block/genhd.c: remove useless cast in diskstats_show()
[linux-2.6.git] / block / blk-lib.c
1 /*
2  * Functions related to generic helpers functions
3  */
4 #include <linux/kernel.h>
5 #include <linux/module.h>
6 #include <linux/bio.h>
7 #include <linux/blkdev.h>
8 #include <linux/scatterlist.h>
9
10 #include "blk.h"
11
12 struct bio_batch {
13         atomic_t                done;
14         unsigned long           flags;
15         struct completion       *wait;
16 };
17
18 static void bio_batch_end_io(struct bio *bio, int err)
19 {
20         struct bio_batch *bb = bio->bi_private;
21
22         if (err && (err != -EOPNOTSUPP))
23                 clear_bit(BIO_UPTODATE, &bb->flags);
24         if (atomic_dec_and_test(&bb->done))
25                 complete(bb->wait);
26         bio_put(bio);
27 }
28
29 /**
30  * blkdev_issue_discard - queue a discard
31  * @bdev:       blockdev to issue discard for
32  * @sector:     start sector
33  * @nr_sects:   number of sectors to discard
34  * @gfp_mask:   memory allocation flags (for bio_alloc)
35  * @flags:      BLKDEV_IFL_* flags to control behaviour
36  *
37  * Description:
38  *    Issue a discard request for the sectors in question.
39  */
40 int blkdev_issue_discard(struct block_device *bdev, sector_t sector,
41                 sector_t nr_sects, gfp_t gfp_mask, unsigned long flags)
42 {
43         DECLARE_COMPLETION_ONSTACK(wait);
44         struct request_queue *q = bdev_get_queue(bdev);
45         int type = REQ_WRITE | REQ_DISCARD;
46         unsigned int max_discard_sectors;
47         struct bio_batch bb;
48         struct bio *bio;
49         int ret = 0;
50
51         if (!q)
52                 return -ENXIO;
53
54         if (!blk_queue_discard(q))
55                 return -EOPNOTSUPP;
56
57         /*
58          * Ensure that max_discard_sectors is of the proper
59          * granularity
60          */
61         max_discard_sectors = min(q->limits.max_discard_sectors, UINT_MAX >> 9);
62         if (unlikely(!max_discard_sectors)) {
63                 /* Avoid infinite loop below. Being cautious never hurts. */
64                 return -EOPNOTSUPP;
65         } else if (q->limits.discard_granularity) {
66                 unsigned int disc_sects = q->limits.discard_granularity >> 9;
67
68                 max_discard_sectors &= ~(disc_sects - 1);
69         }
70
71         if (flags & BLKDEV_DISCARD_SECURE) {
72                 if (!blk_queue_secdiscard(q))
73                         return -EOPNOTSUPP;
74                 type |= REQ_SECURE;
75         }
76
77         atomic_set(&bb.done, 1);
78         bb.flags = 1 << BIO_UPTODATE;
79         bb.wait = &wait;
80
81         while (nr_sects) {
82                 bio = bio_alloc(gfp_mask, 1);
83                 if (!bio) {
84                         ret = -ENOMEM;
85                         break;
86                 }
87
88                 bio->bi_sector = sector;
89                 bio->bi_end_io = bio_batch_end_io;
90                 bio->bi_bdev = bdev;
91                 bio->bi_private = &bb;
92
93                 if (nr_sects > max_discard_sectors) {
94                         bio->bi_size = max_discard_sectors << 9;
95                         nr_sects -= max_discard_sectors;
96                         sector += max_discard_sectors;
97                 } else {
98                         bio->bi_size = nr_sects << 9;
99                         nr_sects = 0;
100                 }
101
102                 atomic_inc(&bb.done);
103                 submit_bio(type, bio);
104         }
105
106         /* Wait for bios in-flight */
107         if (!atomic_dec_and_test(&bb.done))
108                 wait_for_completion(&wait);
109
110         if (!test_bit(BIO_UPTODATE, &bb.flags))
111                 ret = -EIO;
112
113         return ret;
114 }
115 EXPORT_SYMBOL(blkdev_issue_discard);
116
117 /**
118  * blkdev_issue_zeroout - generate number of zero filed write bios
119  * @bdev:       blockdev to issue
120  * @sector:     start sector
121  * @nr_sects:   number of sectors to write
122  * @gfp_mask:   memory allocation flags (for bio_alloc)
123  *
124  * Description:
125  *  Generate and issue number of bios with zerofiled pages.
126  */
127
128 int blkdev_issue_zeroout(struct block_device *bdev, sector_t sector,
129                         sector_t nr_sects, gfp_t gfp_mask)
130 {
131         int ret;
132         struct bio *bio;
133         struct bio_batch bb;
134         unsigned int sz;
135         DECLARE_COMPLETION_ONSTACK(wait);
136
137         atomic_set(&bb.done, 1);
138         bb.flags = 1 << BIO_UPTODATE;
139         bb.wait = &wait;
140
141         ret = 0;
142         while (nr_sects != 0) {
143                 bio = bio_alloc(gfp_mask,
144                                 min(nr_sects, (sector_t)BIO_MAX_PAGES));
145                 if (!bio) {
146                         ret = -ENOMEM;
147                         break;
148                 }
149
150                 bio->bi_sector = sector;
151                 bio->bi_bdev   = bdev;
152                 bio->bi_end_io = bio_batch_end_io;
153                 bio->bi_private = &bb;
154
155                 while (nr_sects != 0) {
156                         sz = min((sector_t) PAGE_SIZE >> 9 , nr_sects);
157                         ret = bio_add_page(bio, ZERO_PAGE(0), sz << 9, 0);
158                         nr_sects -= ret >> 9;
159                         sector += ret >> 9;
160                         if (ret < (sz << 9))
161                                 break;
162                 }
163                 ret = 0;
164                 atomic_inc(&bb.done);
165                 submit_bio(WRITE, bio);
166         }
167
168         /* Wait for bios in-flight */
169         if (!atomic_dec_and_test(&bb.done))
170                 wait_for_completion(&wait);
171
172         if (!test_bit(BIO_UPTODATE, &bb.flags))
173                 /* One of bios in the batch was completed with error.*/
174                 ret = -EIO;
175
176         return ret;
177 }
178 EXPORT_SYMBOL(blkdev_issue_zeroout);