*/
static DECLARE_RWSEM(swap_unplug_sem);
-#define SWAPFILE_CLUSTER 256
-
void swap_unplug_io_fn(struct backing_dev_info *unused_bdi, struct page *page)
{
swp_entry_t entry;
up_read(&swap_unplug_sem);
}
-static inline int scan_swap_map(struct swap_info_struct *si)
+#define SWAPFILE_CLUSTER 256
+#define LATENCY_LIMIT 256
+
+static inline unsigned long scan_swap_map(struct swap_info_struct *si)
{
- unsigned long offset;
+ unsigned long offset, last_in_cluster;
+ int latency_ration = LATENCY_LIMIT;
+
/*
- * 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++;
+ * 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
+ * But we do now try to find an empty cluster. -Andrea
+ */
+
+ si->flags += SWP_SCANNING;
+ if (unlikely(!si->cluster_nr)) {
+ si->cluster_nr = SWAPFILE_CLUSTER - 1;
+ if (si->pages - si->inuse_pages < SWAPFILE_CLUSTER)
+ goto lowest;
+ swap_device_unlock(si);
+
+ offset = si->lowest_bit;
+ last_in_cluster = offset + SWAPFILE_CLUSTER - 1;
+
+ /* Locate the first empty (unaligned) cluster */
+ for (; last_in_cluster <= si->highest_bit; offset++) {
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)
- {
- unsigned long nr;
- for (nr = offset; nr < offset+SWAPFILE_CLUSTER; nr++)
- if (si->swap_map[nr])
- {
- offset = nr+1;
- goto check_next_cluster;
+ last_in_cluster = offset + SWAPFILE_CLUSTER;
+ else if (offset == last_in_cluster) {
+ swap_device_lock(si);
+ si->cluster_next = offset-SWAPFILE_CLUSTER-1;
+ goto cluster;
}
- /* We found a completly empty cluster, so start
- * using it.
- */
- goto got_page;
+ if (unlikely(--latency_ration < 0)) {
+ cond_resched();
+ latency_ration = LATENCY_LIMIT;
+ }
+ }
+ swap_device_lock(si);
+ goto lowest;
}
- /* 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:
+
+ si->cluster_nr--;
+cluster:
+ offset = si->cluster_next;
+ if (offset > si->highest_bit)
+lowest: offset = si->lowest_bit;
+checks: if (!(si->flags & SWP_WRITEOK))
+ goto no_page;
+ if (!si->highest_bit)
+ goto no_page;
+ if (!si->swap_map[offset]) {
if (offset == si->lowest_bit)
si->lowest_bit++;
if (offset == si->highest_bit)
si->highest_bit--;
- if (si->lowest_bit > si->highest_bit) {
+ si->inuse_pages++;
+ if (si->inuse_pages == si->pages) {
si->lowest_bit = si->max;
si->highest_bit = 0;
}
si->swap_map[offset] = 1;
- si->inuse_pages++;
- nr_swap_pages--;
- si->cluster_next = offset+1;
+ si->cluster_next = offset + 1;
+ si->flags -= SWP_SCANNING;
return offset;
}
- si->lowest_bit = si->max;
- si->highest_bit = 0;
+
+ swap_device_unlock(si);
+ while (++offset <= si->highest_bit) {
+ if (!si->swap_map[offset]) {
+ swap_device_lock(si);
+ goto checks;
+ }
+ if (unlikely(--latency_ration < 0)) {
+ cond_resched();
+ latency_ration = LATENCY_LIMIT;
+ }
+ }
+ swap_device_lock(si);
+ goto lowest;
+
+no_page:
+ si->flags -= SWP_SCANNING;
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;
+ struct swap_info_struct *si;
+ pgoff_t offset;
+ int type, next;
+ int 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_ACTIVE) == SWP_ACTIVE) {
- 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;
- }
+ goto noswap;
+ nr_swap_pages--;
+
+ for (type = swap_list.next; type >= 0 && wrapped < 2; type = next) {
+ si = swap_info + type;
+ next = si->next;
+ if (next < 0 ||
+ (!wrapped && si->prio != swap_info[next].prio)) {
+ next = swap_list.head;
+ wrapped++;
}
- 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 */
+
+ if (!si->highest_bit)
+ continue;
+ if (!(si->flags & SWP_WRITEOK))
+ continue;
+
+ swap_list.next = next;
+ swap_device_lock(si);
+ swap_list_unlock();
+ offset = scan_swap_map(si);
+ swap_device_unlock(si);
+ if (offset)
+ return swp_entry(type, offset);
+ swap_list_lock();
+ next = swap_list.next;
}
-out:
+
+ nr_swap_pages++;
+noswap:
swap_list_unlock();
- return entry;
+ return (swp_entry_t) {0};
}
static struct swap_info_struct * swap_info_get(swp_entry_t entry)
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;
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--;
}
* 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)
+static unsigned int find_next_to_unuse(struct swap_info_struct *si,
+ unsigned int prev)
{
- int max = si->max;
- int i = prev;
+ unsigned int max = si->max;
+ unsigned int i = prev;
int count;
/*
unsigned short swcount;
struct page *page;
swp_entry_t entry;
- int i = 0;
+ unsigned int i = 0;
int retval = 0;
int reset_overflow = 0;
int shmem;
offset < (se->start_page + se->nr_pages)) {
return se->start_block + (offset - se->start_page);
}
- lh = se->list.prev;
+ lh = se->list.next;
if (lh == &sis->extent_list)
- lh = lh->prev;
+ 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 */
list_del(&se->list);
kfree(se);
}
- sis->nr_extents = 0;
}
/*
* Add a block range (and the corresponding page range) into this swapdev's
- * extent list. The extent list is kept sorted in block order.
+ * extent list. The extent list is kept sorted in page order.
*
- * This function rather assumes that it is called in ascending sector_t order.
- * It doesn't look for extent coalescing opportunities.
+ * This function rather assumes that it is called in ascending page order.
*/
static int
add_swap_extent(struct swap_info_struct *sis, unsigned long start_page,
struct swap_extent *new_se;
struct list_head *lh;
- lh = sis->extent_list.next; /* The highest-addressed block */
- while (lh != &sis->extent_list) {
+ lh = sis->extent_list.prev; /* The highest page extent */
+ if (lh != &sis->extent_list) {
se = list_entry(lh, struct swap_extent, list);
- if (se->start_block + se->nr_pages == start_block &&
- se->start_page + se->nr_pages == start_page) {
+ BUG_ON(se->start_page + se->nr_pages != start_page);
+ if (se->start_block + se->nr_pages == start_block) {
/* Merge it */
se->nr_pages += nr_pages;
return 0;
}
- lh = lh->next;
}
/*
new_se->nr_pages = nr_pages;
new_se->start_block = start_block;
- lh = sis->extent_list.prev; /* The lowest block */
- while (lh != &sis->extent_list) {
- se = list_entry(lh, struct swap_extent, list);
- if (se->start_block > start_block)
- break;
- lh = lh->prev;
- }
- list_add_tail(&new_se->list, lh);
- sis->nr_extents++;
- return 0;
+ list_add_tail(&new_se->list, &sis->extent_list);
+ return 1;
}
/*
* requirements, they are simply tossed out - we will never use those blocks
* for swapping.
*
- * For S_ISREG swapfiles we hold i_sem across the life of the swapon. This
+ * For S_ISREG swapfiles we set S_SWAPFILE across the life of the swapon. This
* prevents root from shooting her foot off by ftruncating an in-use swapfile,
* which will scribble on the fs.
*
* This is extremely effective. The average number of iterations in
* map_swap_page() has been measured at about 0.3 per page. - akpm.
*/
-static int setup_swap_extents(struct swap_info_struct *sis)
+static int setup_swap_extents(struct swap_info_struct *sis, sector_t *span)
{
struct inode *inode;
unsigned blocks_per_page;
unsigned blkbits;
sector_t probe_block;
sector_t last_block;
+ sector_t lowest_block = -1;
+ sector_t highest_block = 0;
+ int nr_extents = 0;
int ret;
inode = sis->swap_file->f_mapping->host;
if (S_ISBLK(inode->i_mode)) {
ret = add_swap_extent(sis, 0, sis->max, 0);
+ *span = sis->pages;
goto done;
}
}
}
+ first_block >>= (PAGE_SHIFT - blkbits);
+ if (page_no) { /* exclude the header page */
+ if (first_block < lowest_block)
+ lowest_block = first_block;
+ if (first_block > highest_block)
+ highest_block = first_block;
+ }
+
/*
* We found a PAGE_SIZE-length, PAGE_SIZE-aligned run of blocks
*/
- ret = add_swap_extent(sis, page_no, 1,
- first_block >> (PAGE_SHIFT - blkbits));
- if (ret)
+ ret = add_swap_extent(sis, page_no, 1, first_block);
+ if (ret < 0)
goto out;
+ nr_extents += ret;
page_no++;
probe_block += blocks_per_page;
reprobe:
continue;
}
- ret = 0;
+ ret = nr_extents;
+ *span = 1 + highest_block - lowest_block;
if (page_no == 0)
- ret = -EINVAL;
+ page_no = 1; /* force Empty message */
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,
}
nr_swap_pages -= p->pages;
total_swap_pages -= p->pages;
+ swap_device_lock(p);
p->flags &= ~SWP_WRITEOK;
+ swap_device_unlock(p);
swap_list_unlock();
+
current->flags |= PF_SWAPOFF;
err = try_to_unuse(type);
current->flags &= ~PF_SWAPOFF;
- /* wait for any unplug function to finish */
- down_write(&swap_unplug_sem);
- up_write(&swap_unplug_sem);
-
if (err) {
/* re-insert swap space back into swap_list */
swap_list_lock();
swap_info[prev].next = p - swap_info;
nr_swap_pages += p->pages;
total_swap_pages += p->pages;
+ swap_device_lock(p);
p->flags |= SWP_WRITEOK;
+ swap_device_unlock(p);
swap_list_unlock();
goto out_dput;
}
+
+ /* wait for any unplug function to finish */
+ down_write(&swap_unplug_sem);
+ up_write(&swap_unplug_sem);
+
+ /* wait for anyone still in scan_swap_map */
+ swap_device_lock(p);
+ p->highest_bit = 0; /* cuts scans short */
+ while (p->flags >= SWP_SCANNING) {
+ swap_device_unlock(p);
+ set_current_state(TASK_UNINTERRUPTIBLE);
+ schedule_timeout(1);
+ swap_device_lock(p);
+ }
+ swap_device_unlock(p);
+
+ destroy_swap_extents(p);
down(&swapon_sem);
swap_list_lock();
drain_mmlist();
swap_map = p->swap_map;
p->swap_map = NULL;
p->flags = 0;
- destroy_swap_extents(p);
swap_device_unlock(p);
swap_list_unlock();
up(&swapon_sem);
file = ptr->swap_file;
len = seq_path(swap, file->f_vfsmnt, file->f_dentry, " \t\n\\");
- seq_printf(swap, "%*s%s\t%d\t%ld\t%d\n",
+ seq_printf(swap, "%*s%s\t%u\t%u\t%d\n",
len < 40 ? 40 - len : 1, " ",
S_ISBLK(file->f_dentry->d_inode->i_mode) ?
"partition" : "file\t",
static int least_priority;
union swap_header *swap_header = NULL;
int swap_header_version;
- int nr_good_pages = 0;
+ unsigned int nr_good_pages = 0;
+ int nr_extents = 0;
+ sector_t span;
unsigned long maxpages = 1;
int swapfilesize;
unsigned short *swap_map;
nr_swapfiles = type+1;
INIT_LIST_HEAD(&p->extent_list);
p->flags = SWP_USED;
- p->nr_extents = 0;
p->swap_file = NULL;
p->old_block_size = 0;
p->swap_map = NULL;
}
p->lowest_bit = 1;
+ p->cluster_next = 1;
+
/*
* Find out how many pages are allowed for a single swap
* device. There are two limiting factors: 1) the number of
p->highest_bit = maxpages - 1;
error = -EINVAL;
+ if (!maxpages)
+ goto bad_swap;
+ if (swap_header->info.nr_badpages && S_ISREG(inode->i_mode))
+ goto bad_swap;
if (swap_header->info.nr_badpages > MAX_SWAP_BADPAGES)
goto bad_swap;
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) {
+ p->swap_map[0] = SWAP_MAP_BAD;
+ p->max = maxpages;
+ p->pages = nr_good_pages;
+ nr_extents = setup_swap_extents(p, &span);
+ if (nr_extents < 0) {
+ error = nr_extents;
+ goto bad_swap;
+ }
+ nr_good_pages = p->pages;
+ }
if (!nr_good_pages) {
printk(KERN_WARNING "Empty swap-file\n");
error = -EINVAL;
goto bad_swap;
}
- p->swap_map[0] = SWAP_MAP_BAD;
- p->max = maxpages;
- p->pages = nr_good_pages;
-
- error = setup_swap_extents(p);
- if (error)
- goto bad_swap;
down(&swapon_sem);
swap_list_lock();
p->flags = SWP_ACTIVE;
nr_swap_pages += nr_good_pages;
total_swap_pages += nr_good_pages;
- printk(KERN_INFO "Adding %dk swap on %s. Priority:%d extents:%d\n",
- nr_good_pages<<(PAGE_SHIFT-10), name,
- p->prio, p->nr_extents);
+
+ printk(KERN_INFO "Adding %uk swap on %s. "
+ "Priority:%d extents:%d across:%lluk\n",
+ nr_good_pages<<(PAGE_SHIFT-10), name, p->prio,
+ nr_extents, (unsigned long long)span<<(PAGE_SHIFT-10));
/* insert swap space into swap_list: */
prev = -1;
set_blocksize(bdev, p->old_block_size);
bd_release(bdev);
}
+ destroy_swap_extents(p);
bad_swap_2:
swap_list_lock();
swap_map = p->swap_map;
if (!(swap_flags & SWAP_FLAG_PREFER))
++least_priority;
swap_list_unlock();
- destroy_swap_extents(p);
vfree(swap_map);
if (swap_file)
filp_close(swap_file, NULL);
projects / linux-2.6 / blobdiff