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[PATCH] valid_swaphandles() fix

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akpm draws my attention to the fact that sysctl(VM_PAGE_CLUSTER) might
conceivably change page_cluster to 0 while valid_swaphandles() is in the
middle of using it, leading to an embarrassingly long loop: take a local
snapshot of page_cluster and work with that.

Signed-off-by: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
This commit is contained in:
Hugh Dickins 2006-09-29 02:01:26 -07:00 committed by Linus Torvalds
parent 2d1d43f6a4
commit 3f9e7949f8
1 changed files with 4 additions and 3 deletions
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7
mm/swapfile.c
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@ -1723,13 +1723,14 @@ get_swap_info_struct(unsigned type)
*/
int valid_swaphandles(swp_entry_t entry, unsigned long *offset)
{
int ret = 0, i = 1 << page_cluster;
int our_page_cluster = page_cluster;
int ret = 0, i = 1 << our_page_cluster;
unsigned long toff;
struct swap_info_struct *swapdev = swp_type(entry) + swap_info;
if (!page_cluster) /* no readahead */
if (!our_page_cluster) /* no readahead */
return 0;
toff = (swp_offset(entry) >> page_cluster) << page_cluster;
toff = (swp_offset(entry) >> our_page_cluster) << our_page_cluster;
if (!toff) /* first page is swap header */
toff++, i--;
*offset = toff;