[XFS] write barrier support Issue all log sync operations as ordered

writes.  In addition flush the disk cache on fsync if the sync cached
operation didn't sync the log to disk (this requires some additional
bookeping in the transaction and log code). If the device doesn't claim to
support barriers, the filesystem has an extern log volume or the trial
superblock write with barriers enabled failed we disable barriers and
print a warning.  We should probably fail the mount completely, but that
could lead to nasty boot failures for the root filesystem.  Not enabled by
default yet, needs more destructive testing first.

SGI-PV: 912426
SGI-Modid: xfs-linux:xfs-kern:198723a

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

1 files changed, 29 insertions, 3 deletions

diff --git a/fs/xfs/xfs_vnodeops.c b/fs/xfs/xfs_vnodeops.c
index 58bfe629b933..e2bf2ef58b66 100644
--- a/fs/xfs/xfs_vnodeops.c
+++ b/fs/xfs/xfs_vnodeops.c
@@ -1118,6 +1118,7 @@ xfs_fsync(
         xfs_inode_t     *ip;
         xfs_trans_t     *tp;
         int             error;
+        int             log_flushed = 0, changed = 1;
 
         vn_trace_entry(BHV_TO_VNODE(bdp),
                         __FUNCTION__, (inst_t *)__return_address);
@@ -1171,10 +1172,18 @@ xfs_fsync(
                 xfs_iunlock(ip, XFS_ILOCK_SHARED);
 
                 if (xfs_ipincount(ip)) {
-                        xfs_log_force(ip->i_mount, (xfs_lsn_t)0,
+                        _xfs_log_force(ip->i_mount, (xfs_lsn_t)0,
                                       XFS_LOG_FORCE |
                                       ((flag & FSYNC_WAIT)
-                                       ? XFS_LOG_SYNC : 0));
+                                       ? XFS_LOG_SYNC : 0),
+                                      &log_flushed);
+                } else {
+                        /*
+                         * If the inode is not pinned and nothing
+                         * has changed we don't need to flush the
+                         * cache.
+                         */
+                        changed = 0;
                 }
                 error = 0;
         } else  {
@@ -1210,10 +1219,27 @@ xfs_fsync(
                 xfs_trans_log_inode(tp, ip, XFS_ILOG_CORE);
                 if (flag & FSYNC_WAIT)
                         xfs_trans_set_sync(tp);
-                error = xfs_trans_commit(tp, 0, NULL);
+                error = _xfs_trans_commit(tp, 0, NULL, &log_flushed);
 
                 xfs_iunlock(ip, XFS_ILOCK_EXCL);
         }
+
+        if ((ip->i_mount->m_flags & XFS_MOUNT_BARRIER) && changed) {
+                /*
+                 * If the log write didn't issue an ordered tag we need
+                 * to flush the disk cache for the data device now.
+                 */
+                if (!log_flushed)
+                        xfs_blkdev_issue_flush(ip->i_mount->m_ddev_targp);
+
+                /*
+                 * If this inode is on the RT dev we need to flush that
+                 * cache aswell.
+                 */
+                if (ip->i_d.di_flags & XFS_DIFLAG_REALTIME)
+                        xfs_blkdev_issue_flush(ip->i_mount->m_rtdev_targp);
+        }
+
         return error;
 }