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Diffstat (limited to 'mm/swapfile.c')
-rw-r--r--mm/swapfile.c288
1 files changed, 250 insertions, 38 deletions
diff --git a/mm/swapfile.c b/mm/swapfile.c
index 6ef2d15c5fe3..d1fbeb486de5 100644
--- a/mm/swapfile.c
+++ b/mm/swapfile.c
@@ -184,6 +184,134 @@ static int wait_for_discard(void *word)
#define SWAPFILE_CLUSTER 256
#define LATENCY_LIMIT 256
+static inline void cluster_set_flag(struct swap_cluster_info *info,
+ unsigned int flag)
+{
+ info->flags = flag;
+}
+
+static inline unsigned int cluster_count(struct swap_cluster_info *info)
+{
+ return info->data;
+}
+
+static inline void cluster_set_count(struct swap_cluster_info *info,
+ unsigned int c)
+{
+ info->data = c;
+}
+
+static inline void cluster_set_count_flag(struct swap_cluster_info *info,
+ unsigned int c, unsigned int f)
+{
+ info->flags = f;
+ info->data = c;
+}
+
+static inline unsigned int cluster_next(struct swap_cluster_info *info)
+{
+ return info->data;
+}
+
+static inline void cluster_set_next(struct swap_cluster_info *info,
+ unsigned int n)
+{
+ info->data = n;
+}
+
+static inline void cluster_set_next_flag(struct swap_cluster_info *info,
+ unsigned int n, unsigned int f)
+{
+ info->flags = f;
+ info->data = n;
+}
+
+static inline bool cluster_is_free(struct swap_cluster_info *info)
+{
+ return info->flags & CLUSTER_FLAG_FREE;
+}
+
+static inline bool cluster_is_null(struct swap_cluster_info *info)
+{
+ return info->flags & CLUSTER_FLAG_NEXT_NULL;
+}
+
+static inline void cluster_set_null(struct swap_cluster_info *info)
+{
+ info->flags = CLUSTER_FLAG_NEXT_NULL;
+ info->data = 0;
+}
+
+/*
+ * The cluster corresponding to page_nr will be used. The cluster will be
+ * removed from free cluster list and its usage counter will be increased.
+ */
+static void inc_cluster_info_page(struct swap_info_struct *p,
+ struct swap_cluster_info *cluster_info, unsigned long page_nr)
+{
+ unsigned long idx = page_nr / SWAPFILE_CLUSTER;
+
+ if (!cluster_info)
+ return;
+ if (cluster_is_free(&cluster_info[idx])) {
+ VM_BUG_ON(cluster_next(&p->free_cluster_head) != idx);
+ cluster_set_next_flag(&p->free_cluster_head,
+ cluster_next(&cluster_info[idx]), 0);
+ if (cluster_next(&p->free_cluster_tail) == idx) {
+ cluster_set_null(&p->free_cluster_tail);
+ cluster_set_null(&p->free_cluster_head);
+ }
+ cluster_set_count_flag(&cluster_info[idx], 0, 0);
+ }
+
+ VM_BUG_ON(cluster_count(&cluster_info[idx]) >= SWAPFILE_CLUSTER);
+ cluster_set_count(&cluster_info[idx],
+ cluster_count(&cluster_info[idx]) + 1);
+}
+
+/*
+ * The cluster corresponding to page_nr decreases one usage. If the usage
+ * counter becomes 0, which means no page in the cluster is in using, we can
+ * optionally discard the cluster and add it to free cluster list.
+ */
+static void dec_cluster_info_page(struct swap_info_struct *p,
+ struct swap_cluster_info *cluster_info, unsigned long page_nr)
+{
+ unsigned long idx = page_nr / SWAPFILE_CLUSTER;
+
+ if (!cluster_info)
+ return;
+
+ VM_BUG_ON(cluster_count(&cluster_info[idx]) == 0);
+ cluster_set_count(&cluster_info[idx],
+ cluster_count(&cluster_info[idx]) - 1);
+
+ if (cluster_count(&cluster_info[idx]) == 0) {
+ cluster_set_flag(&cluster_info[idx], CLUSTER_FLAG_FREE);
+ if (cluster_is_null(&p->free_cluster_head)) {
+ cluster_set_next_flag(&p->free_cluster_head, idx, 0);
+ cluster_set_next_flag(&p->free_cluster_tail, idx, 0);
+ } else {
+ unsigned int tail = cluster_next(&p->free_cluster_tail);
+ cluster_set_next(&cluster_info[tail], idx);
+ cluster_set_next_flag(&p->free_cluster_tail, idx, 0);
+ }
+ }
+}
+
+/*
+ * It's possible scan_swap_map() uses a free cluster in the middle of free
+ * cluster list. Avoiding such abuse to avoid list corruption.
+ */
+static inline bool scan_swap_map_recheck_cluster(struct swap_info_struct *si,
+ unsigned long offset)
+{
+ offset /= SWAPFILE_CLUSTER;
+ return !cluster_is_null(&si->free_cluster_head) &&
+ offset != cluster_next(&si->free_cluster_head) &&
+ cluster_is_free(&si->cluster_info[offset]);
+}
+
static unsigned long scan_swap_map(struct swap_info_struct *si,
unsigned char usage)
{
@@ -225,6 +353,25 @@ static unsigned long scan_swap_map(struct swap_info_struct *si,
si->lowest_alloc = si->max;
si->highest_alloc = 0;
}
+check_cluster:
+ if (!cluster_is_null(&si->free_cluster_head)) {
+ offset = cluster_next(&si->free_cluster_head) *
+ SWAPFILE_CLUSTER;
+ last_in_cluster = offset + SWAPFILE_CLUSTER - 1;
+ si->cluster_next = offset;
+ si->cluster_nr = SWAPFILE_CLUSTER - 1;
+ found_free_cluster = 1;
+ goto checks;
+ } else if (si->cluster_info) {
+ /*
+ * Checking free cluster is fast enough, we can do the
+ * check every time
+ */
+ si->cluster_nr = 0;
+ si->lowest_alloc = 0;
+ goto checks;
+ }
+
spin_unlock(&si->lock);
/*
@@ -285,6 +432,8 @@ static unsigned long scan_swap_map(struct swap_info_struct *si,
}
checks:
+ if (scan_swap_map_recheck_cluster(si, offset))
+ goto check_cluster;
if (!(si->flags & SWP_WRITEOK))
goto no_page;
if (!si->highest_bit)
@@ -317,6 +466,7 @@ checks:
si->highest_bit = 0;
}
si->swap_map[offset] = usage;
+ inc_cluster_info_page(si, si->cluster_info, offset);
si->cluster_next = offset + 1;
si->flags -= SWP_SCANNING;
@@ -600,6 +750,7 @@ static unsigned char swap_entry_free(struct swap_info_struct *p,
/* free if no reference */
if (!usage) {
+ dec_cluster_info_page(p, p->cluster_info, offset);
if (offset < p->lowest_bit)
p->lowest_bit = offset;
if (offset > p->highest_bit)
@@ -1524,7 +1675,8 @@ static int setup_swap_extents(struct swap_info_struct *sis, sector_t *span)
}
static void _enable_swap_info(struct swap_info_struct *p, int prio,
- unsigned char *swap_map)
+ unsigned char *swap_map,
+ struct swap_cluster_info *cluster_info)
{
int i, prev;
@@ -1533,6 +1685,7 @@ static void _enable_swap_info(struct swap_info_struct *p, int prio,
else
p->prio = --least_priority;
p->swap_map = swap_map;
+ p->cluster_info = cluster_info;
p->flags |= SWP_WRITEOK;
atomic_long_add(p->pages, &nr_swap_pages);
total_swap_pages += p->pages;
@@ -1553,12 +1706,13 @@ static void _enable_swap_info(struct swap_info_struct *p, int prio,
static void enable_swap_info(struct swap_info_struct *p, int prio,
unsigned char *swap_map,
+ struct swap_cluster_info *cluster_info,
unsigned long *frontswap_map)
{
frontswap_init(p->type, frontswap_map);
spin_lock(&swap_lock);
spin_lock(&p->lock);
- _enable_swap_info(p, prio, swap_map);
+ _enable_swap_info(p, prio, swap_map, cluster_info);
spin_unlock(&p->lock);
spin_unlock(&swap_lock);
}
@@ -1567,7 +1721,7 @@ static void reinsert_swap_info(struct swap_info_struct *p)
{
spin_lock(&swap_lock);
spin_lock(&p->lock);
- _enable_swap_info(p, p->prio, p->swap_map);
+ _enable_swap_info(p, p->prio, p->swap_map, p->cluster_info);
spin_unlock(&p->lock);
spin_unlock(&swap_lock);
}
@@ -1576,6 +1730,7 @@ SYSCALL_DEFINE1(swapoff, const char __user *, specialfile)
{
struct swap_info_struct *p = NULL;
unsigned char *swap_map;
+ struct swap_cluster_info *cluster_info;
unsigned long *frontswap_map;
struct file *swap_file, *victim;
struct address_space *mapping;
@@ -1675,6 +1830,8 @@ SYSCALL_DEFINE1(swapoff, const char __user *, specialfile)
p->max = 0;
swap_map = p->swap_map;
p->swap_map = NULL;
+ cluster_info = p->cluster_info;
+ p->cluster_info = NULL;
p->flags = 0;
frontswap_map = frontswap_map_get(p);
frontswap_map_set(p, NULL);
@@ -1683,6 +1840,7 @@ SYSCALL_DEFINE1(swapoff, const char __user *, specialfile)
frontswap_invalidate_area(type);
mutex_unlock(&swapon_mutex);
vfree(swap_map);
+ vfree(cluster_info);
vfree(frontswap_map);
/* Destroy swap account informatin */
swap_cgroup_swapoff(type);
@@ -2000,15 +2158,21 @@ static unsigned long read_swap_header(struct swap_info_struct *p,
static int setup_swap_map_and_extents(struct swap_info_struct *p,
union swap_header *swap_header,
unsigned char *swap_map,
+ struct swap_cluster_info *cluster_info,
unsigned long maxpages,
sector_t *span)
{
int i;
unsigned int nr_good_pages;
int nr_extents;
+ unsigned long nr_clusters = DIV_ROUND_UP(maxpages, SWAPFILE_CLUSTER);
+ unsigned long idx = p->cluster_next / SWAPFILE_CLUSTER;
nr_good_pages = maxpages - 1; /* omit header page */
+ cluster_set_null(&p->free_cluster_head);
+ cluster_set_null(&p->free_cluster_tail);
+
for (i = 0; i < swap_header->info.nr_badpages; i++) {
unsigned int page_nr = swap_header->info.badpages[i];
if (page_nr == 0 || page_nr > swap_header->info.last_page)
@@ -2016,11 +2180,25 @@ static int setup_swap_map_and_extents(struct swap_info_struct *p,
if (page_nr < maxpages) {
swap_map[page_nr] = SWAP_MAP_BAD;
nr_good_pages--;
+ /*
+ * Haven't marked the cluster free yet, no list
+ * operation involved
+ */
+ inc_cluster_info_page(p, cluster_info, page_nr);
}
}
+ /* Haven't marked the cluster free yet, no list operation involved */
+ for (i = maxpages; i < round_up(maxpages, SWAPFILE_CLUSTER); i++)
+ inc_cluster_info_page(p, cluster_info, i);
+
if (nr_good_pages) {
swap_map[0] = SWAP_MAP_BAD;
+ /*
+ * Not mark the cluster free yet, no list
+ * operation involved
+ */
+ inc_cluster_info_page(p, cluster_info, 0);
p->max = maxpages;
p->pages = nr_good_pages;
nr_extents = setup_swap_extents(p, span);
@@ -2033,6 +2211,30 @@ static int setup_swap_map_and_extents(struct swap_info_struct *p,
return -EINVAL;
}
+ if (!cluster_info)
+ return nr_extents;
+
+ for (i = 0; i < nr_clusters; i++) {
+ if (!cluster_count(&cluster_info[idx])) {
+ cluster_set_flag(&cluster_info[idx], CLUSTER_FLAG_FREE);
+ if (cluster_is_null(&p->free_cluster_head)) {
+ cluster_set_next_flag(&p->free_cluster_head,
+ idx, 0);
+ cluster_set_next_flag(&p->free_cluster_tail,
+ idx, 0);
+ } else {
+ unsigned int tail;
+
+ tail = cluster_next(&p->free_cluster_tail);
+ cluster_set_next(&cluster_info[tail], idx);
+ cluster_set_next_flag(&p->free_cluster_tail,
+ idx, 0);
+ }
+ }
+ idx++;
+ if (idx == nr_clusters)
+ idx = 0;
+ }
return nr_extents;
}
@@ -2064,6 +2266,7 @@ SYSCALL_DEFINE2(swapon, const char __user *, specialfile, int, swap_flags)
sector_t span;
unsigned long maxpages;
unsigned char *swap_map = NULL;
+ struct swap_cluster_info *cluster_info = NULL;
unsigned long *frontswap_map = NULL;
struct page *page = NULL;
struct inode *inode = NULL;
@@ -2137,13 +2340,28 @@ SYSCALL_DEFINE2(swapon, const char __user *, specialfile, int, swap_flags)
error = -ENOMEM;
goto bad_swap;
}
+ if (p->bdev && blk_queue_nonrot(bdev_get_queue(p->bdev))) {
+ p->flags |= SWP_SOLIDSTATE;
+ /*
+ * select a random position to start with to help wear leveling
+ * SSD
+ */
+ p->cluster_next = 1 + (prandom_u32() % p->highest_bit);
+
+ cluster_info = vzalloc(DIV_ROUND_UP(maxpages,
+ SWAPFILE_CLUSTER) * sizeof(*cluster_info));
+ if (!cluster_info) {
+ error = -ENOMEM;
+ goto bad_swap;
+ }
+ }
error = swap_cgroup_swapon(p->type, maxpages);
if (error)
goto bad_swap;
nr_extents = setup_swap_map_and_extents(p, swap_header, swap_map,
- maxpages, &span);
+ cluster_info, maxpages, &span);
if (unlikely(nr_extents < 0)) {
error = nr_extents;
goto bad_swap;
@@ -2152,40 +2370,33 @@ SYSCALL_DEFINE2(swapon, const char __user *, specialfile, int, swap_flags)
if (frontswap_enabled)
frontswap_map = vzalloc(BITS_TO_LONGS(maxpages) * sizeof(long));
- if (p->bdev) {
- if (blk_queue_nonrot(bdev_get_queue(p->bdev))) {
- p->flags |= SWP_SOLIDSTATE;
- p->cluster_next = 1 + (prandom_u32() % p->highest_bit);
- }
-
- if ((swap_flags & SWAP_FLAG_DISCARD) && swap_discardable(p)) {
- /*
- * When discard is enabled for swap with no particular
- * policy flagged, we set all swap discard flags here in
- * order to sustain backward compatibility with older
- * swapon(8) releases.
- */
- p->flags |= (SWP_DISCARDABLE | SWP_AREA_DISCARD |
- SWP_PAGE_DISCARD);
+ if (p->bdev &&(swap_flags & SWAP_FLAG_DISCARD) && swap_discardable(p)) {
+ /*
+ * When discard is enabled for swap with no particular
+ * policy flagged, we set all swap discard flags here in
+ * order to sustain backward compatibility with older
+ * swapon(8) releases.
+ */
+ p->flags |= (SWP_DISCARDABLE | SWP_AREA_DISCARD |
+ SWP_PAGE_DISCARD);
- /*
- * By flagging sys_swapon, a sysadmin can tell us to
- * either do single-time area discards only, or to just
- * perform discards for released swap page-clusters.
- * Now it's time to adjust the p->flags accordingly.
- */
- if (swap_flags & SWAP_FLAG_DISCARD_ONCE)
- p->flags &= ~SWP_PAGE_DISCARD;
- else if (swap_flags & SWAP_FLAG_DISCARD_PAGES)
- p->flags &= ~SWP_AREA_DISCARD;
-
- /* issue a swapon-time discard if it's still required */
- if (p->flags & SWP_AREA_DISCARD) {
- int err = discard_swap(p);
- if (unlikely(err))
- pr_err("swapon: discard_swap(%p): %d\n",
- p, err);
- }
+ /*
+ * By flagging sys_swapon, a sysadmin can tell us to
+ * either do single-time area discards only, or to just
+ * perform discards for released swap page-clusters.
+ * Now it's time to adjust the p->flags accordingly.
+ */
+ if (swap_flags & SWAP_FLAG_DISCARD_ONCE)
+ p->flags &= ~SWP_PAGE_DISCARD;
+ else if (swap_flags & SWAP_FLAG_DISCARD_PAGES)
+ p->flags &= ~SWP_AREA_DISCARD;
+
+ /* issue a swapon-time discard if it's still required */
+ if (p->flags & SWP_AREA_DISCARD) {
+ int err = discard_swap(p);
+ if (unlikely(err))
+ pr_err("swapon: discard_swap(%p): %d\n",
+ p, err);
}
}
@@ -2194,7 +2405,7 @@ SYSCALL_DEFINE2(swapon, const char __user *, specialfile, int, swap_flags)
if (swap_flags & SWAP_FLAG_PREFER)
prio =
(swap_flags & SWAP_FLAG_PRIO_MASK) >> SWAP_FLAG_PRIO_SHIFT;
- enable_swap_info(p, prio, swap_map, frontswap_map);
+ enable_swap_info(p, prio, swap_map, cluster_info, frontswap_map);
pr_info("Adding %uk swap on %s. "
"Priority:%d extents:%d across:%lluk %s%s%s%s%s\n",
@@ -2226,6 +2437,7 @@ bad_swap:
p->flags = 0;
spin_unlock(&swap_lock);
vfree(swap_map);
+ vfree(cluster_info);
if (swap_file) {
if (inode && S_ISREG(inode->i_mode)) {
mutex_unlock(&inode->i_mutex);
generated by cgit v1.2.3-58-ga151 (git 2.39.0) at 2024-12-12 19:54:29 +0000