X-Git-Url: http://ftp.safe.ca/?a=blobdiff_plain;f=mm%2Fswapfile.c;h=9c590eef79122dc0597dac27912f60e6b7dc6a72;hb=12045a6ee9908b38b6d286530c7d816e39071346;hp=b0f56603b9be8d96eff85ad8e2c9fc0704a24157;hpb=20137a490f397d9c01fc9fadd83a8d198bda4477;p=safe%2Fjmp%2Flinux-2.6 diff --git a/mm/swapfile.c b/mm/swapfile.c index b0f5660..9c590ee 100644 --- a/mm/swapfile.c +++ b/mm/swapfile.c @@ -33,6 +33,7 @@ #include #include #include +#include static DEFINE_SPINLOCK(swap_lock); static unsigned int nr_swapfiles; @@ -52,6 +53,59 @@ 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; +} + +/* returnes 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); + 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 @@ -96,7 +150,7 @@ static int discard_swap(struct swap_info_struct *si) list_for_each_entry(se, &si->extent_list, list) { sector_t start_block = se->start_block << (PAGE_SHIFT - 9); - pgoff_t nr_blocks = se->nr_pages << (PAGE_SHIFT - 9); + sector_t nr_blocks = (sector_t)se->nr_pages << (PAGE_SHIFT - 9); if (se->start_page == 0) { /* Do not discard the swap header page! */ @@ -107,7 +161,8 @@ static int discard_swap(struct swap_info_struct *si) } err = blkdev_issue_discard(si->bdev, start_block, - nr_blocks, GFP_KERNEL); + nr_blocks, GFP_KERNEL, + DISCARD_FL_BARRIER); if (err) break; @@ -133,7 +188,7 @@ static void discard_swap_cluster(struct swap_info_struct *si, start_page < se->start_page + se->nr_pages) { pgoff_t offset = start_page - se->start_page; sector_t start_block = se->start_block + offset; - pgoff_t nr_blocks = se->nr_pages - offset; + sector_t nr_blocks = se->nr_pages - offset; if (nr_blocks > nr_pages) nr_blocks = nr_pages; @@ -146,7 +201,8 @@ static void discard_swap_cluster(struct swap_info_struct *si, 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; } @@ -166,9 +222,11 @@ static int wait_for_discard(void *word) #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; unsigned long last_in_cluster = 0; int latency_ration = LATENCY_LIMIT; int found_free_cluster = 0; @@ -181,10 +239,11 @@ static inline unsigned long scan_swap_map(struct swap_info_struct *si) * 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 + * And we let swap pages go all over an SSD partition. Hugh */ si->flags += SWP_SCANNING; - offset = si->cluster_next; + scan_base = offset = si->cluster_next; if (unlikely(!si->cluster_nr--)) { if (si->pages - si->inuse_pages < SWAPFILE_CLUSTER) { @@ -206,7 +265,16 @@ static inline unsigned long scan_swap_map(struct swap_info_struct *si) } spin_unlock(&swap_lock); - offset = si->lowest_bit; + /* + * If seek is expensive, start searching for new cluster from + * start of partition, to minimize the span of allocated swap. + * But if seek is cheap, search from our current position, so + * that swap is allocated from all over the partition: if the + * Flash Translation Layer only remaps within limited zones, + * we don't want to wear out the first zone too quickly. + */ + if (!(si->flags & SWP_SOLIDSTATE)) + scan_base = offset = si->lowest_bit; last_in_cluster = offset + SWAPFILE_CLUSTER - 1; /* Locate the first empty (unaligned) cluster */ @@ -228,6 +296,27 @@ static inline unsigned long scan_swap_map(struct swap_info_struct *si) } offset = si->lowest_bit; + last_in_cluster = offset + SWAPFILE_CLUSTER - 1; + + /* Locate the first empty (unaligned) cluster */ + for (; last_in_cluster < scan_base; offset++) { + if (si->swap_map[offset]) + last_in_cluster = offset + SWAPFILE_CLUSTER; + else if (offset == last_in_cluster) { + spin_lock(&swap_lock); + offset -= SWAPFILE_CLUSTER - 1; + si->cluster_next = offset; + si->cluster_nr = SWAPFILE_CLUSTER - 1; + found_free_cluster = 1; + goto checks; + } + if (unlikely(--latency_ration < 0)) { + cond_resched(); + latency_ration = LATENCY_LIMIT; + } + } + + offset = scan_base; spin_lock(&swap_lock); si->cluster_nr = SWAPFILE_CLUSTER - 1; si->lowest_alloc = 0; @@ -239,7 +328,20 @@ checks: if (!si->highest_bit) goto no_page; if (offset > si->highest_bit) - offset = si->lowest_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; @@ -252,7 +354,10 @@ checks: 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; @@ -318,13 +423,31 @@ scan: 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; + } + } + offset = si->lowest_bit; + while (++offset < scan_base) { + if (!si->swap_map[offset]) { + 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; no_page: si->flags -= SWP_SCANNING; @@ -358,7 +481,8 @@ swp_entry_t get_swap_page(void) 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); @@ -372,6 +496,7 @@ noswap: 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; @@ -381,7 +506,8 @@ swp_entry_t get_swap_page_of_type(int type) si = swap_info + type; if (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); @@ -428,24 +554,40 @@ out: 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 (p->prio > swap_info[swap_list.next].prio) + swap_list.next = p - swap_info; + nr_swap_pages++; + p->inuse_pages--; } + if (!swap_count(count)) + mem_cgroup_uncharge_swap(ent); return count; } @@ -459,12 +601,36 @@ void swap_free(swp_entry_t entry) 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); + } + return; +} + +/* * How many references to page are currently swapped out? */ static inline int page_swapcount(struct page *page) @@ -476,8 +642,7 @@ static inline int page_swapcount(struct page *page) 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; @@ -529,17 +694,17 @@ int try_to_free_swap(struct page *page) * 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) +int free_swap_and_cache(swp_entry_t entry) { - struct swap_info_struct * p; + struct swap_info_struct *p; struct page *page = NULL; - if (is_migration_entry(entry)) - return; + 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); @@ -561,6 +726,7 @@ void free_swap_and_cache(swp_entry_t entry) unlock_page(page); page_cache_release(page); } + return p != NULL; } #ifdef CONFIG_HIBERNATION @@ -589,7 +755,7 @@ int swap_type_of(dev_t device, sector_t offset, struct block_device **bdev_p) if (!bdev) { if (bdev_p) - *bdev_p = sis->bdev; + *bdev_p = bdgrab(sis->bdev); spin_unlock(&swap_lock); return i; @@ -601,7 +767,7 @@ int swap_type_of(dev_t device, sector_t offset, struct block_device **bdev_p) 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); @@ -647,17 +813,20 @@ unsigned int count_swap_pages(int type, int free) static int unuse_pte(struct vm_area_struct *vma, pmd_t *pmd, unsigned long addr, swp_entry_t entry, struct page *page) { + struct mem_cgroup *ptr = NULL; spinlock_t *ptl; pte_t *pte; int ret = 1; - if (mem_cgroup_charge(page, vma->vm_mm, GFP_KERNEL)) + 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)))) { if (ret > 0) - mem_cgroup_uncharge_page(page); + mem_cgroup_cancel_charge_swapin(ptr); ret = 0; goto out; } @@ -667,6 +836,7 @@ static int unuse_pte(struct vm_area_struct *vma, pmd_t *pmd, set_pte_at(vma->vm_mm, addr, pte, pte_mkold(mk_pte(page, vma->vm_page_prot))); page_add_anon_rmap(page, vma, addr); + mem_cgroup_commit_charge_swapin(page, ptr); swap_free(entry); /* * Move the page to the active list so it is not @@ -675,6 +845,7 @@ static int unuse_pte(struct vm_area_struct *vma, pmd_t *pmd, activate_page(page); out: pte_unmap_unlock(pte, ptl); +out_nolock: return ret; } @@ -840,7 +1011,7 @@ static unsigned int find_next_to_unuse(struct swap_info_struct *si, i = 1; } count = si->swap_map[i]; - if (count && count != SWAP_MAP_BAD) + if (count && swap_count(count) != SWAP_MAP_BAD) break; } return i; @@ -944,13 +1115,13 @@ static int try_to_unuse(unsigned int type) */ 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; @@ -960,7 +1131,7 @@ static int try_to_unuse(unsigned int type) 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)) @@ -972,13 +1143,14 @@ static int try_to_unuse(unsigned int type) 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); @@ -1006,21 +1178,25 @@ static int try_to_unuse(unsigned int type) } /* - * 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; } @@ -1038,7 +1214,8 @@ static int try_to_unuse(unsigned int type) * 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, }; @@ -1065,6 +1242,7 @@ static int try_to_unuse(unsigned int type) * mark page dirty so shrink_page_list will preserve it. */ SetPageDirty(page); +retry: unlock_page(page); page_cache_release(page); @@ -1329,27 +1507,7 @@ out: return ret; } -#if 0 /* We don't need this yet */ -#include -int page_queue_congested(struct page *page) -{ - struct backing_dev_info *bdi; - - VM_BUG_ON(!PageLocked(page)); /* It pins the swap_info_struct */ - - if (PageSwapCache(page)) { - swp_entry_t entry = { .val = page_private(page) }; - struct swap_info_struct *sis; - - sis = get_swap_info_struct(swp_type(entry)); - bdi = sis->bdev->bd_inode->i_mapping->backing_dev_info; - } else - bdi = page->mapping->backing_dev_info; - return bdi_write_congested(bdi); -} -#endif - -asmlinkage long sys_swapoff(const char __user * specialfile) +SYSCALL_DEFINE1(swapoff, const char __user *, specialfile) { struct swap_info_struct * p = NULL; unsigned short *swap_map; @@ -1416,9 +1574,9 @@ asmlinkage long sys_swapoff(const char __user * specialfile) 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 */ @@ -1469,6 +1627,9 @@ asmlinkage long sys_swapoff(const char __user * specialfile) spin_unlock(&swap_lock); mutex_unlock(&swapon_mutex); vfree(swap_map); + /* Destroy swap account informatin */ + swap_cgroup_swapoff(type); + inode = mapping->host; if (S_ISBLK(inode->i_mode)) { struct block_device *bdev = I_BDEV(inode); @@ -1602,7 +1763,7 @@ late_initcall(max_swapfiles_check); * * 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; char *name = NULL; @@ -1786,6 +1947,11 @@ asmlinkage long sys_swapon(const char __user * specialfile, int swap_flags) } swap_map[page_nr] = SWAP_MAP_BAD; } + + error = swap_cgroup_swapon(type, maxpages); + if (error) + goto bad_swap; + nr_good_pages = swap_header->info.last_page - swap_header->info.nr_badpages - 1 /* header page */; @@ -1807,13 +1973,14 @@ asmlinkage long sys_swapon(const char __user * specialfile, int swap_flags) goto bad_swap; } - if (blk_queue_nonrot(bdev_get_queue(p->bdev))) { - p->flags |= SWP_SOLIDSTATE; - srandom32((u32)get_seconds()); - 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); @@ -1858,6 +2025,7 @@ bad_swap: bd_release(bdev); } destroy_swap_extents(p); + swap_cgroup_swapoff(type); bad_swap_2: spin_lock(&swap_lock); p->swap_file = NULL; @@ -1903,15 +2071,23 @@ void si_swapinfo(struct sysinfo *val) * * 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; 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) @@ -1920,17 +2096,40 @@ int swap_duplicate(swp_entry_t entry) 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; @@ -1939,6 +2138,27 @@ bad_file: 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); +} + +/* + * @entry: swap entry for which we allocate swap cache. + * + * Called when allocating swap cache for exising 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_duplicate(entry, SWAP_CACHE); +} + struct swap_info_struct * get_swap_info_struct(unsigned type) @@ -1977,7 +2197,7 @@ int valid_swaphandles(swp_entry_t entry, unsigned long *offset) /* 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 */ @@ -1985,7 +2205,7 @@ int valid_swaphandles(swp_entry_t entry, unsigned long *offset) /* 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);