[XFS] quiesce the filesystem proper when freezing

SGI-PV: 936977
SGI-Modid: xfs-linux:xfs-kern:193840a

Signed-off-by: Christoph Hellwig <hch@sgi.com>
Signed-off-by: Nathan Scott <nathans@sgi.com>

3 files changed, 40 insertions, 27 deletions

diff --git a/fs/xfs/linux-2.6/xfs_super.c b/fs/xfs/linux-2.6/xfs_super.c
index d5f0340ddcd9..5fe9af38aa20 100644
--- a/fs/xfs/linux-2.6/xfs_super.c
+++ b/fs/xfs/linux-2.6/xfs_super.c
@@ -590,8 +590,10 @@ linvfs_sync_super(
         int             error;
         int             flags = SYNC_FSDATA;
 
-        if (wait)
-                flags |= SYNC_WAIT;
+        if (unlikely(sb->s_frozen == SB_FREEZE_WRITE))
+                flags = SYNC_QUIESCE;
+        else
+                flags = SYNC_FSDATA | (wait ? SYNC_WAIT : 0);
 
         VFS_SYNC(vfsp, flags, NULL, error);
         sb->s_dirt = 0;
diff --git a/fs/xfs/linux-2.6/xfs_vfs.h b/fs/xfs/linux-2.6/xfs_vfs.h
index 76493991578f..7ee1f714e9ba 100644
--- a/fs/xfs/linux-2.6/xfs_vfs.h
+++ b/fs/xfs/linux-2.6/xfs_vfs.h
@@ -107,6 +107,7 @@ typedef enum {
 #define SYNC_FSDATA             0x0020  /* flush fs data (e.g. superblocks) */
 #define SYNC_REFCACHE           0x0040  /* prune some of the nfs ref cache */
 #define SYNC_REMOUNT            0x0080  /* remount readonly, no dummy LRs */
+#define SYNC_QUIESCE            0x0100  /* quiesce fileystem for a snapshot */
 
 typedef int     (*vfs_mount_t)(bhv_desc_t *,
                                 struct xfs_mount_args *, struct cred *);
diff --git a/fs/xfs/xfs_vfsops.c b/fs/xfs/xfs_vfsops.c
index 103500498342..42bcc0215203 100644
--- a/fs/xfs/xfs_vfsops.c
+++ b/fs/xfs/xfs_vfsops.c
@@ -612,7 +612,34 @@ out:
         return XFS_ERROR(error);
 }
 
-#define REMOUNT_READONLY_FLAGS  (SYNC_REMOUNT|SYNC_ATTR|SYNC_WAIT)
+STATIC int
+xfs_quiesce_fs(
+        xfs_mount_t             *mp)
+{
+        int                     count = 0, pincount;
+                
+        xfs_refcache_purge_mp(mp);
+        xfs_flush_buftarg(mp->m_ddev_targp, 0);
+        xfs_finish_reclaim_all(mp, 0);
+
+        /* 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.
+         */ 
+        do {
+                xfs_syncsub(mp, SYNC_REMOUNT|SYNC_ATTR|SYNC_WAIT, 0, NULL);
+                pincount = xfs_flush_buftarg(mp->m_ddev_targp, 1);
+                if (!pincount) {
+                        delay(50);
+                        count++;
+                }
+        } while (count < 2);
+
+        return 0;
+}
 
 STATIC int
 xfs_mntupdate(
@@ -622,8 +649,7 @@ xfs_mntupdate(
 {
         struct vfs      *vfsp = bhvtovfs(bdp);
         xfs_mount_t     *mp = XFS_BHVTOM(bdp);
-        int             pincount, error;
-        int             count = 0;
+        int             error;
 
         if (args->flags & XFSMNT_NOATIME)
                 mp->m_flags |= XFS_MOUNT_NOATIME;
@@ -635,25 +661,7 @@ xfs_mntupdate(
         }
 
         if (*flags & MS_RDONLY) {
-                xfs_refcache_purge_mp(mp);
-                xfs_flush_buftarg(mp->m_ddev_targp, 0);
-                xfs_finish_reclaim_all(mp, 0);
-
-                /* 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.
-                 */ 
-                do {
-                        VFS_SYNC(vfsp, REMOUNT_READONLY_FLAGS, NULL, error);
-                        pincount = xfs_flush_buftarg(mp->m_ddev_targp, 1);
-                        if (!pincount) {
-                                delay(50);
-                                count++;
-                        }
-                } while (count < 2);
+                xfs_quiesce_fs(mp);
 
                 /* Ok now write out an unmount record */
                 xfs_log_unmount_write(mp);
@@ -869,10 +877,12 @@ xfs_sync(
         int             flags,
         cred_t          *credp)
 {
-        xfs_mount_t     *mp;
+        xfs_mount_t     *mp = XFS_BHVTOM(bdp);
 
-        mp = XFS_BHVTOM(bdp);
-        return (xfs_syncsub(mp, flags, 0, NULL));
+        if (unlikely(flags == SYNC_QUIESCE))
+                return xfs_quiesce_fs(mp);
+        else
+                return xfs_syncsub(mp, flags, 0, NULL);
 }
 
 /*