4 * Copyright (C) 1991, 1992, 1993, 1994 Linus Torvalds
6 * Swap reorganised 29.12.95,
7 * Asynchronous swapping added 30.12.95. Stephen Tweedie
8 * Removed race in async swapping. 14.4.1996. Bruno Haible
9 * Add swap of shared pages through the page cache. 20.2.1998. Stephen Tweedie
10 * Always use brw_page, life becomes simpler. 12 May 1998 Eric Biederman
14 #include <linux/kernel_stat.h>
15 #include <linux/gfp.h>
16 #include <linux/pagemap.h>
17 #include <linux/swap.h>
18 #include <linux/bio.h>
19 #include <linux/swapops.h>
20 #include <linux/buffer_head.h>
21 #include <linux/writeback.h>
22 #include <linux/frontswap.h>
23 #include <asm/pgtable.h>
25 static struct bio *get_swap_bio(gfp_t gfp_flags,
26 struct page *page, bio_end_io_t end_io)
30 bio = bio_alloc(gfp_flags, 1);
32 bio->bi_sector = map_swap_page(page, &bio->bi_bdev);
33 bio->bi_sector <<= PAGE_SHIFT - 9;
34 bio->bi_io_vec[0].bv_page = page;
35 bio->bi_io_vec[0].bv_len = PAGE_SIZE;
36 bio->bi_io_vec[0].bv_offset = 0;
38 bio->bi_size = PAGE_SIZE;
39 bio->bi_end_io = end_io;
44 static void end_swap_bio_write(struct bio *bio, int err)
46 const int uptodate = test_bit(BIO_UPTODATE, &bio->bi_flags);
47 struct page *page = bio->bi_io_vec[0].bv_page;
52 * We failed to write the page out to swap-space.
53 * Re-dirty the page in order to avoid it being reclaimed.
54 * Also print a dire warning that things will go BAD (tm)
57 * Also clear PG_reclaim to avoid rotate_reclaimable_page()
60 printk(KERN_ALERT "Write-error on swap-device (%u:%u:%Lu)\n",
61 imajor(bio->bi_bdev->bd_inode),
62 iminor(bio->bi_bdev->bd_inode),
63 (unsigned long long)bio->bi_sector);
64 ClearPageReclaim(page);
66 end_page_writeback(page);
70 void end_swap_bio_read(struct bio *bio, int err)
72 const int uptodate = test_bit(BIO_UPTODATE, &bio->bi_flags);
73 struct page *page = bio->bi_io_vec[0].bv_page;
77 ClearPageUptodate(page);
78 printk(KERN_ALERT "Read-error on swap-device (%u:%u:%Lu)\n",
79 imajor(bio->bi_bdev->bd_inode),
80 iminor(bio->bi_bdev->bd_inode),
81 (unsigned long long)bio->bi_sector);
83 SetPageUptodate(page);
89 int generic_swapfile_activate(struct swap_info_struct *sis,
90 struct file *swap_file,
93 struct address_space *mapping = swap_file->f_mapping;
94 struct inode *inode = mapping->host;
95 unsigned blocks_per_page;
96 unsigned long page_no;
100 sector_t lowest_block = -1;
101 sector_t highest_block = 0;
105 blkbits = inode->i_blkbits;
106 blocks_per_page = PAGE_SIZE >> blkbits;
109 * Map all the blocks into the extent list. This code doesn't try
114 last_block = i_size_read(inode) >> blkbits;
115 while ((probe_block + blocks_per_page) <= last_block &&
116 page_no < sis->max) {
117 unsigned block_in_page;
118 sector_t first_block;
120 first_block = bmap(inode, probe_block);
121 if (first_block == 0)
125 * It must be PAGE_SIZE aligned on-disk
127 if (first_block & (blocks_per_page - 1)) {
132 for (block_in_page = 1; block_in_page < blocks_per_page;
136 block = bmap(inode, probe_block + block_in_page);
139 if (block != first_block + block_in_page) {
146 first_block >>= (PAGE_SHIFT - blkbits);
147 if (page_no) { /* exclude the header page */
148 if (first_block < lowest_block)
149 lowest_block = first_block;
150 if (first_block > highest_block)
151 highest_block = first_block;
155 * We found a PAGE_SIZE-length, PAGE_SIZE-aligned run of blocks
157 ret = add_swap_extent(sis, page_no, 1, first_block);
162 probe_block += blocks_per_page;
167 *span = 1 + highest_block - lowest_block;
169 page_no = 1; /* force Empty message */
171 sis->pages = page_no - 1;
172 sis->highest_bit = page_no - 1;
176 printk(KERN_ERR "swapon: swapfile has holes\n");
182 * We may have stale swap cache pages in memory: notice
183 * them here and get rid of the unnecessary final write.
185 int swap_writepage(struct page *page, struct writeback_control *wbc)
188 int ret = 0, rw = WRITE;
189 struct swap_info_struct *sis = page_swap_info(page);
191 if (try_to_free_swap(page)) {
195 if (frontswap_store(page) == 0) {
196 set_page_writeback(page);
198 end_page_writeback(page);
202 if (sis->flags & SWP_FILE) {
204 struct file *swap_file = sis->swap_file;
205 struct address_space *mapping = swap_file->f_mapping;
207 .iov_base = kmap(page),
208 .iov_len = PAGE_SIZE,
211 init_sync_kiocb(&kiocb, swap_file);
212 kiocb.ki_pos = page_file_offset(page);
213 kiocb.ki_left = PAGE_SIZE;
214 kiocb.ki_nbytes = PAGE_SIZE;
217 ret = mapping->a_ops->direct_IO(KERNEL_WRITE,
221 if (ret == PAGE_SIZE) {
222 count_vm_event(PSWPOUT);
228 bio = get_swap_bio(GFP_NOIO, page, end_swap_bio_write);
230 set_page_dirty(page);
235 if (wbc->sync_mode == WB_SYNC_ALL)
237 count_vm_event(PSWPOUT);
238 set_page_writeback(page);
245 int swap_readpage(struct page *page)
249 struct swap_info_struct *sis = page_swap_info(page);
251 VM_BUG_ON(!PageLocked(page));
252 VM_BUG_ON(PageUptodate(page));
253 if (frontswap_load(page) == 0) {
254 SetPageUptodate(page);
259 if (sis->flags & SWP_FILE) {
260 struct file *swap_file = sis->swap_file;
261 struct address_space *mapping = swap_file->f_mapping;
263 ret = mapping->a_ops->readpage(swap_file, page);
265 count_vm_event(PSWPIN);
269 bio = get_swap_bio(GFP_KERNEL, page, end_swap_bio_read);
275 count_vm_event(PSWPIN);
276 submit_bio(READ, bio);
281 int swap_set_page_dirty(struct page *page)
283 struct swap_info_struct *sis = page_swap_info(page);
285 if (sis->flags & SWP_FILE) {
286 struct address_space *mapping = sis->swap_file->f_mapping;
287 return mapping->a_ops->set_page_dirty(page);
289 return __set_page_dirty_no_writeback(page);