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 page_cache_release(page
);
84 } while (bvec
>= bio
->bi_io_vec
);
86 if (atomic_dec_and_test(&super
->s_pending_writes
))
90 static int __bdev_writeseg(struct super_block
*sb
, u64 ofs
, pgoff_t index
,
93 struct logfs_super
*super
= logfs_super(sb
);
94 struct address_space
*mapping
= super
->s_mapping_inode
->i_mapping
;
97 struct request_queue
*q
= bdev_get_queue(sb
->s_bdev
);
98 unsigned int max_pages
= queue_max_hw_sectors(q
) >> (PAGE_SHIFT
- 9);
101 if (max_pages
> BIO_MAX_PAGES
)
102 max_pages
= BIO_MAX_PAGES
;
103 bio
= bio_alloc(GFP_NOFS
, max_pages
);
106 for (i
= 0; i
< nr_pages
; i
++) {
107 if (i
>= max_pages
) {
108 /* Block layer cannot split bios :( */
111 bio
->bi_size
= i
* PAGE_SIZE
;
112 bio
->bi_bdev
= super
->s_bdev
;
113 bio
->bi_sector
= ofs
>> 9;
114 bio
->bi_private
= sb
;
115 bio
->bi_end_io
= writeseg_end_io
;
116 atomic_inc(&super
->s_pending_writes
);
117 submit_bio(WRITE
, bio
);
119 ofs
+= i
* PAGE_SIZE
;
124 bio
= bio_alloc(GFP_NOFS
, max_pages
);
127 page
= find_lock_page(mapping
, index
+ i
);
129 bio
->bi_io_vec
[i
].bv_page
= page
;
130 bio
->bi_io_vec
[i
].bv_len
= PAGE_SIZE
;
131 bio
->bi_io_vec
[i
].bv_offset
= 0;
133 BUG_ON(PageWriteback(page
));
134 set_page_writeback(page
);
137 bio
->bi_vcnt
= nr_pages
;
139 bio
->bi_size
= nr_pages
* PAGE_SIZE
;
140 bio
->bi_bdev
= super
->s_bdev
;
141 bio
->bi_sector
= ofs
>> 9;
142 bio
->bi_private
= sb
;
143 bio
->bi_end_io
= writeseg_end_io
;
144 atomic_inc(&super
->s_pending_writes
);
145 submit_bio(WRITE
, bio
);
149 static void bdev_writeseg(struct super_block
*sb
, u64 ofs
, size_t len
)
151 struct logfs_super
*super
= logfs_super(sb
);
154 BUG_ON(super
->s_flags
& LOGFS_SB_FLAG_RO
);
157 /* This can happen when the object fit perfectly into a
158 * segment, the segment gets written per sync and subsequently
163 head
= ofs
& (PAGE_SIZE
- 1);
168 len
= PAGE_ALIGN(len
);
169 __bdev_writeseg(sb
, ofs
, ofs
>> PAGE_SHIFT
, len
>> PAGE_SHIFT
);
170 generic_unplug_device(bdev_get_queue(logfs_super(sb
)->s_bdev
));
174 static void erase_end_io(struct bio
*bio
, int err
)
176 const int uptodate
= test_bit(BIO_UPTODATE
, &bio
->bi_flags
);
177 struct super_block
*sb
= bio
->bi_private
;
178 struct logfs_super
*super
= logfs_super(sb
);
180 BUG_ON(!uptodate
); /* FIXME: Retry io or write elsewhere */
182 BUG_ON(bio
->bi_vcnt
== 0);
184 if (atomic_dec_and_test(&super
->s_pending_writes
))
188 static int do_erase(struct super_block
*sb
, u64 ofs
, pgoff_t index
,
191 struct logfs_super
*super
= logfs_super(sb
);
193 struct request_queue
*q
= bdev_get_queue(sb
->s_bdev
);
194 unsigned int max_pages
= queue_max_hw_sectors(q
) >> (PAGE_SHIFT
- 9);
197 if (max_pages
> BIO_MAX_PAGES
)
198 max_pages
= BIO_MAX_PAGES
;
199 bio
= bio_alloc(GFP_NOFS
, max_pages
);
202 for (i
= 0; i
< nr_pages
; i
++) {
203 if (i
>= max_pages
) {
204 /* Block layer cannot split bios :( */
207 bio
->bi_size
= i
* PAGE_SIZE
;
208 bio
->bi_bdev
= super
->s_bdev
;
209 bio
->bi_sector
= ofs
>> 9;
210 bio
->bi_private
= sb
;
211 bio
->bi_end_io
= erase_end_io
;
212 atomic_inc(&super
->s_pending_writes
);
213 submit_bio(WRITE
, bio
);
215 ofs
+= i
* PAGE_SIZE
;
220 bio
= bio_alloc(GFP_NOFS
, max_pages
);
223 bio
->bi_io_vec
[i
].bv_page
= super
->s_erase_page
;
224 bio
->bi_io_vec
[i
].bv_len
= PAGE_SIZE
;
225 bio
->bi_io_vec
[i
].bv_offset
= 0;
227 bio
->bi_vcnt
= nr_pages
;
229 bio
->bi_size
= nr_pages
* PAGE_SIZE
;
230 bio
->bi_bdev
= super
->s_bdev
;
231 bio
->bi_sector
= ofs
>> 9;
232 bio
->bi_private
= sb
;
233 bio
->bi_end_io
= erase_end_io
;
234 atomic_inc(&super
->s_pending_writes
);
235 submit_bio(WRITE
, bio
);
239 static int bdev_erase(struct super_block
*sb
, loff_t to
, size_t len
,
242 struct logfs_super
*super
= logfs_super(sb
);
244 BUG_ON(to
& (PAGE_SIZE
- 1));
245 BUG_ON(len
& (PAGE_SIZE
- 1));
247 if (super
->s_flags
& LOGFS_SB_FLAG_RO
)
252 * Object store doesn't care whether erases happen or not.
253 * But for the journal they are required. Otherwise a scan
254 * can find an old commit entry and assume it is the current
255 * one, travelling back in time.
257 do_erase(sb
, to
, to
>> PAGE_SHIFT
, len
>> PAGE_SHIFT
);
263 static void bdev_sync(struct super_block
*sb
)
265 struct logfs_super
*super
= logfs_super(sb
);
267 wait_event(wq
, atomic_read(&super
->s_pending_writes
) == 0);
270 static struct page
*bdev_find_first_sb(struct super_block
*sb
, u64
*ofs
)
272 struct logfs_super
*super
= logfs_super(sb
);
273 struct address_space
*mapping
= super
->s_mapping_inode
->i_mapping
;
274 filler_t
*filler
= bdev_readpage
;
277 return read_cache_page(mapping
, 0, filler
, sb
);
280 static struct page
*bdev_find_last_sb(struct super_block
*sb
, u64
*ofs
)
282 struct logfs_super
*super
= logfs_super(sb
);
283 struct address_space
*mapping
= super
->s_mapping_inode
->i_mapping
;
284 filler_t
*filler
= bdev_readpage
;
285 u64 pos
= (super
->s_bdev
->bd_inode
->i_size
& ~0xfffULL
) - 0x1000;
286 pgoff_t index
= pos
>> PAGE_SHIFT
;
289 return read_cache_page(mapping
, index
, filler
, sb
);
292 static int bdev_write_sb(struct super_block
*sb
, struct page
*page
)
294 struct block_device
*bdev
= logfs_super(sb
)->s_bdev
;
296 /* Nothing special to do for block devices. */
297 return sync_request(page
, bdev
, WRITE
);
300 static void bdev_put_device(struct super_block
*sb
)
302 close_bdev_exclusive(logfs_super(sb
)->s_bdev
, FMODE_READ
|FMODE_WRITE
);
305 static const struct logfs_device_ops bd_devops
= {
306 .find_first_sb
= bdev_find_first_sb
,
307 .find_last_sb
= bdev_find_last_sb
,
308 .write_sb
= bdev_write_sb
,
309 .readpage
= bdev_readpage
,
310 .writeseg
= bdev_writeseg
,
313 .put_device
= bdev_put_device
,
316 int logfs_get_sb_bdev(struct file_system_type
*type
, int flags
,
317 const char *devname
, struct vfsmount
*mnt
)
319 struct block_device
*bdev
;
321 bdev
= open_bdev_exclusive(devname
, FMODE_READ
|FMODE_WRITE
, type
);
323 return PTR_ERR(bdev
);
325 if (MAJOR(bdev
->bd_dev
) == MTD_BLOCK_MAJOR
) {
326 int mtdnr
= MINOR(bdev
->bd_dev
);
327 close_bdev_exclusive(bdev
, FMODE_READ
|FMODE_WRITE
);
328 return logfs_get_sb_mtd(type
, flags
, mtdnr
, mnt
);
331 return logfs_get_sb_device(type
, flags
, NULL
, bdev
, &bd_devops
, mnt
);