Commit d1afb678 authored by Lachlan McIlroy's avatar Lachlan McIlroy Committed by Lachlan McIlroy
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[XFS] Fixed a few bugs in xfs_buf_associate_memory() 



- calculation of 'page_count' was incorrect as it did not
  consider the offset of 'mem' into the first page. The
  logic to bump 'page_count' didn't work if 'len' was <=
  PAGE_CACHE_SIZE (ie offset = 3k, len = 2k).
- setting b_buffer_length to 'len' is incorrect if 'offset'
  is > 0. Set it to the total length of the buffer.
- I suspect that passing a non-aligned address into
  mem_to_page() for the first page may have been causing
  issues - don't know but just tidy up that code anyway.

SGI-PV: 971596
SGI-Modid: xfs-linux-melb:xfs-kern:30143a

Signed-off-by: default avatarLachlan McIlroy <lachlan@sgi.com>
Signed-off-by: default avatarChristoph Hellwig <hch@infradead.org>
parent cd57e594

fs/xfs/linux-2.6/xfs_buf.c

+13 −20
Original line number Diff line number Diff line
@@ -725,15 +725,15 @@ xfs_buf_associate_memory( 
{

	int			rval;

	int			i = 0;

	size_t			ptr;

	size_t			end, end_cur;

	off_t			offset;

	unsigned long		pageaddr;

	unsigned long		offset;

	size_t			buflen;

	int			page_count;



	page_count = PAGE_CACHE_ALIGN(len) >> PAGE_CACHE_SHIFT;

	offset = (off_t) mem - ((off_t)mem & PAGE_CACHE_MASK);

	if (offset && (len > PAGE_CACHE_SIZE))

		page_count++;

	pageaddr = (unsigned long)mem & PAGE_CACHE_MASK;

	offset = (unsigned long)mem - pageaddr;

	buflen = PAGE_CACHE_ALIGN(len + offset);

	page_count = buflen >> PAGE_CACHE_SHIFT;



	/* Free any previous set of page pointers */

	if (bp->b_pages)
@@ -747,22 +747,15 @@ xfs_buf_associate_memory( 
		return rval;



	bp->b_offset = offset;

	ptr = (size_t) mem & PAGE_CACHE_MASK;

	end = PAGE_CACHE_ALIGN((size_t) mem + len);

	end_cur = end;

	/* set up first page */

	bp->b_pages[0] = mem_to_page(mem);



	ptr += PAGE_CACHE_SIZE;

	bp->b_page_count = ++i;

	while (ptr < end) {

		bp->b_pages[i] = mem_to_page((void *)ptr);

		bp->b_page_count = ++i;

		ptr += PAGE_CACHE_SIZE;



	for (i = 0; i < bp->b_page_count; i++) {

		bp->b_pages[i] = mem_to_page((void *)pageaddr);

		pageaddr += PAGE_CACHE_SIZE;

	}

	bp->b_locked = 0;



	bp->b_count_desired = bp->b_buffer_length = len;

	bp->b_count_desired = len;

	bp->b_buffer_length = buflen;

	bp->b_flags |= XBF_MAPPED;



	return 0;

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