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@cesarb.net> Tested-by: Eric B Munson <emunson@mgebm.net> Acked-by: Eric B Munson <emunson@mgebm.net> Reviewed-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Hugh Dickins <hughd@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Cesar Eduardo Barros
Linus Torvalds
parent
5de771e41f
commit
ca8bd38bf6
140
mm/swapfile.c
140
mm/swapfile.c
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@ -1918,6 +1918,82 @@ static int claim_swapfile(struct swap_info_struct *p, struct inode *inode)
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return 0;
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}
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static unsigned long read_swap_header(struct swap_info_struct *p,
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union swap_header *swap_header,
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struct inode *inode)
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{
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int i;
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unsigned long maxpages;
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unsigned long swapfilepages;
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if (memcmp("SWAPSPACE2", swap_header->magic.magic, 10)) {
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printk(KERN_ERR "Unable to find swap-space signature\n");
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goto bad_swap;
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}
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/* swap partition endianess hack... */
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if (swab32(swap_header->info.version) == 1) {
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swab32s(&swap_header->info.version);
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swab32s(&swap_header->info.last_page);
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swab32s(&swap_header->info.nr_badpages);
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for (i = 0; i < swap_header->info.nr_badpages; i++)
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swab32s(&swap_header->info.badpages[i]);
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}
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/* Check the swap header's sub-version */
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if (swap_header->info.version != 1) {
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printk(KERN_WARNING
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"Unable to handle swap header version %d\n",
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swap_header->info.version);
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goto bad_swap;
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}
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p->lowest_bit = 1;
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p->cluster_next = 1;
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p->cluster_nr = 0;
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/*
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* Find out how many pages are allowed for a single swap
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* device. There are two limiting factors: 1) the number of
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* bits for the swap offset in the swp_entry_t type and
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* 2) the number of bits in the a swap pte as defined by
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* the different architectures. In order to find the
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* largest possible bit mask a swap entry with swap type 0
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* and swap offset ~0UL is created, encoded to a swap pte,
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* decoded to a swp_entry_t again and finally the swap
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* offset is extracted. This will mask all the bits from
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* the initial ~0UL mask that can't be encoded in either
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* the swp_entry_t or the architecture definition of a
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* swap pte.
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*/
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maxpages = swp_offset(pte_to_swp_entry(
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swp_entry_to_pte(swp_entry(0, ~0UL)))) + 1;
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if (maxpages > swap_header->info.last_page) {
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maxpages = swap_header->info.last_page + 1;
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/* p->max is an unsigned int: don't overflow it */
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if ((unsigned int)maxpages == 0)
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maxpages = UINT_MAX;
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}
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p->highest_bit = maxpages - 1;
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if (!maxpages)
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goto bad_swap;
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swapfilepages = i_size_read(inode) >> PAGE_SHIFT;
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if (swapfilepages && maxpages > swapfilepages) {
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printk(KERN_WARNING
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"Swap area shorter than signature indicates\n");
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goto bad_swap;
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}
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if (swap_header->info.nr_badpages && S_ISREG(inode->i_mode))
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goto bad_swap;
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if (swap_header->info.nr_badpages > MAX_SWAP_BADPAGES)
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goto bad_swap;
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return maxpages;
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bad_swap:
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return 0;
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}
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SYSCALL_DEFINE2(swapon, const char __user *, specialfile, int, swap_flags)
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{
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struct swap_info_struct *p;
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@ -1931,7 +2007,6 @@ SYSCALL_DEFINE2(swapon, const char __user *, specialfile, int, swap_flags)
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int nr_extents = 0;
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sector_t span;
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unsigned long maxpages;
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unsigned long swapfilepages;
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unsigned char *swap_map = NULL;
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struct page *page = NULL;
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struct inode *inode = NULL;
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@ -1989,71 +2064,12 @@ SYSCALL_DEFINE2(swapon, const char __user *, specialfile, int, swap_flags)
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}
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swap_header = kmap(page);
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if (memcmp("SWAPSPACE2", swap_header->magic.magic, 10)) {
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printk(KERN_ERR "Unable to find swap-space signature\n");
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maxpages = read_swap_header(p, swap_header, inode);
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if (unlikely(!maxpages)) {
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error = -EINVAL;
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goto bad_swap;
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}
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/* swap partition endianess hack... */
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if (swab32(swap_header->info.version) == 1) {
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swab32s(&swap_header->info.version);
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swab32s(&swap_header->info.last_page);
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swab32s(&swap_header->info.nr_badpages);
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for (i = 0; i < swap_header->info.nr_badpages; i++)
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swab32s(&swap_header->info.badpages[i]);
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}
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/* Check the swap header's sub-version */
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if (swap_header->info.version != 1) {
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printk(KERN_WARNING
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"Unable to handle swap header version %d\n",
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swap_header->info.version);
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error = -EINVAL;
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goto bad_swap;
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}
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p->lowest_bit = 1;
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p->cluster_next = 1;
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p->cluster_nr = 0;
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/*
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* Find out how many pages are allowed for a single swap
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* device. There are two limiting factors: 1) the number of
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* bits for the swap offset in the swp_entry_t type and
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* 2) the number of bits in the a swap pte as defined by
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* the different architectures. In order to find the
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* largest possible bit mask a swap entry with swap type 0
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* and swap offset ~0UL is created, encoded to a swap pte,
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* decoded to a swp_entry_t again and finally the swap
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* offset is extracted. This will mask all the bits from
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* the initial ~0UL mask that can't be encoded in either
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* the swp_entry_t or the architecture definition of a
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* swap pte.
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*/
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maxpages = swp_offset(pte_to_swp_entry(
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swp_entry_to_pte(swp_entry(0, ~0UL)))) + 1;
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if (maxpages > swap_header->info.last_page) {
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maxpages = swap_header->info.last_page + 1;
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/* p->max is an unsigned int: don't overflow it */
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if ((unsigned int)maxpages == 0)
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maxpages = UINT_MAX;
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}
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p->highest_bit = maxpages - 1;
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error = -EINVAL;
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if (!maxpages)
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goto bad_swap;
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swapfilepages = i_size_read(inode) >> PAGE_SHIFT;
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if (swapfilepages && maxpages > swapfilepages) {
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printk(KERN_WARNING
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"Swap area shorter than signature indicates\n");
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goto bad_swap;
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}
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if (swap_header->info.nr_badpages && S_ISREG(inode->i_mode))
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goto bad_swap;
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if (swap_header->info.nr_badpages > MAX_SWAP_BADPAGES)
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goto bad_swap;
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/* OK, set up the swap map and apply the bad block list */
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swap_map = vzalloc(maxpages);
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if (!swap_map) {
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