1/* 2 * fs/logfs/dev_bdev.c - Device access methods for block devices 3 * 4 * As should be obvious for Linux kernel code, license is GPLv2 5 * 6 * Copyright (c) 2005-2008 Joern Engel <joern@logfs.org> 7 */ 8#include "logfs.h" 9#include <linux/bio.h> 10#include <linux/blkdev.h> 11#include <linux/buffer_head.h> 12#include <linux/gfp.h> 13 14#define PAGE_OFS(ofs) ((ofs) & (PAGE_SIZE-1)) 15 16static void request_complete(struct bio *bio, int err) 17{ 18 complete((struct completion *)bio->bi_private); 19} 20 21static int sync_request(struct page *page, struct block_device *bdev, int rw) 22{ 23 struct bio bio; 24 struct bio_vec bio_vec; 25 struct completion complete; 26 27 bio_init(&bio); 28 bio.bi_io_vec = &bio_vec; 29 bio_vec.bv_page = page; 30 bio_vec.bv_len = PAGE_SIZE; 31 bio_vec.bv_offset = 0; 32 bio.bi_vcnt = 1; 33 bio.bi_idx = 0; 34 bio.bi_size = PAGE_SIZE; 35 bio.bi_bdev = bdev; 36 bio.bi_sector = page->index * (PAGE_SIZE >> 9); 37 init_completion(&complete); 38 bio.bi_private = &complete; 39 bio.bi_end_io = request_complete; 40 41 submit_bio(rw, &bio); 42 generic_unplug_device(bdev_get_queue(bdev)); 43 wait_for_completion(&complete); 44 return test_bit(BIO_UPTODATE, &bio.bi_flags) ? 0 : -EIO; 45} 46 47static int bdev_readpage(void *_sb, struct page *page) 48{ 49 struct super_block *sb = _sb; 50 struct block_device *bdev = logfs_super(sb)->s_bdev; 51 int err; 52 53 err = sync_request(page, bdev, READ); 54 if (err) { 55 ClearPageUptodate(page); 56 SetPageError(page); 57 } else { 58 SetPageUptodate(page); 59 ClearPageError(page); 60 } 61 unlock_page(page); 62 return err; 63} 64 65static DECLARE_WAIT_QUEUE_HEAD(wq); 66 67static void writeseg_end_io(struct bio *bio, int err) 68{ 69 const int uptodate = test_bit(BIO_UPTODATE, &bio->bi_flags); 70 struct bio_vec *bvec = bio->bi_io_vec + bio->bi_vcnt - 1; 71 struct super_block *sb = bio->bi_private; 72 struct logfs_super *super = logfs_super(sb); 73 struct page *page; 74 75 BUG_ON(!uptodate); 76 BUG_ON(err); 77 BUG_ON(bio->bi_vcnt == 0); 78 do { 79 page = bvec->bv_page; 80 if (--bvec >= bio->bi_io_vec) 81 prefetchw(&bvec->bv_page->flags); 82 83 end_page_writeback(page); 84 page_cache_release(page); 85 } while (bvec >= bio->bi_io_vec); 86 bio_put(bio); 87 if (atomic_dec_and_test(&super->s_pending_writes)) 88 wake_up(&wq); 89} 90 91static int __bdev_writeseg(struct super_block *sb, u64 ofs, pgoff_t index, 92 size_t nr_pages) 93{ 94 struct logfs_super *super = logfs_super(sb); 95 struct address_space *mapping = super->s_mapping_inode->i_mapping; 96 struct bio *bio; 97 struct page *page; 98 struct request_queue *q = bdev_get_queue(sb->s_bdev); 99 unsigned int max_pages = queue_max_hw_sectors(q) >> (PAGE_SHIFT - 9); 100 int i; 101 102 if (max_pages > BIO_MAX_PAGES) 103 max_pages = BIO_MAX_PAGES; 104 bio = bio_alloc(GFP_NOFS, max_pages); 105 BUG_ON(!bio); 106 107 for (i = 0; i < nr_pages; i++) { 108 if (i >= max_pages) { 109 /* Block layer cannot split bios :( */ 110 bio->bi_vcnt = i; 111 bio->bi_idx = 0; 112 bio->bi_size = i * PAGE_SIZE; 113 bio->bi_bdev = super->s_bdev; 114 bio->bi_sector = ofs >> 9; 115 bio->bi_private = sb; 116 bio->bi_end_io = writeseg_end_io; 117 atomic_inc(&super->s_pending_writes); 118 submit_bio(WRITE, bio); 119 120 ofs += i * PAGE_SIZE; 121 index += i; 122 nr_pages -= i; 123 i = 0; 124 125 bio = bio_alloc(GFP_NOFS, max_pages); 126 BUG_ON(!bio); 127 } 128 page = find_lock_page(mapping, index + i); 129 BUG_ON(!page); 130 bio->bi_io_vec[i].bv_page = page; 131 bio->bi_io_vec[i].bv_len = PAGE_SIZE; 132 bio->bi_io_vec[i].bv_offset = 0; 133 134 BUG_ON(PageWriteback(page)); 135 set_page_writeback(page); 136 unlock_page(page); 137 } 138 bio->bi_vcnt = nr_pages; 139 bio->bi_idx = 0; 140 bio->bi_size = nr_pages * PAGE_SIZE; 141 bio->bi_bdev = super->s_bdev; 142 bio->bi_sector = ofs >> 9; 143 bio->bi_private = sb; 144 bio->bi_end_io = writeseg_end_io; 145 atomic_inc(&super->s_pending_writes); 146 submit_bio(WRITE, bio); 147 return 0; 148} 149 150static void bdev_writeseg(struct super_block *sb, u64 ofs, size_t len) 151{ 152 struct logfs_super *super = logfs_super(sb); 153 int head; 154 155 BUG_ON(super->s_flags & LOGFS_SB_FLAG_RO); 156 157 if (len == 0) { 158 /* This can happen when the object fit perfectly into a 159 * segment, the segment gets written per sync and subsequently 160 * closed. 161 */ 162 return; 163 } 164 head = ofs & (PAGE_SIZE - 1); 165 if (head) { 166 ofs -= head; 167 len += head; 168 } 169 len = PAGE_ALIGN(len); 170 __bdev_writeseg(sb, ofs, ofs >> PAGE_SHIFT, len >> PAGE_SHIFT); 171 generic_unplug_device(bdev_get_queue(logfs_super(sb)->s_bdev)); 172} 173 174 175static void erase_end_io(struct bio *bio, int err) 176{ 177 const int uptodate = test_bit(BIO_UPTODATE, &bio->bi_flags); 178 struct super_block *sb = bio->bi_private; 179 struct logfs_super *super = logfs_super(sb); 180 181 BUG_ON(!uptodate); 182 BUG_ON(err); 183 BUG_ON(bio->bi_vcnt == 0); 184 bio_put(bio); 185 if (atomic_dec_and_test(&super->s_pending_writes)) 186 wake_up(&wq); 187} 188 189static int do_erase(struct super_block *sb, u64 ofs, pgoff_t index, 190 size_t nr_pages) 191{ 192 struct logfs_super *super = logfs_super(sb); 193 struct bio *bio; 194 struct request_queue *q = bdev_get_queue(sb->s_bdev); 195 unsigned int max_pages = queue_max_hw_sectors(q) >> (PAGE_SHIFT - 9); 196 int i; 197 198 if (max_pages > BIO_MAX_PAGES) 199 max_pages = BIO_MAX_PAGES; 200 bio = bio_alloc(GFP_NOFS, max_pages); 201 BUG_ON(!bio); 202 203 for (i = 0; i < nr_pages; i++) { 204 if (i >= max_pages) { 205 /* Block layer cannot split bios :( */ 206 bio->bi_vcnt = i; 207 bio->bi_idx = 0; 208 bio->bi_size = i * PAGE_SIZE; 209 bio->bi_bdev = super->s_bdev; 210 bio->bi_sector = ofs >> 9; 211 bio->bi_private = sb; 212 bio->bi_end_io = erase_end_io; 213 atomic_inc(&super->s_pending_writes); 214 submit_bio(WRITE, bio); 215 216 ofs += i * PAGE_SIZE; 217 index += i; 218 nr_pages -= i; 219 i = 0; 220 221 bio = bio_alloc(GFP_NOFS, max_pages); 222 BUG_ON(!bio); 223 } 224 bio->bi_io_vec[i].bv_page = super->s_erase_page; 225 bio->bi_io_vec[i].bv_len = PAGE_SIZE; 226 bio->bi_io_vec[i].bv_offset = 0; 227 } 228 bio->bi_vcnt = nr_pages; 229 bio->bi_idx = 0; 230 bio->bi_size = nr_pages * PAGE_SIZE; 231 bio->bi_bdev = super->s_bdev; 232 bio->bi_sector = ofs >> 9; 233 bio->bi_private = sb; 234 bio->bi_end_io = erase_end_io; 235 atomic_inc(&super->s_pending_writes); 236 submit_bio(WRITE, bio); 237 return 0; 238} 239 240static int bdev_erase(struct super_block *sb, loff_t to, size_t len, 241 int ensure_write) 242{ 243 struct logfs_super *super = logfs_super(sb); 244 245 BUG_ON(to & (PAGE_SIZE - 1)); 246 BUG_ON(len & (PAGE_SIZE - 1)); 247 248 if (super->s_flags & LOGFS_SB_FLAG_RO) 249 return -EROFS; 250 251 if (ensure_write) { 252 /* 253 * Object store doesn't care whether erases happen or not. 254 * But for the journal they are required. Otherwise a scan 255 * can find an old commit entry and assume it is the current 256 * one, travelling back in time. 257 */ 258 do_erase(sb, to, to >> PAGE_SHIFT, len >> PAGE_SHIFT); 259 } 260 261 return 0; 262} 263 264static void bdev_sync(struct super_block *sb) 265{ 266 struct logfs_super *super = logfs_super(sb); 267 268 wait_event(wq, atomic_read(&super->s_pending_writes) == 0); 269} 270 271static struct page *bdev_find_first_sb(struct super_block *sb, u64 *ofs) 272{ 273 struct logfs_super *super = logfs_super(sb); 274 struct address_space *mapping = super->s_mapping_inode->i_mapping; 275 filler_t *filler = bdev_readpage; 276 277 *ofs = 0; 278 return read_cache_page(mapping, 0, filler, sb); 279} 280 281static struct page *bdev_find_last_sb(struct super_block *sb, u64 *ofs) 282{ 283 struct logfs_super *super = logfs_super(sb); 284 struct address_space *mapping = super->s_mapping_inode->i_mapping; 285 filler_t *filler = bdev_readpage; 286 u64 pos = (super->s_bdev->bd_inode->i_size & ~0xfffULL) - 0x1000; 287 pgoff_t index = pos >> PAGE_SHIFT; 288 289 *ofs = pos; 290 return read_cache_page(mapping, index, filler, sb); 291} 292 293static int bdev_write_sb(struct super_block *sb, struct page *page) 294{ 295 struct block_device *bdev = logfs_super(sb)->s_bdev; 296 297 /* Nothing special to do for block devices. */ 298 return sync_request(page, bdev, WRITE); 299} 300 301static void bdev_put_device(struct super_block *sb) 302{ 303 close_bdev_exclusive(logfs_super(sb)->s_bdev, FMODE_READ|FMODE_WRITE); 304} 305 306static int bdev_can_write_buf(struct super_block *sb, u64 ofs) 307{ 308 return 0; 309} 310 311static const struct logfs_device_ops bd_devops = { 312 .find_first_sb = bdev_find_first_sb, 313 .find_last_sb = bdev_find_last_sb, 314 .write_sb = bdev_write_sb, 315 .readpage = bdev_readpage, 316 .writeseg = bdev_writeseg, 317 .erase = bdev_erase, 318 .can_write_buf = bdev_can_write_buf, 319 .sync = bdev_sync, 320 .put_device = bdev_put_device, 321}; 322 323int logfs_get_sb_bdev(struct file_system_type *type, int flags, 324 const char *devname, struct vfsmount *mnt) 325{ 326 struct block_device *bdev; 327 328 bdev = open_bdev_exclusive(devname, FMODE_READ|FMODE_WRITE, type); 329 if (IS_ERR(bdev)) 330 return PTR_ERR(bdev); 331 332 if (MAJOR(bdev->bd_dev) == MTD_BLOCK_MAJOR) { 333 int mtdnr = MINOR(bdev->bd_dev); 334 close_bdev_exclusive(bdev, FMODE_READ|FMODE_WRITE); 335 return logfs_get_sb_mtd(type, flags, mtdnr, mnt); 336 } 337 338 return logfs_get_sb_device(type, flags, NULL, bdev, &bd_devops, mnt); 339} 340