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authorDave Chinner <dchinner@redhat.com>2012-06-22 18:50:08 +1000
committerBen Myers <bpm@sgi.com>2012-07-01 14:50:04 -0500
commitcbb7baab285a540f173ef1ec3d5bcf9d0ad29d16 (patch)
tree33b570bfdf1a9e50482968823b05dd7c99b1e665 /fs/xfs/xfs_buf.c
parent77c1a08fc9ece4cb130b9fd279738e799f0c2864 (diff)
xfs: separate buffer indexing from block map
To support discontiguous buffers in the buffer cache, we need to separate the cache index variables from the I/O map. While this is currently a 1:1 mapping, discontiguous buffer support will break this relationship. However, for caching purposes, we can still treat them the same as a contiguous buffer - the block number of the first block and the length of the buffer - as that is still a unique representation. Also, the only way we will ever access the discontiguous regions of buffers is via bulding the complete buffer in the first place, so using the initial block number and entire buffer length is a sane way to index the buffers. Add a block mapping vector construct to the xfs_buf and use it in the places where we are doing IO instead of the current b_bn/b_length variables. Signed-off-by: Dave Chinner <dchinner@redhat.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Ben Myers <bpm@sgi.com>
Diffstat (limited to 'fs/xfs/xfs_buf.c')
-rw-r--r--fs/xfs/xfs_buf.c21
1 files changed, 12 insertions, 9 deletions
diff --git a/fs/xfs/xfs_buf.c b/fs/xfs/xfs_buf.c
index a4beb421018..a843873b095 100644
--- a/fs/xfs/xfs_buf.c
+++ b/fs/xfs/xfs_buf.c
@@ -202,6 +202,8 @@ xfs_buf_alloc(
bp->b_io_length = numblks;
bp->b_flags = flags;
bp->b_bn = blkno;
+ bp->b_map.bm_bn = blkno;
+ bp->b_map.bm_len = numblks;
atomic_set(&bp->b_pin_count, 0);
init_waitqueue_head(&bp->b_waiters);
@@ -327,8 +329,9 @@ xfs_buf_allocate_memory(
}
use_alloc_page:
- start = BBTOB(bp->b_bn) >> PAGE_SHIFT;
- end = (BBTOB(bp->b_bn + bp->b_length) + PAGE_SIZE - 1) >> PAGE_SHIFT;
+ start = BBTOB(bp->b_map.bm_bn) >> PAGE_SHIFT;
+ end = (BBTOB(bp->b_map.bm_bn + bp->b_length) + PAGE_SIZE - 1)
+ >> PAGE_SHIFT;
page_count = end - start;
error = _xfs_buf_get_pages(bp, page_count, flags);
if (unlikely(error))
@@ -560,8 +563,6 @@ xfs_buf_get(
if (bp != new_bp)
xfs_buf_free(new_bp);
- bp->b_io_length = bp->b_length;
-
found:
if (!bp->b_addr) {
error = _xfs_buf_map_pages(bp, flags);
@@ -584,7 +585,7 @@ _xfs_buf_read(
xfs_buf_flags_t flags)
{
ASSERT(!(flags & XBF_WRITE));
- ASSERT(bp->b_bn != XFS_BUF_DADDR_NULL);
+ ASSERT(bp->b_map.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);
@@ -665,8 +666,8 @@ xfs_buf_read_uncached(
return NULL;
/* set up the buffer for a read IO */
- XFS_BUF_SET_ADDR(bp, daddr);
- XFS_BUF_READ(bp);
+ bp->b_map.bm_bn = daddr;
+ bp->b_flags |= XBF_READ;
xfsbdstrat(target->bt_mount, bp);
error = xfs_buf_iowait(bp);
@@ -695,6 +696,8 @@ xfs_buf_set_empty(
bp->b_length = numblks;
bp->b_io_length = numblks;
bp->b_bn = XFS_BUF_DADDR_NULL;
+ bp->b_map.bm_bn = XFS_BUF_DADDR_NULL;
+ bp->b_map.bm_len = bp->b_length;
}
static inline struct page *
@@ -1159,7 +1162,7 @@ _xfs_buf_ioapply(
struct bio *bio;
int offset = bp->b_offset;
int size = BBTOB(bp->b_io_length);
- sector_t sector = bp->b_bn;
+ sector_t sector = bp->b_map.bm_bn;
total_nr_pages = bp->b_page_count;
map_i = 0;
@@ -1564,7 +1567,7 @@ xfs_buf_cmp(
struct xfs_buf *bp = container_of(b, struct xfs_buf, b_list);
xfs_daddr_t diff;
- diff = ap->b_bn - bp->b_bn;
+ diff = ap->b_map.bm_bn - bp->b_map.bm_bn;
if (diff < 0)
return -1;
if (diff > 0)