[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: Lachlan McIlroy <lachlan@sgi.com>
Signed-off-by: Christoph Hellwig <hch@infradead.org>
diff --git a/fs/xfs/linux-2.6/xfs_buf.c b/fs/xfs/linux-2.6/xfs_buf.c
index b9c8589..48bf477 100644
--- a/fs/xfs/linux-2.6/xfs_buf.c
+++ b/fs/xfs/linux-2.6/xfs_buf.c
@@ -725,15 +725,15 @@
{
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 @@
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;