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)56 static void writeseg_end_io(struct bio *bio)
57 {
58 struct bio_vec *bvec;
59 int i;
60 struct super_block *sb = bio->bi_private;
61 struct logfs_super *super = logfs_super(sb);
62
63 BUG_ON(bio->bi_error); /* FIXME: Retry io or write elsewhere */
64
65 bio_for_each_segment_all(bvec, bio, i) {
66 end_page_writeback(bvec->bv_page);
67 page_cache_release(bvec->bv_page);
68 }
69 bio_put(bio);
70 if (atomic_dec_and_test(&super->s_pending_writes))
71 wake_up(&wq);
72 }
73
__bdev_writeseg(struct super_block * sb,u64 ofs,pgoff_t index,size_t nr_pages)74 static int __bdev_writeseg(struct super_block *sb, u64 ofs, pgoff_t index,
75 size_t nr_pages)
76 {
77 struct logfs_super *super = logfs_super(sb);
78 struct address_space *mapping = super->s_mapping_inode->i_mapping;
79 struct bio *bio;
80 struct page *page;
81 unsigned int max_pages;
82 int i;
83
84 max_pages = min_t(size_t, nr_pages, BIO_MAX_PAGES);
85
86 bio = bio_alloc(GFP_NOFS, max_pages);
87 BUG_ON(!bio);
88
89 for (i = 0; i < nr_pages; i++) {
90 if (i >= max_pages) {
91 /* Block layer cannot split bios :( */
92 bio->bi_vcnt = i;
93 bio->bi_iter.bi_size = i * PAGE_SIZE;
94 bio->bi_bdev = super->s_bdev;
95 bio->bi_iter.bi_sector = ofs >> 9;
96 bio->bi_private = sb;
97 bio->bi_end_io = writeseg_end_io;
98 atomic_inc(&super->s_pending_writes);
99 submit_bio(WRITE, bio);
100
101 ofs += i * PAGE_SIZE;
102 index += i;
103 nr_pages -= i;
104 i = 0;
105
106 bio = bio_alloc(GFP_NOFS, max_pages);
107 BUG_ON(!bio);
108 }
109 page = find_lock_page(mapping, index + i);
110 BUG_ON(!page);
111 bio->bi_io_vec[i].bv_page = page;
112 bio->bi_io_vec[i].bv_len = PAGE_SIZE;
113 bio->bi_io_vec[i].bv_offset = 0;
114
115 BUG_ON(PageWriteback(page));
116 set_page_writeback(page);
117 unlock_page(page);
118 }
119 bio->bi_vcnt = nr_pages;
120 bio->bi_iter.bi_size = nr_pages * PAGE_SIZE;
121 bio->bi_bdev = super->s_bdev;
122 bio->bi_iter.bi_sector = ofs >> 9;
123 bio->bi_private = sb;
124 bio->bi_end_io = writeseg_end_io;
125 atomic_inc(&super->s_pending_writes);
126 submit_bio(WRITE, bio);
127 return 0;
128 }
129
bdev_writeseg(struct super_block * sb,u64 ofs,size_t len)130 static void bdev_writeseg(struct super_block *sb, u64 ofs, size_t len)
131 {
132 struct logfs_super *super = logfs_super(sb);
133 int head;
134
135 BUG_ON(super->s_flags & LOGFS_SB_FLAG_RO);
136
137 if (len == 0) {
138 /* This can happen when the object fit perfectly into a
139 * segment, the segment gets written per sync and subsequently
140 * closed.
141 */
142 return;
143 }
144 head = ofs & (PAGE_SIZE - 1);
145 if (head) {
146 ofs -= head;
147 len += head;
148 }
149 len = PAGE_ALIGN(len);
150 __bdev_writeseg(sb, ofs, ofs >> PAGE_SHIFT, len >> PAGE_SHIFT);
151 }
152
153
erase_end_io(struct bio * bio)154 static void erase_end_io(struct bio *bio)
155 {
156 struct super_block *sb = bio->bi_private;
157 struct logfs_super *super = logfs_super(sb);
158
159 BUG_ON(bio->bi_error); /* FIXME: Retry io or write elsewhere */
160 BUG_ON(bio->bi_vcnt == 0);
161 bio_put(bio);
162 if (atomic_dec_and_test(&super->s_pending_writes))
163 wake_up(&wq);
164 }
165
do_erase(struct super_block * sb,u64 ofs,pgoff_t index,size_t nr_pages)166 static int do_erase(struct super_block *sb, u64 ofs, pgoff_t index,
167 size_t nr_pages)
168 {
169 struct logfs_super *super = logfs_super(sb);
170 struct bio *bio;
171 unsigned int max_pages;
172 int i;
173
174 max_pages = min_t(size_t, nr_pages, BIO_MAX_PAGES);
175
176 bio = bio_alloc(GFP_NOFS, max_pages);
177 BUG_ON(!bio);
178
179 for (i = 0; i < nr_pages; i++) {
180 if (i >= max_pages) {
181 /* Block layer cannot split bios :( */
182 bio->bi_vcnt = i;
183 bio->bi_iter.bi_size = i * PAGE_SIZE;
184 bio->bi_bdev = super->s_bdev;
185 bio->bi_iter.bi_sector = ofs >> 9;
186 bio->bi_private = sb;
187 bio->bi_end_io = erase_end_io;
188 atomic_inc(&super->s_pending_writes);
189 submit_bio(WRITE, bio);
190
191 ofs += i * PAGE_SIZE;
192 index += i;
193 nr_pages -= i;
194 i = 0;
195
196 bio = bio_alloc(GFP_NOFS, max_pages);
197 BUG_ON(!bio);
198 }
199 bio->bi_io_vec[i].bv_page = super->s_erase_page;
200 bio->bi_io_vec[i].bv_len = PAGE_SIZE;
201 bio->bi_io_vec[i].bv_offset = 0;
202 }
203 bio->bi_vcnt = nr_pages;
204 bio->bi_iter.bi_size = nr_pages * PAGE_SIZE;
205 bio->bi_bdev = super->s_bdev;
206 bio->bi_iter.bi_sector = ofs >> 9;
207 bio->bi_private = sb;
208 bio->bi_end_io = erase_end_io;
209 atomic_inc(&super->s_pending_writes);
210 submit_bio(WRITE, bio);
211 return 0;
212 }
213
bdev_erase(struct super_block * sb,loff_t to,size_t len,int ensure_write)214 static int bdev_erase(struct super_block *sb, loff_t to, size_t len,
215 int ensure_write)
216 {
217 struct logfs_super *super = logfs_super(sb);
218
219 BUG_ON(to & (PAGE_SIZE - 1));
220 BUG_ON(len & (PAGE_SIZE - 1));
221
222 if (super->s_flags & LOGFS_SB_FLAG_RO)
223 return -EROFS;
224
225 if (ensure_write) {
226 /*
227 * Object store doesn't care whether erases happen or not.
228 * But for the journal they are required. Otherwise a scan
229 * can find an old commit entry and assume it is the current
230 * one, travelling back in time.
231 */
232 do_erase(sb, to, to >> PAGE_SHIFT, len >> PAGE_SHIFT);
233 }
234
235 return 0;
236 }
237
bdev_sync(struct super_block * sb)238 static void bdev_sync(struct super_block *sb)
239 {
240 struct logfs_super *super = logfs_super(sb);
241
242 wait_event(wq, atomic_read(&super->s_pending_writes) == 0);
243 }
244
bdev_find_first_sb(struct super_block * sb,u64 * ofs)245 static struct page *bdev_find_first_sb(struct super_block *sb, u64 *ofs)
246 {
247 struct logfs_super *super = logfs_super(sb);
248 struct address_space *mapping = super->s_mapping_inode->i_mapping;
249 filler_t *filler = bdev_readpage;
250
251 *ofs = 0;
252 return read_cache_page(mapping, 0, filler, sb);
253 }
254
bdev_find_last_sb(struct super_block * sb,u64 * ofs)255 static struct page *bdev_find_last_sb(struct super_block *sb, u64 *ofs)
256 {
257 struct logfs_super *super = logfs_super(sb);
258 struct address_space *mapping = super->s_mapping_inode->i_mapping;
259 filler_t *filler = bdev_readpage;
260 u64 pos = (super->s_bdev->bd_inode->i_size & ~0xfffULL) - 0x1000;
261 pgoff_t index = pos >> PAGE_SHIFT;
262
263 *ofs = pos;
264 return read_cache_page(mapping, index, filler, sb);
265 }
266
bdev_write_sb(struct super_block * sb,struct page * page)267 static int bdev_write_sb(struct super_block *sb, struct page *page)
268 {
269 struct block_device *bdev = logfs_super(sb)->s_bdev;
270
271 /* Nothing special to do for block devices. */
272 return sync_request(page, bdev, WRITE);
273 }
274
bdev_put_device(struct logfs_super * s)275 static void bdev_put_device(struct logfs_super *s)
276 {
277 blkdev_put(s->s_bdev, FMODE_READ|FMODE_WRITE|FMODE_EXCL);
278 }
279
bdev_can_write_buf(struct super_block * sb,u64 ofs)280 static int bdev_can_write_buf(struct super_block *sb, u64 ofs)
281 {
282 return 0;
283 }
284
285 static const struct logfs_device_ops bd_devops = {
286 .find_first_sb = bdev_find_first_sb,
287 .find_last_sb = bdev_find_last_sb,
288 .write_sb = bdev_write_sb,
289 .readpage = bdev_readpage,
290 .writeseg = bdev_writeseg,
291 .erase = bdev_erase,
292 .can_write_buf = bdev_can_write_buf,
293 .sync = bdev_sync,
294 .put_device = bdev_put_device,
295 };
296
logfs_get_sb_bdev(struct logfs_super * p,struct file_system_type * type,const char * devname)297 int logfs_get_sb_bdev(struct logfs_super *p, struct file_system_type *type,
298 const char *devname)
299 {
300 struct block_device *bdev;
301
302 bdev = blkdev_get_by_path(devname, FMODE_READ|FMODE_WRITE|FMODE_EXCL,
303 type);
304 if (IS_ERR(bdev))
305 return PTR_ERR(bdev);
306
307 if (MAJOR(bdev->bd_dev) == MTD_BLOCK_MAJOR) {
308 int mtdnr = MINOR(bdev->bd_dev);
309 blkdev_put(bdev, FMODE_READ|FMODE_WRITE|FMODE_EXCL);
310 return logfs_get_sb_mtd(p, mtdnr);
311 }
312
313 p->s_bdev = bdev;
314 p->s_mtd = NULL;
315 p->s_devops = &bd_devops;
316 return 0;
317 }
318