/* * linux/mm/swapfile.c * * Copyright (C) 1991, 1992, 1993, 1994 Linus Torvalds * Swap reorganised 29.12.95, Stephen Tweedie */ #include #include #include #include #include #include /* for blk_size */ #include #include #include #include #include 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) == 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); } 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; /* * 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. */ swcount = *swap_map; if (swcount > 1) { flush_page_to_ram(page); if (start_mm == &init_mm) 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; shmem_unuse(entry, page); } 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 its from swap cache. */ swcount = *swap_map; if ((swcount > 0) != PageSwapCache(page)) BUG(); if ((swcount > 1) && PageDirty(page)) { rw_swap_page(WRITE, page); lock_page(page); } if (PageSwapCache(page)) 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? */ debug_lock_break(551); 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; 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; iinfo.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) { if (conditional_schedule_needed()) { debug_lock_break(551); swap_list_unlock(); debug_lock_break(551); unconditional_schedule(); swap_list_lock(); } 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; } /* * Page lock needs to be held in all cases to prevent races with * swap file deletion. */ int swap_count(struct page *page) { struct swap_info_struct * p; unsigned long offset, type; swp_entry_t entry; int retval = 0; entry.val = page->index; if (!entry.val) goto bad_entry; type = SWP_TYPE(entry); if (type >= nr_swapfiles) goto bad_file; p = type + swap_info; offset = SWP_OFFSET(entry); if (offset >= p->max) goto bad_offset; if (!p->swap_map[offset]) goto bad_unused; retval = p->swap_map[offset]; out: return retval; bad_entry: printk(KERN_ERR "swap_count: null entry!\n"); goto out; bad_file: printk(KERN_ERR "swap_count: %s%08lx\n", Bad_file, entry.val); goto out; bad_offset: printk(KERN_ERR "swap_count: %s%08lx\n", Bad_offset, entry.val); goto out; bad_unused: printk(KERN_ERR "swap_count: %s%08lx\n", Unused_offset, 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; }