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>
This commit is contained in:
Christoph Hellwig 2010-04-28 12:28:59 +00:00 committed by Alex Elder
parent 558e689169
commit 2b8f12b7e4

View File

@ -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);
xfs_off_t mapping_size;
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);
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;