Commit f4b42421 authored by Mark Tinguely's avatar Mark Tinguely Committed by Ben Myers
Browse files

xfs: use b_maps[] for discontiguous buffers 



Commits starting at 77c1a08f introduced a multiple segment support
to xfs_buf. xfs_trans_buf_item_match() could not find a multi-segment
buffer in the transaction because it was looking at the single segment
block number rather than the multi-segment b_maps[0].bm.bn. This
results on a recursive buffer lock that can never be satisfied.

This patch:
 1) Changed the remaining b_map accesses to be b_maps[0] accesses.
 2) Renames the single segment b_map structure to __b_map to avoid
    future confusion.

Signed-off-by: default avatarMark Tinguely <tinguely@sgi.com>
Reviewed-by: default avatarDave Chinner <dchinner@redhat.com>
Reviewed-by: default avatarChristoph Hellwig <hch@lst.de>
Signed-off-by: default avatarBen Myers <bpm@sgi.com>
parent f9668a09

fs/xfs/xfs_buf.c

+6 −6
Original line number Diff line number Diff line
@@ -175,7 +175,7 @@ xfs_buf_get_maps( 
	bp->b_map_count = map_count;



	if (map_count == 1) {

		bp->b_maps = &bp->b_map;

		bp->b_maps = &bp->__b_map;

		return 0;

	}
@@ -193,7 +193,7 @@ static void 
xfs_buf_free_maps(

	struct xfs_buf	*bp)

{

	if (bp->b_maps != &bp->b_map) {

	if (bp->b_maps != &bp->__b_map) {

		kmem_free(bp->b_maps);

		bp->b_maps = NULL;

	}
@@ -377,8 +377,8 @@ xfs_buf_allocate_memory( 
	}



use_alloc_page:

	start = BBTOB(bp->b_map.bm_bn) >> PAGE_SHIFT;

	end = (BBTOB(bp->b_map.bm_bn + bp->b_length) + PAGE_SIZE - 1)

	start = BBTOB(bp->b_maps[0].bm_bn) >> PAGE_SHIFT;

	end = (BBTOB(bp->b_maps[0].bm_bn + bp->b_length) + PAGE_SIZE - 1)

								>> PAGE_SHIFT;

	page_count = end - start;

	error = _xfs_buf_get_pages(bp, page_count, flags);
@@ -640,7 +640,7 @@ _xfs_buf_read( 
	xfs_buf_flags_t		flags)

{

	ASSERT(!(flags & XBF_WRITE));

	ASSERT(bp->b_map.bm_bn != XFS_BUF_DADDR_NULL);

	ASSERT(bp->b_maps[0].bm_bn != XFS_BUF_DADDR_NULL);



	bp->b_flags &= ~(XBF_WRITE | XBF_ASYNC | XBF_READ_AHEAD);

	bp->b_flags |= flags & (XBF_READ | XBF_ASYNC | XBF_READ_AHEAD);
@@ -1709,7 +1709,7 @@ xfs_buf_cmp( 
	struct xfs_buf	*bp = container_of(b, struct xfs_buf, b_list);

	xfs_daddr_t		diff;



	diff = ap->b_map.bm_bn - bp->b_map.bm_bn;

	diff = ap->b_maps[0].bm_bn - bp->b_maps[0].bm_bn;

	if (diff < 0)

		return -1;

	if (diff > 0)

fs/xfs/xfs_buf.h

+3 −3
Original line number Diff line number Diff line
@@ -151,7 +151,7 @@ typedef struct xfs_buf { 
	struct page		**b_pages;	/* array of page pointers */

	struct page		*b_page_array[XB_PAGES]; /* inline pages */

	struct xfs_buf_map	*b_maps;	/* compound buffer map */

	struct xfs_buf_map	b_map;		/* inline compound buffer map */

	struct xfs_buf_map	__b_map;	/* inline compound buffer map */

	int			b_map_count;

	int			b_io_length;	/* IO size in BBs */

	atomic_t		b_pin_count;	/* pin count */
@@ -330,8 +330,8 @@ void xfs_buf_stale(struct xfs_buf *bp); 
 * In future, uncached buffers will pass the block number directly to the io

 * request function and hence these macros will go away at that point.

 */

#define XFS_BUF_ADDR(bp)		((bp)->b_map.bm_bn)

#define XFS_BUF_SET_ADDR(bp, bno)	((bp)->b_map.bm_bn = (xfs_daddr_t)(bno))

#define XFS_BUF_ADDR(bp)		((bp)->b_maps[0].bm_bn)

#define XFS_BUF_SET_ADDR(bp, bno)	((bp)->b_maps[0].bm_bn = (xfs_daddr_t)(bno))



static inline void xfs_buf_set_ref(struct xfs_buf *bp, int lru_ref)

{

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