1 files changed, 146 insertions, 119 deletions

diff --git a/fs/xfs/linux-2.6/xfs_sync.c b/fs/xfs/linux-2.6/xfs_sync.c
index e22f0057d21f..e4f9c1b0836c 100644
--- a/fs/xfs/linux-2.6/xfs_sync.c
+++ b/fs/xfs/linux-2.6/xfs_sync.c
@@ -22,6 +22,7 @@
 #include "xfs_log.h"
 #include "xfs_inum.h"
 #include "xfs_trans.h"
+#include "xfs_trans_priv.h"
 #include "xfs_sb.h"
 #include "xfs_ag.h"
 #include "xfs_mount.h"
@@ -39,6 +40,8 @@
 #include <linux/kthread.h>
 #include <linux/freezer.h>
 
+struct workqueue_struct *xfs_syncd_wq;  /* sync workqueue */
+
 /*
  * The inode lookup is done in batches to keep the amount of lock traffic and
  * radix tree lookups to a minimum. The batch size is a trade off between
@@ -401,7 +404,7 @@ xfs_quiesce_fs(
 /*
  * Second stage of a quiesce. The data is already synced, now we have to take
  * care of the metadata. New transactions are already blocked, so we need to
- * wait for any remaining transactions to drain out before proceding.
+ * wait for any remaining transactions to drain out before proceeding.
  */
 void
 xfs_quiesce_attr(
@@ -425,69 +428,18 @@ xfs_quiesce_attr(
         /* Push the superblock and write an unmount record */
         error = xfs_log_sbcount(mp, 1);
         if (error)
-                xfs_fs_cmn_err(CE_WARN, mp,
-                                "xfs_attr_quiesce: failed to log sb changes. "
+                xfs_warn(mp, "xfs_attr_quiesce: failed to log sb changes. "
                                 "Frozen image may not be consistent.");
         xfs_log_unmount_write(mp);
         xfs_unmountfs_writesb(mp);
 }
 
-/*
- * Enqueue a work item to be picked up by the vfs xfssyncd thread.
- * Doing this has two advantages:
- * - It saves on stack space, which is tight in certain situations
- * - It can be used (with care) as a mechanism to avoid deadlocks.
- * Flushing while allocating in a full filesystem requires both.
- */
-STATIC void
-xfs_syncd_queue_work(
-        struct xfs_mount *mp,
-        void            *data,
-        void            (*syncer)(struct xfs_mount *, void *),
-        struct completion *completion)
-{
-        struct xfs_sync_work *work;
-
-        work = kmem_alloc(sizeof(struct xfs_sync_work), KM_SLEEP);
-        INIT_LIST_HEAD(&work->w_list);
-        work->w_syncer = syncer;
-        work->w_data = data;
-        work->w_mount = mp;
-        work->w_completion = completion;
-        spin_lock(&mp->m_sync_lock);
-        list_add_tail(&work->w_list, &mp->m_sync_list);
-        spin_unlock(&mp->m_sync_lock);
-        wake_up_process(mp->m_sync_task);
-}
-
-/*
- * Flush delayed allocate data, attempting to free up reserved space
- * from existing allocations.  At this point a new allocation attempt
- * has failed with ENOSPC and we are in the process of scratching our
- * heads, looking about for more room...
- */
-STATIC void
-xfs_flush_inodes_work(
-        struct xfs_mount *mp,
-        void            *arg)
-{
-        struct inode    *inode = arg;
-        xfs_sync_data(mp, SYNC_TRYLOCK);
-        xfs_sync_data(mp, SYNC_TRYLOCK | SYNC_WAIT);
-        iput(inode);
-}
-
-void
-xfs_flush_inodes(
-        xfs_inode_t     *ip)
+static void
+xfs_syncd_queue_sync(
+        struct xfs_mount        *mp)
 {
-        struct inode    *inode = VFS_I(ip);
-        DECLARE_COMPLETION_ONSTACK(completion);
-
-        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_LOG_SYNC);
+        queue_delayed_work(xfs_syncd_wq, &mp->m_sync_work,
+                                msecs_to_jiffies(xfs_syncd_centisecs * 10));
 }
 
 /*
@@ -497,9 +449,10 @@ xfs_flush_inodes(
  */
 STATIC void
 xfs_sync_worker(
-        struct xfs_mount *mp,
-        void            *unused)
+        struct work_struct *work)
 {
+        struct xfs_mount *mp = container_of(to_delayed_work(work),
+                                        struct xfs_mount, m_sync_work);
         int             error;
 
         if (!(mp->m_flags & XFS_MOUNT_RDONLY)) {
@@ -509,73 +462,106 @@ xfs_sync_worker(
                         error = xfs_fs_log_dummy(mp);
                 else
                         xfs_log_force(mp, 0);
-                xfs_reclaim_inodes(mp, 0);
                 error = xfs_qm_sync(mp, SYNC_TRYLOCK);
+
+                /* start pushing all the metadata that is currently dirty */
+                xfs_ail_push_all(mp->m_ail);
         }
-        mp->m_sync_seq++;
-        wake_up(&mp->m_wait_single_sync_task);
+
+        /* queue us up again */
+        xfs_syncd_queue_sync(mp);
 }
 
-STATIC int
-xfssyncd(
-        void                    *arg)
+/*
+ * Queue a new inode reclaim pass if there are reclaimable inodes and there
+ * isn't a reclaim pass already in progress. By default it runs every 5s based
+ * on the xfs syncd work default of 30s. Perhaps this should have it's own
+ * tunable, but that can be done if this method proves to be ineffective or too
+ * aggressive.
+ */
+static void
+xfs_syncd_queue_reclaim(
+        struct xfs_mount        *mp)
 {
-        struct xfs_mount        *mp = arg;
-        long                    timeleft;
-        xfs_sync_work_t         *work, *n;
-        LIST_HEAD               (tmp);
-
-        set_freezable();
-        timeleft = xfs_syncd_centisecs * msecs_to_jiffies(10);
-        for (;;) {
-                if (list_empty(&mp->m_sync_list))
-                        timeleft = schedule_timeout_interruptible(timeleft);
-                /* swsusp */
-                try_to_freeze();
-                if (kthread_should_stop() && list_empty(&mp->m_sync_list))
-                        break;
 
-                spin_lock(&mp->m_sync_lock);
-                /*
-                 * We can get woken by laptop mode, to do a sync -
-                 * that's the (only!) case where the list would be
-                 * empty with time remaining.
-                 */
-                if (!timeleft || list_empty(&mp->m_sync_list)) {
-                        if (!timeleft)
-                                timeleft = xfs_syncd_centisecs *
-                                                        msecs_to_jiffies(10);
-                        INIT_LIST_HEAD(&mp->m_sync_work.w_list);
-                        list_add_tail(&mp->m_sync_work.w_list,
-                                        &mp->m_sync_list);
-                }
-                list_splice_init(&mp->m_sync_list, &tmp);
-                spin_unlock(&mp->m_sync_lock);
+        /*
+         * We can have inodes enter reclaim after we've shut down the syncd
+         * workqueue during unmount, so don't allow reclaim work to be queued
+         * during unmount.
+         */
+        if (!(mp->m_super->s_flags & MS_ACTIVE))
+                return;
 
-                list_for_each_entry_safe(work, n, &tmp, w_list) {
-                        (*work->w_syncer)(mp, work->w_data);
-                        list_del(&work->w_list);
-                        if (work == &mp->m_sync_work)
-                                continue;
-                        if (work->w_completion)
-                                complete(work->w_completion);
-                        kmem_free(work);
-                }
+        rcu_read_lock();
+        if (radix_tree_tagged(&mp->m_perag_tree, XFS_ICI_RECLAIM_TAG)) {
+                queue_delayed_work(xfs_syncd_wq, &mp->m_reclaim_work,
+                        msecs_to_jiffies(xfs_syncd_centisecs / 6 * 10));
         }
+        rcu_read_unlock();
+}
 
-        return 0;
+/*
+ * This is a fast pass over the inode cache to try to get reclaim moving on as
+ * many inodes as possible in a short period of time. It kicks itself every few
+ * seconds, as well as being kicked by the inode cache shrinker when memory
+ * goes low. It scans as quickly as possible avoiding locked inodes or those
+ * already being flushed, and once done schedules a future pass.
+ */
+STATIC void
+xfs_reclaim_worker(
+        struct work_struct *work)
+{
+        struct xfs_mount *mp = container_of(to_delayed_work(work),
+                                        struct xfs_mount, m_reclaim_work);
+
+        xfs_reclaim_inodes(mp, SYNC_TRYLOCK);
+        xfs_syncd_queue_reclaim(mp);
+}
+
+/*
+ * Flush delayed allocate data, attempting to free up reserved space
+ * from existing allocations.  At this point a new allocation attempt
+ * has failed with ENOSPC and we are in the process of scratching our
+ * heads, looking about for more room.
+ *
+ * Queue a new data flush if there isn't one already in progress and
+ * wait for completion of the flush. This means that we only ever have one
+ * inode flush in progress no matter how many ENOSPC events are occurring and
+ * so will prevent the system from bogging down due to every concurrent
+ * ENOSPC event scanning all the active inodes in the system for writeback.
+ */
+void
+xfs_flush_inodes(
+        struct xfs_inode        *ip)
+{
+        struct xfs_mount        *mp = ip->i_mount;
+
+        queue_work(xfs_syncd_wq, &mp->m_flush_work);
+        flush_work_sync(&mp->m_flush_work);
+}
+
+STATIC void
+xfs_flush_worker(
+        struct work_struct *work)
+{
+        struct xfs_mount *mp = container_of(work,
+                                        struct xfs_mount, m_flush_work);
+
+        xfs_sync_data(mp, SYNC_TRYLOCK);
+        xfs_sync_data(mp, SYNC_TRYLOCK | SYNC_WAIT);
 }
 
 int
 xfs_syncd_init(
         struct xfs_mount        *mp)
 {
-        mp->m_sync_work.w_syncer = xfs_sync_worker;
-        mp->m_sync_work.w_mount = mp;
-        mp->m_sync_work.w_completion = NULL;
-        mp->m_sync_task = kthread_run(xfssyncd, mp, "xfssyncd/%s", mp->m_fsname);
-        if (IS_ERR(mp->m_sync_task))
-                return -PTR_ERR(mp->m_sync_task);
+        INIT_WORK(&mp->m_flush_work, xfs_flush_worker);
+        INIT_DELAYED_WORK(&mp->m_sync_work, xfs_sync_worker);
+        INIT_DELAYED_WORK(&mp->m_reclaim_work, xfs_reclaim_worker);
+
+        xfs_syncd_queue_sync(mp);
+        xfs_syncd_queue_reclaim(mp);
+
         return 0;
 }
 
@@ -583,7 +569,9 @@ void
 xfs_syncd_stop(
         struct xfs_mount        *mp)
 {
-        kthread_stop(mp->m_sync_task);
+        cancel_delayed_work_sync(&mp->m_sync_work);
+        cancel_delayed_work_sync(&mp->m_reclaim_work);
+        cancel_work_sync(&mp->m_flush_work);
 }
 
 void
@@ -602,6 +590,10 @@ __xfs_inode_set_reclaim_tag(
                                 XFS_INO_TO_AGNO(ip->i_mount, ip->i_ino),
                                 XFS_ICI_RECLAIM_TAG);
                 spin_unlock(&ip->i_mount->m_perag_lock);
+
+                /* schedule periodic background inode reclaim */
+                xfs_syncd_queue_reclaim(ip->i_mount);
+
                 trace_xfs_perag_set_reclaim(ip->i_mount, pag->pag_agno,
                                                         -1, _RET_IP_);
         }
@@ -762,8 +754,10 @@ xfs_reclaim_inode(
         struct xfs_perag        *pag,
         int                     sync_mode)
 {
-        int     error = 0;
+        int     error;
 
+restart:
+        error = 0;
         xfs_ilock(ip, XFS_ILOCK_EXCL);
         if (!xfs_iflock_nowait(ip)) {
                 if (!(sync_mode & SYNC_WAIT))
@@ -789,9 +783,31 @@ xfs_reclaim_inode(
         if (xfs_inode_clean(ip))
                 goto reclaim;
 
-        /* Now we have an inode that needs flushing */
-        error = xfs_iflush(ip, sync_mode);
+        /*
+         * Now we have an inode that needs flushing.
+         *
+         * We do a nonblocking flush here even if we are doing a SYNC_WAIT
+         * reclaim as we can deadlock with inode cluster removal.
+         * xfs_ifree_cluster() can lock the inode buffer before it locks the
+         * ip->i_lock, and we are doing the exact opposite here. As a result,
+         * doing a blocking xfs_itobp() to get the cluster buffer will result
+         * in an ABBA deadlock with xfs_ifree_cluster().
+         *
+         * As xfs_ifree_cluser() must gather all inodes that are active in the
+         * cache to mark them stale, if we hit this case we don't actually want
+         * to do IO here - we want the inode marked stale so we can simply
+         * reclaim it. Hence if we get an EAGAIN error on a SYNC_WAIT flush,
+         * just unlock the inode, back off and try again. Hopefully the next
+         * pass through will see the stale flag set on the inode.
+         */
+        error = xfs_iflush(ip, SYNC_TRYLOCK | sync_mode);
         if (sync_mode & SYNC_WAIT) {
+                if (error == EAGAIN) {
+                        xfs_iunlock(ip, XFS_ILOCK_EXCL);
+                        /* backoff longer than in xfs_ifree_cluster */
+                        delay(2);
+                        goto restart;
+                }
                 xfs_iflock(ip);
                 goto reclaim;
         }
@@ -806,7 +822,7 @@ xfs_reclaim_inode(
          * pass on the error.
          */
         if (error && error != EAGAIN && !XFS_FORCED_SHUTDOWN(ip->i_mount)) {
-                xfs_fs_cmn_err(CE_WARN, ip->i_mount,
+                xfs_warn(ip->i_mount,
                         "inode 0x%llx background reclaim flush failed with %d",
                         (long long)ip->i_ino, error);
         }
@@ -994,7 +1010,13 @@ xfs_reclaim_inodes(
 }
 
 /*
- * Shrinker infrastructure.
+ * Inode cache shrinker.
+ *
+ * When called we make sure that there is a background (fast) inode reclaim in
+ * progress, while we will throttle the speed of reclaim via doiing synchronous
+ * reclaim of inodes. That means if we come across dirty inodes, we wait for
+ * them to be cleaned, which we hope will not be very long due to the
+ * background walker having already kicked the IO off on those dirty inodes.
  */
 static int
 xfs_reclaim_inode_shrink(
@@ -1009,10 +1031,15 @@ xfs_reclaim_inode_shrink(
 
         mp = container_of(shrink, struct xfs_mount, m_inode_shrink);
         if (nr_to_scan) {
+                /* kick background reclaimer and push the AIL */
+                xfs_syncd_queue_reclaim(mp);
+                xfs_ail_push_all(mp->m_ail);
+
                 if (!(gfp_mask & __GFP_FS))
                         return -1;
 
-                xfs_reclaim_inodes_ag(mp, SYNC_TRYLOCK, &nr_to_scan);
+                xfs_reclaim_inodes_ag(mp, SYNC_TRYLOCK | SYNC_WAIT,
+                                        &nr_to_scan);
                 /* terminate if we don't exhaust the scan */
                 if (nr_to_scan > 0)
                         return -1;