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
29 * Aligning 'struct io' reduces the number of bits required to store
30 * its address. Refer to store_io_and_region_in_bio() below.
33 unsigned long error_bits
;
35 struct task_struct
*sleeper
;
36 struct dm_io_client
*client
;
37 io_notify_fn callback
;
39 } __attribute__((aligned(DM_IO_MAX_REGIONS
)));
41 static struct kmem_cache
*_dm_io_cache
;
44 * io contexts are only dynamically allocated for asynchronous
45 * io. Since async io is likely to be the majority of io we'll
46 * have the same number of io contexts as bios! (FIXME: must reduce this).
49 static unsigned int pages_to_ios(unsigned int pages
)
51 return 4 * pages
; /* too many ? */
55 * Create a client with mempool and bioset.
57 struct dm_io_client
*dm_io_client_create(unsigned num_pages
)
59 unsigned ios
= pages_to_ios(num_pages
);
60 struct dm_io_client
*client
;
62 client
= kmalloc(sizeof(*client
), GFP_KERNEL
);
64 return ERR_PTR(-ENOMEM
);
66 client
->pool
= mempool_create_slab_pool(ios
, _dm_io_cache
);
70 client
->bios
= bioset_create(16, 0);
78 mempool_destroy(client
->pool
);
80 return ERR_PTR(-ENOMEM
);
82 EXPORT_SYMBOL(dm_io_client_create
);
84 int dm_io_client_resize(unsigned num_pages
, struct dm_io_client
*client
)
86 return mempool_resize(client
->pool
, pages_to_ios(num_pages
),
89 EXPORT_SYMBOL(dm_io_client_resize
);
91 void dm_io_client_destroy(struct dm_io_client
*client
)
93 mempool_destroy(client
->pool
);
94 bioset_free(client
->bios
);
97 EXPORT_SYMBOL(dm_io_client_destroy
);
99 /*-----------------------------------------------------------------
100 * We need to keep track of which region a bio is doing io for.
101 * To avoid a memory allocation to store just 5 or 6 bits, we
102 * ensure the 'struct io' pointer is aligned so enough low bits are
103 * always zero and then combine it with the region number directly in
105 *---------------------------------------------------------------*/
106 static void store_io_and_region_in_bio(struct bio
*bio
, struct io
*io
,
109 if (unlikely(!IS_ALIGNED((unsigned long)io
, DM_IO_MAX_REGIONS
))) {
110 DMCRIT("Unaligned struct io pointer %p", io
);
114 bio
->bi_private
= (void *)((unsigned long)io
| region
);
117 static void retrieve_io_and_region_from_bio(struct bio
*bio
, struct io
**io
,
120 unsigned long val
= (unsigned long)bio
->bi_private
;
122 *io
= (void *)(val
& -(unsigned long)DM_IO_MAX_REGIONS
);
123 *region
= val
& (DM_IO_MAX_REGIONS
- 1);
126 /*-----------------------------------------------------------------
127 * We need an io object to keep track of the number of bios that
128 * have been dispatched for a particular io.
129 *---------------------------------------------------------------*/
130 static void dec_count(struct io
*io
, unsigned int region
, int error
)
133 set_bit(region
, &io
->error_bits
);
135 if (atomic_dec_and_test(&io
->count
)) {
137 wake_up_process(io
->sleeper
);
140 unsigned long r
= io
->error_bits
;
141 io_notify_fn fn
= io
->callback
;
142 void *context
= io
->context
;
144 mempool_free(io
, io
->client
->pool
);
150 static void endio(struct bio
*bio
, int error
)
155 if (error
&& bio_data_dir(bio
) == READ
)
159 * The bio destructor in bio_put() may use the io object.
161 retrieve_io_and_region_from_bio(bio
, &io
, ®ion
);
165 dec_count(io
, region
, error
);
168 /*-----------------------------------------------------------------
169 * These little objects provide an abstraction for getting a new
170 * destination page for io.
171 *---------------------------------------------------------------*/
173 void (*get_page
)(struct dpages
*dp
,
174 struct page
**p
, unsigned long *len
, unsigned *offset
);
175 void (*next_page
)(struct dpages
*dp
);
182 * Functions for getting the pages from a list.
184 static void list_get_page(struct dpages
*dp
,
185 struct page
**p
, unsigned long *len
, unsigned *offset
)
187 unsigned o
= dp
->context_u
;
188 struct page_list
*pl
= (struct page_list
*) dp
->context_ptr
;
191 *len
= PAGE_SIZE
- o
;
195 static void list_next_page(struct dpages
*dp
)
197 struct page_list
*pl
= (struct page_list
*) dp
->context_ptr
;
198 dp
->context_ptr
= pl
->next
;
202 static void list_dp_init(struct dpages
*dp
, struct page_list
*pl
, unsigned offset
)
204 dp
->get_page
= list_get_page
;
205 dp
->next_page
= list_next_page
;
206 dp
->context_u
= offset
;
207 dp
->context_ptr
= pl
;
211 * Functions for getting the pages from a bvec.
213 static void bvec_get_page(struct dpages
*dp
,
214 struct page
**p
, unsigned long *len
, unsigned *offset
)
216 struct bio_vec
*bvec
= (struct bio_vec
*) dp
->context_ptr
;
219 *offset
= bvec
->bv_offset
;
222 static void bvec_next_page(struct dpages
*dp
)
224 struct bio_vec
*bvec
= (struct bio_vec
*) dp
->context_ptr
;
225 dp
->context_ptr
= bvec
+ 1;
228 static void bvec_dp_init(struct dpages
*dp
, struct bio_vec
*bvec
)
230 dp
->get_page
= bvec_get_page
;
231 dp
->next_page
= bvec_next_page
;
232 dp
->context_ptr
= bvec
;
236 * Functions for getting the pages from a VMA.
238 static void vm_get_page(struct dpages
*dp
,
239 struct page
**p
, unsigned long *len
, unsigned *offset
)
241 *p
= vmalloc_to_page(dp
->context_ptr
);
242 *offset
= dp
->context_u
;
243 *len
= PAGE_SIZE
- dp
->context_u
;
246 static void vm_next_page(struct dpages
*dp
)
248 dp
->context_ptr
+= PAGE_SIZE
- dp
->context_u
;
252 static void vm_dp_init(struct dpages
*dp
, void *data
)
254 dp
->get_page
= vm_get_page
;
255 dp
->next_page
= vm_next_page
;
256 dp
->context_u
= ((unsigned long) data
) & (PAGE_SIZE
- 1);
257 dp
->context_ptr
= data
;
260 static void dm_bio_destructor(struct bio
*bio
)
265 retrieve_io_and_region_from_bio(bio
, &io
, ®ion
);
267 bio_free(bio
, io
->client
->bios
);
271 * Functions for getting the pages from kernel memory.
273 static void km_get_page(struct dpages
*dp
, struct page
**p
, unsigned long *len
,
276 *p
= virt_to_page(dp
->context_ptr
);
277 *offset
= dp
->context_u
;
278 *len
= PAGE_SIZE
- dp
->context_u
;
281 static void km_next_page(struct dpages
*dp
)
283 dp
->context_ptr
+= PAGE_SIZE
- dp
->context_u
;
287 static void km_dp_init(struct dpages
*dp
, void *data
)
289 dp
->get_page
= km_get_page
;
290 dp
->next_page
= km_next_page
;
291 dp
->context_u
= ((unsigned long) data
) & (PAGE_SIZE
- 1);
292 dp
->context_ptr
= data
;
295 /*-----------------------------------------------------------------
296 * IO routines that accept a list of pages.
297 *---------------------------------------------------------------*/
298 static void do_region(int rw
, unsigned region
, struct dm_io_region
*where
,
299 struct dpages
*dp
, struct io
*io
)
306 sector_t remaining
= where
->count
;
309 * where->count may be zero if rw holds a flush and we need to
310 * send a zero-sized flush.
314 * Allocate a suitably sized-bio.
316 num_bvecs
= dm_sector_div_up(remaining
,
317 (PAGE_SIZE
>> SECTOR_SHIFT
));
318 num_bvecs
= min_t(int, bio_get_nr_vecs(where
->bdev
), num_bvecs
);
319 bio
= bio_alloc_bioset(GFP_NOIO
, num_bvecs
, io
->client
->bios
);
320 bio
->bi_sector
= where
->sector
+ (where
->count
- remaining
);
321 bio
->bi_bdev
= where
->bdev
;
322 bio
->bi_end_io
= endio
;
323 bio
->bi_destructor
= dm_bio_destructor
;
324 store_io_and_region_in_bio(bio
, io
, region
);
327 * Try and add as many pages as possible.
330 dp
->get_page(dp
, &page
, &len
, &offset
);
331 len
= min(len
, to_bytes(remaining
));
332 if (!bio_add_page(bio
, page
, len
, offset
))
336 remaining
-= to_sector(len
);
340 atomic_inc(&io
->count
);
345 static void dispatch_io(int rw
, unsigned int num_regions
,
346 struct dm_io_region
*where
, struct dpages
*dp
,
347 struct io
*io
, int sync
)
350 struct dpages old_pages
= *dp
;
352 BUG_ON(num_regions
> DM_IO_MAX_REGIONS
);
355 rw
|= REQ_SYNC
| REQ_UNPLUG
;
358 * For multiple regions we need to be careful to rewind
359 * the dp object for each call to do_region.
361 for (i
= 0; i
< num_regions
; i
++) {
363 if (where
[i
].count
|| (rw
& REQ_FLUSH
))
364 do_region(rw
, i
, where
+ i
, dp
, io
);
368 * Drop the extra reference that we were holding to avoid
369 * the io being completed too early.
374 static int sync_io(struct dm_io_client
*client
, unsigned int num_regions
,
375 struct dm_io_region
*where
, int rw
, struct dpages
*dp
,
376 unsigned long *error_bits
)
379 * gcc <= 4.3 can't do the alignment for stack variables, so we must
380 * align it on our own.
381 * volatile prevents the optimizer from removing or reusing
382 * "io_" field from the stack frame (allowed in ANSI C).
384 volatile char io_
[sizeof(struct io
) + __alignof__(struct io
) - 1];
385 struct io
*io
= (struct io
*)PTR_ALIGN(&io_
, __alignof__(struct io
));
387 if (num_regions
> 1 && (rw
& RW_MASK
) != WRITE
) {
393 atomic_set(&io
->count
, 1); /* see dispatch_io() */
394 io
->sleeper
= current
;
397 dispatch_io(rw
, num_regions
, where
, dp
, io
, 1);
400 set_current_state(TASK_UNINTERRUPTIBLE
);
402 if (!atomic_read(&io
->count
))
407 set_current_state(TASK_RUNNING
);
410 *error_bits
= io
->error_bits
;
412 return io
->error_bits
? -EIO
: 0;
415 static int async_io(struct dm_io_client
*client
, unsigned int num_regions
,
416 struct dm_io_region
*where
, int rw
, struct dpages
*dp
,
417 io_notify_fn fn
, void *context
)
421 if (num_regions
> 1 && (rw
& RW_MASK
) != WRITE
) {
427 io
= mempool_alloc(client
->pool
, GFP_NOIO
);
429 atomic_set(&io
->count
, 1); /* see dispatch_io() */
433 io
->context
= context
;
435 dispatch_io(rw
, num_regions
, where
, dp
, io
, 0);
439 static int dp_init(struct dm_io_request
*io_req
, struct dpages
*dp
)
441 /* Set up dpages based on memory type */
442 switch (io_req
->mem
.type
) {
443 case DM_IO_PAGE_LIST
:
444 list_dp_init(dp
, io_req
->mem
.ptr
.pl
, io_req
->mem
.offset
);
448 bvec_dp_init(dp
, io_req
->mem
.ptr
.bvec
);
452 vm_dp_init(dp
, io_req
->mem
.ptr
.vma
);
456 km_dp_init(dp
, io_req
->mem
.ptr
.addr
);
467 * New collapsed (a)synchronous interface.
469 * If the IO is asynchronous (i.e. it has notify.fn), you must either unplug
470 * the queue with blk_unplug() some time later or set REQ_SYNC in
471 io_req->bi_rw. If you fail to do one of these, the IO will be submitted to
472 * the disk after q->unplug_delay, which defaults to 3ms in blk-settings.c.
474 int dm_io(struct dm_io_request
*io_req
, unsigned num_regions
,
475 struct dm_io_region
*where
, unsigned long *sync_error_bits
)
480 r
= dp_init(io_req
, &dp
);
484 if (!io_req
->notify
.fn
)
485 return sync_io(io_req
->client
, num_regions
, where
,
486 io_req
->bi_rw
, &dp
, sync_error_bits
);
488 return async_io(io_req
->client
, num_regions
, where
, io_req
->bi_rw
,
489 &dp
, io_req
->notify
.fn
, io_req
->notify
.context
);
491 EXPORT_SYMBOL(dm_io
);
493 int __init
dm_io_init(void)
495 _dm_io_cache
= KMEM_CACHE(io
, 0);
502 void dm_io_exit(void)
504 kmem_cache_destroy(_dm_io_cache
);
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