diff --git a/include/linux/swap.h b/include/linux/swap.h
index 82aa7e121c05a6ac1b9c4780c3fde29012bfcf71..f1c248796fb8cec28734a1d4d9745a9dd8ce34fb 100644
--- a/include/linux/swap.h
+++ b/include/linux/swap.h
@@ -159,9 +159,10 @@ enum {
* The in-memory structure used to track swap areas.
*/
struct swap_info_struct {
- unsigned long flags;
- int prio; /* swap priority */
- int next; /* next entry on swap list */
+ unsigned long flags; /* SWP_USED etc: see above */
+ signed short prio; /* swap priority of this type */
+ signed char type; /* strange name for an index */
+ signed char next; /* next type on the swap list */
struct file *swap_file;
struct block_device *bdev;
struct list_head extent_list;
diff --git a/mm/swapfile.c b/mm/swapfile.c
index f83f1c6f6196490052426c1e46e3e2ce506565dc..dc88a7e4257ec529a9a4944b2cb06620276d1e2f 100644
--- a/mm/swapfile.c
+++ b/mm/swapfile.c
@@ -49,7 +49,7 @@ static const char Unused_offset[] = "Unused swap offset entry ";
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);
@@ -79,12 +79,11 @@ static inline unsigned short encode_swapmap(int count, bool has_cache)
return ret;
}
-/* returnes 1 if swap entry is freed */
+/* returns 1 if swap entry is freed */
static int
__try_to_reclaim_swap(struct swap_info_struct *si, unsigned long offset)
{
- int type = si - swap_info;
- swp_entry_t entry = swp_entry(type, offset);
+ swp_entry_t entry = swp_entry(si->type, offset);
struct page *page;
int ret = 0;
@@ -120,7 +119,7 @@ void swap_unplug_io_fn(struct backing_dev_info *unused_bdi, struct page *page)
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;
/*
@@ -467,10 +466,10 @@ swp_entry_t get_swap_page(void)
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++;
}
@@ -503,8 +502,8 @@ swp_entry_t get_swap_page_of_type(int type)
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--;
/* This is called for allocating swap entry, not cache */
offset = scan_swap_map(si, SWAP_MAP);
@@ -528,7 +527,7 @@ static struct swap_info_struct * swap_info_get(swp_entry_t entry)
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);
@@ -581,8 +580,9 @@ static int swap_entry_free(struct swap_info_struct *p,
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;
+ if (swap_list.next >= 0 &&
+ p->prio > swap_info[swap_list.next]->prio)
+ swap_list.next = p->type;
nr_swap_pages++;
p->inuse_pages--;
}
@@ -741,14 +741,14 @@ int free_swap_and_cache(swp_entry_t entry)
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;
@@ -758,7 +758,7 @@ int swap_type_of(dev_t device, sector_t offset, struct block_device **bdev_p)
*bdev_p = bdgrab(sis->bdev);
spin_unlock(&swap_lock);
- return i;
+ return type;
}
if (bdev == sis->bdev) {
struct swap_extent *se;
@@ -771,7 +771,7 @@ int swap_type_of(dev_t device, sector_t offset, struct block_device **bdev_p)
spin_unlock(&swap_lock);
bdput(bdev);
- return i;
+ return type;
}
}
}
@@ -792,15 +792,17 @@ unsigned int count_swap_pages(int type, int 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
@@ -1024,7 +1026,7 @@ static unsigned int find_next_to_unuse(struct swap_info_struct *si,
*/
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;
@@ -1270,10 +1272,10 @@ retry:
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)
@@ -1293,7 +1295,7 @@ sector_t map_swap_page(swp_entry_t entry, struct block_device **bdev)
struct swap_extent *se;
pgoff_t offset;
- sis = swap_info + swp_type(entry);
+ sis = swap_info[swp_type(entry)];
*bdev = sis->bdev;
offset = swp_offset(entry);
@@ -1321,17 +1323,15 @@ sector_t map_swap_page(swp_entry_t entry, struct block_device **bdev)
* 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)
+sector_t swapdev_block(int type, pgoff_t offset)
{
- struct swap_info_struct *sis;
struct block_device *bdev;
- if (swap_type >= nr_swapfiles)
+ if ((unsigned int)type >= nr_swapfiles)
return 0;
-
- sis = swap_info + swap_type;
- return (sis->flags & SWP_WRITEOK) ?
- map_swap_page(swp_entry(swap_type, offset), &bdev) : 0;
+ if (!(swap_info[type]->flags & SWP_WRITEOK))
+ return 0;
+ return map_swap_page(swp_entry(type, offset), &bdev);
}
#endif /* CONFIG_HIBERNATION */
@@ -1547,8 +1547,8 @@ SYSCALL_DEFINE1(swapoff, const char __user *, specialfile)
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;
@@ -1567,18 +1567,17 @@ SYSCALL_DEFINE1(swapoff, const char __user *, specialfile)
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;
@@ -1596,16 +1595,16 @@ SYSCALL_DEFINE1(swapoff, const char __user *, specialfile)
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;
@@ -1665,8 +1664,8 @@ out:
/* 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);
@@ -1674,11 +1673,13 @@ static void *swap_start(struct seq_file *swap, loff_t *pos)
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;
@@ -1686,21 +1687,21 @@ static void *swap_start(struct seq_file *swap, loff_t *pos)
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;
@@ -1713,24 +1714,24 @@ static void swap_stop(struct seq_file *swap, void *v)
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;
}
@@ -1798,23 +1799,45 @@ SYSCALL_DEFINE2(swapon, const char __user *, specialfile, int, swap_flags)
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.
+ */
+ }
p->flags = SWP_USED;
p->next = -1;
spin_unlock(&swap_lock);
+
name = getname(specialfile);
error = PTR_ERR(name);
if (IS_ERR(name)) {
@@ -1834,7 +1857,7 @@ SYSCALL_DEFINE2(swapon, const char __user *, specialfile, int, swap_flags)
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;
@@ -1909,6 +1932,7 @@ SYSCALL_DEFINE2(swapon, const char __user *, specialfile, int, swap_flags)
p->lowest_bit = 1;
p->cluster_next = 1;
+ p->cluster_nr = 0;
/*
* Find out how many pages are allowed for a single swap
@@ -2015,18 +2039,16 @@ SYSCALL_DEFINE2(swapon, const char __user *, specialfile, int, swap_flags)
/* 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;
@@ -2063,15 +2085,15 @@ out:
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;
@@ -2104,7 +2126,7 @@ static int __swap_duplicate(swp_entry_t entry, bool cache)
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);
@@ -2186,7 +2208,7 @@ int valid_swaphandles(swp_entry_t entry, unsigned long *offset)
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);