xfs: clean up mapping size calculation in __xfs_get_blocks

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Alex Elder <aelder@sgi.com>

diff --git a/fs/xfs/linux-2.6/xfs_aops.c b/fs/xfs/linux-2.6/xfs_aops.c
index 6feecd2..1d51bdd 100644 (file)
--- a/fs/xfs/linux-2.6/xfs_aops.c
+++ b/fs/xfs/linux-2.6/xfs_aops.c
@@ -1536,16 +1536,23 @@ __xfs_get_blocks(
                }
        }
 
+       /*
+        * If this is O_DIRECT or the mpage code calling tell them how large
+        * the mapping is, so that we can avoid repeated get_blocks calls.
+        */
        if (direct || size > (1 << inode->i_blkbits)) {
-               struct xfs_mount        *mp = XFS_I(inode)->i_mount;
-               xfs_off_t               iomap_offset = XFS_FSB_TO_B(mp, imap.br_startoff);
-               xfs_off_t               iomap_delta = offset - iomap_offset;
-               xfs_off_t               iomap_bsize = XFS_FSB_TO_B(mp, imap.br_blockcount);
-
-               ASSERT(iomap_bsize - iomap_delta > 0);
-               offset = min_t(xfs_off_t,
-                               iomap_bsize - iomap_delta, size);
-               bh_result->b_size = (ssize_t)min_t(xfs_off_t, LONG_MAX, offset);
+               xfs_off_t               mapping_size;
+
+               mapping_size = imap.br_startoff + imap.br_blockcount - iblock;
+               mapping_size <<= inode->i_blkbits;
+
+               ASSERT(mapping_size > 0);
+               if (mapping_size > size)
+                       mapping_size = size;
+               if (mapping_size > LONG_MAX)
+                       mapping_size = LONG_MAX;
+
+               bh_result->b_size = mapping_size;
        }
 
        return 0;