static struct swap_list_t swap_list = {-1, -1};
-static struct swap_info_struct swap_info[MAX_SWAPFILES];
+static struct swap_info_struct *swap_info[MAX_SWAPFILES];
static DEFINE_MUTEX(swapon_mutex);
+/* For reference count accounting in swap_map */
+/* enum for swap_map[] handling. internal use only */
+enum {
+ SWAP_MAP = 0, /* ops for reference from swap users */
+ SWAP_CACHE, /* ops for reference from swap cache */
+};
+
+static inline int swap_count(unsigned short ent)
+{
+ return ent & SWAP_COUNT_MASK;
+}
+
+static inline bool swap_has_cache(unsigned short ent)
+{
+ return !!(ent & SWAP_HAS_CACHE);
+}
+
+static inline unsigned short encode_swapmap(int count, bool has_cache)
+{
+ unsigned short ret = count;
+
+ if (has_cache)
+ return SWAP_HAS_CACHE | ret;
+ return ret;
+}
+
+/* returns 1 if swap entry is freed */
+static int
+__try_to_reclaim_swap(struct swap_info_struct *si, unsigned long offset)
+{
+ swp_entry_t entry = swp_entry(si->type, offset);
+ struct page *page;
+ int ret = 0;
+
+ page = find_get_page(&swapper_space, entry.val);
+ if (!page)
+ return 0;
+ /*
+ * This function is called from scan_swap_map() and it's called
+ * by vmscan.c at reclaiming pages. So, we hold a lock on a page, here.
+ * We have to use trylock for avoiding deadlock. This is a special
+ * case and you should use try_to_free_swap() with explicit lock_page()
+ * in usual operations.
+ */
+ if (trylock_page(page)) {
+ ret = try_to_free_swap(page);
+ unlock_page(page);
+ }
+ page_cache_release(page);
+ return ret;
+}
+
/*
* We need this because the bdev->unplug_fn can sleep and we cannot
* hold swap_lock while calling the unplug_fn. And swap_lock
down_read(&swap_unplug_sem);
entry.val = page_private(page);
if (PageSwapCache(page)) {
- struct block_device *bdev = swap_info[swp_type(entry)].bdev;
+ struct block_device *bdev = swap_info[swp_type(entry)]->bdev;
struct backing_dev_info *bdi;
/*
static int discard_swap(struct swap_info_struct *si)
{
struct swap_extent *se;
+ sector_t start_block;
+ sector_t nr_blocks;
int err = 0;
- list_for_each_entry(se, &si->extent_list, list) {
- sector_t start_block = se->start_block << (PAGE_SHIFT - 9);
- sector_t nr_blocks = (sector_t)se->nr_pages << (PAGE_SHIFT - 9);
+ /* Do not discard the swap header page! */
+ se = &si->first_swap_extent;
+ start_block = (se->start_block + 1) << (PAGE_SHIFT - 9);
+ nr_blocks = ((sector_t)se->nr_pages - 1) << (PAGE_SHIFT - 9);
+ if (nr_blocks) {
+ err = blkdev_issue_discard(si->bdev, start_block,
+ nr_blocks, GFP_KERNEL, DISCARD_FL_BARRIER);
+ if (err)
+ return err;
+ cond_resched();
+ }
- if (se->start_page == 0) {
- /* Do not discard the swap header page! */
- start_block += 1 << (PAGE_SHIFT - 9);
- nr_blocks -= 1 << (PAGE_SHIFT - 9);
- if (!nr_blocks)
- continue;
- }
+ list_for_each_entry(se, &si->first_swap_extent.list, list) {
+ start_block = se->start_block << (PAGE_SHIFT - 9);
+ nr_blocks = (sector_t)se->nr_pages << (PAGE_SHIFT - 9);
err = blkdev_issue_discard(si->bdev, start_block,
- nr_blocks, GFP_KERNEL);
+ nr_blocks, GFP_KERNEL, DISCARD_FL_BARRIER);
if (err)
break;
start_block <<= PAGE_SHIFT - 9;
nr_blocks <<= PAGE_SHIFT - 9;
if (blkdev_issue_discard(si->bdev, start_block,
- nr_blocks, GFP_NOIO))
+ nr_blocks, GFP_NOIO, DISCARD_FL_BARRIER))
break;
}
lh = se->list.next;
- if (lh == &si->extent_list)
- lh = lh->next;
se = list_entry(lh, struct swap_extent, list);
}
}
#define SWAPFILE_CLUSTER 256
#define LATENCY_LIMIT 256
-static inline unsigned long scan_swap_map(struct swap_info_struct *si)
+static inline unsigned long scan_swap_map(struct swap_info_struct *si,
+ int cache)
{
unsigned long offset;
unsigned long scan_base;
goto no_page;
if (offset > si->highest_bit)
scan_base = offset = si->lowest_bit;
+
+ /* reuse swap entry of cache-only swap if not busy. */
+ if (vm_swap_full() && si->swap_map[offset] == SWAP_HAS_CACHE) {
+ int swap_was_freed;
+ spin_unlock(&swap_lock);
+ swap_was_freed = __try_to_reclaim_swap(si, offset);
+ spin_lock(&swap_lock);
+ /* entry was freed successfully, try to use this again */
+ if (swap_was_freed)
+ goto checks;
+ goto scan; /* check next one */
+ }
+
if (si->swap_map[offset])
goto scan;
si->lowest_bit = si->max;
si->highest_bit = 0;
}
- si->swap_map[offset] = 1;
+ if (cache == SWAP_CACHE) /* at usual swap-out via vmscan.c */
+ si->swap_map[offset] = encode_swapmap(0, true);
+ else /* at suspend */
+ si->swap_map[offset] = encode_swapmap(1, false);
si->cluster_next = offset + 1;
si->flags -= SWP_SCANNING;
spin_lock(&swap_lock);
goto checks;
}
+ if (vm_swap_full() && si->swap_map[offset] == SWAP_HAS_CACHE) {
+ spin_lock(&swap_lock);
+ goto checks;
+ }
if (unlikely(--latency_ration < 0)) {
cond_resched();
latency_ration = LATENCY_LIMIT;
spin_lock(&swap_lock);
goto checks;
}
+ if (vm_swap_full() && si->swap_map[offset] == SWAP_HAS_CACHE) {
+ spin_lock(&swap_lock);
+ goto checks;
+ }
if (unlikely(--latency_ration < 0)) {
cond_resched();
latency_ration = LATENCY_LIMIT;
nr_swap_pages--;
for (type = swap_list.next; type >= 0 && wrapped < 2; type = next) {
- si = swap_info + type;
+ si = swap_info[type];
next = si->next;
if (next < 0 ||
- (!wrapped && si->prio != swap_info[next].prio)) {
+ (!wrapped && si->prio != swap_info[next]->prio)) {
next = swap_list.head;
wrapped++;
}
continue;
swap_list.next = next;
- offset = scan_swap_map(si);
+ /* This is called for allocating swap entry for cache */
+ offset = scan_swap_map(si, SWAP_CACHE);
if (offset) {
spin_unlock(&swap_lock);
return swp_entry(type, offset);
return (swp_entry_t) {0};
}
+/* The only caller of this function is now susupend routine */
swp_entry_t get_swap_page_of_type(int type)
{
struct swap_info_struct *si;
pgoff_t offset;
spin_lock(&swap_lock);
- si = swap_info + type;
- if (si->flags & SWP_WRITEOK) {
+ si = swap_info[type];
+ if (si && (si->flags & SWP_WRITEOK)) {
nr_swap_pages--;
- offset = scan_swap_map(si);
+ /* This is called for allocating swap entry, not cache */
+ offset = scan_swap_map(si, SWAP_MAP);
if (offset) {
spin_unlock(&swap_lock);
return swp_entry(type, offset);
return (swp_entry_t) {0};
}
-static struct swap_info_struct * swap_info_get(swp_entry_t entry)
+static struct swap_info_struct *swap_info_get(swp_entry_t entry)
{
- struct swap_info_struct * p;
+ struct swap_info_struct *p;
unsigned long offset, type;
if (!entry.val)
type = swp_type(entry);
if (type >= nr_swapfiles)
goto bad_nofile;
- p = & swap_info[type];
+ p = swap_info[type];
if (!(p->flags & SWP_USED))
goto bad_device;
offset = swp_offset(entry);
return NULL;
}
-static int swap_entry_free(struct swap_info_struct *p, unsigned long offset)
+static int swap_entry_free(struct swap_info_struct *p,
+ swp_entry_t ent, int cache)
{
- 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;
- if (p->prio > swap_info[swap_list.next].prio)
- swap_list.next = p - swap_info;
- nr_swap_pages++;
- p->inuse_pages--;
+ unsigned long offset = swp_offset(ent);
+ int count = swap_count(p->swap_map[offset]);
+ bool has_cache;
+
+ has_cache = swap_has_cache(p->swap_map[offset]);
+
+ if (cache == SWAP_MAP) { /* dropping usage count of swap */
+ if (count < SWAP_MAP_MAX) {
+ count--;
+ p->swap_map[offset] = encode_swapmap(count, has_cache);
}
+ } else { /* dropping swap cache flag */
+ VM_BUG_ON(!has_cache);
+ p->swap_map[offset] = encode_swapmap(count, false);
+
+ }
+ /* return code. */
+ count = p->swap_map[offset];
+ /* free if no reference */
+ if (!count) {
+ if (offset < p->lowest_bit)
+ p->lowest_bit = offset;
+ if (offset > p->highest_bit)
+ p->highest_bit = offset;
+ if (swap_list.next >= 0 &&
+ p->prio > swap_info[swap_list.next]->prio)
+ swap_list.next = p->type;
+ nr_swap_pages++;
+ p->inuse_pages--;
}
+ if (!swap_count(count))
+ mem_cgroup_uncharge_swap(ent);
return count;
}
*/
void swap_free(swp_entry_t entry)
{
- struct swap_info_struct * p;
+ struct swap_info_struct *p;
p = swap_info_get(entry);
if (p) {
- swap_entry_free(p, swp_offset(entry));
+ swap_entry_free(p, entry, SWAP_MAP);
+ spin_unlock(&swap_lock);
+ }
+}
+
+/*
+ * Called after dropping swapcache to decrease refcnt to swap entries.
+ */
+void swapcache_free(swp_entry_t entry, struct page *page)
+{
+ struct swap_info_struct *p;
+ int ret;
+
+ p = swap_info_get(entry);
+ if (p) {
+ ret = swap_entry_free(p, entry, SWAP_CACHE);
+ if (page) {
+ bool swapout;
+ if (ret)
+ swapout = true; /* the end of swap out */
+ else
+ swapout = false; /* no more swap users! */
+ mem_cgroup_uncharge_swapcache(page, entry, swapout);
+ }
spin_unlock(&swap_lock);
}
}
entry.val = page_private(page);
p = swap_info_get(entry);
if (p) {
- /* Subtract the 1 for the swap cache itself */
- count = p->swap_map[swp_offset(entry)] - 1;
+ count = swap_count(p->swap_map[swp_offset(entry)]);
spin_unlock(&swap_lock);
}
return count;
struct swap_info_struct *p;
struct page *page = NULL;
- if (is_migration_entry(entry))
+ if (non_swap_entry(entry))
return 1;
p = swap_info_get(entry);
if (p) {
- if (swap_entry_free(p, swp_offset(entry)) == 1) {
+ if (swap_entry_free(p, entry, SWAP_MAP) == SWAP_HAS_CACHE) {
page = find_get_page(&swapper_space, entry.val);
if (page && !trylock_page(page)) {
page_cache_release(page);
int swap_type_of(dev_t device, sector_t offset, struct block_device **bdev_p)
{
struct block_device *bdev = NULL;
- int i;
+ int type;
if (device)
bdev = bdget(device);
spin_lock(&swap_lock);
- for (i = 0; i < nr_swapfiles; i++) {
- struct swap_info_struct *sis = swap_info + i;
+ for (type = 0; type < nr_swapfiles; type++) {
+ struct swap_info_struct *sis = swap_info[type];
if (!(sis->flags & SWP_WRITEOK))
continue;
if (!bdev) {
if (bdev_p)
- *bdev_p = sis->bdev;
+ *bdev_p = bdgrab(sis->bdev);
spin_unlock(&swap_lock);
- return i;
+ return type;
}
if (bdev == sis->bdev) {
- struct swap_extent *se;
+ struct swap_extent *se = &sis->first_swap_extent;
- se = list_entry(sis->extent_list.next,
- struct swap_extent, list);
if (se->start_block == offset) {
if (bdev_p)
- *bdev_p = sis->bdev;
+ *bdev_p = bdgrab(sis->bdev);
spin_unlock(&swap_lock);
bdput(bdev);
- return i;
+ return type;
}
}
}
}
/*
+ * Get the (PAGE_SIZE) block corresponding to given offset on the swapdev
+ * corresponding to given index in swap_info (swap type).
+ */
+sector_t swapdev_block(int type, pgoff_t offset)
+{
+ struct block_device *bdev;
+
+ if ((unsigned int)type >= nr_swapfiles)
+ return 0;
+ if (!(swap_info[type]->flags & SWP_WRITEOK))
+ return 0;
+ return map_swap_page(swp_entry(type, offset), &bdev);
+}
+
+/*
* Return either the total number of swap pages of given type, or the number
* of free pages of that type (depending on @free)
*
{
unsigned int n = 0;
- if (type < nr_swapfiles) {
- spin_lock(&swap_lock);
- if (swap_info[type].flags & SWP_WRITEOK) {
- n = swap_info[type].pages;
+ spin_lock(&swap_lock);
+ if ((unsigned int)type < nr_swapfiles) {
+ struct swap_info_struct *sis = swap_info[type];
+
+ if (sis->flags & SWP_WRITEOK) {
+ n = sis->pages;
if (free)
- n -= swap_info[type].inuse_pages;
+ n -= sis->inuse_pages;
}
- spin_unlock(&swap_lock);
}
+ spin_unlock(&swap_lock);
return n;
}
-#endif
+#endif /* CONFIG_HIBERNATION */
/*
* No need to decide whether this PTE shares the swap entry with others,
pte_t *pte;
int ret = 1;
- if (mem_cgroup_try_charge(vma->vm_mm, GFP_HIGHUSER_MOVABLE, &ptr))
+ if (mem_cgroup_try_charge_swapin(vma->vm_mm, page, GFP_KERNEL, &ptr)) {
ret = -ENOMEM;
+ goto out_nolock;
+ }
pte = pte_offset_map_lock(vma->vm_mm, pmd, addr, &ptl);
if (unlikely(!pte_same(*pte, swp_entry_to_pte(entry)))) {
activate_page(page);
out:
pte_unmap_unlock(pte, ptl);
+out_nolock:
return ret;
}
i = 1;
}
count = si->swap_map[i];
- if (count && count != SWAP_MAP_BAD)
+ if (count && swap_count(count) != SWAP_MAP_BAD)
break;
}
return i;
*/
static int try_to_unuse(unsigned int type)
{
- struct swap_info_struct * si = &swap_info[type];
+ struct swap_info_struct *si = swap_info[type];
struct mm_struct *start_mm;
unsigned short *swap_map;
unsigned short swcount;
*/
shmem = 0;
swcount = *swap_map;
- if (swcount > 1) {
+ if (swap_count(swcount)) {
if (start_mm == &init_mm)
shmem = shmem_unuse(entry, page);
else
retval = unuse_mm(start_mm, entry, page);
}
- if (*swap_map > 1) {
+ if (swap_count(*swap_map)) {
int set_start_mm = (*swap_map >= swcount);
struct list_head *p = &start_mm->mmlist;
struct mm_struct *new_start_mm = start_mm;
atomic_inc(&new_start_mm->mm_users);
atomic_inc(&prev_mm->mm_users);
spin_lock(&mmlist_lock);
- while (*swap_map > 1 && !retval && !shmem &&
+ while (swap_count(*swap_map) && !retval && !shmem &&
(p = p->next) != &start_mm->mmlist) {
mm = list_entry(p, struct mm_struct, mmlist);
if (!atomic_inc_not_zero(&mm->mm_users))
cond_resched();
swcount = *swap_map;
- if (swcount <= 1)
+ if (!swap_count(swcount)) /* any usage ? */
;
else if (mm == &init_mm) {
set_start_mm = 1;
shmem = shmem_unuse(entry, page);
} else
retval = unuse_mm(mm, entry, page);
+
if (set_start_mm && *swap_map < swcount) {
mmput(new_start_mm);
atomic_inc(&mm->mm_users);
}
/*
- * 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.
- *
+ * How could swap count reach 0x7ffe ?
+ * 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.(if occur, unsigned
+ * short is too small....)
* 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) {
+ /* We might release the lock_page() in unuse_mm(). */
+ if (!PageSwapCache(page) || page_private(page) != entry.val)
+ goto retry;
+
+ if (swap_count(*swap_map) == SWAP_MAP_MAX) {
spin_lock(&swap_lock);
- *swap_map = 1;
+ *swap_map = encode_swapmap(0, true);
spin_unlock(&swap_lock);
reset_overflow = 1;
}
* pages would be incorrect if swap supported "shared
* private" pages, but they are handled by tmpfs files.
*/
- if ((*swap_map > 1) && PageDirty(page) && PageSwapCache(page)) {
+ if (swap_count(*swap_map) &&
+ PageDirty(page) && PageSwapCache(page)) {
struct writeback_control wbc = {
.sync_mode = WB_SYNC_NONE,
};
* mark page dirty so shrink_page_list will preserve it.
*/
SetPageDirty(page);
+retry:
unlock_page(page);
page_cache_release(page);
static void drain_mmlist(void)
{
struct list_head *p, *next;
- unsigned int i;
+ unsigned int type;
- for (i = 0; i < nr_swapfiles; i++)
- if (swap_info[i].inuse_pages)
+ for (type = 0; type < nr_swapfiles; type++)
+ if (swap_info[type]->inuse_pages)
return;
spin_lock(&mmlist_lock);
list_for_each_safe(p, next, &init_mm.mmlist)
/*
* Use this swapdev's extent info to locate the (PAGE_SIZE) block which
- * corresponds to page offset `offset'.
+ * corresponds to page offset `offset'. Note that the type of this function
+ * is sector_t, but it returns page offset into the bdev, not sector offset.
*/
-sector_t map_swap_page(struct swap_info_struct *sis, pgoff_t offset)
+sector_t map_swap_page(swp_entry_t entry, struct block_device **bdev)
{
- struct swap_extent *se = sis->curr_swap_extent;
- struct swap_extent *start_se = se;
+ struct swap_info_struct *sis;
+ struct swap_extent *start_se;
+ struct swap_extent *se;
+ pgoff_t offset;
+
+ sis = swap_info[swp_type(entry)];
+ *bdev = sis->bdev;
+
+ offset = swp_offset(entry);
+ start_se = sis->curr_swap_extent;
+ se = start_se;
for ( ; ; ) {
struct list_head *lh;
return se->start_block + (offset - se->start_page);
}
lh = se->list.next;
- if (lh == &sis->extent_list)
- lh = lh->next;
se = list_entry(lh, struct swap_extent, list);
sis->curr_swap_extent = se;
BUG_ON(se == start_se); /* It *must* be present */
}
}
-#ifdef CONFIG_HIBERNATION
-/*
- * Get the (PAGE_SIZE) block corresponding to given offset on the swapdev
- * corresponding to given index in swap_info (swap type).
- */
-sector_t swapdev_block(int swap_type, pgoff_t offset)
-{
- struct swap_info_struct *sis;
-
- if (swap_type >= nr_swapfiles)
- return 0;
-
- sis = swap_info + swap_type;
- return (sis->flags & SWP_WRITEOK) ? map_swap_page(sis, offset) : 0;
-}
-#endif /* CONFIG_HIBERNATION */
-
/*
* Free all of a swapdev's extent information
*/
static void destroy_swap_extents(struct swap_info_struct *sis)
{
- while (!list_empty(&sis->extent_list)) {
+ while (!list_empty(&sis->first_swap_extent.list)) {
struct swap_extent *se;
- se = list_entry(sis->extent_list.next,
+ se = list_entry(sis->first_swap_extent.list.next,
struct swap_extent, list);
list_del(&se->list);
kfree(se);
struct swap_extent *new_se;
struct list_head *lh;
- lh = sis->extent_list.prev; /* The highest page extent */
- if (lh != &sis->extent_list) {
+ if (start_page == 0) {
+ se = &sis->first_swap_extent;
+ sis->curr_swap_extent = se;
+ se->start_page = 0;
+ se->nr_pages = nr_pages;
+ se->start_block = start_block;
+ return 1;
+ } else {
+ lh = sis->first_swap_extent.list.prev; /* Highest extent */
se = list_entry(lh, struct swap_extent, list);
BUG_ON(se->start_page + se->nr_pages != start_page);
if (se->start_block + se->nr_pages == start_block) {
new_se->nr_pages = nr_pages;
new_se->start_block = start_block;
- list_add_tail(&new_se->list, &sis->extent_list);
+ list_add_tail(&new_se->list, &sis->first_swap_extent.list);
return 1;
}
if (S_ISBLK(inode->i_mode)) {
ret = add_swap_extent(sis, 0, sis->max, 0);
*span = sis->pages;
- goto done;
+ goto out;
}
blkbits = inode->i_blkbits;
sis->max = page_no;
sis->pages = page_no - 1;
sis->highest_bit = page_no - 1;
-done:
- sis->curr_swap_extent = list_entry(sis->extent_list.prev,
- struct swap_extent, list);
- goto out;
+out:
+ return ret;
bad_bmap:
printk(KERN_ERR "swapon: swapfile has holes\n");
ret = -EINVAL;
-out:
- return ret;
+ goto out;
}
-asmlinkage long sys_swapoff(const char __user * specialfile)
+SYSCALL_DEFINE1(swapoff, const char __user *, specialfile)
{
- struct swap_info_struct * p = NULL;
+ struct swap_info_struct *p = NULL;
unsigned short *swap_map;
struct file *swap_file, *victim;
struct address_space *mapping;
struct inode *inode;
- char * pathname;
+ char *pathname;
int i, type, prev;
int err;
mapping = victim->f_mapping;
prev = -1;
spin_lock(&swap_lock);
- for (type = swap_list.head; type >= 0; type = swap_info[type].next) {
- p = swap_info + type;
+ for (type = swap_list.head; type >= 0; type = swap_info[type]->next) {
+ p = swap_info[type];
if (p->flags & SWP_WRITEOK) {
if (p->swap_file->f_mapping == mapping)
break;
spin_unlock(&swap_lock);
goto out_dput;
}
- if (prev < 0) {
+ if (prev < 0)
swap_list.head = p->next;
- } else {
- swap_info[prev].next = 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;
}
if (p->prio < 0) {
- for (i = p->next; i >= 0; i = swap_info[i].next)
- swap_info[i].prio = p->prio--;
+ for (i = p->next; i >= 0; i = swap_info[i]->next)
+ swap_info[i]->prio = p->prio--;
least_priority++;
}
nr_swap_pages -= p->pages;
p->flags &= ~SWP_WRITEOK;
spin_unlock(&swap_lock);
- current->flags |= PF_SWAPOFF;
+ current->flags |= PF_OOM_ORIGIN;
err = try_to_unuse(type);
- current->flags &= ~PF_SWAPOFF;
+ current->flags &= ~PF_OOM_ORIGIN;
if (err) {
/* re-insert swap space back into swap_list */
if (p->prio < 0)
p->prio = --least_priority;
prev = -1;
- for (i = swap_list.head; i >= 0; i = swap_info[i].next) {
- if (p->prio >= swap_info[i].prio)
+ 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;
+ swap_list.head = swap_list.next = type;
else
- swap_info[prev].next = p - swap_info;
+ swap_info[prev]->next = type;
nr_swap_pages += p->pages;
total_swap_pages += p->pages;
p->flags |= SWP_WRITEOK;
/* iterator */
static void *swap_start(struct seq_file *swap, loff_t *pos)
{
- struct swap_info_struct *ptr = swap_info;
- int i;
+ struct swap_info_struct *si;
+ int type;
loff_t l = *pos;
mutex_lock(&swapon_mutex);
if (!l)
return SEQ_START_TOKEN;
- for (i = 0; i < nr_swapfiles; i++, ptr++) {
- if (!(ptr->flags & SWP_USED) || !ptr->swap_map)
+ for (type = 0; type < nr_swapfiles; type++) {
+ smp_rmb(); /* read nr_swapfiles before swap_info[type] */
+ si = swap_info[type];
+ if (!(si->flags & SWP_USED) || !si->swap_map)
continue;
if (!--l)
- return ptr;
+ return si;
}
return NULL;
static void *swap_next(struct seq_file *swap, void *v, loff_t *pos)
{
- struct swap_info_struct *ptr;
- struct swap_info_struct *endptr = swap_info + nr_swapfiles;
+ struct swap_info_struct *si = v;
+ int type;
if (v == SEQ_START_TOKEN)
- ptr = swap_info;
- else {
- ptr = v;
- ptr++;
- }
+ type = 0;
+ else
+ type = si->type + 1;
- for (; ptr < endptr; ptr++) {
- if (!(ptr->flags & SWP_USED) || !ptr->swap_map)
+ for (; type < nr_swapfiles; type++) {
+ smp_rmb(); /* read nr_swapfiles before swap_info[type] */
+ si = swap_info[type];
+ if (!(si->flags & SWP_USED) || !si->swap_map)
continue;
++*pos;
- return ptr;
+ return si;
}
return NULL;
static int swap_show(struct seq_file *swap, void *v)
{
- struct swap_info_struct *ptr = v;
+ struct swap_info_struct *si = v;
struct file *file;
int len;
- if (ptr == SEQ_START_TOKEN) {
+ if (si == SEQ_START_TOKEN) {
seq_puts(swap,"Filename\t\t\t\tType\t\tSize\tUsed\tPriority\n");
return 0;
}
- file = ptr->swap_file;
+ file = si->swap_file;
len = seq_path(swap, &file->f_path, " \t\n\\");
seq_printf(swap, "%*s%s\t%u\t%u\t%d\n",
len < 40 ? 40 - len : 1, " ",
S_ISBLK(file->f_path.dentry->d_inode->i_mode) ?
"partition" : "file\t",
- ptr->pages << (PAGE_SHIFT - 10),
- ptr->inuse_pages << (PAGE_SHIFT - 10),
- ptr->prio);
+ si->pages << (PAGE_SHIFT - 10),
+ si->inuse_pages << (PAGE_SHIFT - 10),
+ si->prio);
return 0;
}
*
* The swapon system call
*/
-asmlinkage long sys_swapon(const char __user * specialfile, int swap_flags)
+SYSCALL_DEFINE2(swapon, const char __user *, specialfile, int, swap_flags)
{
- struct swap_info_struct * p;
+ struct swap_info_struct *p;
char *name = NULL;
struct block_device *bdev = NULL;
struct file *swap_file = NULL;
if (!capable(CAP_SYS_ADMIN))
return -EPERM;
+
+ p = kzalloc(sizeof(*p), GFP_KERNEL);
+ if (!p)
+ return -ENOMEM;
+
spin_lock(&swap_lock);
- p = swap_info;
- for (type = 0 ; type < nr_swapfiles ; type++,p++)
- if (!(p->flags & SWP_USED))
+ for (type = 0; type < nr_swapfiles; type++) {
+ if (!(swap_info[type]->flags & SWP_USED))
break;
+ }
error = -EPERM;
if (type >= MAX_SWAPFILES) {
spin_unlock(&swap_lock);
+ kfree(p);
goto out;
}
- if (type >= nr_swapfiles)
- nr_swapfiles = type+1;
- memset(p, 0, sizeof(*p));
- INIT_LIST_HEAD(&p->extent_list);
+ if (type >= nr_swapfiles) {
+ p->type = type;
+ swap_info[type] = p;
+ /*
+ * Write swap_info[type] before nr_swapfiles, in case a
+ * racing procfs swap_start() or swap_next() is reading them.
+ * (We never shrink nr_swapfiles, we never free this entry.)
+ */
+ smp_wmb();
+ nr_swapfiles++;
+ } else {
+ kfree(p);
+ p = swap_info[type];
+ /*
+ * Do not memset this entry: a racing procfs swap_next()
+ * would be relying on p->type to remain valid.
+ */
+ }
+ INIT_LIST_HEAD(&p->first_swap_extent.list);
p->flags = SWP_USED;
p->next = -1;
spin_unlock(&swap_lock);
+
name = getname(specialfile);
error = PTR_ERR(name);
if (IS_ERR(name)) {
error = -EBUSY;
for (i = 0; i < nr_swapfiles; i++) {
- struct swap_info_struct *q = &swap_info[i];
+ struct swap_info_struct *q = swap_info[i];
if (i == type || !q->swap_file)
continue;
p->lowest_bit = 1;
p->cluster_next = 1;
+ p->cluster_nr = 0;
/*
* Find out how many pages are allowed for a single swap
goto bad_swap;
}
- if (blk_queue_nonrot(bdev_get_queue(p->bdev))) {
- p->flags |= SWP_SOLIDSTATE;
- p->cluster_next = 1 + (random32() % p->highest_bit);
+ if (p->bdev) {
+ if (blk_queue_nonrot(bdev_get_queue(p->bdev))) {
+ p->flags |= SWP_SOLIDSTATE;
+ p->cluster_next = 1 + (random32() % p->highest_bit);
+ }
+ if (discard_swap(p) == 0)
+ p->flags |= SWP_DISCARDABLE;
}
- if (discard_swap(p) == 0)
- p->flags |= SWP_DISCARDABLE;
mutex_lock(&swapon_mutex);
spin_lock(&swap_lock);
/* 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) {
+ 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;
- }
+ if (prev < 0)
+ swap_list.head = swap_list.next = type;
+ else
+ swap_info[prev]->next = type;
spin_unlock(&swap_lock);
mutex_unlock(&swapon_mutex);
error = 0;
void si_swapinfo(struct sysinfo *val)
{
- unsigned int i;
+ unsigned int type;
unsigned long nr_to_be_unused = 0;
spin_lock(&swap_lock);
- for (i = 0; i < nr_swapfiles; i++) {
- if (!(swap_info[i].flags & SWP_USED) ||
- (swap_info[i].flags & SWP_WRITEOK))
- continue;
- nr_to_be_unused += swap_info[i].inuse_pages;
+ for (type = 0; type < nr_swapfiles; type++) {
+ struct swap_info_struct *si = swap_info[type];
+
+ if ((si->flags & SWP_USED) && !(si->flags & SWP_WRITEOK))
+ nr_to_be_unused += si->inuse_pages;
}
val->freeswap = nr_swap_pages + nr_to_be_unused;
val->totalswap = total_swap_pages + nr_to_be_unused;
*
* Note: if swap_map[] reaches SWAP_MAP_MAX the entries are treated as
* "permanent", but will be reclaimed by the next swapoff.
+ * Returns error code in following case.
+ * - success -> 0
+ * - swp_entry is invalid -> EINVAL
+ * - swp_entry is migration entry -> EINVAL
+ * - swap-cache reference is requested but there is already one. -> EEXIST
+ * - swap-cache reference is requested but the entry is not used. -> ENOENT
*/
-int swap_duplicate(swp_entry_t entry)
+static int __swap_duplicate(swp_entry_t entry, bool cache)
{
- struct swap_info_struct * p;
+ struct swap_info_struct *p;
unsigned long offset, type;
- int result = 0;
+ int result = -EINVAL;
+ int count;
+ bool has_cache;
- if (is_migration_entry(entry))
- return 1;
+ if (non_swap_entry(entry))
+ return -EINVAL;
type = swp_type(entry);
if (type >= nr_swapfiles)
goto bad_file;
- p = type + swap_info;
+ p = swap_info[type];
offset = swp_offset(entry);
spin_lock(&swap_lock);
- 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 (unlikely(offset >= p->max))
+ goto unlock_out;
+
+ count = swap_count(p->swap_map[offset]);
+ has_cache = swap_has_cache(p->swap_map[offset]);
+
+ if (cache == SWAP_CACHE) { /* called for swapcache/swapin-readahead */
+
+ /* set SWAP_HAS_CACHE if there is no cache and entry is used */
+ if (!has_cache && count) {
+ p->swap_map[offset] = encode_swapmap(count, true);
+ result = 0;
+ } else if (has_cache) /* someone added cache */
+ result = -EEXIST;
+ else if (!count) /* no users */
+ result = -ENOENT;
+
+ } else if (count || has_cache) {
+ if (count < SWAP_MAP_MAX - 1) {
+ p->swap_map[offset] = encode_swapmap(count + 1,
+ has_cache);
+ result = 0;
+ } else if (count <= 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;
+ printk(KERN_WARNING
+ "swap_dup: swap entry overflow\n");
+ p->swap_map[offset] = encode_swapmap(SWAP_MAP_MAX,
+ has_cache);
+ result = 0;
}
- }
+ } else
+ result = -ENOENT; /* unused swap entry */
+unlock_out:
spin_unlock(&swap_lock);
out:
return result;
printk(KERN_ERR "swap_dup: %s%08lx\n", Bad_file, entry.val);
goto out;
}
+/*
+ * increase reference count of swap entry by 1.
+ */
+void swap_duplicate(swp_entry_t entry)
+{
+ __swap_duplicate(entry, SWAP_MAP);
+}
-struct swap_info_struct *
-get_swap_info_struct(unsigned type)
+/*
+ * @entry: swap entry for which we allocate swap cache.
+ *
+ * Called when allocating swap cache for existing swap entry,
+ * This can return error codes. Returns 0 at success.
+ * -EBUSY means there is a swap cache.
+ * Note: return code is different from swap_duplicate().
+ */
+int swapcache_prepare(swp_entry_t entry)
{
- return &swap_info[type];
+ return __swap_duplicate(entry, SWAP_CACHE);
}
/*
if (!our_page_cluster) /* no readahead */
return 0;
- si = &swap_info[swp_type(entry)];
+ si = swap_info[swp_type(entry)];
target = swp_offset(entry);
base = (target >> our_page_cluster) << our_page_cluster;
end = base + (1 << our_page_cluster);
/* Don't read in free or bad pages */
if (!si->swap_map[toff])
break;
- if (si->swap_map[toff] == SWAP_MAP_BAD)
+ if (swap_count(si->swap_map[toff]) == SWAP_MAP_BAD)
break;
}
/* Count contiguous allocated slots below our target */
/* Don't read in free or bad pages */
if (!si->swap_map[toff])
break;
- if (si->swap_map[toff] == SWAP_MAP_BAD)
+ if (swap_count(si->swap_map[toff]) == SWAP_MAP_BAD)
break;
}
spin_unlock(&swap_lock);