Root/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
12struct bio_batch {
13    atomic_t done;
14    unsigned long flags;
15    struct completion *wait;
16};
17
18static 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 */
40int 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    sector_t max_discard_sectors;
47    sector_t granularity, alignment;
48    struct bio_batch bb;
49    struct bio *bio;
50    int ret = 0;
51    struct blk_plug plug;
52
53    if (!q)
54        return -ENXIO;
55
56    if (!blk_queue_discard(q))
57        return -EOPNOTSUPP;
58
59    /* Zero-sector (unknown) and one-sector granularities are the same. */
60    granularity = max(q->limits.discard_granularity >> 9, 1U);
61    alignment = bdev_discard_alignment(bdev) >> 9;
62    alignment = sector_div(alignment, granularity);
63
64    /*
65     * Ensure that max_discard_sectors is of the proper
66     * granularity, so that requests stay aligned after a split.
67     */
68    max_discard_sectors = min(q->limits.max_discard_sectors, UINT_MAX >> 9);
69    sector_div(max_discard_sectors, granularity);
70    max_discard_sectors *= granularity;
71    if (unlikely(!max_discard_sectors)) {
72        /* Avoid infinite loop below. Being cautious never hurts. */
73        return -EOPNOTSUPP;
74    }
75
76    if (flags & BLKDEV_DISCARD_SECURE) {
77        if (!blk_queue_secdiscard(q))
78            return -EOPNOTSUPP;
79        type |= REQ_SECURE;
80    }
81
82    atomic_set(&bb.done, 1);
83    bb.flags = 1 << BIO_UPTODATE;
84    bb.wait = &wait;
85
86    blk_start_plug(&plug);
87    while (nr_sects) {
88        unsigned int req_sects;
89        sector_t end_sect, tmp;
90
91        bio = bio_alloc(gfp_mask, 1);
92        if (!bio) {
93            ret = -ENOMEM;
94            break;
95        }
96
97        req_sects = min_t(sector_t, nr_sects, max_discard_sectors);
98
99        /*
100         * If splitting a request, and the next starting sector would be
101         * misaligned, stop the discard at the previous aligned sector.
102         */
103        end_sect = sector + req_sects;
104        tmp = end_sect;
105        if (req_sects < nr_sects &&
106            sector_div(tmp, granularity) != alignment) {
107            end_sect = end_sect - alignment;
108            sector_div(end_sect, granularity);
109            end_sect = end_sect * granularity + alignment;
110            req_sects = end_sect - sector;
111        }
112
113        bio->bi_sector = sector;
114        bio->bi_end_io = bio_batch_end_io;
115        bio->bi_bdev = bdev;
116        bio->bi_private = &bb;
117
118        bio->bi_size = req_sects << 9;
119        nr_sects -= req_sects;
120        sector = end_sect;
121
122        atomic_inc(&bb.done);
123        submit_bio(type, bio);
124    }
125    blk_finish_plug(&plug);
126
127    /* Wait for bios in-flight */
128    if (!atomic_dec_and_test(&bb.done))
129        wait_for_completion_io(&wait);
130
131    if (!test_bit(BIO_UPTODATE, &bb.flags))
132        ret = -EIO;
133
134    return ret;
135}
136EXPORT_SYMBOL(blkdev_issue_discard);
137
138/**
139 * blkdev_issue_write_same - queue a write same operation
140 * @bdev: target blockdev
141 * @sector: start sector
142 * @nr_sects: number of sectors to write
143 * @gfp_mask: memory allocation flags (for bio_alloc)
144 * @page: page containing data to write
145 *
146 * Description:
147 * Issue a write same request for the sectors in question.
148 */
149int blkdev_issue_write_same(struct block_device *bdev, sector_t sector,
150                sector_t nr_sects, gfp_t gfp_mask,
151                struct page *page)
152{
153    DECLARE_COMPLETION_ONSTACK(wait);
154    struct request_queue *q = bdev_get_queue(bdev);
155    unsigned int max_write_same_sectors;
156    struct bio_batch bb;
157    struct bio *bio;
158    int ret = 0;
159
160    if (!q)
161        return -ENXIO;
162
163    max_write_same_sectors = q->limits.max_write_same_sectors;
164
165    if (max_write_same_sectors == 0)
166        return -EOPNOTSUPP;
167
168    atomic_set(&bb.done, 1);
169    bb.flags = 1 << BIO_UPTODATE;
170    bb.wait = &wait;
171
172    while (nr_sects) {
173        bio = bio_alloc(gfp_mask, 1);
174        if (!bio) {
175            ret = -ENOMEM;
176            break;
177        }
178
179        bio->bi_sector = sector;
180        bio->bi_end_io = bio_batch_end_io;
181        bio->bi_bdev = bdev;
182        bio->bi_private = &bb;
183        bio->bi_vcnt = 1;
184        bio->bi_io_vec->bv_page = page;
185        bio->bi_io_vec->bv_offset = 0;
186        bio->bi_io_vec->bv_len = bdev_logical_block_size(bdev);
187
188        if (nr_sects > max_write_same_sectors) {
189            bio->bi_size = max_write_same_sectors << 9;
190            nr_sects -= max_write_same_sectors;
191            sector += max_write_same_sectors;
192        } else {
193            bio->bi_size = nr_sects << 9;
194            nr_sects = 0;
195        }
196
197        atomic_inc(&bb.done);
198        submit_bio(REQ_WRITE | REQ_WRITE_SAME, bio);
199    }
200
201    /* Wait for bios in-flight */
202    if (!atomic_dec_and_test(&bb.done))
203        wait_for_completion_io(&wait);
204
205    if (!test_bit(BIO_UPTODATE, &bb.flags))
206        ret = -ENOTSUPP;
207
208    return ret;
209}
210EXPORT_SYMBOL(blkdev_issue_write_same);
211
212/**
213 * blkdev_issue_zeroout - generate number of zero filed write bios
214 * @bdev: blockdev to issue
215 * @sector: start sector
216 * @nr_sects: number of sectors to write
217 * @gfp_mask: memory allocation flags (for bio_alloc)
218 *
219 * Description:
220 * Generate and issue number of bios with zerofiled pages.
221 */
222
223int __blkdev_issue_zeroout(struct block_device *bdev, sector_t sector,
224            sector_t nr_sects, gfp_t gfp_mask)
225{
226    int ret;
227    struct bio *bio;
228    struct bio_batch bb;
229    unsigned int sz;
230    DECLARE_COMPLETION_ONSTACK(wait);
231
232    atomic_set(&bb.done, 1);
233    bb.flags = 1 << BIO_UPTODATE;
234    bb.wait = &wait;
235
236    ret = 0;
237    while (nr_sects != 0) {
238        bio = bio_alloc(gfp_mask,
239                min(nr_sects, (sector_t)BIO_MAX_PAGES));
240        if (!bio) {
241            ret = -ENOMEM;
242            break;
243        }
244
245        bio->bi_sector = sector;
246        bio->bi_bdev = bdev;
247        bio->bi_end_io = bio_batch_end_io;
248        bio->bi_private = &bb;
249
250        while (nr_sects != 0) {
251            sz = min((sector_t) PAGE_SIZE >> 9 , nr_sects);
252            ret = bio_add_page(bio, ZERO_PAGE(0), sz << 9, 0);
253            nr_sects -= ret >> 9;
254            sector += ret >> 9;
255            if (ret < (sz << 9))
256                break;
257        }
258        ret = 0;
259        atomic_inc(&bb.done);
260        submit_bio(WRITE, bio);
261    }
262
263    /* Wait for bios in-flight */
264    if (!atomic_dec_and_test(&bb.done))
265        wait_for_completion_io(&wait);
266
267    if (!test_bit(BIO_UPTODATE, &bb.flags))
268        /* One of bios in the batch was completed with error.*/
269        ret = -EIO;
270
271    return ret;
272}
273
274/**
275 * blkdev_issue_zeroout - zero-fill a block range
276 * @bdev: blockdev to write
277 * @sector: start sector
278 * @nr_sects: number of sectors to write
279 * @gfp_mask: memory allocation flags (for bio_alloc)
280 *
281 * Description:
282 * Generate and issue number of bios with zerofiled pages.
283 */
284
285int blkdev_issue_zeroout(struct block_device *bdev, sector_t sector,
286             sector_t nr_sects, gfp_t gfp_mask)
287{
288    if (bdev_write_same(bdev)) {
289        unsigned char bdn[BDEVNAME_SIZE];
290
291        if (!blkdev_issue_write_same(bdev, sector, nr_sects, gfp_mask,
292                         ZERO_PAGE(0)))
293            return 0;
294
295        bdevname(bdev, bdn);
296        pr_err("%s: WRITE SAME failed. Manually zeroing.\n", bdn);
297    }
298
299    return __blkdev_issue_zeroout(bdev, sector, nr_sects, gfp_mask);
300}
301EXPORT_SYMBOL(blkdev_issue_zeroout);
302

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