[XFS] Prevent a couple transactions from happening on ro mounts

SGI Modid: 2.5.x-xfs:slinx:131187a

fs/xfs/xfs_log.c

@@ -480,9 +480,17 @@ xfs_log_mount(xfs_mount_t	*mp,
 	 * just worked.
 	 */
 	if (!(mp->m_flags & XFS_MOUNT_NORECOVERY)) {
-		int    error;
+		int	error;
+		vfs_t	*vfsp = XFS_MTOVFS(mp);
+		int	readonly = (vfsp->vfs_flag & VFS_RDONLY);
 
-		error = xlog_recover(log,XFS_MTOVFS(mp)->vfs_flag & VFS_RDONLY);
+		if (readonly)
+			vfsp->vfs_flag &= ~VFS_RDONLY;
+
+		error = xlog_recover(log, readonly);
+
+		if (readonly)
+			vfsp->vfs_flag |= VFS_RDONLY;
 		if (error) {
 			cmn_err(CE_WARN, "XFS: log mount/recovery failed");
 			xlog_unalloc_log(log);

fs/xfs/xfs_vnodeops.c

@@ -1625,6 +1625,10 @@ xfs_release(
 		return 0;
 	}
 
+	/* If this is a read-only mount, don't do this (would generate I/O) */
+	if (vp->v_vfsp->vfs_flag & VFS_RDONLY)
+		return 0;
+
 	mp = ip->i_mount;
 
 	if (ip->i_d.di_nlink != 0) {
@@ -1700,6 +1704,11 @@ xfs_inactive(
 	}
 
 	error = 0;
+
+	/* If this is a read-only mount, don't do this (would generate I/O) */
+	if (vp->v_vfsp->vfs_flag & VFS_RDONLY)
+		goto out;
+
 	if (ip->i_d.di_nlink != 0) {
 		if ((((ip->i_d.di_mode & IFMT) == IFREG) &&
 		     ((ip->i_d.di_size > 0) || (VN_CACHED(vp) > 0)) &&