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