4 files changed, 76 insertions, 4 deletions

diff --git a/fs/xfs/linux-2.6/xfs_buf.c b/fs/xfs/linux-2.6/xfs_buf.c
index 188cbbd5b74a..4663f7dbff1c 100644
--- a/fs/xfs/linux-2.6/xfs_buf.c
+++ b/fs/xfs/linux-2.6/xfs_buf.c
@@ -1295,6 +1295,11 @@ _pagebuf_ioapply(
                 rw = (pb->pb_flags & PBF_READ) ? READ : WRITE;
         }
 
+        if (pb->pb_flags & PBF_ORDERED) {
+                ASSERT(!(pb->pb_flags & PBF_READ));
+                rw = WRITE_BARRIER;
+        }
+
         /* Special code path for reading a sub page size pagebuf in --
          * we populate up the whole page, and hence the other metadata
          * in the same page.  This optimization is only valid when the
diff --git a/fs/xfs/linux-2.6/xfs_buf.h b/fs/xfs/linux-2.6/xfs_buf.h
index 39c8ca122534..fa21d1f9cb0b 100644
--- a/fs/xfs/linux-2.6/xfs_buf.h
+++ b/fs/xfs/linux-2.6/xfs_buf.h
@@ -74,7 +74,7 @@ typedef enum page_buf_flags_e {		/* pb_flags values */
         PBF_DELWRI = (1 << 6),  /* buffer has dirty pages                  */
         PBF_STALE = (1 << 7),   /* buffer has been staled, do not find it  */
         PBF_FS_MANAGED = (1 << 8),  /* filesystem controls freeing memory  */
-        PBF_FLUSH = (1 << 11),      /* flush disk write cache              */
+        PBF_ORDERED = (1 << 11),    /* use ordered writes                  */
         PBF_READ_AHEAD = (1 << 12), /* asynchronous read-ahead             */
 
         /* flags used only as arguments to access routines */
@@ -383,9 +383,9 @@ extern void pagebuf_trace(
 #define XFS_BUF_UNASYNC(x)       ((x)->pb_flags &= ~PBF_ASYNC)
 #define XFS_BUF_ISASYNC(x)       ((x)->pb_flags & PBF_ASYNC)
 
-#define XFS_BUF_FLUSH(x)         ((x)->pb_flags |= PBF_FLUSH)
-#define XFS_BUF_UNFLUSH(x)       ((x)->pb_flags &= ~PBF_FLUSH)
-#define XFS_BUF_ISFLUSH(x)       ((x)->pb_flags & PBF_FLUSH)
+#define XFS_BUF_ORDERED(x)       ((x)->pb_flags |= PBF_ORDERED)
+#define XFS_BUF_UNORDERED(x)     ((x)->pb_flags &= ~PBF_ORDERED)
+#define XFS_BUF_ISORDERED(x)     ((x)->pb_flags & PBF_ORDERED)
 
 #define XFS_BUF_SHUT(x)          printk("XFS_BUF_SHUT not implemented yet\n")
 #define XFS_BUF_UNSHUT(x)        printk("XFS_BUF_UNSHUT not implemented yet\n")
diff --git a/fs/xfs/linux-2.6/xfs_super.c b/fs/xfs/linux-2.6/xfs_super.c
index 2302454d8d47..d2701cc624b9 100644
--- a/fs/xfs/linux-2.6/xfs_super.c
+++ b/fs/xfs/linux-2.6/xfs_super.c
@@ -278,6 +278,72 @@ xfs_blkdev_put(
                 close_bdev_excl(bdev);
 }
 
+/*
+ * Try to write out the superblock using barriers.
+ */
+STATIC int
+xfs_barrier_test(
+        xfs_mount_t     *mp)
+{
+        xfs_buf_t       *sbp = xfs_getsb(mp, 0);
+        int             error;
+
+        XFS_BUF_UNDONE(sbp);
+        XFS_BUF_UNREAD(sbp);
+        XFS_BUF_UNDELAYWRITE(sbp);
+        XFS_BUF_WRITE(sbp);
+        XFS_BUF_UNASYNC(sbp);
+        XFS_BUF_ORDERED(sbp);
+
+        xfsbdstrat(mp, sbp);
+        error = xfs_iowait(sbp);
+
+        /*
+         * Clear all the flags we set and possible error state in the
+         * buffer.  We only did the write to try out whether barriers
+         * worked and shouldn't leave any traces in the superblock
+         * buffer.
+         */
+        XFS_BUF_DONE(sbp);
+        XFS_BUF_ERROR(sbp, 0);
+        XFS_BUF_UNORDERED(sbp);
+
+        xfs_buf_relse(sbp);
+        return error;
+}
+
+void
+xfs_mountfs_check_barriers(xfs_mount_t *mp)
+{
+        int error;
+
+        if (mp->m_logdev_targp != mp->m_ddev_targp) {
+                xfs_fs_cmn_err(CE_NOTE, mp,
+                  "Disabling barriers, not supported with external log device");
+                mp->m_flags &= ~XFS_MOUNT_BARRIER;
+        }
+
+        if (mp->m_ddev_targp->pbr_bdev->bd_disk->queue->ordered ==
+                                        QUEUE_ORDERED_NONE) {
+                xfs_fs_cmn_err(CE_NOTE, mp,
+                  "Disabling barriers, not supported by the underlying device");
+                mp->m_flags &= ~XFS_MOUNT_BARRIER;
+        }
+
+        error = xfs_barrier_test(mp);
+        if (error) {
+                xfs_fs_cmn_err(CE_NOTE, mp,
+                  "Disabling barriers, trial barrier write failed");
+                mp->m_flags &= ~XFS_MOUNT_BARRIER;
+        }
+}
+
+void
+xfs_blkdev_issue_flush(
+        xfs_buftarg_t           *buftarg)
+{
+        blkdev_issue_flush(buftarg->pbr_bdev, NULL);
+}
 
 STATIC struct inode *
 linvfs_alloc_inode(
diff --git a/fs/xfs/linux-2.6/xfs_super.h b/fs/xfs/linux-2.6/xfs_super.h
index ec7e0035c731..ad77e3743e04 100644
--- a/fs/xfs/linux-2.6/xfs_super.h
+++ b/fs/xfs/linux-2.6/xfs_super.h
@@ -132,6 +132,7 @@ extern void xfs_flush_device(struct xfs_inode *);
 extern int  xfs_blkdev_get(struct xfs_mount *, const char *,
                                 struct block_device **);
 extern void xfs_blkdev_put(struct block_device *);
+extern void xfs_blkdev_issue_flush(struct xfs_buftarg *);
 
 extern struct export_operations linvfs_export_ops;