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5db53f3e JE |
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 | ||
13 | #define PAGE_OFS(ofs) ((ofs) & (PAGE_SIZE-1)) | |
14 | ||
15 | static void request_complete(struct bio *bio, int err) | |
16 | { | |
17 | complete((struct completion *)bio->bi_private); | |
18 | } | |
19 | ||
20 | static int sync_request(struct page *page, struct block_device *bdev, int rw) | |
21 | { | |
22 | struct bio bio; | |
23 | struct bio_vec bio_vec; | |
24 | struct completion complete; | |
25 | ||
26 | bio_init(&bio); | |
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; | |
31 | bio.bi_vcnt = 1; | |
32 | bio.bi_idx = 0; | |
33 | bio.bi_size = PAGE_SIZE; | |
34 | bio.bi_bdev = bdev; | |
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; | |
39 | ||
40 | submit_bio(rw, &bio); | |
41 | generic_unplug_device(bdev_get_queue(bdev)); | |
42 | wait_for_completion(&complete); | |
43 | return test_bit(BIO_UPTODATE, &bio.bi_flags) ? 0 : -EIO; | |
44 | } | |
45 | ||
46 | static int bdev_readpage(void *_sb, struct page *page) | |
47 | { | |
48 | struct super_block *sb = _sb; | |
49 | struct block_device *bdev = logfs_super(sb)->s_bdev; | |
50 | int err; | |
51 | ||
52 | err = sync_request(page, bdev, READ); | |
53 | if (err) { | |
54 | ClearPageUptodate(page); | |
55 | SetPageError(page); | |
56 | } else { | |
57 | SetPageUptodate(page); | |
58 | ClearPageError(page); | |
59 | } | |
60 | unlock_page(page); | |
61 | return err; | |
62 | } | |
63 | ||
64 | static DECLARE_WAIT_QUEUE_HEAD(wq); | |
65 | ||
66 | static void writeseg_end_io(struct bio *bio, int err) | |
67 | { | |
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); | |
72 | struct page *page; | |
73 | ||
74 | BUG_ON(!uptodate); /* FIXME: Retry io or write elsewhere */ | |
75 | BUG_ON(err); | |
76 | BUG_ON(bio->bi_vcnt == 0); | |
77 | do { | |
78 | page = bvec->bv_page; | |
79 | if (--bvec >= bio->bi_io_vec) | |
80 | prefetchw(&bvec->bv_page->flags); | |
81 | ||
82 | end_page_writeback(page); | |
83 | } while (bvec >= bio->bi_io_vec); | |
84 | bio_put(bio); | |
85 | if (atomic_dec_and_test(&super->s_pending_writes)) | |
86 | wake_up(&wq); | |
87 | } | |
88 | ||
89 | static int __bdev_writeseg(struct super_block *sb, u64 ofs, pgoff_t index, | |
90 | size_t nr_pages) | |
91 | { | |
92 | struct logfs_super *super = logfs_super(sb); | |
93 | struct address_space *mapping = super->s_mapping_inode->i_mapping; | |
94 | struct bio *bio; | |
95 | struct page *page; | |
96 | struct request_queue *q = bdev_get_queue(sb->s_bdev); | |
97 | unsigned int max_pages = queue_max_hw_sectors(q) >> (PAGE_SHIFT - 9); | |
98 | int i; | |
99 | ||
100 | bio = bio_alloc(GFP_NOFS, max_pages); | |
101 | BUG_ON(!bio); /* FIXME: handle this */ | |
102 | ||
103 | for (i = 0; i < nr_pages; i++) { | |
104 | if (i >= max_pages) { | |
105 | /* Block layer cannot split bios :( */ | |
106 | bio->bi_vcnt = i; | |
107 | bio->bi_idx = 0; | |
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); | |
115 | ||
116 | ofs += i * PAGE_SIZE; | |
117 | index += i; | |
118 | nr_pages -= i; | |
119 | i = 0; | |
120 | ||
121 | bio = bio_alloc(GFP_NOFS, max_pages); | |
122 | BUG_ON(!bio); | |
123 | } | |
124 | page = find_lock_page(mapping, index + i); | |
125 | BUG_ON(!page); | |
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; | |
129 | ||
130 | BUG_ON(PageWriteback(page)); | |
131 | set_page_writeback(page); | |
132 | unlock_page(page); | |
133 | } | |
134 | bio->bi_vcnt = nr_pages; | |
135 | bio->bi_idx = 0; | |
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); | |
143 | return 0; | |
144 | } | |
145 | ||
146 | static void bdev_writeseg(struct super_block *sb, u64 ofs, size_t len) | |
147 | { | |
148 | struct logfs_super *super = logfs_super(sb); | |
149 | int head; | |
150 | ||
151 | BUG_ON(super->s_flags & LOGFS_SB_FLAG_RO); | |
152 | ||
153 | if (len == 0) { | |
154 | /* This can happen when the object fit perfectly into a | |
155 | * segment, the segment gets written per sync and subsequently | |
156 | * closed. | |
157 | */ | |
158 | return; | |
159 | } | |
160 | head = ofs & (PAGE_SIZE - 1); | |
161 | if (head) { | |
162 | ofs -= head; | |
163 | len += head; | |
164 | } | |
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)); | |
168 | } | |
169 | ||
170 | static int bdev_erase(struct super_block *sb, loff_t to, size_t len) | |
171 | { | |
172 | struct logfs_super *super = logfs_super(sb); | |
173 | struct address_space *mapping = super->s_mapping_inode->i_mapping; | |
174 | struct page *page; | |
175 | pgoff_t index = to >> PAGE_SHIFT; | |
176 | int i, nr_pages = len >> PAGE_SHIFT; | |
177 | ||
178 | BUG_ON(to & (PAGE_SIZE - 1)); | |
179 | BUG_ON(len & (PAGE_SIZE - 1)); | |
180 | ||
181 | if (logfs_super(sb)->s_flags & LOGFS_SB_FLAG_RO) | |
182 | return -EROFS; | |
183 | ||
184 | for (i = 0; i < nr_pages; i++) { | |
185 | page = find_get_page(mapping, index + i); | |
186 | if (page) { | |
187 | memset(page_address(page), 0xFF, PAGE_SIZE); | |
188 | page_cache_release(page); | |
189 | } | |
190 | } | |
191 | return 0; | |
192 | } | |
193 | ||
194 | static void bdev_sync(struct super_block *sb) | |
195 | { | |
196 | struct logfs_super *super = logfs_super(sb); | |
197 | ||
198 | wait_event(wq, atomic_read(&super->s_pending_writes) == 0); | |
199 | } | |
200 | ||
201 | static struct page *bdev_find_first_sb(struct super_block *sb, u64 *ofs) | |
202 | { | |
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; | |
206 | ||
207 | *ofs = 0; | |
208 | return read_cache_page(mapping, 0, filler, sb); | |
209 | } | |
210 | ||
211 | static struct page *bdev_find_last_sb(struct super_block *sb, u64 *ofs) | |
212 | { | |
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; | |
218 | ||
219 | *ofs = pos; | |
220 | return read_cache_page(mapping, index, filler, sb); | |
221 | } | |
222 | ||
223 | static int bdev_write_sb(struct super_block *sb, struct page *page) | |
224 | { | |
225 | struct block_device *bdev = logfs_super(sb)->s_bdev; | |
226 | ||
227 | /* Nothing special to do for block devices. */ | |
228 | return sync_request(page, bdev, WRITE); | |
229 | } | |
230 | ||
231 | static void bdev_put_device(struct super_block *sb) | |
232 | { | |
233 | close_bdev_exclusive(logfs_super(sb)->s_bdev, FMODE_READ|FMODE_WRITE); | |
234 | } | |
235 | ||
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, | |
242 | .erase = bdev_erase, | |
243 | .sync = bdev_sync, | |
244 | .put_device = bdev_put_device, | |
245 | }; | |
246 | ||
247 | int logfs_get_sb_bdev(struct file_system_type *type, int flags, | |
248 | const char *devname, struct vfsmount *mnt) | |
249 | { | |
250 | struct block_device *bdev; | |
251 | ||
252 | bdev = open_bdev_exclusive(devname, FMODE_READ|FMODE_WRITE, type); | |
253 | if (IS_ERR(bdev)) | |
254 | return PTR_ERR(bdev); | |
255 | ||
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); | |
260 | } | |
261 | ||
262 | return logfs_get_sb_device(type, flags, NULL, bdev, &bd_devops, mnt); | |
263 | } |