[XFS] Make freeze code a little cleaner.

Fixes a few small issues (mostly cosmetic) that were picked up during the
review cycle for the last set of freeze path changes.

SGI-PV: 959267
SGI-Modid: xfs-linux-melb:xfs-kern:28035a
Signed-off-by: NDavid Chinner <dgc@sgi.com>
Signed-off-by: NChristoph Hellwig <hch@infradead.org>
Signed-off-by: NTim Shimmin <tes@sgi.com>

fs/xfs/linux-2.6/xfs_super.c

@@ -667,7 +667,7 @@ xfs_fs_sync_super(
 		 * occur here so don't bother flushing the buftarg (i.e
 		 * SYNC_QUIESCE) because it'll just get dirty again.
 		 */
-		flags = SYNC_FSDATA | SYNC_DELWRI | SYNC_WAIT | SYNC_DIO_WAIT;
+		flags = SYNC_FSDATA | SYNC_DELWRI | SYNC_WAIT | SYNC_IOWAIT;
 	} else
 		flags = SYNC_FSDATA | (wait ? SYNC_WAIT : 0);
 

fs/xfs/linux-2.6/xfs_vfs.h

@@ -91,8 +91,7 @@ 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 */
-#define SYNC_DIO_WAIT		0x0200  /* wait for direct I/O to complete */
+#define SYNC_IOWAIT		0x0100  /* wait for all I/O to complete */
 
 #define SHUTDOWN_META_IO_ERROR	0x0001	/* write attempt to metadata failed */
 #define SHUTDOWN_LOG_IO_ERROR	0x0002	/* write attempt to the log failed */

fs/xfs/xfs_vfsops.c

@@ -872,10 +872,10 @@ xfs_statvfs(
  *		       this by simply making sure the log gets flushed
  *		       if SYNC_BDFLUSH is set, and by actually writing it
  *		       out otherwise.
- *	SYNC_DIO_WAIT - The caller wants us to wait for all direct I/Os
- *		       as well to ensure all data I/O completes before we
- *		       return. Forms the drain side of the write barrier needed
- *		       to safely quiesce the filesystem.
+ *	SYNC_IOWAIT  - The caller wants us to wait for all data I/O to complete
+ *		       before we return (including direct I/O). Forms the drain
+ *		       side of the write barrier needed to safely quiesce the
+ *		       filesystem.
  *
  */
 /*ARGSUSED*/
@@ -1174,10 +1174,11 @@ xfs_sync_inodes(
 
 		}
 		/*
-		 * When freezing, we need to wait ensure direct I/O is complete
-		 * as well to ensure all data modification is complete here
+		 * When freezing, we need to wait ensure all I/O (including direct
+		 * I/O) is complete to ensure no further data modification can take
+		 * place after this point
 		 */
-		if (flags & SYNC_DIO_WAIT)
+		if (flags & SYNC_IOWAIT)
 			vn_iowait(vp);
 
 		if (flags & SYNC_BDFLUSH) {
@@ -1975,7 +1976,7 @@ xfs_freeze(
 	/* flush inodes and push all remaining buffers out to disk */
 	xfs_quiesce_fs(mp);
 
-	BUG_ON(atomic_read(&mp->m_active_trans) > 0);
+	ASSERT_ALWAYS(atomic_read(&mp->m_active_trans) == 0);
 
 	/* Push the superblock and write an unmount record */
 	xfs_log_unmount_write(mp);