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/mempool.h>
14 #include <linux/module.h>
15 #include <linux/sched.h>
16 #include <linux/slab.h>
17 #include <linux/dm-io.h>
19 #define DM_MSG_PREFIX "io"
21 #define DM_IO_MAX_REGIONS BITS_PER_LONG
31 * Aligning 'struct io' reduces the number of bits required to store
32 * its address. Refer to store_io_and_region_in_bio() below.
35 unsigned long error_bits;
37 struct task_struct *sleeper;
38 struct dm_io_client *client;
39 io_notify_fn callback;
41 void *vma_invalidate_address;
42 unsigned long vma_invalidate_size;
43 } __attribute__((aligned(DM_IO_MAX_REGIONS)));
45 static struct kmem_cache *_dm_io_cache;
48 * Create a client with mempool and bioset.
50 struct dm_io_client *dm_io_client_create(void)
52 struct dm_io_client *client;
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_BIOS, 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);
126 wake_up_process(io->sleeper);
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 bvec_get_page(struct dpages *dp,
206 struct page **p, unsigned long *len, unsigned *offset)
208 struct bio_vec *bvec = (struct bio_vec *) dp->context_ptr;
211 *offset = bvec->bv_offset;
214 static void bvec_next_page(struct dpages *dp)
216 struct bio_vec *bvec = (struct bio_vec *) dp->context_ptr;
217 dp->context_ptr = bvec + 1;
220 static void bvec_dp_init(struct dpages *dp, struct bio_vec *bvec)
222 dp->get_page = bvec_get_page;
223 dp->next_page = bvec_next_page;
224 dp->context_ptr = bvec;
228 * Functions for getting the pages from a VMA.
230 static void vm_get_page(struct dpages *dp,
231 struct page **p, unsigned long *len, unsigned *offset)
233 *p = vmalloc_to_page(dp->context_ptr);
234 *offset = dp->context_u;
235 *len = PAGE_SIZE - dp->context_u;
238 static void vm_next_page(struct dpages *dp)
240 dp->context_ptr += PAGE_SIZE - dp->context_u;
244 static void vm_dp_init(struct dpages *dp, void *data)
246 dp->get_page = vm_get_page;
247 dp->next_page = vm_next_page;
248 dp->context_u = ((unsigned long) data) & (PAGE_SIZE - 1);
249 dp->context_ptr = data;
252 static void dm_bio_destructor(struct bio *bio)
257 retrieve_io_and_region_from_bio(bio, &io, ®ion);
259 bio_free(bio, io->client->bios);
263 * Functions for getting the pages from kernel memory.
265 static void km_get_page(struct dpages *dp, struct page **p, unsigned long *len,
268 *p = virt_to_page(dp->context_ptr);
269 *offset = dp->context_u;
270 *len = PAGE_SIZE - dp->context_u;
273 static void km_next_page(struct dpages *dp)
275 dp->context_ptr += PAGE_SIZE - dp->context_u;
279 static void km_dp_init(struct dpages *dp, void *data)
281 dp->get_page = km_get_page;
282 dp->next_page = km_next_page;
283 dp->context_u = ((unsigned long) data) & (PAGE_SIZE - 1);
284 dp->context_ptr = data;
287 /*-----------------------------------------------------------------
288 * IO routines that accept a list of pages.
289 *---------------------------------------------------------------*/
290 static void do_region(int rw, unsigned region, struct dm_io_region *where,
291 struct dpages *dp, struct io *io)
298 sector_t remaining = where->count;
301 * where->count may be zero if rw holds a flush and we need to
302 * send a zero-sized flush.
306 * Allocate a suitably sized-bio.
308 num_bvecs = dm_sector_div_up(remaining,
309 (PAGE_SIZE >> SECTOR_SHIFT));
310 num_bvecs = min_t(int, bio_get_nr_vecs(where->bdev), num_bvecs);
311 bio = bio_alloc_bioset(GFP_NOIO, num_bvecs, io->client->bios);
312 bio->bi_sector = where->sector + (where->count - remaining);
313 bio->bi_bdev = where->bdev;
314 bio->bi_end_io = endio;
315 bio->bi_destructor = dm_bio_destructor;
316 store_io_and_region_in_bio(bio, io, region);
319 * Try and add as many pages as possible.
322 dp->get_page(dp, &page, &len, &offset);
323 len = min(len, to_bytes(remaining));
324 if (!bio_add_page(bio, page, len, offset))
328 remaining -= to_sector(len);
332 atomic_inc(&io->count);
337 static void dispatch_io(int rw, unsigned int num_regions,
338 struct dm_io_region *where, struct dpages *dp,
339 struct io *io, int sync)
342 struct dpages old_pages = *dp;
344 BUG_ON(num_regions > DM_IO_MAX_REGIONS);
350 * For multiple regions we need to be careful to rewind
351 * the dp object for each call to do_region.
353 for (i = 0; i < num_regions; i++) {
355 if (where[i].count || (rw & REQ_FLUSH))
356 do_region(rw, i, where + i, dp, io);
360 * Drop the extra reference that we were holding to avoid
361 * the io being completed too early.
366 static int sync_io(struct dm_io_client *client, unsigned int num_regions,
367 struct dm_io_region *where, int rw, struct dpages *dp,
368 unsigned long *error_bits)
371 * gcc <= 4.3 can't do the alignment for stack variables, so we must
372 * align it on our own.
373 * volatile prevents the optimizer from removing or reusing
374 * "io_" field from the stack frame (allowed in ANSI C).
376 volatile char io_[sizeof(struct io) + __alignof__(struct io) - 1];
377 struct io *io = (struct io *)PTR_ALIGN(&io_, __alignof__(struct io));
379 if (num_regions > 1 && (rw & RW_MASK) != WRITE) {
385 atomic_set(&io->count, 1); /* see dispatch_io() */
386 io->sleeper = current;
389 io->vma_invalidate_address = dp->vma_invalidate_address;
390 io->vma_invalidate_size = dp->vma_invalidate_size;
392 dispatch_io(rw, num_regions, where, dp, io, 1);
395 set_current_state(TASK_UNINTERRUPTIBLE);
397 if (!atomic_read(&io->count))
402 set_current_state(TASK_RUNNING);
405 *error_bits = io->error_bits;
407 return io->error_bits ? -EIO : 0;
410 static int async_io(struct dm_io_client *client, unsigned int num_regions,
411 struct dm_io_region *where, int rw, struct dpages *dp,
412 io_notify_fn fn, void *context)
416 if (num_regions > 1 && (rw & RW_MASK) != WRITE) {
422 io = mempool_alloc(client->pool, GFP_NOIO);
424 atomic_set(&io->count, 1); /* see dispatch_io() */
428 io->context = context;
430 io->vma_invalidate_address = dp->vma_invalidate_address;
431 io->vma_invalidate_size = dp->vma_invalidate_size;
433 dispatch_io(rw, num_regions, where, dp, io, 0);
437 static int dp_init(struct dm_io_request *io_req, struct dpages *dp,
440 /* Set up dpages based on memory type */
442 dp->vma_invalidate_address = NULL;
443 dp->vma_invalidate_size = 0;
445 switch (io_req->mem.type) {
446 case DM_IO_PAGE_LIST:
447 list_dp_init(dp, io_req->mem.ptr.pl, io_req->mem.offset);
451 bvec_dp_init(dp, io_req->mem.ptr.bvec);
455 flush_kernel_vmap_range(io_req->mem.ptr.vma, size);
456 if ((io_req->bi_rw & RW_MASK) == READ) {
457 dp->vma_invalidate_address = io_req->mem.ptr.vma;
458 dp->vma_invalidate_size = size;
460 vm_dp_init(dp, io_req->mem.ptr.vma);
464 km_dp_init(dp, io_req->mem.ptr.addr);
475 * New collapsed (a)synchronous interface.
477 * If the IO is asynchronous (i.e. it has notify.fn), you must either unplug
478 * the queue with blk_unplug() some time later or set REQ_SYNC in
479 io_req->bi_rw. If you fail to do one of these, the IO will be submitted to
480 * the disk after q->unplug_delay, which defaults to 3ms in blk-settings.c.
482 int dm_io(struct dm_io_request *io_req, unsigned num_regions,
483 struct dm_io_region *where, unsigned long *sync_error_bits)
488 r = dp_init(io_req, &dp, (unsigned long)where->count << SECTOR_SHIFT);
492 if (!io_req->notify.fn)
493 return sync_io(io_req->client, num_regions, where,
494 io_req->bi_rw, &dp, sync_error_bits);
496 return async_io(io_req->client, num_regions, where, io_req->bi_rw,
497 &dp, io_req->notify.fn, io_req->notify.context);
499 EXPORT_SYMBOL(dm_io);
501 int __init dm_io_init(void)
503 _dm_io_cache = KMEM_CACHE(io, 0);
510 void dm_io_exit(void)
512 kmem_cache_destroy(_dm_io_cache);