xfs: buffer type overruns blf_flags field

The buffer type passed to log recvoery in the buffer log item
overruns the blf_flags field. I had assumed that flags field was a
32 bit value, and it turns out it is a unisgned short. Therefore
having 19 flags doesn't really work.

Convert the buffer type field to numeric value, and use the top 5
bits of the flags field for it. We currently have 17 types of
buffers, so using 5 bits gives us plenty of room for expansion in
future....

Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Ben Myers <bpm@sgi.com>
Signed-off-by: Ben Myers <bpm@sgi.com>

fs/xfs/xfs_buf_item.h

@@ -39,45 +39,6 @@ extern kmem_zone_t	*xfs_buf_item_zone;
 #define XFS_BLF_PDQUOT_BUF	(1<<3)
 #define	XFS_BLF_GDQUOT_BUF	(1<<4)
 
-/*
- * all buffers now need flags to tell recovery where the magic number
- * is so that it can verify and calculate the CRCs on the buffer correctly
- * once the changes have been replayed into the buffer.
- */
-#define XFS_BLF_BTREE_BUF	(1<<5)
-#define XFS_BLF_AGF_BUF		(1<<6)
-#define XFS_BLF_AGFL_BUF	(1<<7)
-#define XFS_BLF_AGI_BUF		(1<<8)
-#define XFS_BLF_DINO_BUF	(1<<9)
-#define XFS_BLF_SYMLINK_BUF	(1<<10)
-#define XFS_BLF_DIR_BLOCK_BUF	(1<<11)
-#define XFS_BLF_DIR_DATA_BUF	(1<<12)
-#define XFS_BLF_DIR_FREE_BUF	(1<<13)
-#define XFS_BLF_DIR_LEAF1_BUF	(1<<14)
-#define XFS_BLF_DIR_LEAFN_BUF	(1<<15)
-#define XFS_BLF_DA_NODE_BUF	(1<<16)
-#define XFS_BLF_ATTR_LEAF_BUF	(1<<17)
-#define XFS_BLF_ATTR_RMT_BUF	(1<<18)
-
-#define XFS_BLF_TYPE_MASK	\
-		(XFS_BLF_UDQUOT_BUF | \
-		 XFS_BLF_PDQUOT_BUF | \
-		 XFS_BLF_GDQUOT_BUF | \
-		 XFS_BLF_BTREE_BUF | \
-		 XFS_BLF_AGF_BUF | \
-		 XFS_BLF_AGFL_BUF | \
-		 XFS_BLF_AGI_BUF | \
-		 XFS_BLF_DINO_BUF | \
-		 XFS_BLF_SYMLINK_BUF | \
-		 XFS_BLF_DIR_BLOCK_BUF | \
-		 XFS_BLF_DIR_DATA_BUF | \
-		 XFS_BLF_DIR_FREE_BUF | \
-		 XFS_BLF_DIR_LEAF1_BUF | \
-		 XFS_BLF_DIR_LEAFN_BUF | \
-		 XFS_BLF_DA_NODE_BUF | \
-		 XFS_BLF_ATTR_LEAF_BUF | \
-		 XFS_BLF_ATTR_RMT_BUF)
-
 #define	XFS_BLF_CHUNK		128
 #define	XFS_BLF_SHIFT		7
 #define	BIT_TO_WORD_SHIFT	5
@@ -100,6 +61,55 @@ typedef struct xfs_buf_log_format {
 	unsigned int	blf_data_map[XFS_BLF_DATAMAP_SIZE]; /* dirty bitmap */
 } xfs_buf_log_format_t;
 
+/*
+ * All buffers now need to tell recovery where the magic number
+ * is so that it can verify and calculate the CRCs on the buffer correctly
+ * once the changes have been replayed into the buffer.
+ *
+ * The type value is held in the upper 5 bits of the blf_flags field, which is
+ * an unsigned 16 bit field. Hence we need to shift it 11 bits up and down.
+ */
+#define XFS_BLFT_BITS	5
+#define XFS_BLFT_SHIFT	11
+#define XFS_BLFT_MASK	(((1 << XFS_BLFT_BITS) - 1) << XFS_BLFT_SHIFT)
+
+enum xfs_blft {
+	XFS_BLFT_UNKNOWN_BUF = 0,
+	XFS_BLFT_UDQUOT_BUF,
+	XFS_BLFT_PDQUOT_BUF,
+	XFS_BLFT_GDQUOT_BUF,
+	XFS_BLFT_BTREE_BUF,
+	XFS_BLFT_AGF_BUF,
+	XFS_BLFT_AGFL_BUF,
+	XFS_BLFT_AGI_BUF,
+	XFS_BLFT_DINO_BUF,
+	XFS_BLFT_SYMLINK_BUF,
+	XFS_BLFT_DIR_BLOCK_BUF,
+	XFS_BLFT_DIR_DATA_BUF,
+	XFS_BLFT_DIR_FREE_BUF,
+	XFS_BLFT_DIR_LEAF1_BUF,
+	XFS_BLFT_DIR_LEAFN_BUF,
+	XFS_BLFT_DA_NODE_BUF,
+	XFS_BLFT_ATTR_LEAF_BUF,
+	XFS_BLFT_ATTR_RMT_BUF,
+	XFS_BLFT_SB_BUF,
+	XFS_BLFT_MAX_BUF = (1 << XFS_BLFT_BITS),
+};
+
+static inline void
+xfs_blft_to_flags(struct xfs_buf_log_format *blf, enum xfs_blft type)
+{
+	ASSERT(type > XFS_BLFT_UNKNOWN_BUF && type < XFS_BLFT_MAX_BUF);
+	blf->blf_flags &= ~XFS_BLFT_MASK;
+	blf->blf_flags |= ((type << XFS_BLFT_SHIFT) & XFS_BLFT_MASK);
+}
+
+static inline __uint16_t
+xfs_blft_from_flags(struct xfs_buf_log_format *blf)
+{
+	return (blf->blf_flags & XFS_BLFT_MASK) >> XFS_BLFT_SHIFT;
+}
+
 /*
  * buf log item flags
  */
@@ -153,6 +163,10 @@ void	xfs_buf_attach_iodone(struct xfs_buf *,
 void	xfs_buf_iodone_callbacks(struct xfs_buf *);
 void	xfs_buf_iodone(struct xfs_buf *, struct xfs_log_item *);
 
+void	xfs_trans_buf_set_type(struct xfs_trans *, struct xfs_buf *,
+			       enum xfs_blft);
+void	xfs_trans_buf_copy_type(struct xfs_buf *dst_bp, struct xfs_buf *src_bp);
+
 #endif	/* __KERNEL__ */
 
 #endif	/* __XFS_BUF_ITEM_H__ */