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Subject[PATCHv2 19/24] sys_swapon: separate parsing of bad blocks and extents
Date
Move the code which parses the bad block list and the extents to a
separate function. Only code movement, no functional changes.

This change uses the fact that, after the success path, nr_good_pages ==
p->pages.

Signed-off-by: Cesar Eduardo Barros <cesarb@cesarb.net>
Tested-by: Eric B Munson <emunson@mgebm.net>
Acked-by: Eric B Munson <emunson@mgebm.net>
---
mm/swapfile.c | 83 +++++++++++++++++++++++++++++++++++++--------------------
1 files changed, 54 insertions(+), 29 deletions(-)

diff --git a/mm/swapfile.c b/mm/swapfile.c
index 7ac81fe..26eb84a 100644
--- a/mm/swapfile.c
+++ b/mm/swapfile.c
@@ -1991,6 +1991,54 @@ static unsigned long read_swap_header(struct swap_info_struct *p,
return maxpages;
}

+static int setup_swap_map_and_extents(struct swap_info_struct *p,
+ union swap_header *swap_header,
+ unsigned char *swap_map,
+ unsigned long maxpages,
+ sector_t *span)
+{
+ int i;
+ int error;
+ unsigned int nr_good_pages;
+ int nr_extents;
+
+ nr_good_pages = maxpages - 1; /* omit header page */
+
+ for (i = 0; i < swap_header->info.nr_badpages; i++) {
+ unsigned int page_nr = swap_header->info.badpages[i];
+ if (page_nr == 0 || page_nr > swap_header->info.last_page) {
+ error = -EINVAL;
+ goto bad_swap;
+ }
+ if (page_nr < maxpages) {
+ swap_map[page_nr] = SWAP_MAP_BAD;
+ nr_good_pages--;
+ }
+ }
+
+ if (nr_good_pages) {
+ swap_map[0] = SWAP_MAP_BAD;
+ p->max = maxpages;
+ p->pages = nr_good_pages;
+ nr_extents = setup_swap_extents(p, span);
+ if (nr_extents < 0) {
+ error = nr_extents;
+ goto bad_swap;
+ }
+ nr_good_pages = p->pages;
+ }
+ if (!nr_good_pages) {
+ printk(KERN_WARNING "Empty swap-file\n");
+ error = -EINVAL;
+ goto bad_swap;
+ }
+
+ return nr_extents;
+
+bad_swap:
+ return error;
+}
+
SYSCALL_DEFINE2(swapon, const char __user *, specialfile, int, swap_flags)
{
struct swap_info_struct *p;
@@ -2001,7 +2049,7 @@ SYSCALL_DEFINE2(swapon, const char __user *, specialfile, int, swap_flags)
int error;
union swap_header *swap_header;
unsigned int nr_good_pages;
- int nr_extents = 0;
+ int nr_extents;
sector_t span;
unsigned long maxpages;
unsigned char *swap_map = NULL;
@@ -2078,36 +2126,13 @@ SYSCALL_DEFINE2(swapon, const char __user *, specialfile, int, swap_flags)
if (error)
goto bad_swap;

- nr_good_pages = maxpages - 1; /* omit header page */
-
- for (i = 0; i < swap_header->info.nr_badpages; i++) {
- unsigned int page_nr = swap_header->info.badpages[i];
- if (page_nr == 0 || page_nr > swap_header->info.last_page) {
- error = -EINVAL;
- goto bad_swap;
- }
- if (page_nr < maxpages) {
- swap_map[page_nr] = SWAP_MAP_BAD;
- nr_good_pages--;
- }
- }
-
- if (nr_good_pages) {
- swap_map[0] = SWAP_MAP_BAD;
- p->max = maxpages;
- p->pages = nr_good_pages;
- nr_extents = setup_swap_extents(p, &span);
- if (nr_extents < 0) {
- error = nr_extents;
- goto bad_swap;
- }
- nr_good_pages = p->pages;
- }
- if (!nr_good_pages) {
- printk(KERN_WARNING "Empty swap-file\n");
- error = -EINVAL;
+ nr_extents = setup_swap_map_and_extents(p, swap_header, swap_map,
+ maxpages, &span);
+ if (unlikely(nr_extents < 0)) {
+ error = nr_extents;
goto bad_swap;
}
+ nr_good_pages = p->pages;

if (p->bdev) {
if (blk_queue_nonrot(bdev_get_queue(p->bdev))) {
--
1.7.4


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