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Message-Id: <1299343345-3984-17-git-send-email-cesarb@cesarb.net>
Date: Sat, 5 Mar 2011 13:42:17 -0300
From: Cesar Eduardo Barros <cesarb@...arb.net>
To: linux-mm@...ck.org
Cc: Andrew Morton <akpm@...ux-foundation.org>,
Hugh Dickins <hughd@...gle.com>,
KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>,
Minchan Kim <minchan.kim@...il.com>,
Jens Axboe <jaxboe@...ionio.com>, linux-kernel@...r.kernel.org,
Eric B Munson <emunson@...bm.net>,
Cesar Eduardo Barros <cesarb@...arb.net>
Subject: [PATCHv2 16/24] sys_swapon: separate parsing of swapfile header
Move the code which parses and checks the swapfile header (except for
the bad block list) to a separate function. Only code movement, no
functional changes.
Signed-off-by: Cesar Eduardo Barros <cesarb@...arb.net>
Tested-by: Eric B Munson <emunson@...bm.net>
Acked-by: Eric B Munson <emunson@...bm.net>
---
mm/swapfile.c | 140 ++++++++++++++++++++++++++++++++-------------------------
1 files changed, 78 insertions(+), 62 deletions(-)
diff --git a/mm/swapfile.c b/mm/swapfile.c
index f3f413b..a56e6fe 100644
--- a/mm/swapfile.c
+++ b/mm/swapfile.c
@@ -1918,6 +1918,82 @@ static int claim_swapfile(struct swap_info_struct *p, struct inode *inode)
return 0;
}
+static unsigned long read_swap_header(struct swap_info_struct *p,
+ union swap_header *swap_header,
+ struct inode *inode)
+{
+ int i;
+ unsigned long maxpages;
+ unsigned long swapfilepages;
+
+ if (memcmp("SWAPSPACE2", swap_header->magic.magic, 10)) {
+ printk(KERN_ERR "Unable to find swap-space signature\n");
+ goto bad_swap;
+ }
+
+ /* swap partition endianess hack... */
+ if (swab32(swap_header->info.version) == 1) {
+ swab32s(&swap_header->info.version);
+ swab32s(&swap_header->info.last_page);
+ swab32s(&swap_header->info.nr_badpages);
+ for (i = 0; i < swap_header->info.nr_badpages; i++)
+ swab32s(&swap_header->info.badpages[i]);
+ }
+ /* Check the swap header's sub-version */
+ if (swap_header->info.version != 1) {
+ printk(KERN_WARNING
+ "Unable to handle swap header version %d\n",
+ swap_header->info.version);
+ goto bad_swap;
+ }
+
+ p->lowest_bit = 1;
+ p->cluster_next = 1;
+ p->cluster_nr = 0;
+
+ /*
+ * Find out how many pages are allowed for a single swap
+ * device. There are two limiting factors: 1) the number of
+ * bits for the swap offset in the swp_entry_t type and
+ * 2) the number of bits in the a swap pte as defined by
+ * the different architectures. In order to find the
+ * largest possible bit mask a swap entry with swap type 0
+ * and swap offset ~0UL is created, encoded to a swap pte,
+ * decoded to a swp_entry_t again and finally the swap
+ * offset is extracted. This will mask all the bits from
+ * the initial ~0UL mask that can't be encoded in either
+ * the swp_entry_t or the architecture definition of a
+ * swap pte.
+ */
+ maxpages = swp_offset(pte_to_swp_entry(
+ swp_entry_to_pte(swp_entry(0, ~0UL)))) + 1;
+ if (maxpages > swap_header->info.last_page) {
+ maxpages = swap_header->info.last_page + 1;
+ /* p->max is an unsigned int: don't overflow it */
+ if ((unsigned int)maxpages == 0)
+ maxpages = UINT_MAX;
+ }
+ p->highest_bit = maxpages - 1;
+
+ if (!maxpages)
+ goto bad_swap;
+ swapfilepages = i_size_read(inode) >> PAGE_SHIFT;
+ if (swapfilepages && maxpages > swapfilepages) {
+ printk(KERN_WARNING
+ "Swap area shorter than signature indicates\n");
+ goto bad_swap;
+ }
+ if (swap_header->info.nr_badpages && S_ISREG(inode->i_mode))
+ goto bad_swap;
+ if (swap_header->info.nr_badpages > MAX_SWAP_BADPAGES)
+ goto bad_swap;
+
+ return maxpages;
+
+bad_swap:
+ return 0;
+}
+
SYSCALL_DEFINE2(swapon, const char __user *, specialfile, int, swap_flags)
{
struct swap_info_struct *p;
@@ -1931,7 +2007,6 @@ SYSCALL_DEFINE2(swapon, const char __user *, specialfile, int, swap_flags)
int nr_extents = 0;
sector_t span;
unsigned long maxpages;
- unsigned long swapfilepages;
unsigned char *swap_map = NULL;
struct page *page = NULL;
struct inode *inode = NULL;
@@ -1989,71 +2064,12 @@ SYSCALL_DEFINE2(swapon, const char __user *, specialfile, int, swap_flags)
}
swap_header = kmap(page);
- if (memcmp("SWAPSPACE2", swap_header->magic.magic, 10)) {
- printk(KERN_ERR "Unable to find swap-space signature\n");
+ maxpages = read_swap_header(p, swap_header, inode);
+ if (unlikely(!maxpages)) {
error = -EINVAL;
goto bad_swap;
}
- /* swap partition endianess hack... */
- if (swab32(swap_header->info.version) == 1) {
- swab32s(&swap_header->info.version);
- swab32s(&swap_header->info.last_page);
- swab32s(&swap_header->info.nr_badpages);
- for (i = 0; i < swap_header->info.nr_badpages; i++)
- swab32s(&swap_header->info.badpages[i]);
- }
- /* Check the swap header's sub-version */
- if (swap_header->info.version != 1) {
- printk(KERN_WARNING
- "Unable to handle swap header version %d\n",
- swap_header->info.version);
- error = -EINVAL;
- goto bad_swap;
- }
-
- p->lowest_bit = 1;
- p->cluster_next = 1;
- p->cluster_nr = 0;
-
- /*
- * Find out how many pages are allowed for a single swap
- * device. There are two limiting factors: 1) the number of
- * bits for the swap offset in the swp_entry_t type and
- * 2) the number of bits in the a swap pte as defined by
- * the different architectures. In order to find the
- * largest possible bit mask a swap entry with swap type 0
- * and swap offset ~0UL is created, encoded to a swap pte,
- * decoded to a swp_entry_t again and finally the swap
- * offset is extracted. This will mask all the bits from
- * the initial ~0UL mask that can't be encoded in either
- * the swp_entry_t or the architecture definition of a
- * swap pte.
- */
- maxpages = swp_offset(pte_to_swp_entry(
- swp_entry_to_pte(swp_entry(0, ~0UL)))) + 1;
- if (maxpages > swap_header->info.last_page) {
- maxpages = swap_header->info.last_page + 1;
- /* p->max is an unsigned int: don't overflow it */
- if ((unsigned int)maxpages == 0)
- maxpages = UINT_MAX;
- }
- p->highest_bit = maxpages - 1;
-
- error = -EINVAL;
- if (!maxpages)
- goto bad_swap;
- swapfilepages = i_size_read(inode) >> PAGE_SHIFT;
- if (swapfilepages && maxpages > swapfilepages) {
- printk(KERN_WARNING
- "Swap area shorter than signature indicates\n");
- goto bad_swap;
- }
- if (swap_header->info.nr_badpages && S_ISREG(inode->i_mode))
- goto bad_swap;
- if (swap_header->info.nr_badpages > MAX_SWAP_BADPAGES)
- goto bad_swap;
-
/* OK, set up the swap map and apply the bad block list */
swap_map = vzalloc(maxpages);
if (!swap_map) {
--
1.7.4
--
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