[XFS] move xfssyncd code to xfs_sync.c

Move all the xfssyncd code to the new xfs_sync.c file. This places it
closer to the actual code that it interacts with, rather than just being
associated with high level VFS code.

SGI-PV: 988139

SGI-Modid: xfs-linux-melb:xfs-kern:32283a

Signed-off-by: David Chinner <david@fromorbit.com>
Signed-off-by: Lachlan McIlroy <lachlan@sgi.com>
Signed-off-by: Christoph Hellwig <hch@infradead.org>

1 files changed, 163 insertions, 0 deletions

diff --git a/fs/xfs/linux-2.6/xfs_sync.c b/fs/xfs/linux-2.6/xfs_sync.c
index c765eb2a8dc..a51534c71b3 100644
--- a/fs/xfs/linux-2.6/xfs_sync.c
+++ b/fs/xfs/linux-2.6/xfs_sync.c
@@ -44,6 +44,9 @@
 #include "xfs_inode_item.h"
 #include "xfs_rw.h"
 
+#include <linux/kthread.h>
+#include <linux/freezer.h>
+
 /*
  * xfs_sync flushes any pending I/O to file system vfsp.
  *
@@ -603,3 +606,163 @@ xfs_syncsub(
 
         return XFS_ERROR(last_error);
 }
+
+/*
+ * 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 bhv_vfs_sync_work *work;
+
+        work = kmem_alloc(sizeof(struct bhv_vfs_sync_work), KM_SLEEP);
+        INIT_LIST_HEAD(&work->w_list);
+        work->w_syncer = syncer;
+        work->w_data = data;
+        work->w_mount = mp;
+        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_inode_work(
+        struct xfs_mount *mp,
+        void            *arg)
+{
+        struct inode    *inode = arg;
+        filemap_flush(inode->i_mapping);
+        iput(inode);
+}
+
+void
+xfs_flush_inode(
+        xfs_inode_t     *ip)
+{
+        struct inode    *inode = VFS_I(ip);
+
+        igrab(inode);
+        xfs_syncd_queue_work(ip->i_mount, inode, xfs_flush_inode_work);
+        delay(msecs_to_jiffies(500));
+}
+
+/*
+ * This is the "bigger hammer" version of xfs_flush_inode_work...
+ * (IOW, "If at first you don't succeed, use a Bigger Hammer").
+ */
+STATIC void
+xfs_flush_device_work(
+        struct xfs_mount *mp,
+        void            *arg)
+{
+        struct inode    *inode = arg;
+        sync_blockdev(mp->m_super->s_bdev);
+        iput(inode);
+}
+
+void
+xfs_flush_device(
+        xfs_inode_t     *ip)
+{
+        struct inode    *inode = VFS_I(ip);
+
+        igrab(inode);
+        xfs_syncd_queue_work(ip->i_mount, inode, xfs_flush_device_work);
+        delay(msecs_to_jiffies(500));
+        xfs_log_force(ip->i_mount, (xfs_lsn_t)0, XFS_LOG_FORCE|XFS_LOG_SYNC);
+}
+
+STATIC void
+xfs_sync_worker(
+        struct xfs_mount *mp,
+        void            *unused)
+{
+        int             error;
+
+        if (!(mp->m_flags & XFS_MOUNT_RDONLY))
+                error = xfs_sync(mp, SYNC_FSDATA | SYNC_BDFLUSH | SYNC_ATTR);
+        mp->m_sync_seq++;
+        wake_up(&mp->m_wait_single_sync_task);
+}
+
+STATIC int
+xfssyncd(
+        void                    *arg)
+{
+        struct xfs_mount        *mp = arg;
+        long                    timeleft;
+        bhv_vfs_sync_work_t     *work, *n;
+        LIST_HEAD               (tmp);
+
+        set_freezable();
+        timeleft = xfs_syncd_centisecs * msecs_to_jiffies(10);
+        for (;;) {
+                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_for_each_entry_safe(work, n, &mp->m_sync_list, w_list)
+                        list_move(&work->w_list, &tmp);
+                spin_unlock(&mp->m_sync_lock);
+
+                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;
+                        kmem_free(work);
+                }
+        }
+
+        return 0;
+}
+
+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_task = kthread_run(xfssyncd, mp, "xfssyncd");
+        if (IS_ERR(mp->m_sync_task))
+                return -PTR_ERR(mp->m_sync_task);
+        return 0;
+}
+
+void
+xfs_syncd_stop(
+        struct xfs_mount        *mp)
+{
+        kthread_stop(mp->m_sync_task);
+}
+