diff options
Diffstat (limited to 'xenolinux-2.4.24-sparse/mm/swapfile.c')
| -rw-r--r-- | xenolinux-2.4.24-sparse/mm/swapfile.c | 1267 |
1 files changed, 1267 insertions, 0 deletions
diff --git a/xenolinux-2.4.24-sparse/mm/swapfile.c b/xenolinux-2.4.24-sparse/mm/swapfile.c new file mode 100644 index 0000000000..de04a376d2 --- /dev/null +++ b/xenolinux-2.4.24-sparse/mm/swapfile.c @@ -0,0 +1,1267 @@ +/* + * linux/mm/swapfile.c + * + * Copyright (C) 1991, 1992, 1993, 1994 Linus Torvalds + * Swap reorganised 29.12.95, Stephen Tweedie + */ + +#include <linux/slab.h> +#include <linux/smp_lock.h> +#include <linux/kernel_stat.h> +#include <linux/swap.h> +#include <linux/swapctl.h> +#include <linux/blkdev.h> /* for blk_size */ +#include <linux/vmalloc.h> +#include <linux/pagemap.h> +#include <linux/shm.h> + +#include <asm/pgtable.h> + +spinlock_t swaplock = SPIN_LOCK_UNLOCKED; +unsigned int nr_swapfiles; +int total_swap_pages; +static int swap_overflow; + +static const char Bad_file[] = "Bad swap file entry "; +static const char Unused_file[] = "Unused swap file entry "; +static const char Bad_offset[] = "Bad swap offset entry "; +static const char Unused_offset[] = "Unused swap offset entry "; + +struct swap_list_t swap_list = {-1, -1}; + +struct swap_info_struct swap_info[MAX_SWAPFILES]; + +#define SWAPFILE_CLUSTER 256 + +static inline int scan_swap_map(struct swap_info_struct *si) +{ + unsigned long offset; + /* + * 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++; + 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) + { + int nr; + for (nr = offset; nr < offset+SWAPFILE_CLUSTER; nr++) + if (si->swap_map[nr]) + { + offset = nr+1; + goto check_next_cluster; + } + /* We found a completly empty cluster, so start + * using it. + */ + goto got_page; + } + /* 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: + if (offset == si->lowest_bit) + si->lowest_bit++; + if (offset == si->highest_bit) + si->highest_bit--; + if (si->lowest_bit > si->highest_bit) { + si->lowest_bit = si->max; + si->highest_bit = 0; + } + si->swap_map[offset] = 1; + nr_swap_pages--; + si->cluster_next = offset+1; + return offset; + } + si->lowest_bit = si->max; + si->highest_bit = 0; + 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; + + 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_WRITEOK) == SWP_WRITEOK) { + 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; + } + } + 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 */ + } +out: + swap_list_unlock(); + return entry; +} + +static struct swap_info_struct * swap_info_get(swp_entry_t entry) +{ + struct swap_info_struct * p; + unsigned long offset, type; + + if (!entry.val) + goto out; + type = SWP_TYPE(entry); + if (type >= nr_swapfiles) + goto bad_nofile; + p = & swap_info[type]; + if (!(p->flags & SWP_USED)) + goto bad_device; + offset = SWP_OFFSET(entry); + if (offset >= p->max) + goto bad_offset; + 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; + +bad_free: + printk(KERN_ERR "swap_free: %s%08lx\n", Unused_offset, entry.val); + goto out; +bad_offset: + printk(KERN_ERR "swap_free: %s%08lx\n", Bad_offset, entry.val); + goto out; +bad_device: + printk(KERN_ERR "swap_free: %s%08lx\n", Unused_file, entry.val); + goto out; +bad_nofile: + printk(KERN_ERR "swap_free: %s%08lx\n", Bad_file, entry.val); +out: + return NULL; +} + +static void swap_info_put(struct swap_info_struct * p) +{ + swap_device_unlock(p); + swap_list_unlock(); +} + +static int swap_entry_free(struct swap_info_struct *p, unsigned long offset) +{ + 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; + nr_swap_pages++; + } + } + return count; +} + +/* + * Caller has made sure that the swapdevice corresponding to entry + * is still around or has not been recycled. + */ +void swap_free(swp_entry_t entry) +{ + struct swap_info_struct * p; + + p = swap_info_get(entry); + if (p) { + swap_entry_free(p, SWP_OFFSET(entry)); + swap_info_put(p); + } +} + +/* + * Check if we're the only user of a swap page, + * when the page is locked. + */ +static int exclusive_swap_page(struct page *page) +{ + int retval = 0; + struct swap_info_struct * p; + swp_entry_t entry; + + entry.val = page->index; + p = swap_info_get(entry); + if (p) { + /* Is the only swap cache user the cache itself? */ + if (p->swap_map[SWP_OFFSET(entry)] == 1) { + /* Recheck the page count with the pagecache lock held.. */ + spin_lock(&pagecache_lock); + if (page_count(page) - !!page->buffers == 2) + retval = 1; + spin_unlock(&pagecache_lock); + } + swap_info_put(p); + } + return retval; +} + +/* + * We can use this swap cache entry directly + * if there are no other references to it. + * + * Here "exclusive_swap_page()" does the real + * work, but we opportunistically check whether + * we need to get all the locks first.. + */ +int can_share_swap_page(struct page *page) +{ + int retval = 0; + + if (!PageLocked(page)) + BUG(); + switch (page_count(page)) { + case 3: + if (!page->buffers) + break; + /* Fallthrough */ + case 2: + if (!PageSwapCache(page)) + break; + retval = exclusive_swap_page(page); + break; + case 1: + if (PageReserved(page)) + break; + retval = 1; + } + return retval; +} + +/* + * Work out if there are any other processes sharing this + * swap cache page. Free it if you can. Return success. + */ +int remove_exclusive_swap_page(struct page *page) +{ + int retval; + struct swap_info_struct * p; + swp_entry_t entry; + + if (!PageLocked(page)) + BUG(); + if (!PageSwapCache(page)) + return 0; + if (page_count(page) - !!page->buffers != 2) /* 2: us + cache */ + return 0; + + entry.val = page->index; + p = swap_info_get(entry); + if (!p) + return 0; + + /* Is the only swap cache user the cache itself? */ + retval = 0; + if (p->swap_map[SWP_OFFSET(entry)] == 1) { + /* Recheck the page count with the pagecache lock held.. */ + spin_lock(&pagecache_lock); + if (page_count(page) - !!page->buffers == 2) { + __delete_from_swap_cache(page); + SetPageDirty(page); + retval = 1; + } + spin_unlock(&pagecache_lock); + } + swap_info_put(p); + + if (retval) { + block_flushpage(page, 0); + swap_free(entry); + page_cache_release(page); + } + + return retval; +} + +/* + * 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) +{ + struct swap_info_struct * p; + struct page *page = NULL; + + p = swap_info_get(entry); + if (p) { + if (swap_entry_free(p, SWP_OFFSET(entry)) == 1) + page = find_trylock_page(&swapper_space, entry.val); + swap_info_put(p); + } + if (page) { + page_cache_get(page); + /* Only cache user (+us), or swap space full? Free it! */ + if (page_count(page) - !!page->buffers == 2 || vm_swap_full()) { + delete_from_swap_cache(page); + SetPageDirty(page); + } + UnlockPage(page); + page_cache_release(page); + } +} + +/* + * The swap entry has been read in advance, and we return 1 to indicate + * that the page has been used or is no longer needed. + * + * Always set the resulting pte to be nowrite (the same as COW pages + * after one process has exited). We don't know just how many PTEs will + * share this swap entry, so be cautious and let do_wp_page work out + * what to do if a write is requested later. + */ +/* mmlist_lock and vma->vm_mm->page_table_lock are held */ +static inline void unuse_pte(struct vm_area_struct * vma, unsigned long address, + pte_t *dir, swp_entry_t entry, struct page* page) +{ + pte_t pte = *dir; + + if (likely(pte_to_swp_entry(pte).val != entry.val)) + return; + if (unlikely(pte_none(pte) || pte_present(pte))) + return; + get_page(page); + set_pte(dir, pte_mkold(mk_pte(page, vma->vm_page_prot))); + swap_free(entry); + ++vma->vm_mm->rss; +} + +/* mmlist_lock and vma->vm_mm->page_table_lock are held */ +static inline void unuse_pmd(struct vm_area_struct * vma, pmd_t *dir, + unsigned long address, unsigned long size, unsigned long offset, + swp_entry_t entry, struct page* page) +{ + pte_t * pte; + unsigned long end; + + if (pmd_none(*dir)) + return; + if (pmd_bad(*dir)) { + pmd_ERROR(*dir); + pmd_clear(dir); + return; + } + pte = pte_offset(dir, address); + offset += address & PMD_MASK; + address &= ~PMD_MASK; + end = address + size; + if (end > PMD_SIZE) + end = PMD_SIZE; + do { + unuse_pte(vma, offset+address-vma->vm_start, pte, entry, page); + address += PAGE_SIZE; + pte++; + } while (address && (address < end)); +} + +/* mmlist_lock and vma->vm_mm->page_table_lock are held */ +static inline void unuse_pgd(struct vm_area_struct * vma, pgd_t *dir, + unsigned long address, unsigned long size, + swp_entry_t entry, struct page* page) +{ + pmd_t * pmd; + unsigned long offset, end; + + if (pgd_none(*dir)) + return; + if (pgd_bad(*dir)) { + pgd_ERROR(*dir); + pgd_clear(dir); + return; + } + pmd = pmd_offset(dir, address); + offset = address & PGDIR_MASK; + address &= ~PGDIR_MASK; + end = address + size; + if (end > PGDIR_SIZE) + end = PGDIR_SIZE; + if (address >= end) + BUG(); + do { + unuse_pmd(vma, pmd, address, end - address, offset, entry, + page); + address = (address + PMD_SIZE) & PMD_MASK; + pmd++; + } while (address && (address < end)); +} + +/* mmlist_lock and vma->vm_mm->page_table_lock are held */ +static void unuse_vma(struct vm_area_struct * vma, pgd_t *pgdir, + swp_entry_t entry, struct page* page) +{ + unsigned long start = vma->vm_start, end = vma->vm_end; + + if (start >= end) + BUG(); + do { + unuse_pgd(vma, pgdir, start, end - start, entry, page); + start = (start + PGDIR_SIZE) & PGDIR_MASK; + pgdir++; + } while (start && (start < end)); +} + +static void unuse_process(struct mm_struct * mm, + swp_entry_t entry, struct page* page) +{ + struct vm_area_struct* vma; + + /* + * Go through process' page directory. + */ + spin_lock(&mm->page_table_lock); + for (vma = mm->mmap; vma; vma = vma->vm_next) { + pgd_t * pgd = pgd_offset(mm, vma->vm_start); + unuse_vma(vma, pgd, entry, page); + } + XENO_flush_page_update_queue(); + spin_unlock(&mm->page_table_lock); + return; +} + +/* + * 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) +{ + int max = si->max; + int i = prev; + int count; + + /* + * No need for swap_device_lock(si) here: we're just looking + * for whether an entry is in use, not modifying it; false + * hits are okay, and sys_swapoff() has already prevented new + * allocations from this area (while holding swap_list_lock()). + */ + for (;;) { + if (++i >= max) { + if (!prev) { + i = 0; + break; + } + /* + * No entries in use at top of swap_map, + * loop back to start and recheck there. + */ + max = prev + 1; + prev = 0; + i = 1; + } + count = si->swap_map[i]; + if (count && count != SWAP_MAP_BAD) + break; + } + return i; +} + +/* + * We completely avoid races by reading each swap page in advance, + * and then search for the process using it. All the necessary + * page table adjustments can then be made atomically. + */ +static int try_to_unuse(unsigned int type) +{ + struct swap_info_struct * si = &swap_info[type]; + struct mm_struct *start_mm; + unsigned short *swap_map; + unsigned short swcount; + struct page *page; + swp_entry_t entry; + int i = 0; + int retval = 0; + int reset_overflow = 0; + int shmem; + + /* + * When searching mms for an entry, a good strategy is to + * start at the first mm we freed the previous entry from + * (though actually we don't notice whether we or coincidence + * freed the entry). Initialize this start_mm with a hold. + * + * A simpler strategy would be to start at the last mm we + * freed the previous entry from; but that would take less + * advantage of mmlist ordering (now preserved by swap_out()), + * which clusters forked address spaces together, most recent + * child immediately after parent. If we race with dup_mmap(), + * we very much want to resolve parent before child, otherwise + * we may miss some entries: using last mm would invert that. + */ + start_mm = &init_mm; + atomic_inc(&init_mm.mm_users); + + /* + * Keep on scanning until all entries have gone. Usually, + * one pass through swap_map is enough, but not necessarily: + * mmput() removes mm from mmlist before exit_mmap() and its + * zap_page_range(). That's not too bad, those entries are + * on their way out, and handled faster there than here. + * do_munmap() behaves similarly, taking the range out of mm's + * vma list before zap_page_range(). But unfortunately, when + * unmapping a part of a vma, it takes the whole out first, + * then reinserts what's left after (might even reschedule if + * open() method called) - so swap entries may be invisible + * to swapoff for a while, then reappear - but that is rare. + */ + while ((i = find_next_to_unuse(si, i))) { + /* + * Get a page for the entry, using the existing swap + * cache page if there is one. Otherwise, get a clean + * page and read the swap into it. + */ + swap_map = &si->swap_map[i]; + entry = SWP_ENTRY(type, i); + page = read_swap_cache_async(entry); + if (!page) { + /* + * Either swap_duplicate() failed because entry + * has been freed independently, and will not be + * reused since sys_swapoff() already disabled + * allocation from here, or alloc_page() failed. + */ + if (!*swap_map) + continue; + retval = -ENOMEM; + break; + } + + /* + * Don't hold on to start_mm if it looks like exiting. + */ + if (atomic_read(&start_mm->mm_users) == 1) { + mmput(start_mm); + start_mm = &init_mm; + atomic_inc(&init_mm.mm_users); + } + + /* + * Wait for and lock page. When do_swap_page races with + * try_to_unuse, do_swap_page can handle the fault much + * faster than try_to_unuse can locate the entry. This + * apparently redundant "wait_on_page" lets try_to_unuse + * defer to do_swap_page in such a case - in some tests, + * do_swap_page and try_to_unuse repeatedly compete. + */ + wait_on_page(page); + lock_page(page); + + /* + * Remove all references to entry, without blocking. + * Whenever we reach init_mm, there's no address space + * to search, but use it as a reminder to search shmem. + */ + shmem = 0; + swcount = *swap_map; + if (swcount > 1) { + flush_page_to_ram(page); + if (start_mm == &init_mm) + shmem = shmem_unuse(entry, page); + else + unuse_process(start_mm, entry, page); + } + if (*swap_map > 1) { + int set_start_mm = (*swap_map >= swcount); + struct list_head *p = &start_mm->mmlist; + struct mm_struct *new_start_mm = start_mm; + struct mm_struct *mm; + + spin_lock(&mmlist_lock); + while (*swap_map > 1 && + (p = p->next) != &start_mm->mmlist) { + mm = list_entry(p, struct mm_struct, mmlist); + swcount = *swap_map; + if (mm == &init_mm) { + set_start_mm = 1; + spin_unlock(&mmlist_lock); + shmem = shmem_unuse(entry, page); + spin_lock(&mmlist_lock); + } else + unuse_process(mm, entry, page); + if (set_start_mm && *swap_map < swcount) { + new_start_mm = mm; + set_start_mm = 0; + } + } + atomic_inc(&new_start_mm->mm_users); + spin_unlock(&mmlist_lock); + mmput(start_mm); + start_mm = new_start_mm; + } + + /* + * 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. + * + * 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) { + swap_list_lock(); + swap_device_lock(si); + nr_swap_pages++; + *swap_map = 1; + swap_device_unlock(si); + swap_list_unlock(); + reset_overflow = 1; + } + + /* + * If a reference remains (rare), we would like to leave + * the page in the swap cache; but try_to_swap_out could + * then re-duplicate the entry once we drop page lock, + * so we might loop indefinitely; also, that page could + * not be swapped out to other storage meanwhile. So: + * delete from cache even if there's another reference, + * after ensuring that the data has been saved to disk - + * since if the reference remains (rarer), it will be + * read from disk into another page. Splitting into two + * pages would be incorrect if swap supported "shared + * private" pages, but they are handled by tmpfs files. + * + * Note shmem_unuse already deleted swappage from cache, + * unless corresponding filepage found already in cache: + * in which case it left swappage in cache, lowered its + * swap count to pass quickly through the loops above, + * and now we must reincrement count to try again later. + */ + if ((*swap_map > 1) && PageDirty(page) && PageSwapCache(page)) { + rw_swap_page(WRITE, page); + lock_page(page); + } + if (PageSwapCache(page)) { + if (shmem) + swap_duplicate(entry); + else + delete_from_swap_cache(page); + } + + /* + * So we could skip searching mms once swap count went + * to 1, we did not mark any present ptes as dirty: must + * mark page dirty so try_to_swap_out will preserve it. + */ + SetPageDirty(page); + UnlockPage(page); + page_cache_release(page); + + /* + * Make sure that we aren't completely killing + * interactive performance. Interruptible check on + * signal_pending() would be nice, but changes the spec? + */ + if (current->need_resched) + schedule(); + } + + mmput(start_mm); + if (reset_overflow) { + printk(KERN_WARNING "swapoff: cleared swap entry overflow\n"); + swap_overflow = 0; + } + return retval; +} + +asmlinkage long sys_swapoff(const char * specialfile) +{ + struct swap_info_struct * p = NULL; + unsigned short *swap_map; + struct nameidata nd; + int i, type, prev; + int err; + + if (!capable(CAP_SYS_ADMIN)) + return -EPERM; + + err = user_path_walk(specialfile, &nd); + if (err) + goto out; + + lock_kernel(); + prev = -1; + swap_list_lock(); + for (type = swap_list.head; type >= 0; type = swap_info[type].next) { + p = swap_info + type; + if ((p->flags & SWP_WRITEOK) == SWP_WRITEOK) { + if (p->swap_file == nd.dentry) + break; + } + prev = type; + } + err = -EINVAL; + if (type < 0) { + swap_list_unlock(); + goto out_dput; + } + + if (prev < 0) { + swap_list.head = 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; + } + nr_swap_pages -= p->pages; + total_swap_pages -= p->pages; + p->flags = SWP_USED; + swap_list_unlock(); + unlock_kernel(); + err = try_to_unuse(type); + lock_kernel(); + if (err) { + /* re-insert swap space back into swap_list */ + swap_list_lock(); + for (prev = -1, i = swap_list.head; i >= 0; prev = i, i = swap_info[i].next) + if (p->prio >= swap_info[i].prio) + break; + p->next = i; + if (prev < 0) + swap_list.head = swap_list.next = p - swap_info; + else + swap_info[prev].next = p - swap_info; + nr_swap_pages += p->pages; + total_swap_pages += p->pages; + p->flags = SWP_WRITEOK; + swap_list_unlock(); + goto out_dput; + } + if (p->swap_device) + blkdev_put(p->swap_file->d_inode->i_bdev, BDEV_SWAP); + path_release(&nd); + + swap_list_lock(); + swap_device_lock(p); + nd.mnt = p->swap_vfsmnt; + nd.dentry = p->swap_file; + p->swap_vfsmnt = NULL; + p->swap_file = NULL; + p->swap_device = 0; + p->max = 0; + swap_map = p->swap_map; + p->swap_map = NULL; + p->flags = 0; + swap_device_unlock(p); + swap_list_unlock(); + vfree(swap_map); + err = 0; + +out_dput: + unlock_kernel(); + path_release(&nd); +out: + return err; +} + +int get_swaparea_info(char *buf) +{ + char * page = (char *) __get_free_page(GFP_KERNEL); + struct swap_info_struct *ptr = swap_info; + int i, j, len = 0, usedswap; + + if (!page) + return -ENOMEM; + + len += sprintf(buf, "Filename\t\t\tType\t\tSize\tUsed\tPriority\n"); + for (i = 0 ; i < nr_swapfiles ; i++, ptr++) { + if ((ptr->flags & SWP_USED) && ptr->swap_map) { + char * path = d_path(ptr->swap_file, ptr->swap_vfsmnt, + page, PAGE_SIZE); + + len += sprintf(buf + len, "%-31s ", path); + + if (!ptr->swap_device) + len += sprintf(buf + len, "file\t\t"); + else + len += sprintf(buf + len, "partition\t"); + + usedswap = 0; + for (j = 0; j < ptr->max; ++j) + switch (ptr->swap_map[j]) { + case SWAP_MAP_BAD: + case 0: + continue; + default: + usedswap++; + } + len += sprintf(buf + len, "%d\t%d\t%d\n", ptr->pages << (PAGE_SHIFT - 10), + usedswap << (PAGE_SHIFT - 10), ptr->prio); + } + } + free_page((unsigned long) page); + return len; +} + +int is_swap_partition(kdev_t dev) { + struct swap_info_struct *ptr = swap_info; + int i; + + for (i = 0 ; i < nr_swapfiles ; i++, ptr++) { + if (ptr->flags & SWP_USED) + if (ptr->swap_device == dev) + return 1; + } + return 0; +} + +/* + * Written 01/25/92 by Simmule Turner, heavily changed by Linus. + * + * The swapon system call + */ +asmlinkage long sys_swapon(const char * specialfile, int swap_flags) +{ + struct swap_info_struct * p; + struct nameidata nd; + struct inode * swap_inode; + unsigned int type; + int i, j, prev; + int error; + static int least_priority = 0; + union swap_header *swap_header = 0; + int swap_header_version; + int nr_good_pages = 0; + unsigned long maxpages = 1; + int swapfilesize; + struct block_device *bdev = NULL; + unsigned short *swap_map; + + if (!capable(CAP_SYS_ADMIN)) + return -EPERM; + lock_kernel(); + swap_list_lock(); + p = swap_info; + for (type = 0 ; type < nr_swapfiles ; type++,p++) + if (!(p->flags & SWP_USED)) + break; + error = -EPERM; + if (type >= MAX_SWAPFILES) { + swap_list_unlock(); + goto out; + } + if (type >= nr_swapfiles) + nr_swapfiles = type+1; + p->flags = SWP_USED; + p->swap_file = NULL; + p->swap_vfsmnt = NULL; + p->swap_device = 0; + p->swap_map = NULL; + p->lowest_bit = 0; + p->highest_bit = 0; + p->cluster_nr = 0; + p->sdev_lock = SPIN_LOCK_UNLOCKED; + p->next = -1; + if (swap_flags & SWAP_FLAG_PREFER) { + p->prio = + (swap_flags & SWAP_FLAG_PRIO_MASK)>>SWAP_FLAG_PRIO_SHIFT; + } else { + p->prio = --least_priority; + } + swap_list_unlock(); + error = user_path_walk(specialfile, &nd); + if (error) + goto bad_swap_2; + + p->swap_file = nd.dentry; + p->swap_vfsmnt = nd.mnt; + swap_inode = nd.dentry->d_inode; + error = -EINVAL; + + if (S_ISBLK(swap_inode->i_mode)) { + kdev_t dev = swap_inode->i_rdev; + struct block_device_operations *bdops; + devfs_handle_t de; + + if (is_mounted(dev)) { + error = -EBUSY; + goto bad_swap_2; + } + + p->swap_device = dev; + set_blocksize(dev, PAGE_SIZE); + + bd_acquire(swap_inode); + bdev = swap_inode->i_bdev; + de = devfs_get_handle_from_inode(swap_inode); + bdops = devfs_get_ops(de); /* Increments module use count */ + if (bdops) bdev->bd_op = bdops; + + error = blkdev_get(bdev, FMODE_READ|FMODE_WRITE, 0, BDEV_SWAP); + devfs_put_ops(de);/*Decrement module use count now we're safe*/ + if (error) + goto bad_swap_2; + set_blocksize(dev, PAGE_SIZE); + error = -ENODEV; + if (!dev || (blk_size[MAJOR(dev)] && + !blk_size[MAJOR(dev)][MINOR(dev)])) + goto bad_swap; + swapfilesize = 0; + if (blk_size[MAJOR(dev)]) + swapfilesize = blk_size[MAJOR(dev)][MINOR(dev)] + >> (PAGE_SHIFT - 10); + } else if (S_ISREG(swap_inode->i_mode)) + swapfilesize = swap_inode->i_size >> PAGE_SHIFT; + else + goto bad_swap; + + error = -EBUSY; + for (i = 0 ; i < nr_swapfiles ; i++) { + struct swap_info_struct *q = &swap_info[i]; + if (i == type || !q->swap_file) + continue; + if (swap_inode->i_mapping == q->swap_file->d_inode->i_mapping) + goto bad_swap; + } + + swap_header = (void *) __get_free_page(GFP_USER); + if (!swap_header) { + printk("Unable to start swapping: out of memory :-)\n"); + error = -ENOMEM; + goto bad_swap; + } + + lock_page(virt_to_page(swap_header)); + rw_swap_page_nolock(READ, SWP_ENTRY(type,0), (char *) swap_header); + + if (!memcmp("SWAP-SPACE",swap_header->magic.magic,10)) + swap_header_version = 1; + else if (!memcmp("SWAPSPACE2",swap_header->magic.magic,10)) + swap_header_version = 2; + else { + printk("Unable to find swap-space signature\n"); + error = -EINVAL; + goto bad_swap; + } + + switch (swap_header_version) { + case 1: + memset(((char *) swap_header)+PAGE_SIZE-10,0,10); + j = 0; + p->lowest_bit = 0; + p->highest_bit = 0; + for (i = 1 ; i < 8*PAGE_SIZE ; i++) { + if (test_bit(i,(char *) swap_header)) { + if (!p->lowest_bit) + p->lowest_bit = i; + p->highest_bit = i; + maxpages = i+1; + j++; + } + } + nr_good_pages = j; + p->swap_map = vmalloc(maxpages * sizeof(short)); + if (!p->swap_map) { + error = -ENOMEM; + goto bad_swap; + } + for (i = 1 ; i < maxpages ; i++) { + if (test_bit(i,(char *) swap_header)) + p->swap_map[i] = 0; + else + p->swap_map[i] = SWAP_MAP_BAD; + } + break; + + case 2: + /* Check the swap header's sub-version and the size of + the swap file and bad block lists */ + if (swap_header->info.version != 1) { + printk(KERN_WARNING + "Unable to handle swap header version %d\n", + swap_header->info.version); + error = -EINVAL; + goto bad_swap; + } + + p->lowest_bit = 1; + maxpages = SWP_OFFSET(SWP_ENTRY(0,~0UL)) - 1; + if (maxpages > swap_header->info.last_page) + maxpages = swap_header->info.last_page; + p->highest_bit = maxpages - 1; + + error = -EINVAL; + if (swap_header->info.nr_badpages > MAX_SWAP_BADPAGES) + goto bad_swap; + + /* OK, set up the swap map and apply the bad block list */ + if (!(p->swap_map = vmalloc(maxpages * sizeof(short)))) { + error = -ENOMEM; + goto bad_swap; + } + + error = 0; + memset(p->swap_map, 0, maxpages * sizeof(short)); + for (i=0; i<swap_header->info.nr_badpages; i++) { + int page = swap_header->info.badpages[i]; + if (page <= 0 || page >= swap_header->info.last_page) + error = -EINVAL; + else + p->swap_map[page] = SWAP_MAP_BAD; + } + nr_good_pages = swap_header->info.last_page - + swap_header->info.nr_badpages - + 1 /* header page */; + 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) { + printk(KERN_WARNING "Empty swap-file\n"); + error = -EINVAL; + goto bad_swap; + } + p->swap_map[0] = SWAP_MAP_BAD; + swap_list_lock(); + swap_device_lock(p); + p->max = maxpages; + p->flags = SWP_WRITEOK; + p->pages = nr_good_pages; + nr_swap_pages += nr_good_pages; + total_swap_pages += nr_good_pages; + printk(KERN_INFO "Adding Swap: %dk swap-space (priority %d)\n", + nr_good_pages<<(PAGE_SHIFT-10), p->prio); + + /* 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) { + 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; + } + swap_device_unlock(p); + swap_list_unlock(); + error = 0; + goto out; +bad_swap: + if (bdev) + blkdev_put(bdev, BDEV_SWAP); +bad_swap_2: + swap_list_lock(); + swap_map = p->swap_map; + nd.mnt = p->swap_vfsmnt; + nd.dentry = p->swap_file; + p->swap_device = 0; + p->swap_file = NULL; + p->swap_vfsmnt = NULL; + p->swap_map = NULL; + p->flags = 0; + if (!(swap_flags & SWAP_FLAG_PREFER)) + ++least_priority; + swap_list_unlock(); + if (swap_map) + vfree(swap_map); + path_release(&nd); +out: + if (swap_header) + free_page((long) swap_header); + unlock_kernel(); + return error; +} + +void si_swapinfo(struct sysinfo *val) +{ + unsigned int i; + unsigned long nr_to_be_unused = 0; + + swap_list_lock(); + for (i = 0; i < nr_swapfiles; i++) { + unsigned int j; + if (swap_info[i].flags != SWP_USED) + continue; + for (j = 0; j < swap_info[i].max; ++j) { + switch (swap_info[i].swap_map[j]) { + case 0: + case SWAP_MAP_BAD: + continue; + default: + nr_to_be_unused++; + } + } + } + val->freeswap = nr_swap_pages + nr_to_be_unused; + val->totalswap = total_swap_pages + nr_to_be_unused; + swap_list_unlock(); +} + +/* + * Verify that a swap entry is valid and increment its swap map count. + * + * Note: if swap_map[] reaches SWAP_MAP_MAX the entries are treated as + * "permanent", but will be reclaimed by the next swapoff. + */ +int swap_duplicate(swp_entry_t entry) +{ + struct swap_info_struct * p; + unsigned long offset, type; + int result = 0; + + type = SWP_TYPE(entry); + if (type >= nr_swapfiles) + goto bad_file; + p = type + swap_info; + offset = SWP_OFFSET(entry); + + swap_device_lock(p); + 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 (swap_overflow++ < 5) + printk(KERN_WARNING "swap_dup: swap entry overflow\n"); + p->swap_map[offset] = SWAP_MAP_MAX; + result = 1; + } + } + swap_device_unlock(p); +out: + return result; + +bad_file: + printk(KERN_ERR "swap_dup: %s%08lx\n", Bad_file, entry.val); + goto out; +} + +/* + * Prior swap_duplicate protects against swap device deletion. + */ +void get_swaphandle_info(swp_entry_t entry, unsigned long *offset, + kdev_t *dev, struct inode **swapf) +{ + unsigned long type; + struct swap_info_struct *p; + + type = SWP_TYPE(entry); + if (type >= nr_swapfiles) { + printk(KERN_ERR "rw_swap_page: %s%08lx\n", Bad_file, entry.val); + return; + } + + p = &swap_info[type]; + *offset = SWP_OFFSET(entry); + if (*offset >= p->max && *offset != 0) { + printk(KERN_ERR "rw_swap_page: %s%08lx\n", Bad_offset, entry.val); + return; + } + if (p->swap_map && !p->swap_map[*offset]) { + printk(KERN_ERR "rw_swap_page: %s%08lx\n", Unused_offset, entry.val); + return; + } + if (!(p->flags & SWP_USED)) { + printk(KERN_ERR "rw_swap_page: %s%08lx\n", Unused_file, entry.val); + return; + } + + if (p->swap_device) { + *dev = p->swap_device; + } else if (p->swap_file) { + *swapf = p->swap_file->d_inode; + } else { + printk(KERN_ERR "rw_swap_page: no swap file or device\n"); + } + return; +} + +/* + * swap_device_lock prevents swap_map being freed. Don't grab an extra + * reference on the swaphandle, it doesn't matter if it becomes unused. + */ +int valid_swaphandles(swp_entry_t entry, unsigned long *offset) +{ + int ret = 0, i = 1 << page_cluster; + unsigned long toff; + struct swap_info_struct *swapdev = SWP_TYPE(entry) + swap_info; + + if (!page_cluster) /* no readahead */ + return 0; + toff = (SWP_OFFSET(entry) >> page_cluster) << page_cluster; + if (!toff) /* first page is swap header */ + toff++, i--; + *offset = toff; + + swap_device_lock(swapdev); + do { + /* Don't read-ahead past the end of the swap area */ + if (toff >= swapdev->max) + break; + /* Don't read in free or bad pages */ + if (!swapdev->swap_map[toff]) + break; + if (swapdev->swap_map[toff] == SWAP_MAP_BAD) + break; + toff++; + ret++; + } while (--i); + swap_device_unlock(swapdev); + return ret; +} |