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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: Lachlan McIlroy <lachlan@sgi.com>
Signed-off-by: Christoph Hellwig <hch@infradead.org>
hifive-unleashed-5.1
Lachlan McIlroy 2007-11-27 17:01:24 +11:00 committed by Lachlan McIlroy
parent cd57e594ad
commit d1afb678ce
1 changed files with 12 additions and 19 deletions
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31
fs/xfs/linux-2.6/xfs_buf.c
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@ -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;