2 * fs/logfs/dev_bdev.c - Device access methods for block devices
4 * As should be obvious for Linux kernel code, license is GPLv2
6 * Copyright (c) 2005-2008 Joern Engel <joern@logfs.org>
10 #include <linux/blkdev.h>
11 #include <linux/buffer_head.h>
13 #define PAGE_OFS(ofs) ((ofs) & (PAGE_SIZE-1))
15 static void request_complete(struct bio *bio, int err)
17 complete((struct completion *)bio->bi_private);
20 static int sync_request(struct page *page, struct block_device *bdev, int rw)
23 struct bio_vec bio_vec;
24 struct completion complete;
27 bio.bi_io_vec = &bio_vec;
28 bio_vec.bv_page = page;
29 bio_vec.bv_len = PAGE_SIZE;
30 bio_vec.bv_offset = 0;
33 bio.bi_size = PAGE_SIZE;
35 bio.bi_sector = page->index * (PAGE_SIZE >> 9);
36 init_completion(&complete);
37 bio.bi_private = &complete;
38 bio.bi_end_io = request_complete;
41 generic_unplug_device(bdev_get_queue(bdev));
42 wait_for_completion(&complete);
43 return test_bit(BIO_UPTODATE, &bio.bi_flags) ? 0 : -EIO;
46 static int bdev_readpage(void *_sb, struct page *page)
48 struct super_block *sb = _sb;
49 struct block_device *bdev = logfs_super(sb)->s_bdev;
52 err = sync_request(page, bdev, READ);
54 ClearPageUptodate(page);
57 SetPageUptodate(page);
64 static DECLARE_WAIT_QUEUE_HEAD(wq);
66 static void writeseg_end_io(struct bio *bio, int err)
68 const int uptodate = test_bit(BIO_UPTODATE, &bio->bi_flags);
69 struct bio_vec *bvec = bio->bi_io_vec + bio->bi_vcnt - 1;
70 struct super_block *sb = bio->bi_private;
71 struct logfs_super *super = logfs_super(sb);
74 BUG_ON(!uptodate); /* FIXME: Retry io or write elsewhere */
76 BUG_ON(bio->bi_vcnt == 0);
79 if (--bvec >= bio->bi_io_vec)
80 prefetchw(&bvec->bv_page->flags);
82 end_page_writeback(page);
83 } while (bvec >= bio->bi_io_vec);
85 if (atomic_dec_and_test(&super->s_pending_writes))
89 static int __bdev_writeseg(struct super_block *sb, u64 ofs, pgoff_t index,
92 struct logfs_super *super = logfs_super(sb);
93 struct address_space *mapping = super->s_mapping_inode->i_mapping;
96 struct request_queue *q = bdev_get_queue(sb->s_bdev);
97 unsigned int max_pages = queue_max_hw_sectors(q) >> (PAGE_SHIFT - 9);
100 bio = bio_alloc(GFP_NOFS, max_pages);
101 BUG_ON(!bio); /* FIXME: handle this */
103 for (i = 0; i < nr_pages; i++) {
104 if (i >= max_pages) {
105 /* Block layer cannot split bios :( */
108 bio->bi_size = i * PAGE_SIZE;
109 bio->bi_bdev = super->s_bdev;
110 bio->bi_sector = ofs >> 9;
111 bio->bi_private = sb;
112 bio->bi_end_io = writeseg_end_io;
113 atomic_inc(&super->s_pending_writes);
114 submit_bio(WRITE, bio);
116 ofs += i * PAGE_SIZE;
121 bio = bio_alloc(GFP_NOFS, max_pages);
124 page = find_lock_page(mapping, index + i);
126 bio->bi_io_vec[i].bv_page = page;
127 bio->bi_io_vec[i].bv_len = PAGE_SIZE;
128 bio->bi_io_vec[i].bv_offset = 0;
130 BUG_ON(PageWriteback(page));
131 set_page_writeback(page);
134 bio->bi_vcnt = nr_pages;
136 bio->bi_size = nr_pages * PAGE_SIZE;
137 bio->bi_bdev = super->s_bdev;
138 bio->bi_sector = ofs >> 9;
139 bio->bi_private = sb;
140 bio->bi_end_io = writeseg_end_io;
141 atomic_inc(&super->s_pending_writes);
142 submit_bio(WRITE, bio);
146 static void bdev_writeseg(struct super_block *sb, u64 ofs, size_t len)
148 struct logfs_super *super = logfs_super(sb);
151 BUG_ON(super->s_flags & LOGFS_SB_FLAG_RO);
154 /* This can happen when the object fit perfectly into a
155 * segment, the segment gets written per sync and subsequently
160 head = ofs & (PAGE_SIZE - 1);
165 len = PAGE_ALIGN(len);
166 __bdev_writeseg(sb, ofs, ofs >> PAGE_SHIFT, len >> PAGE_SHIFT);
167 generic_unplug_device(bdev_get_queue(logfs_super(sb)->s_bdev));
170 static int bdev_erase(struct super_block *sb, loff_t to, size_t len)
172 struct logfs_super *super = logfs_super(sb);
173 struct address_space *mapping = super->s_mapping_inode->i_mapping;
175 pgoff_t index = to >> PAGE_SHIFT;
176 int i, nr_pages = len >> PAGE_SHIFT;
178 BUG_ON(to & (PAGE_SIZE - 1));
179 BUG_ON(len & (PAGE_SIZE - 1));
181 if (logfs_super(sb)->s_flags & LOGFS_SB_FLAG_RO)
184 for (i = 0; i < nr_pages; i++) {
185 page = find_get_page(mapping, index + i);
187 memset(page_address(page), 0xFF, PAGE_SIZE);
188 page_cache_release(page);
194 static void bdev_sync(struct super_block *sb)
196 struct logfs_super *super = logfs_super(sb);
198 wait_event(wq, atomic_read(&super->s_pending_writes) == 0);
201 static struct page *bdev_find_first_sb(struct super_block *sb, u64 *ofs)
203 struct logfs_super *super = logfs_super(sb);
204 struct address_space *mapping = super->s_mapping_inode->i_mapping;
205 filler_t *filler = bdev_readpage;
208 return read_cache_page(mapping, 0, filler, sb);
211 static struct page *bdev_find_last_sb(struct super_block *sb, u64 *ofs)
213 struct logfs_super *super = logfs_super(sb);
214 struct address_space *mapping = super->s_mapping_inode->i_mapping;
215 filler_t *filler = bdev_readpage;
216 u64 pos = (super->s_bdev->bd_inode->i_size & ~0xfffULL) - 0x1000;
217 pgoff_t index = pos >> PAGE_SHIFT;
220 return read_cache_page(mapping, index, filler, sb);
223 static int bdev_write_sb(struct super_block *sb, struct page *page)
225 struct block_device *bdev = logfs_super(sb)->s_bdev;
227 /* Nothing special to do for block devices. */
228 return sync_request(page, bdev, WRITE);
231 static void bdev_put_device(struct super_block *sb)
233 close_bdev_exclusive(logfs_super(sb)->s_bdev, FMODE_READ|FMODE_WRITE);
236 static const struct logfs_device_ops bd_devops = {
237 .find_first_sb = bdev_find_first_sb,
238 .find_last_sb = bdev_find_last_sb,
239 .write_sb = bdev_write_sb,
240 .readpage = bdev_readpage,
241 .writeseg = bdev_writeseg,
244 .put_device = bdev_put_device,
247 int logfs_get_sb_bdev(struct file_system_type *type, int flags,
248 const char *devname, struct vfsmount *mnt)
250 struct block_device *bdev;
252 bdev = open_bdev_exclusive(devname, FMODE_READ|FMODE_WRITE, type);
254 return PTR_ERR(bdev);
256 if (MAJOR(bdev->bd_dev) == MTD_BLOCK_MAJOR) {
257 int mtdnr = MINOR(bdev->bd_dev);
258 close_bdev_exclusive(bdev, FMODE_READ|FMODE_WRITE);
259 return logfs_get_sb_mtd(type, flags, mtdnr, mnt);
262 return logfs_get_sb_device(type, flags, NULL, bdev, &bd_devops, mnt);