+         * we can run checkpoint completion before we've updated and unlocked
+         * the log items. This affects (at least) processing of stale buffers,
+         * inodes and EFIs.
+         */
+        xfs_trans_free_items(tp, *commit_lsn, 0);
+
+        /* check for background commit before unlock */
+        if (log->l_cilp->xc_ctx->space_used > XLOG_CIL_SPACE_LIMIT(log))
+                push = 1;
+
+        up_read(&log->l_cilp->xc_ctx_lock);
+
+        /*
+         * We need to push CIL every so often so we don't cache more than we
+         * can fit in the log. The limit really is that a checkpoint can't be
+         * more than half the log (the current checkpoint is not allowed to
+         * overwrite the previous checkpoint), but commit latency and memory
+         * usage limit this to a smaller size in most cases.
+         */
+        if (push)
+                xlog_cil_push(log, 0);
+        return 0;
+}
+
+/*
  * Conditionally push the CIL based on the sequence passed in.
  *
  * We only need to push if we haven't already pushed the sequence
@@ -639,39 +695,34 @@ out_abort:
  * commit lsn is there. It'll be empty, so this is broken for now.
  */
 xfs_lsn_t
-xlog_cil_push_lsn(
+xlog_cil_force_lsn(
         struct log      *log,
-        xfs_lsn_t       push_seq)
+        xfs_lsn_t       sequence)
 {
         struct xfs_cil          *cil = log->l_cilp;
         struct xfs_cil_ctx      *ctx;
         xfs_lsn_t               commit_lsn = NULLCOMMITLSN;
 
-restart:
-        down_write(&cil->xc_ctx_lock);
-        ASSERT(push_seq <= cil->xc_ctx->sequence);
-
-        /* check to see if we need to force out the current context */
-        if (push_seq == cil->xc_ctx->sequence) {
-                up_write(&cil->xc_ctx_lock);
-                xlog_cil_push(log, 1);
-                goto restart;
-        }
+        ASSERT(sequence <= cil->xc_current_sequence);
+
+        /*
+         * check to see if we need to force out the current context.
+         * xlog_cil_push() handles racing pushes for the same sequence,
+         * so no need to deal with it here.
+         */
+        if (sequence == cil->xc_current_sequence)
+                xlog_cil_push(log, sequence);
 
         /*
          * See if we can find a previous sequence still committing.
-         * We can drop the flush lock as soon as we have the cil lock
-         * because we are now only comparing contexts protected by
-         * the cil lock.
-         *
          * We need to wait for all previous sequence commits to complete
          * before allowing the force of push_seq to go ahead. Hence block
          * on commits for those as well.
          */
+restart:
         spin_lock(&cil->xc_cil_lock);
-        up_write(&cil->xc_ctx_lock);
         list_for_each_entry(ctx, &cil->xc_committing, committing) {
-                if (ctx->sequence > push_seq)
+                if (ctx->sequence > sequence)
                         continue;
                 if (!ctx->commit_lsn) {
                         /*
@@ -681,7 +732,7 @@ restart:
                         sv_wait(&cil->xc_commit_wait, 0, &cil->xc_cil_lock, 0);
                         goto restart;
                 }
-                if (ctx->sequence != push_seq)
+                if (ctx->sequence != sequence)
                         continue;
                 /* found it! */
                 commit_lsn = ctx->commit_lsn;
diff --git a/fs/xfs/xfs_log_priv.h b/fs/xfs/xfs_log_priv.h
index 8c072618965c..ced52b98b322 100644
--- a/fs/xfs/xfs_log_priv.h
+++ b/fs/xfs/xfs_log_priv.h
@@ -422,6 +422,7 @@ struct xfs_cil {
         struct rw_semaphore     xc_ctx_lock;
         struct list_head        xc_committing;
         sv_t                    xc_commit_wait;
+        xfs_lsn_t               xc_current_sequence;
 };
 
 /*
@@ -562,8 +563,16 @@ int	xlog_cil_init(struct log *log);
 void    xlog_cil_init_post_recovery(struct log *log);
 void    xlog_cil_destroy(struct log *log);
 
-int     xlog_cil_push(struct log *log, int push_now);
-xfs_lsn_t xlog_cil_push_lsn(struct log *log, xfs_lsn_t push_sequence);
+/*
+ * CIL force routines
+ */
+xfs_lsn_t xlog_cil_force_lsn(struct log *log, xfs_lsn_t sequence);
+
+static inline void
+xlog_cil_force(struct log *log)
+{
+        xlog_cil_force_lsn(log, log->l_cilp->xc_current_sequence);
+}
 
 /*
  * Unmount record type is used as a pseudo transaction type for the ticket.
diff --git a/fs/xfs/xfs_trans.c b/fs/xfs/xfs_trans.c
index fdca7416c754..1c47edaea0d2 100644
--- a/fs/xfs/xfs_trans.c
+++ b/fs/xfs/xfs_trans.c
@@ -1167,7 +1167,7 @@ xfs_trans_del_item(
  * Unlock all of the items of a transaction and free all the descriptors
  * of that transaction.
  */
-STATIC void
+void
 xfs_trans_free_items(
         struct xfs_trans        *tp,
         xfs_lsn_t               commit_lsn,
@@ -1653,9 +1653,6 @@ xfs_trans_commit_cil(
                 return error;
 
         current_restore_flags_nested(&tp->t_pflags, PF_FSTRANS);
-
-        /* xfs_trans_free_items() unlocks them first */
-        xfs_trans_free_items(tp, *commit_lsn, 0);
         xfs_trans_free(tp);
         return 0;
 }
diff --git a/fs/xfs/xfs_trans_priv.h b/fs/xfs/xfs_trans_priv.h
index e2d93d8ead7b..62da86c90de5 100644
--- a/fs/xfs/xfs_trans_priv.h
+++ b/fs/xfs/xfs_trans_priv.h
@@ -25,7 +25,8 @@ struct xfs_trans;
 
 void    xfs_trans_add_item(struct xfs_trans *, struct xfs_log_item *);
 void    xfs_trans_del_item(struct xfs_log_item *);
-
+void    xfs_trans_free_items(struct xfs_trans *tp, xfs_lsn_t commit_lsn,
+                                int flags);
 void    xfs_trans_item_committed(struct xfs_log_item *lip,
                                 xfs_lsn_t commit_lsn, int aborted);
 void    xfs_trans_unreserve_and_mod_sb(struct xfs_trans *tp);
diff --git a/mm/page-writeback.c b/mm/page-writeback.c
index c09ef5219cbe..a803f5e33471 100644
--- a/mm/page-writeback.c
+++ b/mm/page-writeback.c
@@ -985,22 +985,16 @@ continue_unlock:
                                 }
                         }
 
-                        if (wbc->nr_to_write > 0) {
-                                if (--wbc->nr_to_write == 0 &&
-                                    wbc->sync_mode == WB_SYNC_NONE) {
-                                        /*
-                                         * We stop writing back only if we are
-                                         * not doing integrity sync. In case of
-                                         * integrity sync we have to keep going
-                                         * because someone may be concurrently
-                                         * dirtying pages, and we might have
-                                         * synced a lot of newly appeared dirty
-                                         * pages, but have not synced all of the
-                                         * old dirty pages.
-                                         */
-                                        done = 1;
-                                        break;
-                                }
+                        /*
+                         * We stop writing back only if we are not doing
+                         * integrity sync. In case of integrity sync we have to
+                         * keep going until we have written all the pages
+                         * we tagged for writeback prior to entering this loop.
+                         */
+                        if (--wbc->nr_to_write <= 0 &&
+                            wbc->sync_mode == WB_SYNC_NONE) {
+                                done = 1;
+                                break;
                         }
                 }
                 pagevec_release(&pvec);