path: root/block/blk-lib.c (plain)
blob: af1d26f798783fe858087454fde5c1ccde013640

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	static struct bio *next_bio(struct bio *bio, unsigned int nr_pages,
13	gfp_t gfp)
14	{
15	struct bio *new = bio_alloc(gfp, nr_pages);
16
17	if (bio) {
18	bio_chain(bio, new);
19	submit_bio(bio);
20	}
21
22	return new;
23	}
24
25	int __blkdev_issue_discard(struct block_device *bdev, sector_t sector,
26	sector_t nr_sects, gfp_t gfp_mask, int flags,
27	struct bio **biop)
28	{
29	struct request_queue *q = bdev_get_queue(bdev);
30	struct bio *bio = *biop;
31	unsigned int granularity;
32	enum req_op op;
33	int alignment;
34	sector_t bs_mask;
35
36	if (!q)
37	return -ENXIO;
38
39	if (flags & BLKDEV_DISCARD_SECURE) {
40	if (flags & BLKDEV_DISCARD_ZERO)
41	return -EOPNOTSUPP;
42	if (!blk_queue_secure_erase(q))
43	return -EOPNOTSUPP;
44	op = REQ_OP_SECURE_ERASE;
45	} else {
46	if (!blk_queue_discard(q))
47	return -EOPNOTSUPP;
48	if ((flags & BLKDEV_DISCARD_ZERO) &&
49	!q->limits.discard_zeroes_data)
50	return -EOPNOTSUPP;
51	op = REQ_OP_DISCARD;
52	}
53
54	bs_mask = (bdev_logical_block_size(bdev) >> 9) - 1;
55	if ((sector | nr_sects) & bs_mask)
56	return -EINVAL;
57
58	/* Zero-sector (unknown) and one-sector granularities are the same. */
59	granularity = max(q->limits.discard_granularity >> 9, 1U);
60	alignment = (bdev_discard_alignment(bdev) >> 9) % granularity;
61
62	while (nr_sects) {
63	unsigned int req_sects;
64	sector_t end_sect, tmp;
65
66	/*
67	* Issue in chunks of the user defined max discard setting,
68	* ensuring that bi_size doesn't overflow
69	*/
70	req_sects = min_t(sector_t, nr_sects,
71	q->limits.max_discard_sectors);
72	if (!req_sects)
73	goto fail;
74	if (req_sects > UINT_MAX >> 9)
75	req_sects = UINT_MAX >> 9;
76
77	/*
78	* If splitting a request, and the next starting sector would be
79	* misaligned, stop the discard at the previous aligned sector.
80	*/
81	end_sect = sector + req_sects;
82	tmp = end_sect;
83	if (req_sects < nr_sects &&
84	sector_div(tmp, granularity) != alignment) {
85	end_sect = end_sect - alignment;
86	sector_div(end_sect, granularity);
87	end_sect = end_sect * granularity + alignment;
88	req_sects = end_sect - sector;
89	}
90
91	bio = next_bio(bio, 1, gfp_mask);
92	bio->bi_iter.bi_sector = sector;
93	bio->bi_bdev = bdev;
94	bio_set_op_attrs(bio, op, 0);
95
96	bio->bi_iter.bi_size = req_sects << 9;
97	nr_sects -= req_sects;
98	sector = end_sect;
99
100	/*
101	* We can loop for a long time in here, if someone does
102	* full device discards (like mkfs). Be nice and allow
103	* us to schedule out to avoid softlocking if preempt
104	* is disabled.
105	*/
106	cond_resched();
107	}
108
109	*biop = bio;
110	return 0;
111
112	fail:
113	if (bio) {
114	submit_bio_wait(bio);
115	bio_put(bio);
116	}
117	*biop = NULL;
118	return -EOPNOTSUPP;
119	}
120	EXPORT_SYMBOL(__blkdev_issue_discard);
121
122	/**
123	* blkdev_issue_discard - queue a discard
124	* @bdev: blockdev to issue discard for
125	* @sector: start sector
126	* @nr_sects: number of sectors to discard
127	* @gfp_mask: memory allocation flags (for bio_alloc)
128	* @flags: BLKDEV_IFL_* flags to control behaviour
129	*
130	* Description:
131	* Issue a discard request for the sectors in question.
132	*/
133	int blkdev_issue_discard(struct block_device *bdev, sector_t sector,
134	sector_t nr_sects, gfp_t gfp_mask, unsigned long flags)
135	{
136	struct bio *bio = NULL;
137	struct blk_plug plug;
138	int ret;
139
140	blk_start_plug(&plug);
141	ret = __blkdev_issue_discard(bdev, sector, nr_sects, gfp_mask, flags,
142	&bio);
143	if (!ret && bio) {
144	ret = submit_bio_wait(bio);
145	if (ret == -EOPNOTSUPP && !(flags & BLKDEV_DISCARD_ZERO))
146	ret = 0;
147	bio_put(bio);
148	}
149	blk_finish_plug(&plug);
150
151	return ret;
152	}
153	EXPORT_SYMBOL(blkdev_issue_discard);
154
155	/**
156	* blkdev_issue_write_same - queue a write same operation
157	* @bdev: target blockdev
158	* @sector: start sector
159	* @nr_sects: number of sectors to write
160	* @gfp_mask: memory allocation flags (for bio_alloc)
161	* @page: page containing data to write
162	*
163	* Description:
164	* Issue a write same request for the sectors in question.
165	*/
166	int blkdev_issue_write_same(struct block_device *bdev, sector_t sector,
167	sector_t nr_sects, gfp_t gfp_mask,
168	struct page *page)
169	{
170	struct request_queue *q = bdev_get_queue(bdev);
171	unsigned int max_write_same_sectors;
172	struct bio *bio = NULL;
173	int ret = 0;
174	sector_t bs_mask;
175
176	if (!q)
177	return -ENXIO;
178
179	bs_mask = (bdev_logical_block_size(bdev) >> 9) - 1;
180	if ((sector | nr_sects) & bs_mask)
181	return -EINVAL;
182
183	/* Ensure that max_write_same_sectors doesn't overflow bi_size */
184	max_write_same_sectors = UINT_MAX >> 9;
185
186	while (nr_sects) {
187	bio = next_bio(bio, 1, gfp_mask);
188	bio->bi_iter.bi_sector = sector;
189	bio->bi_bdev = bdev;
190	bio->bi_vcnt = 1;
191	bio->bi_io_vec->bv_page = page;
192	bio->bi_io_vec->bv_offset = 0;
193	bio->bi_io_vec->bv_len = bdev_logical_block_size(bdev);
194	bio_set_op_attrs(bio, REQ_OP_WRITE_SAME, 0);
195
196	if (nr_sects > max_write_same_sectors) {
197	bio->bi_iter.bi_size = max_write_same_sectors << 9;
198	nr_sects -= max_write_same_sectors;
199	sector += max_write_same_sectors;
200	} else {
201	bio->bi_iter.bi_size = nr_sects << 9;
202	nr_sects = 0;
203	}
204	}
205
206	if (bio) {
207	ret = submit_bio_wait(bio);
208	bio_put(bio);
209	}
210	return ret;
211	}
212	EXPORT_SYMBOL(blkdev_issue_write_same);
213
214	/**
215	* blkdev_issue_zeroout - generate number of zero filed write bios
216	* @bdev: blockdev to issue
217	* @sector: start sector
218	* @nr_sects: number of sectors to write
219	* @gfp_mask: memory allocation flags (for bio_alloc)
220	*
221	* Description:
222	* Generate and issue number of bios with zerofiled pages.
223	*/
224
225	static int __blkdev_issue_zeroout(struct block_device *bdev, sector_t sector,
226	sector_t nr_sects, gfp_t gfp_mask)
227	{
228	int ret;
229	struct bio *bio = NULL;
230	unsigned int sz;
231	sector_t bs_mask;
232
233	bs_mask = (bdev_logical_block_size(bdev) >> 9) - 1;
234	if ((sector | nr_sects) & bs_mask)
235	return -EINVAL;
236
237	while (nr_sects != 0) {
238	bio = next_bio(bio, min(nr_sects, (sector_t)BIO_MAX_PAGES),
239	gfp_mask);
240	bio->bi_iter.bi_sector = sector;
241	bio->bi_bdev = bdev;
242	bio_set_op_attrs(bio, REQ_OP_WRITE, 0);
243
244	while (nr_sects != 0) {
245	sz = min((sector_t) PAGE_SIZE >> 9 , nr_sects);
246	ret = bio_add_page(bio, ZERO_PAGE(0), sz << 9, 0);
247	nr_sects -= ret >> 9;
248	sector += ret >> 9;
249	if (ret < (sz << 9))
250	break;
251	}
252	}
253
254	if (bio) {
255	ret = submit_bio_wait(bio);
256	bio_put(bio);
257	return ret;
258	}
259	return 0;
260	}
261
262	/**
263	* blkdev_issue_zeroout - zero-fill a block range
264	* @bdev: blockdev to write
265	* @sector: start sector
266	* @nr_sects: number of sectors to write
267	* @gfp_mask: memory allocation flags (for bio_alloc)
268	* @discard: whether to discard the block range
269	*
270	* Description:
271	* Zero-fill a block range. If the discard flag is set and the block
272	* device guarantees that subsequent READ operations to the block range
273	* in question will return zeroes, the blocks will be discarded. Should
274	* the discard request fail, if the discard flag is not set, or if
275	* discard_zeroes_data is not supported, this function will resort to
276	* zeroing the blocks manually, thus provisioning (allocating,
277	* anchoring) them. If the block device supports the WRITE SAME command
278	* blkdev_issue_zeroout() will use it to optimize the process of
279	* clearing the block range. Otherwise the zeroing will be performed
280	* using regular WRITE calls.
281	*/
282
283	int blkdev_issue_zeroout(struct block_device *bdev, sector_t sector,
284	sector_t nr_sects, gfp_t gfp_mask, bool discard)
285	{
286	if (discard) {
287	if (!blkdev_issue_discard(bdev, sector, nr_sects, gfp_mask,
288	BLKDEV_DISCARD_ZERO))
289	return 0;
290	}
291
292	if (bdev_write_same(bdev) &&
293	blkdev_issue_write_same(bdev, sector, nr_sects, gfp_mask,
294	ZERO_PAGE(0)) == 0)
295	return 0;
296
297	return __blkdev_issue_zeroout(bdev, sector, nr_sects, gfp_mask);
298	}
299	EXPORT_SYMBOL(blkdev_issue_zeroout);
300