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/*
* linux/mm/swapfile.c
*
* Copyright (C) 1991, 1992, 1993, 1994 Linus Torvalds
* Swap reorganised 29.12.95, Stephen Tweedie
*/
#include <linux/slab.h>
#include <linux/smp_lock.h>
#include <linux/kernel_stat.h>
#include <linux/swap.h>
#include <linux/swapctl.h>
#include <linux/blkdev.h> /* for blk_size */
#include <linux/vmalloc.h>
#include <linux/pagemap.h>
#include <linux/shm.h>
#include <linux/compiler.h>
#include <asm/pgtable.h>
spinlock_t swaplock = SPIN_LOCK_UNLOCKED;
unsigned int nr_swapfiles;
int total_swap_pages;
static int swap_overflow;
static const char Bad_file[] = "Bad swap file entry ";
static const char Unused_file[] = "Unused swap file entry ";
static const char Bad_offset[] = "Bad swap offset entry ";
static const char Unused_offset[] = "Unused swap offset entry ";
struct swap_list_t swap_list = {-1, -1};
struct swap_info_struct swap_info[MAX_SWAPFILES];
#define SWAPFILE_CLUSTER 256
static inline int scan_swap_map(struct swap_info_struct *si)
{
unsigned long offset;
/*
* We try to cluster swap pages by allocating them
* sequentially in swap. Once we've allocated
* SWAPFILE_CLUSTER pages this way, however, we resort to
* first-free allocation, starting a new cluster. This
* prevents us from scattering swap pages all over the entire
* swap partition, so that we reduce overall disk seek times
* between swap pages. -- sct */
if (si->cluster_nr) {
while (si->cluster_next <= si->highest_bit) {
offset = si->cluster_next++;
if (si->swap_map[offset])
continue;
si->cluster_nr--;
goto got_page;
}
}
si->cluster_nr = SWAPFILE_CLUSTER;
/* try to find an empty (even not aligned) cluster. */
offset = si->lowest_bit;
check_next_cluster:
if (offset+SWAPFILE_CLUSTER-1 <= si->highest_bit)
{
int nr;
for (nr = offset; nr < offset+SWAPFILE_CLUSTER; nr++)
if (si->swap_map[nr])
{
offset = nr+1;
goto check_next_cluster;
}
/* We found a completly empty cluster, so start
* using it.
*/
goto got_page;
}
/* No luck, so now go finegrined as usual. -Andrea */
for (offset = si->lowest_bit; offset <= si->highest_bit ; offset++) {
if (si->swap_map[offset])
continue;
si->lowest_bit = offset+1;
got_page:
if (offset == si->lowest_bit)
si->lowest_bit++;
if (offset == si->highest_bit)
si->highest_bit--;
if (si->lowest_bit > si->highest_bit) {
si->lowest_bit = si->max;
si->highest_bit = 0;
}
si->swap_map[offset] = 1;
nr_swap_pages--;
si->cluster_next = offset+1;
return offset;
}
si->lowest_bit = si->max;
si->highest_bit = 0;
return 0;
}
swp_entry_t get_swap_page(void)
{
struct swap_info_struct * p;
unsigned long offset;
swp_entry_t entry;
int type, wrapped = 0;
entry.val = 0; /* Out of memory */
swap_list_lock();
type = swap_list.next;
if (type < 0)
goto out;
if (nr_swap_pages <= 0)
goto out;
while (1) {
p = &swap_info[type];
if ((p->flags & SWP_WRITEOK) == SWP_WRITEOK) {
swap_device_lock(p);
offset = scan_swap_map(p);
swap_device_unlock(p);
if (offset) {
entry = SWP_ENTRY(type,offset);
type = swap_info[type].next;
if (type < 0 ||
p->prio != swap_info[type].prio) {
swap_list.next = swap_list.head;
} else {
swap_list.next = type;
}
goto out;
}
}
type = p->next;
if (!wrapped) {
if (type < 0 || p->prio != swap_info[type].prio) {
type = swap_list.head;
wrapped = 1;
}
} else
if (type < 0)
goto out; /* out of swap space */
}
out:
swap_list_unlock();
return entry;
}
static struct swap_info_struct * swap_info_get(swp_entry_t entry)
{
struct swap_info_struct * p;
unsigned long offset, type;
if (!entry.val)
goto out;
type = SWP_TYPE(entry);
if (type >= nr_swapfiles)
goto bad_nofile;
p = & swap_info[type];
if (!(p->flags & SWP_USED))
goto bad_device;
offset = SWP_OFFSET(entry);
if (offset >= p->max)
goto bad_offset;
if (!p->swap_map[offset])
goto bad_free;
swap_list_lock();
if (p->prio > swap_info[swap_list.next].prio)
swap_list.next = type;
swap_device_lock(p);
return p;
bad_free:
printk(KERN_ERR "swap_free: %s%08lx\n", Unused_offset, entry.val);
goto out;
bad_offset:
printk(KERN_ERR "swap_free: %s%08lx\n", Bad_offset, entry.val);
goto out;
bad_device:
printk(KERN_ERR "swap_free: %s%08lx\n", Unused_file, entry.val);
goto out;
bad_nofile:
printk(KERN_ERR "swap_free: %s%08lx\n", Bad_file, entry.val);
out:
return NULL;
}
static void swap_info_put(struct swap_info_struct * p)
{
swap_device_unlock(p);
swap_list_unlock();
}
static int swap_entry_free(struct swap_info_struct *p, unsigned long offset)
{
int count = p->swap_map[offset];
if (count < SWAP_MAP_MAX) {
count--;
p->swap_map[offset] = count;
if (!count) {
if (offset < p->lowest_bit)
p->lowest_bit = offset;
if (offset > p->highest_bit)
p->highest_bit = offset;
nr_swap_pages++;
}
}
return count;
}
/*
* Caller has made sure that the swapdevice corresponding to entry
* is still around or has not been recycled.
*/
void swap_free(swp_entry_t entry)
{
struct swap_info_struct * p;
p = swap_info_get(entry);
if (p) {
swap_entry_free(p, SWP_OFFSET(entry));
swap_info_put(p);
}
}
/*
* Check if we're the only user of a swap page,
* when the page is locked.
*/
static int exclusive_swap_page(struct page *page)
{
int retval = 0;
struct swap_info_struct * p;
swp_entry_t entry;
entry.val = page->index;
p = swap_info_get(entry);
if (p) {
/* Is the only swap cache user the cache itself? */
if (p->swap_map[SWP_OFFSET(entry)] == 1) {
/* Recheck the page count with the pagecache lock held.. */
spin_lock(&pagecache_lock);
if (page_count(page) - !!page->buffers == 2)
retval = 1;
spin_unlock(&pagecache_lock);
}
swap_info_put(p);
}
return retval;
}
/*
* We can use this swap cache entry directly
* if there are no other references to it.
*
* Here "exclusive_swap_page()" does the real
* work, but we opportunistically check whether
* we need to get all the locks first..
*/
int can_share_swap_page(struct page *page)
{
int retval = 0;
if (!PageLocked(page))
BUG();
switch (page_count(page)) {
case 3:
if (!page->buffers)
break;
/* Fallthrough */
case 2:
if (!PageSwapCache(page))
break;
retval = exclusive_swap_page(page);
break;
case 1:
if (PageReserved(page))
break;
retval = 1;
}
return retval;
}
/*
* Work out if there are any other processes sharing this
* swap cache page. Free it if you can. Return success.
*/
int remove_exclusive_swap_page(struct page *page)
{
int retval;
struct swap_info_struct * p;
swp_entry_t entry;
if (!PageLocked(page))
BUG();
if (!PageSwapCache(page))
return 0;
if (page_count(page) - !!page->buffers != 2) /* 2: us + cache */
return 0;
entry.val = page->index;
p = swap_info_get(entry);
if (!p)
return 0;
/* Is the only swap cache user the cache itself? */
retval = 0;
if (p->swap_map[SWP_OFFSET(entry)] == 1) {
/* Recheck the page count with the pagecache lock held.. */
spin_lock(&pagecache_lock);
if (page_count(page) - !!page->buffers == 2) {
__delete_from_swap_cache(page);
SetPageDirty(page);
retval = 1;
}
spin_unlock(&pagecache_lock);
}
swap_info_put(p);
if (retval) {
block_flushpage(page, 0);
swap_free(entry);
page_cache_release(page);
}
return retval;
}
/*
* Free the swap entry like above, but also try to
* free the page cache entry if it is the last user.
*/
void free_swap_and_cache(swp_entry_t entry)
{
struct swap_info_struct * p;
struct page *page = NULL;
p = swap_info_get(entry);
if (p) {
if (swap_entry_free(p, SWP_OFFSET(entry)) == 1)
page = find_trylock_page(&swapper_space, entry.val);
swap_info_put(p);
}
if (page) {
page_cache_get(page);
/* Only cache user (+us), or swap space full? Free it! */
if (page_count(page) - !!page->buffers == 2 || vm_swap_full()) {
delete_from_swap_cache(page);
SetPageDirty(page);
}
UnlockPage(page);
page_cache_release(page);
}
}
/*
* The swap entry has been read in advance, and we return 1 to indicate
* that the page has been used or is no longer needed.
*
* Always set the resulting pte to be nowrite (the same as COW pages
* after one process has exited). We don't know just how many PTEs will
* share this swap entry, so be cautious and let do_wp_page work out
* what to do if a write is requested later.
*/
/* mmlist_lock and vma->vm_mm->page_table_lock are held */
static inline void unuse_pte(struct vm_area_struct * vma, unsigned long address,
pte_t *dir, swp_entry_t entry, struct page* page)
{
pte_t pte = *dir;
if (likely(pte_to_swp_entry(pte).val != entry.val))
return;
if (unlikely(pte_none(pte) || pte_present(pte)))
return;
get_page(page);
set_pte(dir, pte_mkold(mk_pte(page, vma->vm_page_prot)));
swap_free(entry);
++vma->vm_mm->rss;
}
/* mmlist_lock and vma->vm_mm->page_table_lock are held */
static inline void unuse_pmd(struct vm_area_struct * vma, pmd_t *dir,
unsigned long address, unsigned long size, unsigned long offset,
swp_entry_t entry, struct page* page)
{
pte_t * pte;
unsigned long end;
if (pmd_none(*dir))
return;
if (pmd_bad(*dir)) {
pmd_ERROR(*dir);
pmd_clear(dir);
return;
}
pte = pte_offset(dir, address);
offset += address & PMD_MASK;
address &= ~PMD_MASK;
end = address + size;
if (end > PMD_SIZE)
end = PMD_SIZE;
do {
unuse_pte(vma, offset+address-vma->vm_start, pte, entry, page);
address += PAGE_SIZE;
pte++;
} while (address && (address < end));
}
/* mmlist_lock and vma->vm_mm->page_table_lock are held */
static inline void unuse_pgd(struct vm_area_struct * vma, pgd_t *dir,
unsigned long address, unsigned long size,
swp_entry_t entry, struct page* page)
{
pmd_t * pmd;
unsigned long offset, end;
if (pgd_none(*dir))
return;
if (pgd_bad(*dir)) {
pgd_ERROR(*dir);
pgd_clear(dir);
return;
}
pmd = pmd_offset(dir, address);
offset = address & PGDIR_MASK;
address &= ~PGDIR_MASK;
end = address + size;
if (end > PGDIR_SIZE)
end = PGDIR_SIZE;
if (address >= end)
BUG();
do {
unuse_pmd(vma, pmd, address, end - address, offset, entry,
page);
address = (address + PMD_SIZE) & PMD_MASK;
pmd++;
} while (address && (address < end));
}
/* mmlist_lock and vma->vm_mm->page_table_lock are held */
static void unuse_vma(struct vm_area_struct * vma, pgd_t *pgdir,
swp_entry_t entry, struct page* page)
{
unsigned long start = vma->vm_start, end = vma->vm_end;
if (start >= end)
BUG();
do {
unuse_pgd(vma, pgdir, start, end - start, entry, page);
start = (start + PGDIR_SIZE) & PGDIR_MASK;
pgdir++;
} while (start && (start < end));
}
static void unuse_process(struct mm_struct * mm,
swp_entry_t entry, struct page* page)
{
struct vm_area_struct* vma;
/*
* Go through process' page directory.
*/
spin_lock(&mm->page_table_lock);
for (vma = mm->mmap; vma; vma = vma->vm_next) {
pgd_t * pgd = pgd_offset(mm, vma->vm_start);
unuse_vma(vma, pgd, entry, page);
}
spin_unlock(&mm->page_table_lock);
return;
}
/*
* Scan swap_map from current position to next entry still in use.
* Recycle to start on reaching the end, returning 0 when empty.
*/
static int find_next_to_unuse(struct swap_info_struct *si, int prev)
{
int max = si->max;
int i = prev;
int count;
/*
* No need for swap_device_lock(si) here: we're just looking
* for whether an entry is in use, not modifying it; false
* hits are okay, and sys_swapoff() has already prevented new
* allocations from this area (while holding swap_list_lock()).
*/
for (;;) {
if (++i >= max) {
if (!prev) {
i = 0;
break;
}
/*
* No entries in use at top of swap_map,
* loop back to start and recheck there.
*/
max = prev + 1;
prev = 0;
i = 1;
}
count = si->swap_map[i];
if (count && count != SWAP_MAP_BAD)
break;
}
return i;
}
/*
* We completely avoid races by reading each swap page in advance,
* and then search for the process using it. All the necessary
* page table adjustments can then be made atomically.
*/
static int try_to_unuse(unsigned int type)
{
struct swap_info_struct * si = &swap_info[type];
struct mm_struct *start_mm;
unsigned short *swap_map;
unsigned short swcount;
struct page *page;
swp_entry_t entry;
int i = 0;
int retval = 0;
int reset_overflow = 0;
/*
* When searching mms for an entry, a good strategy is to
* start at the first mm we freed the previous entry from
* (though actually we don't notice whether we or coincidence
* freed the entry). Initialize this start_mm with a hold.
*
* A simpler strategy would be to start at the last mm we
* freed the previous entry from; but that would take less
* advantage of mmlist ordering (now preserved by swap_out()),
* which clusters forked address spaces together, most recent
* child immediately after parent. If we race with dup_mmap(),
* we very much want to resolve parent before child, otherwise
* we may miss some entries: using last mm would invert that.
*/
start_mm = &init_mm;
atomic_inc(&init_mm.mm_users);
/*
* Keep on scanning until all entries have gone. Usually,
* one pass through swap_map is enough, but not necessarily:
* mmput() removes mm from mmlist before exit_mmap() and its
* zap_page_range(). That's not too bad, those entries are
* on their way out, and handled faster there than here.
* do_munmap() behaves similarly, taking the range out of mm's
* vma list before zap_page_range(). But unfortunately, when
* unmapping a part of a vma, it takes the whole out first,
* then reinserts what's left after (might even reschedule if
* open() method called) - so swap entries may be invisible
* to swapoff for a while, then reappear - but that is rare.
*/
while ((i = find_next_to_unuse(si, i))) {
/*
* Get a page for the entry, using the existing swap
* cache page if there is one. Otherwise, get a clean
* page and read the swap into it.
*/
swap_map = &si->swap_map[i];
entry = SWP_ENTRY(type, i);
page = read_swap_cache_async(entry);
if (!page) {
/*
* Either swap_duplicate() failed because entry
* has been freed independently, and will not be
* reused since sys_swapoff() already disabled
* allocation from here, or alloc_page() failed.
*/
if (!*swap_map)
continue;
retval = -ENOMEM;
break;
}
/*
* Don't hold on to start_mm if it looks like exiting.
*/
if (atomic_read(&start_mm->mm_users) == 1) {
mmput(start_mm);
start_mm = &init_mm;
atomic_inc(&init_mm.mm_users);
}
/*
* Wait for and lock page. When do_swap_page races with
* try_to_unuse, do_swap_page can handle the fault much
* faster than try_to_unuse can locate the entry. This
* apparently redundant "wait_on_page" lets try_to_unuse
* defer to do_swap_page in such a case - in some tests,
* do_swap_page and try_to_unuse repeatedly compete.
*/
wait_on_page(page);
lock_page(page);
/*
* Remove all references to entry, without blocking.
* Whenever we reach init_mm, there's no address space
* to search, but use it as a reminder to search shmem.
*/
swcount = *swap_map;
if (swcount > 1) {
flush_page_to_ram(page);
if (start_mm == &init_mm)
shmem_unuse(entry, page);
else
unuse_process(start_mm, entry, page);
}
if (*swap_map > 1) {
int set_start_mm = (*swap_map >= swcount);
struct list_head *p = &start_mm->mmlist;
struct mm_struct *new_start_mm = start_mm;
struct mm_struct *mm;
spin_lock(&mmlist_lock);
while (*swap_map > 1 &&
(p = p->next) != &start_mm->mmlist) {
mm = list_entry(p, struct mm_struct, mmlist);
swcount = *swap_map;
if (mm == &init_mm) {
set_start_mm = 1;
shmem_unuse(entry, page);
} else
unuse_process(mm, entry, page);
if (set_start_mm && *swap_map < swcount) {
new_start_mm = mm;
set_start_mm = 0;
}
}
atomic_inc(&new_start_mm->mm_users);
spin_unlock(&mmlist_lock);
mmput(start_mm);
start_mm = new_start_mm;
}
/*
* How could swap count reach 0x7fff when the maximum
* pid is 0x7fff, and there's no way to repeat a swap
* page within an mm (except in shmem, where it's the
* shared object which takes the reference count)?
* We believe SWAP_MAP_MAX cannot occur in Linux 2.4.
*
* If that's wrong, then we should worry more about
* exit_mmap() and do_munmap() cases described above:
* we might be resetting SWAP_MAP_MAX too early here.
* We know "Undead"s can happen, they're okay, so don't
* report them; but do report if we reset SWAP_MAP_MAX.
*/
if (*swap_map == SWAP_MAP_MAX) {
swap_list_lock();
swap_device_lock(si);
nr_swap_pages++;
*swap_map = 1;
swap_device_unlock(si);
swap_list_unlock();
reset_overflow = 1;
}
/*
* If a reference remains (rare), we would like to leave
* the page in the swap cache; but try_to_swap_out could
* then re-duplicate the entry once we drop page lock,
* so we might loop indefinitely; also, that page could
* not be swapped out to other storage meanwhile. So:
* delete from cache even if there's another reference,
* after ensuring that the data has been saved to disk -
* since if the reference remains (rarer), it will be
* read from disk into another page. Splitting into two
* pages would be incorrect if swap supported "shared
* private" pages, but they are handled by tmpfs files.
* Note shmem_unuse already deleted its from swap cache.
*/
swcount = *swap_map;
if ((swcount > 0) != PageSwapCache(page))
BUG();
if ((swcount > 1) && PageDirty(page)) {
rw_swap_page(WRITE, page);
lock_page(page);
}
if (PageSwapCache(page))
delete_from_swap_cache(page);
/*
* So we could skip searching mms once swap count went
* to 1, we did not mark any present ptes as dirty: must
* mark page dirty so try_to_swap_out will preserve it.
*/
SetPageDirty(page);
UnlockPage(page);
page_cache_release(page);
/*
* Make sure that we aren't completely killing
* interactive performance. Interruptible check on
* signal_pending() would be nice, but changes the spec?
*/
if (current->need_resched)
schedule();
}
mmput(start_mm);
if (reset_overflow) {
printk(KERN_WARNING "swapoff: cleared swap entry overflow\n");
swap_overflow = 0;
}
return retval;
}
asmlinkage long sys_swapoff(const char * specialfile)
{
struct swap_info_struct * p = NULL;
unsigned short *swap_map;
struct nameidata nd;
int i, type, prev;
int err;
if (!capable(CAP_SYS_ADMIN))
return -EPERM;
err = user_path_walk(specialfile, &nd);
if (err)
goto out;
lock_kernel();
prev = -1;
swap_list_lock();
for (type = swap_list.head; type >= 0; type = swap_info[type].next) {
p = swap_info + type;
if ((p->flags & SWP_WRITEOK) == SWP_WRITEOK) {
if (p->swap_file == nd.dentry ||
(S_ISBLK(nd.dentry->d_inode->i_mode) &&
p->swap_device == nd.dentry->d_inode->i_rdev))
break;
}
prev = type;
}
err = -EINVAL;
if (type < 0) {
swap_list_unlock();
goto out_dput;
}
if (prev < 0) {
swap_list.head = p->next;
} else {
swap_info[prev].next = p->next;
}
if (type == swap_list.next) {
/* just pick something that's safe... */
swap_list.next = swap_list.head;
}
nr_swap_pages -= p->pages;
total_swap_pages -= p->pages;
p->flags = SWP_USED;
swap_list_unlock();
unlock_kernel();
err = try_to_unuse(type);
lock_kernel();
if (err) {
/* re-insert swap space back into swap_list */
swap_list_lock();
for (prev = -1, i = swap_list.head; i >= 0; prev = i, i = swap_info[i].next)
if (p->prio >= swap_info[i].prio)
break;
p->next = i;
if (prev < 0)
swap_list.head = swap_list.next = p - swap_info;
else
swap_info[prev].next = p - swap_info;
nr_swap_pages += p->pages;
total_swap_pages += p->pages;
p->flags = SWP_WRITEOK;
swap_list_unlock();
goto out_dput;
}
if (p->swap_device)
blkdev_put(p->swap_file->d_inode->i_bdev, BDEV_SWAP);
path_release(&nd);
swap_list_lock();
swap_device_lock(p);
nd.mnt = p->swap_vfsmnt;
nd.dentry = p->swap_file;
p->swap_vfsmnt = NULL;
p->swap_file = NULL;
p->swap_device = 0;
p->max = 0;
swap_map = p->swap_map;
p->swap_map = NULL;
p->flags = 0;
swap_device_unlock(p);
swap_list_unlock();
vfree(swap_map);
err = 0;
out_dput:
unlock_kernel();
path_release(&nd);
out:
return err;
}
int get_swaparea_info(char *buf)
{
char * page = (char *) __get_free_page(GFP_KERNEL);
struct swap_info_struct *ptr = swap_info;
int i, j, len = 0, usedswap;
if (!page)
return -ENOMEM;
len += sprintf(buf, "Filename\t\t\tType\t\tSize\tUsed\tPriority\n");
for (i = 0 ; i < nr_swapfiles ; i++, ptr++) {
if ((ptr->flags & SWP_USED) && ptr->swap_map) {
char * path = d_path(ptr->swap_file, ptr->swap_vfsmnt,
page, PAGE_SIZE);
len += sprintf(buf + len, "%-31s ", path);
if (!ptr->swap_device)
len += sprintf(buf + len, "file\t\t");
else
len += sprintf(buf + len, "partition\t");
usedswap = 0;
for (j = 0; j < ptr->max; ++j)
switch (ptr->swap_map[j]) {
case SWAP_MAP_BAD:
case 0:
continue;
default:
usedswap++;
}
len += sprintf(buf + len, "%d\t%d\t%d\n", ptr->pages << (PAGE_SHIFT - 10),
usedswap << (PAGE_SHIFT - 10), ptr->prio);
}
}
free_page((unsigned long) page);
return len;
}
int is_swap_partition(kdev_t dev) {
struct swap_info_struct *ptr = swap_info;
int i;
for (i = 0 ; i < nr_swapfiles ; i++, ptr++) {
if (ptr->flags & SWP_USED)
if (ptr->swap_device == dev)
return 1;
}
return 0;
}
/*
* Written 01/25/92 by Simmule Turner, heavily changed by Linus.
*
* The swapon system call
*/
asmlinkage long sys_swapon(const char * specialfile, int swap_flags)
{
struct swap_info_struct * p;
struct nameidata nd;
struct inode * swap_inode;
unsigned int type;
int i, j, prev;
int error;
static int least_priority = 0;
union swap_header *swap_header = 0;
int swap_header_version;
int nr_good_pages = 0;
unsigned long maxpages = 1;
int swapfilesize;
struct block_device *bdev = NULL;
unsigned short *swap_map;
if (!capable(CAP_SYS_ADMIN))
return -EPERM;
lock_kernel();
swap_list_lock();
p = swap_info;
for (type = 0 ; type < nr_swapfiles ; type++,p++)
if (!(p->flags & SWP_USED))
break;
error = -EPERM;
if (type >= MAX_SWAPFILES) {
swap_list_unlock();
goto out;
}
if (type >= nr_swapfiles)
nr_swapfiles = type+1;
p->flags = SWP_USED;
p->swap_file = NULL;
p->swap_vfsmnt = NULL;
p->swap_device = 0;
p->swap_map = NULL;
p->lowest_bit = 0;
p->highest_bit = 0;
p->cluster_nr = 0;
p->sdev_lock = SPIN_LOCK_UNLOCKED;
p->next = -1;
if (swap_flags & SWAP_FLAG_PREFER) {
p->prio =
(swap_flags & SWAP_FLAG_PRIO_MASK)>>SWAP_FLAG_PRIO_SHIFT;
} else {
p->prio = --least_priority;
}
swap_list_unlock();
error = user_path_walk(specialfile, &nd);
if (error)
goto bad_swap_2;
p->swap_file = nd.dentry;
p->swap_vfsmnt = nd.mnt;
swap_inode = nd.dentry->d_inode;
error = -EINVAL;
if (S_ISBLK(swap_inode->i_mode)) {
kdev_t dev = swap_inode->i_rdev;
struct block_device_operations *bdops;
devfs_handle_t de;
p->swap_device = dev;
set_blocksize(dev, PAGE_SIZE);
bd_acquire(swap_inode);
bdev = swap_inode->i_bdev;
de = devfs_get_handle_from_inode(swap_inode);
bdops = devfs_get_ops(de); /* Increments module use count */
if (bdops) bdev->bd_op = bdops;
error = blkdev_get(bdev, FMODE_READ|FMODE_WRITE, 0, BDEV_SWAP);
devfs_put_ops(de);/*Decrement module use count now we're safe*/
if (error)
goto bad_swap_2;
set_blocksize(dev, PAGE_SIZE);
error = -ENODEV;
if (!dev || (blk_size[MAJOR(dev)] &&
!blk_size[MAJOR(dev)][MINOR(dev)]))
goto bad_swap;
swapfilesize = 0;
if (blk_size[MAJOR(dev)])
swapfilesize = blk_size[MAJOR(dev)][MINOR(dev)]
>> (PAGE_SHIFT - 10);
} else if (S_ISREG(swap_inode->i_mode))
swapfilesize = swap_inode->i_size >> PAGE_SHIFT;
else
goto bad_swap;
error = -EBUSY;
for (i = 0 ; i < nr_swapfiles ; i++) {
struct swap_info_struct *q = &swap_info[i];
if (i == type || !q->swap_file)
continue;
if (swap_inode->i_mapping == q->swap_file->d_inode->i_mapping)
goto bad_swap;
}
swap_header = (void *) __get_free_page(GFP_USER);
if (!swap_header) {
printk("Unable to start swapping: out of memory :-)\n");
error = -ENOMEM;
goto bad_swap;
}
lock_page(virt_to_page(swap_header));
rw_swap_page_nolock(READ, SWP_ENTRY(type,0), (char *) swap_header);
if (!memcmp("SWAP-SPACE",swap_header->magic.magic,10))
swap_header_version = 1;
else if (!memcmp("SWAPSPACE2",swap_header->magic.magic,10))
swap_header_version = 2;
else {
printk("Unable to find swap-space signature\n");
error = -EINVAL;
goto bad_swap;
}
switch (swap_header_version) {
case 1:
memset(((char *) swap_header)+PAGE_SIZE-10,0,10);
j = 0;
p->lowest_bit = 0;
p->highest_bit = 0;
for (i = 1 ; i < 8*PAGE_SIZE ; i++) {
if (test_bit(i,(char *) swap_header)) {
if (!p->lowest_bit)
p->lowest_bit = i;
p->highest_bit = i;
maxpages = i+1;
j++;
}
}
nr_good_pages = j;
p->swap_map = vmalloc(maxpages * sizeof(short));
if (!p->swap_map) {
error = -ENOMEM;
goto bad_swap;
}
for (i = 1 ; i < maxpages ; i++) {
if (test_bit(i,(char *) swap_header))
p->swap_map[i] = 0;
else
p->swap_map[i] = SWAP_MAP_BAD;
}
break;
case 2:
/* Check the swap header's sub-version and the size of
the swap file and bad block lists */
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;
maxpages = SWP_OFFSET(SWP_ENTRY(0,~0UL)) - 1;
if (maxpages > swap_header->info.last_page)
maxpages = swap_header->info.last_page;
p->highest_bit = maxpages - 1;
error = -EINVAL;
if (swap_header->info.nr_badpages > MAX_SWAP_BADPAGES)
goto bad_swap;
/* OK, set up the swap map and apply the bad block list */
if (!(p->swap_map = vmalloc(maxpages * sizeof(short)))) {
error = -ENOMEM;
goto bad_swap;
}
error = 0;
memset(p->swap_map, 0, maxpages * sizeof(short));
for (i=0; i<swap_header->info.nr_badpages; i++) {
int page = swap_header->info.badpages[i];
if (page <= 0 || page >= swap_header->info.last_page)
error = -EINVAL;
else
p->swap_map[page] = SWAP_MAP_BAD;
}
nr_good_pages = swap_header->info.last_page -
swap_header->info.nr_badpages -
1 /* header page */;
if (error)
goto bad_swap;
}
if (swapfilesize && maxpages > swapfilesize) {
printk(KERN_WARNING
"Swap area shorter than signature indicates\n");
error = -EINVAL;
goto bad_swap;
}
if (!nr_good_pages) {
printk(KERN_WARNING "Empty swap-file\n");
error = -EINVAL;
goto bad_swap;
}
p->swap_map[0] = SWAP_MAP_BAD;
swap_list_lock();
swap_device_lock(p);
p->max = maxpages;
p->flags = SWP_WRITEOK;
p->pages = nr_good_pages;
nr_swap_pages += nr_good_pages;
total_swap_pages += nr_good_pages;
printk(KERN_INFO "Adding Swap: %dk swap-space (priority %d)\n",
nr_good_pages<<(PAGE_SHIFT-10), p->prio);
/* insert swap space into swap_list: */
prev = -1;
for (i = swap_list.head; i >= 0; i = swap_info[i].next) {
if (p->prio >= swap_info[i].prio) {
break;
}
prev = i;
}
p->next = i;
if (prev < 0) {
swap_list.head = swap_list.next = p - swap_info;
} else {
swap_info[prev].next = p - swap_info;
}
swap_device_unlock(p);
swap_list_unlock();
error = 0;
goto out;
bad_swap:
if (bdev)
blkdev_put(bdev, BDEV_SWAP);
bad_swap_2:
swap_list_lock();
swap_map = p->swap_map;
nd.mnt = p->swap_vfsmnt;
nd.dentry = p->swap_file;
p->swap_device = 0;
p->swap_file = NULL;
p->swap_vfsmnt = NULL;
p->swap_map = NULL;
p->flags = 0;
if (!(swap_flags & SWAP_FLAG_PREFER))
++least_priority;
swap_list_unlock();
if (swap_map)
vfree(swap_map);
path_release(&nd);
out:
if (swap_header)
free_page((long) swap_header);
unlock_kernel();
return error;
}
void si_swapinfo(struct sysinfo *val)
{
unsigned int i;
unsigned long nr_to_be_unused = 0;
swap_list_lock();
for (i = 0; i < nr_swapfiles; i++) {
unsigned int j;
if (swap_info[i].flags != SWP_USED)
continue;
for (j = 0; j < swap_info[i].max; ++j) {
switch (swap_info[i].swap_map[j]) {
case 0:
case SWAP_MAP_BAD:
continue;
default:
nr_to_be_unused++;
}
}
}
val->freeswap = nr_swap_pages + nr_to_be_unused;
val->totalswap = total_swap_pages + nr_to_be_unused;
swap_list_unlock();
}
/*
* Verify that a swap entry is valid and increment its swap map count.
*
* Note: if swap_map[] reaches SWAP_MAP_MAX the entries are treated as
* "permanent", but will be reclaimed by the next swapoff.
*/
int swap_duplicate(swp_entry_t entry)
{
struct swap_info_struct * p;
unsigned long offset, type;
int result = 0;
type = SWP_TYPE(entry);
if (type >= nr_swapfiles)
goto bad_file;
p = type + swap_info;
offset = SWP_OFFSET(entry);
swap_device_lock(p);
if (offset < p->max && p->swap_map[offset]) {
if (p->swap_map[offset] < SWAP_MAP_MAX - 1) {
p->swap_map[offset]++;
result = 1;
} else if (p->swap_map[offset] <= SWAP_MAP_MAX) {
if (swap_overflow++ < 5)
printk(KERN_WARNING "swap_dup: swap entry overflow\n");
p->swap_map[offset] = SWAP_MAP_MAX;
result = 1;
}
}
swap_device_unlock(p);
out:
return result;
bad_file:
printk(KERN_ERR "swap_dup: %s%08lx\n", Bad_file, entry.val);
goto out;
}
/*
* Page lock needs to be held in all cases to prevent races with
* swap file deletion.
*/
int swap_count(struct page *page)
{
struct swap_info_struct * p;
unsigned long offset, type;
swp_entry_t entry;
int retval = 0;
entry.val = page->index;
if (!entry.val)
goto bad_entry;
type = SWP_TYPE(entry);
if (type >= nr_swapfiles)
goto bad_file;
p = type + swap_info;
offset = SWP_OFFSET(entry);
if (offset >= p->max)
goto bad_offset;
if (!p->swap_map[offset])
goto bad_unused;
retval = p->swap_map[offset];
out:
return retval;
bad_entry:
printk(KERN_ERR "swap_count: null entry!\n");
goto out;
bad_file:
printk(KERN_ERR "swap_count: %s%08lx\n", Bad_file, entry.val);
goto out;
bad_offset:
printk(KERN_ERR "swap_count: %s%08lx\n", Bad_offset, entry.val);
goto out;
bad_unused:
printk(KERN_ERR "swap_count: %s%08lx\n", Unused_offset, entry.val);
goto out;
}
/*
* Prior swap_duplicate protects against swap device deletion.
*/
void get_swaphandle_info(swp_entry_t entry, unsigned long *offset,
kdev_t *dev, struct inode **swapf)
{
unsigned long type;
struct swap_info_struct *p;
type = SWP_TYPE(entry);
if (type >= nr_swapfiles) {
printk(KERN_ERR "rw_swap_page: %s%08lx\n", Bad_file, entry.val);
return;
}
p = &swap_info[type];
*offset = SWP_OFFSET(entry);
if (*offset >= p->max && *offset != 0) {
printk(KERN_ERR "rw_swap_page: %s%08lx\n", Bad_offset, entry.val);
return;
}
if (p->swap_map && !p->swap_map[*offset]) {
printk(KERN_ERR "rw_swap_page: %s%08lx\n", Unused_offset, entry.val);
return;
}
if (!(p->flags & SWP_USED)) {
printk(KERN_ERR "rw_swap_page: %s%08lx\n", Unused_file, entry.val);
return;
}
if (p->swap_device) {
*dev = p->swap_device;
} else if (p->swap_file) {
*swapf = p->swap_file->d_inode;
} else {
printk(KERN_ERR "rw_swap_page: no swap file or device\n");
}
return;
}
/*
* swap_device_lock prevents swap_map being freed. Don't grab an extra
* reference on the swaphandle, it doesn't matter if it becomes unused.
*/
int valid_swaphandles(swp_entry_t entry, unsigned long *offset)
{
int ret = 0, i = 1 << page_cluster;
unsigned long toff;
struct swap_info_struct *swapdev = SWP_TYPE(entry) + swap_info;
if (!page_cluster) /* no readahead */
return 0;
toff = (SWP_OFFSET(entry) >> page_cluster) << page_cluster;
if (!toff) /* first page is swap header */
toff++, i--;
*offset = toff;
swap_device_lock(swapdev);
do {
/* Don't read-ahead past the end of the swap area */
if (toff >= swapdev->max)
break;
/* Don't read in free or bad pages */
if (!swapdev->swap_map[toff])
break;
if (swapdev->swap_map[toff] == SWAP_MAP_BAD)
break;
toff++;
ret++;
} while (--i);
swap_device_unlock(swapdev);
return ret;
}
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