2 * Copyright (C) 2003 Sistina Software
3 * Copyright (C) 2006 Red Hat GmbH
5 * This file is released under the GPL.
10 #include <linux/device-mapper.h>
12 #include <linux/bio.h>
13 #include <linux/completion.h>
14 #include <linux/mempool.h>
15 #include <linux/module.h>
16 #include <linux/sched.h>
17 #include <linux/slab.h>
18 #include <linux/dm-io.h>
20 #define DM_MSG_PREFIX "io"
22 #define DM_IO_MAX_REGIONS BITS_PER_LONG
30 * Aligning 'struct io' reduces the number of bits required to store
31 * its address. Refer to store_io_and_region_in_bio() below.
34 unsigned long error_bits;
36 struct completion *wait;
37 struct dm_io_client *client;
38 io_notify_fn callback;
40 void *vma_invalidate_address;
41 unsigned long vma_invalidate_size;
42 } __attribute__((aligned(DM_IO_MAX_REGIONS)));
44 static struct kmem_cache *_dm_io_cache;
47 * Create a client with mempool and bioset.
49 struct dm_io_client *dm_io_client_create(void)
51 struct dm_io_client *client;
52 unsigned min_ios = dm_get_reserved_bio_based_ios();
54 client = kmalloc(sizeof(*client), GFP_KERNEL);
56 return ERR_PTR(-ENOMEM);
58 client->pool = mempool_create_slab_pool(min_ios, _dm_io_cache);
62 client->bios = bioset_create(min_ios, 0);
70 mempool_destroy(client->pool);
72 return ERR_PTR(-ENOMEM);
74 EXPORT_SYMBOL(dm_io_client_create);
76 void dm_io_client_destroy(struct dm_io_client *client)
78 mempool_destroy(client->pool);
79 bioset_free(client->bios);
82 EXPORT_SYMBOL(dm_io_client_destroy);
84 /*-----------------------------------------------------------------
85 * We need to keep track of which region a bio is doing io for.
86 * To avoid a memory allocation to store just 5 or 6 bits, we
87 * ensure the 'struct io' pointer is aligned so enough low bits are
88 * always zero and then combine it with the region number directly in
90 *---------------------------------------------------------------*/
91 static void store_io_and_region_in_bio(struct bio *bio, struct io *io,
94 if (unlikely(!IS_ALIGNED((unsigned long)io, DM_IO_MAX_REGIONS))) {
95 DMCRIT("Unaligned struct io pointer %p", io);
99 bio->bi_private = (void *)((unsigned long)io | region);
102 static void retrieve_io_and_region_from_bio(struct bio *bio, struct io **io,
105 unsigned long val = (unsigned long)bio->bi_private;
107 *io = (void *)(val & -(unsigned long)DM_IO_MAX_REGIONS);
108 *region = val & (DM_IO_MAX_REGIONS - 1);
111 /*-----------------------------------------------------------------
112 * We need an io object to keep track of the number of bios that
113 * have been dispatched for a particular io.
114 *---------------------------------------------------------------*/
115 static void dec_count(struct io *io, unsigned int region, int error)
118 set_bit(region, &io->error_bits);
120 if (atomic_dec_and_test(&io->count)) {
121 if (io->vma_invalidate_size)
122 invalidate_kernel_vmap_range(io->vma_invalidate_address,
123 io->vma_invalidate_size);
129 unsigned long r = io->error_bits;
130 io_notify_fn fn = io->callback;
131 void *context = io->context;
133 mempool_free(io, io->client->pool);
139 static void endio(struct bio *bio, int error)
144 if (error && bio_data_dir(bio) == READ)
148 * The bio destructor in bio_put() may use the io object.
150 retrieve_io_and_region_from_bio(bio, &io, ®ion);
154 dec_count(io, region, error);
157 /*-----------------------------------------------------------------
158 * These little objects provide an abstraction for getting a new
159 * destination page for io.
160 *---------------------------------------------------------------*/
162 void (*get_page)(struct dpages *dp,
163 struct page **p, unsigned long *len, unsigned *offset);
164 void (*next_page)(struct dpages *dp);
169 void *vma_invalidate_address;
170 unsigned long vma_invalidate_size;
174 * Functions for getting the pages from a list.
176 static void list_get_page(struct dpages *dp,
177 struct page **p, unsigned long *len, unsigned *offset)
179 unsigned o = dp->context_u;
180 struct page_list *pl = (struct page_list *) dp->context_ptr;
183 *len = PAGE_SIZE - o;
187 static void list_next_page(struct dpages *dp)
189 struct page_list *pl = (struct page_list *) dp->context_ptr;
190 dp->context_ptr = pl->next;
194 static void list_dp_init(struct dpages *dp, struct page_list *pl, unsigned offset)
196 dp->get_page = list_get_page;
197 dp->next_page = list_next_page;
198 dp->context_u = offset;
199 dp->context_ptr = pl;
203 * Functions for getting the pages from a bvec.
205 static void bio_get_page(struct dpages *dp, struct page **p,
206 unsigned long *len, unsigned *offset)
208 struct bio_vec *bvec = dp->context_ptr;
210 *len = bvec->bv_len - dp->context_u;
211 *offset = bvec->bv_offset + dp->context_u;
214 static void bio_next_page(struct dpages *dp)
216 struct bio_vec *bvec = dp->context_ptr;
217 dp->context_ptr = bvec + 1;
221 static void bio_dp_init(struct dpages *dp, struct bio *bio)
223 dp->get_page = bio_get_page;
224 dp->next_page = bio_next_page;
225 dp->context_ptr = __bvec_iter_bvec(bio->bi_io_vec, bio->bi_iter);
226 dp->context_u = bio->bi_iter.bi_bvec_done;
230 * Functions for getting the pages from a VMA.
232 static void vm_get_page(struct dpages *dp,
233 struct page **p, unsigned long *len, unsigned *offset)
235 *p = vmalloc_to_page(dp->context_ptr);
236 *offset = dp->context_u;
237 *len = PAGE_SIZE - dp->context_u;
240 static void vm_next_page(struct dpages *dp)
242 dp->context_ptr += PAGE_SIZE - dp->context_u;
246 static void vm_dp_init(struct dpages *dp, void *data)
248 dp->get_page = vm_get_page;
249 dp->next_page = vm_next_page;
250 dp->context_u = ((unsigned long) data) & (PAGE_SIZE - 1);
251 dp->context_ptr = data;
255 * Functions for getting the pages from kernel memory.
257 static void km_get_page(struct dpages *dp, struct page **p, unsigned long *len,
260 *p = virt_to_page(dp->context_ptr);
261 *offset = dp->context_u;
262 *len = PAGE_SIZE - dp->context_u;
265 static void km_next_page(struct dpages *dp)
267 dp->context_ptr += PAGE_SIZE - dp->context_u;
271 static void km_dp_init(struct dpages *dp, void *data)
273 dp->get_page = km_get_page;
274 dp->next_page = km_next_page;
275 dp->context_u = ((unsigned long) data) & (PAGE_SIZE - 1);
276 dp->context_ptr = data;
279 /*-----------------------------------------------------------------
280 * IO routines that accept a list of pages.
281 *---------------------------------------------------------------*/
282 static void do_region(int rw, unsigned region, struct dm_io_region *where,
283 struct dpages *dp, struct io *io)
290 sector_t remaining = where->count;
291 struct request_queue *q = bdev_get_queue(where->bdev);
292 unsigned short logical_block_size = queue_logical_block_size(q);
293 sector_t num_sectors;
296 * where->count may be zero if rw holds a flush and we need to
297 * send a zero-sized flush.
301 * Allocate a suitably sized-bio.
303 if ((rw & REQ_DISCARD) || (rw & REQ_WRITE_SAME))
306 num_bvecs = min_t(int, bio_get_nr_vecs(where->bdev),
307 dm_sector_div_up(remaining, (PAGE_SIZE >> SECTOR_SHIFT)));
309 bio = bio_alloc_bioset(GFP_NOIO, num_bvecs, io->client->bios);
310 bio->bi_iter.bi_sector = where->sector + (where->count - remaining);
311 bio->bi_bdev = where->bdev;
312 bio->bi_end_io = endio;
313 store_io_and_region_in_bio(bio, io, region);
315 if (rw & REQ_DISCARD) {
316 num_sectors = min_t(sector_t, q->limits.max_discard_sectors, remaining);
317 bio->bi_iter.bi_size = num_sectors << SECTOR_SHIFT;
318 remaining -= num_sectors;
319 } else if (rw & REQ_WRITE_SAME) {
321 * WRITE SAME only uses a single page.
323 dp->get_page(dp, &page, &len, &offset);
324 bio_add_page(bio, page, logical_block_size, offset);
325 num_sectors = min_t(sector_t, q->limits.max_write_same_sectors, remaining);
326 bio->bi_iter.bi_size = num_sectors << SECTOR_SHIFT;
329 remaining -= num_sectors;
331 } else while (remaining) {
333 * Try and add as many pages as possible.
335 dp->get_page(dp, &page, &len, &offset);
336 len = min(len, to_bytes(remaining));
337 if (!bio_add_page(bio, page, len, offset))
341 remaining -= to_sector(len);
345 atomic_inc(&io->count);
350 static void dispatch_io(int rw, unsigned int num_regions,
351 struct dm_io_region *where, struct dpages *dp,
352 struct io *io, int sync)
355 struct dpages old_pages = *dp;
357 BUG_ON(num_regions > DM_IO_MAX_REGIONS);
363 * For multiple regions we need to be careful to rewind
364 * the dp object for each call to do_region.
366 for (i = 0; i < num_regions; i++) {
368 if (where[i].count || (rw & REQ_FLUSH))
369 do_region(rw, i, where + i, dp, io);
373 * Drop the extra reference that we were holding to avoid
374 * the io being completed too early.
379 static int sync_io(struct dm_io_client *client, unsigned int num_regions,
380 struct dm_io_region *where, int rw, struct dpages *dp,
381 unsigned long *error_bits)
384 * gcc <= 4.3 can't do the alignment for stack variables, so we must
385 * align it on our own.
386 * volatile prevents the optimizer from removing or reusing
387 * "io_" field from the stack frame (allowed in ANSI C).
389 volatile char io_[sizeof(struct io) + __alignof__(struct io) - 1];
390 struct io *io = (struct io *)PTR_ALIGN(&io_, __alignof__(struct io));
391 DECLARE_COMPLETION_ONSTACK(wait);
393 if (num_regions > 1 && (rw & RW_MASK) != WRITE) {
399 atomic_set(&io->count, 1); /* see dispatch_io() */
403 io->vma_invalidate_address = dp->vma_invalidate_address;
404 io->vma_invalidate_size = dp->vma_invalidate_size;
406 dispatch_io(rw, num_regions, where, dp, io, 1);
408 wait_for_completion_io(&wait);
411 *error_bits = io->error_bits;
413 return io->error_bits ? -EIO : 0;
416 static int async_io(struct dm_io_client *client, unsigned int num_regions,
417 struct dm_io_region *where, int rw, struct dpages *dp,
418 io_notify_fn fn, void *context)
422 if (num_regions > 1 && (rw & RW_MASK) != WRITE) {
428 io = mempool_alloc(client->pool, GFP_NOIO);
430 atomic_set(&io->count, 1); /* see dispatch_io() */
434 io->context = context;
436 io->vma_invalidate_address = dp->vma_invalidate_address;
437 io->vma_invalidate_size = dp->vma_invalidate_size;
439 dispatch_io(rw, num_regions, where, dp, io, 0);
443 static int dp_init(struct dm_io_request *io_req, struct dpages *dp,
446 /* Set up dpages based on memory type */
448 dp->vma_invalidate_address = NULL;
449 dp->vma_invalidate_size = 0;
451 switch (io_req->mem.type) {
452 case DM_IO_PAGE_LIST:
453 list_dp_init(dp, io_req->mem.ptr.pl, io_req->mem.offset);
457 bio_dp_init(dp, io_req->mem.ptr.bio);
461 flush_kernel_vmap_range(io_req->mem.ptr.vma, size);
462 if ((io_req->bi_rw & RW_MASK) == READ) {
463 dp->vma_invalidate_address = io_req->mem.ptr.vma;
464 dp->vma_invalidate_size = size;
466 vm_dp_init(dp, io_req->mem.ptr.vma);
470 km_dp_init(dp, io_req->mem.ptr.addr);
481 * New collapsed (a)synchronous interface.
483 * If the IO is asynchronous (i.e. it has notify.fn), you must either unplug
484 * the queue with blk_unplug() some time later or set REQ_SYNC in
485 io_req->bi_rw. If you fail to do one of these, the IO will be submitted to
486 * the disk after q->unplug_delay, which defaults to 3ms in blk-settings.c.
488 int dm_io(struct dm_io_request *io_req, unsigned num_regions,
489 struct dm_io_region *where, unsigned long *sync_error_bits)
494 r = dp_init(io_req, &dp, (unsigned long)where->count << SECTOR_SHIFT);
498 if (!io_req->notify.fn)
499 return sync_io(io_req->client, num_regions, where,
500 io_req->bi_rw, &dp, sync_error_bits);
502 return async_io(io_req->client, num_regions, where, io_req->bi_rw,
503 &dp, io_req->notify.fn, io_req->notify.context);
505 EXPORT_SYMBOL(dm_io);
507 int __init dm_io_init(void)
509 _dm_io_cache = KMEM_CACHE(io, 0);
516 void dm_io_exit(void)
518 kmem_cache_destroy(_dm_io_cache);