[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, 25 insertions, 13 deletions

diff --git a/fs/xfs/xfs_vfsops.c b/fs/xfs/xfs_vfsops.c
index f1a904e23ad..8238c751782 100644
--- a/fs/xfs/xfs_vfsops.c
+++ b/fs/xfs/xfs_vfsops.c
@@ -321,8 +321,8 @@ xfs_start_flags(
 
         if (ap->flags & XFSMNT_NOUUID)
                 mp->m_flags |= XFS_MOUNT_NOUUID;
-        if (ap->flags & XFSMNT_NOLOGFLUSH)
-                mp->m_flags |= XFS_MOUNT_NOLOGFLUSH;
+        if (ap->flags & XFSMNT_BARRIER)
+                mp->m_flags |= XFS_MOUNT_BARRIER;
 
         return 0;
 }
@@ -512,8 +512,14 @@ xfs_mount(
                 goto error2;
 
         error = XFS_IOINIT(vfsp, args, flags);
-        if (!error)
-                return 0;
+        if (error)
+                goto error2;
+
+        if ((args->flags & XFSMNT_BARRIER) &&
+            !(XFS_MTOVFS(mp)->vfs_flag & VFS_RDONLY))
+                xfs_mountfs_check_barriers(mp);
+        return 0;
+
 error2:
         if (mp->m_sb_bp)
                 xfs_freesb(mp);
@@ -656,19 +662,24 @@ xfs_mntupdate(
         else
                 mp->m_flags &= ~XFS_MOUNT_NOATIME;
 
-        if (!(vfsp->vfs_flag & VFS_RDONLY)) {
-                VFS_SYNC(vfsp, SYNC_FSDATA|SYNC_BDFLUSH|SYNC_ATTR, NULL, error);
+        if ((vfsp->vfs_flag & VFS_RDONLY) &&
+            !(*flags & MS_RDONLY)) {
+                vfsp->vfs_flag &= ~VFS_RDONLY;
+
+                if (args->flags & XFSMNT_BARRIER)
+                        xfs_mountfs_check_barriers(mp);
         }
 
-        if (*flags & MS_RDONLY) {
+        if (!(vfsp->vfs_flag & VFS_RDONLY) &&
+            (*flags & MS_RDONLY)) {
+                VFS_SYNC(vfsp, SYNC_FSDATA|SYNC_BDFLUSH|SYNC_ATTR, NULL, error);
+
                 xfs_quiesce_fs(mp);
 
                 /* Ok now write out an unmount record */
                 xfs_log_unmount_write(mp);
                 xfs_unmountfs_writesb(mp);
                 vfsp->vfs_flag |= VFS_RDONLY;
-        } else {
-                vfsp->vfs_flag &= ~VFS_RDONLY;
         }
 
         return 0;
@@ -1628,7 +1639,8 @@ xfs_vget(
 #define MNTOPT_ALLOCSIZE    "allocsize"    /* preferred allocation size */
 #define MNTOPT_IHASHSIZE    "ihashsize"    /* size of inode hash table */
 #define MNTOPT_NORECOVERY   "norecovery"   /* don't run XFS recovery */
-#define MNTOPT_NOLOGFLUSH   "nologflush"   /* don't hard flush on log writes */
+#define MNTOPT_BARRIER  "barrier"       /* use writer barriers for log write and
+                                           unwritten extent conversion */
 #define MNTOPT_OSYNCISOSYNC "osyncisosync" /* o_sync is REALLY o_sync */
 #define MNTOPT_64BITINODE   "inode64"   /* inodes can be allocated anywhere */
 #define MNTOPT_IKEEP    "ikeep"         /* do not free empty inode clusters */
@@ -1791,8 +1803,8 @@ xfs_parseargs(
 #endif
                 } else if (!strcmp(this_char, MNTOPT_NOUUID)) {
                         args->flags |= XFSMNT_NOUUID;
-                } else if (!strcmp(this_char, MNTOPT_NOLOGFLUSH)) {
-                        args->flags |= XFSMNT_NOLOGFLUSH;
+                } else if (!strcmp(this_char, MNTOPT_BARRIER)) {
+                        args->flags |= XFSMNT_BARRIER;
                 } else if (!strcmp(this_char, MNTOPT_IKEEP)) {
                         args->flags &= ~XFSMNT_IDELETE;
                 } else if (!strcmp(this_char, MNTOPT_NOIKEEP)) {
@@ -1866,7 +1878,7 @@ xfs_showargs(
                 { XFS_MOUNT_NOUUID,             "," MNTOPT_NOUUID },
                 { XFS_MOUNT_NORECOVERY,         "," MNTOPT_NORECOVERY },
                 { XFS_MOUNT_OSYNCISOSYNC,       "," MNTOPT_OSYNCISOSYNC },
-                { XFS_MOUNT_NOLOGFLUSH,         "," MNTOPT_NOLOGFLUSH },
+                { XFS_MOUNT_BARRIER,            "," MNTOPT_BARRIER },
                 { XFS_MOUNT_IDELETE,            "," MNTOPT_NOIKEEP },
                 { 0, NULL }
         };