block: flush MEDIA_CHANGE from drivers on close(2)
[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 (q->limits.discard_granularity) {
63                 unsigned int disc_sects = q->limits.discard_granularity >> 9;
64
65                 max_discard_sectors &= ~(disc_sects - 1);
66         }
67
68         if (flags & BLKDEV_DISCARD_SECURE) {
69                 if (!blk_queue_secdiscard(q))
70                         return -EOPNOTSUPP;
71                 type |= REQ_SECURE;
72         }
73
74         atomic_set(&bb.done, 1);
75         bb.flags = 1 << BIO_UPTODATE;
76         bb.wait = &wait;
77
78         while (nr_sects) {
79                 bio = bio_alloc(gfp_mask, 1);
80                 if (!bio) {
81                         ret = -ENOMEM;
82                         break;
83                 }
84
85                 bio->bi_sector = sector;
86                 bio->bi_end_io = bio_batch_end_io;
87                 bio->bi_bdev = bdev;
88                 bio->bi_private = &bb;
89
90                 if (nr_sects > max_discard_sectors) {
91                         bio->bi_size = max_discard_sectors << 9;
92                         nr_sects -= max_discard_sectors;
93                         sector += max_discard_sectors;
94                 } else {
95                         bio->bi_size = nr_sects << 9;
96                         nr_sects = 0;
97                 }
98
99                 atomic_inc(&bb.done);
100                 submit_bio(type, bio);
101         }
102
103         /* Wait for bios in-flight */
104         if (!atomic_dec_and_test(&bb.done))
105                 wait_for_completion(&wait);
106
107         if (!test_bit(BIO_UPTODATE, &bb.flags))
108                 ret = -EIO;
109
110         return ret;
111 }
112 EXPORT_SYMBOL(blkdev_issue_discard);
113
114 /**
115  * blkdev_issue_zeroout - generate number of zero filed write bios
116  * @bdev:       blockdev to issue
117  * @sector:     start sector
118  * @nr_sects:   number of sectors to write
119  * @gfp_mask:   memory allocation flags (for bio_alloc)
120  *
121  * Description:
122  *  Generate and issue number of bios with zerofiled pages.
123  */
124
125 int blkdev_issue_zeroout(struct block_device *bdev, sector_t sector,
126                         sector_t nr_sects, gfp_t gfp_mask)
127 {
128         int ret;
129         struct bio *bio;
130         struct bio_batch bb;
131         unsigned int sz;
132         DECLARE_COMPLETION_ONSTACK(wait);
133
134         atomic_set(&bb.done, 1);
135         bb.flags = 1 << BIO_UPTODATE;
136         bb.wait = &wait;
137
138         ret = 0;
139         while (nr_sects != 0) {
140                 bio = bio_alloc(gfp_mask,
141                                 min(nr_sects, (sector_t)BIO_MAX_PAGES));
142                 if (!bio) {
143                         ret = -ENOMEM;
144                         break;
145                 }
146
147                 bio->bi_sector = sector;
148                 bio->bi_bdev   = bdev;
149                 bio->bi_end_io = bio_batch_end_io;
150                 bio->bi_private = &bb;
151
152                 while (nr_sects != 0) {
153                         sz = min((sector_t) PAGE_SIZE >> 9 , nr_sects);
154                         ret = bio_add_page(bio, ZERO_PAGE(0), sz << 9, 0);
155                         nr_sects -= ret >> 9;
156                         sector += ret >> 9;
157                         if (ret < (sz << 9))
158                                 break;
159                 }
160                 ret = 0;
161                 atomic_inc(&bb.done);
162                 submit_bio(WRITE, bio);
163         }
164
165         /* Wait for bios in-flight */
166         if (!atomic_dec_and_test(&bb.done))
167                 wait_for_completion(&wait);
168
169         if (!test_bit(BIO_UPTODATE, &bb.flags))
170                 /* One of bios in the batch was completed with error.*/
171                 ret = -EIO;
172
173         return ret;
174 }
175 EXPORT_SYMBOL(blkdev_issue_zeroout);