2 * Copyright (C) 2003 Sistina Software
3 * Copyright (C) 2006 Red Hat GmbH
5 * This file is released under the GPL.
8 #include <linux/device-mapper.h>
10 #include <linux/bio.h>
11 #include <linux/mempool.h>
12 #include <linux/module.h>
13 #include <linux/sched.h>
14 #include <linux/slab.h>
15 #include <linux/dm-io.h>
22 /* FIXME: can we shrink this ? */
24 unsigned long error_bits
;
26 struct task_struct
*sleeper
;
27 struct dm_io_client
*client
;
28 io_notify_fn callback
;
33 * io contexts are only dynamically allocated for asynchronous
34 * io. Since async io is likely to be the majority of io we'll
35 * have the same number of io contexts as bios! (FIXME: must reduce this).
38 static unsigned int pages_to_ios(unsigned int pages
)
40 return 4 * pages
; /* too many ? */
44 * Create a client with mempool and bioset.
46 struct dm_io_client
*dm_io_client_create(unsigned num_pages
)
48 unsigned ios
= pages_to_ios(num_pages
);
49 struct dm_io_client
*client
;
51 client
= kmalloc(sizeof(*client
), GFP_KERNEL
);
53 return ERR_PTR(-ENOMEM
);
55 client
->pool
= mempool_create_kmalloc_pool(ios
, sizeof(struct io
));
59 client
->bios
= bioset_create(16, 0);
67 mempool_destroy(client
->pool
);
69 return ERR_PTR(-ENOMEM
);
71 EXPORT_SYMBOL(dm_io_client_create
);
73 int dm_io_client_resize(unsigned num_pages
, struct dm_io_client
*client
)
75 return mempool_resize(client
->pool
, pages_to_ios(num_pages
),
78 EXPORT_SYMBOL(dm_io_client_resize
);
80 void dm_io_client_destroy(struct dm_io_client
*client
)
82 mempool_destroy(client
->pool
);
83 bioset_free(client
->bios
);
86 EXPORT_SYMBOL(dm_io_client_destroy
);
88 /*-----------------------------------------------------------------
89 * We need to keep track of which region a bio is doing io for.
90 * In order to save a memory allocation we store this the last
91 * bvec which we know is unused (blech).
92 * XXX This is ugly and can OOPS with some configs... find another way.
93 *---------------------------------------------------------------*/
94 static inline void bio_set_region(struct bio
*bio
, unsigned region
)
96 bio
->bi_io_vec
[bio
->bi_max_vecs
].bv_len
= region
;
99 static inline unsigned bio_get_region(struct bio
*bio
)
101 return bio
->bi_io_vec
[bio
->bi_max_vecs
].bv_len
;
104 /*-----------------------------------------------------------------
105 * We need an io object to keep track of the number of bios that
106 * have been dispatched for a particular io.
107 *---------------------------------------------------------------*/
108 static void dec_count(struct io
*io
, unsigned int region
, int error
)
111 set_bit(region
, &io
->error_bits
);
113 if (atomic_dec_and_test(&io
->count
)) {
115 wake_up_process(io
->sleeper
);
118 unsigned long r
= io
->error_bits
;
119 io_notify_fn fn
= io
->callback
;
120 void *context
= io
->context
;
122 mempool_free(io
, io
->client
->pool
);
128 static void endio(struct bio
*bio
, int error
)
133 if (error
&& bio_data_dir(bio
) == READ
)
137 * The bio destructor in bio_put() may use the io object.
139 io
= bio
->bi_private
;
140 region
= bio_get_region(bio
);
145 dec_count(io
, region
, error
);
148 /*-----------------------------------------------------------------
149 * These little objects provide an abstraction for getting a new
150 * destination page for io.
151 *---------------------------------------------------------------*/
153 void (*get_page
)(struct dpages
*dp
,
154 struct page
**p
, unsigned long *len
, unsigned *offset
);
155 void (*next_page
)(struct dpages
*dp
);
162 * Functions for getting the pages from a list.
164 static void list_get_page(struct dpages
*dp
,
165 struct page
**p
, unsigned long *len
, unsigned *offset
)
167 unsigned o
= dp
->context_u
;
168 struct page_list
*pl
= (struct page_list
*) dp
->context_ptr
;
171 *len
= PAGE_SIZE
- o
;
175 static void list_next_page(struct dpages
*dp
)
177 struct page_list
*pl
= (struct page_list
*) dp
->context_ptr
;
178 dp
->context_ptr
= pl
->next
;
182 static void list_dp_init(struct dpages
*dp
, struct page_list
*pl
, unsigned offset
)
184 dp
->get_page
= list_get_page
;
185 dp
->next_page
= list_next_page
;
186 dp
->context_u
= offset
;
187 dp
->context_ptr
= pl
;
191 * Functions for getting the pages from a bvec.
193 static void bvec_get_page(struct dpages
*dp
,
194 struct page
**p
, unsigned long *len
, unsigned *offset
)
196 struct bio_vec
*bvec
= (struct bio_vec
*) dp
->context_ptr
;
199 *offset
= bvec
->bv_offset
;
202 static void bvec_next_page(struct dpages
*dp
)
204 struct bio_vec
*bvec
= (struct bio_vec
*) dp
->context_ptr
;
205 dp
->context_ptr
= bvec
+ 1;
208 static void bvec_dp_init(struct dpages
*dp
, struct bio_vec
*bvec
)
210 dp
->get_page
= bvec_get_page
;
211 dp
->next_page
= bvec_next_page
;
212 dp
->context_ptr
= bvec
;
216 * Functions for getting the pages from a VMA.
218 static void vm_get_page(struct dpages
*dp
,
219 struct page
**p
, unsigned long *len
, unsigned *offset
)
221 *p
= vmalloc_to_page(dp
->context_ptr
);
222 *offset
= dp
->context_u
;
223 *len
= PAGE_SIZE
- dp
->context_u
;
226 static void vm_next_page(struct dpages
*dp
)
228 dp
->context_ptr
+= PAGE_SIZE
- dp
->context_u
;
232 static void vm_dp_init(struct dpages
*dp
, void *data
)
234 dp
->get_page
= vm_get_page
;
235 dp
->next_page
= vm_next_page
;
236 dp
->context_u
= ((unsigned long) data
) & (PAGE_SIZE
- 1);
237 dp
->context_ptr
= data
;
240 static void dm_bio_destructor(struct bio
*bio
)
242 struct io
*io
= bio
->bi_private
;
244 bio_free(bio
, io
->client
->bios
);
248 * Functions for getting the pages from kernel memory.
250 static void km_get_page(struct dpages
*dp
, struct page
**p
, unsigned long *len
,
253 *p
= virt_to_page(dp
->context_ptr
);
254 *offset
= dp
->context_u
;
255 *len
= PAGE_SIZE
- dp
->context_u
;
258 static void km_next_page(struct dpages
*dp
)
260 dp
->context_ptr
+= PAGE_SIZE
- dp
->context_u
;
264 static void km_dp_init(struct dpages
*dp
, void *data
)
266 dp
->get_page
= km_get_page
;
267 dp
->next_page
= km_next_page
;
268 dp
->context_u
= ((unsigned long) data
) & (PAGE_SIZE
- 1);
269 dp
->context_ptr
= data
;
272 /*-----------------------------------------------------------------
273 * IO routines that accept a list of pages.
274 *---------------------------------------------------------------*/
275 static void do_region(int rw
, unsigned region
, struct dm_io_region
*where
,
276 struct dpages
*dp
, struct io
*io
)
283 sector_t remaining
= where
->count
;
287 * Allocate a suitably sized-bio: we add an extra
288 * bvec for bio_get/set_region() and decrement bi_max_vecs
289 * to hide it from bio_add_page().
291 num_bvecs
= dm_sector_div_up(remaining
,
292 (PAGE_SIZE
>> SECTOR_SHIFT
));
293 num_bvecs
= 1 + min_t(int, bio_get_nr_vecs(where
->bdev
),
295 if (unlikely(num_bvecs
> BIO_MAX_PAGES
))
296 num_bvecs
= BIO_MAX_PAGES
;
297 bio
= bio_alloc_bioset(GFP_NOIO
, num_bvecs
, io
->client
->bios
);
298 bio
->bi_sector
= where
->sector
+ (where
->count
- remaining
);
299 bio
->bi_bdev
= where
->bdev
;
300 bio
->bi_end_io
= endio
;
301 bio
->bi_private
= io
;
302 bio
->bi_destructor
= dm_bio_destructor
;
304 bio_set_region(bio
, region
);
307 * Try and add as many pages as possible.
310 dp
->get_page(dp
, &page
, &len
, &offset
);
311 len
= min(len
, to_bytes(remaining
));
312 if (!bio_add_page(bio
, page
, len
, offset
))
316 remaining
-= to_sector(len
);
320 atomic_inc(&io
->count
);
325 static void dispatch_io(int rw
, unsigned int num_regions
,
326 struct dm_io_region
*where
, struct dpages
*dp
,
327 struct io
*io
, int sync
)
330 struct dpages old_pages
= *dp
;
333 rw
|= (1 << BIO_RW_SYNCIO
) | (1 << BIO_RW_UNPLUG
);
336 * For multiple regions we need to be careful to rewind
337 * the dp object for each call to do_region.
339 for (i
= 0; i
< num_regions
; i
++) {
342 do_region(rw
, i
, where
+ i
, dp
, io
);
346 * Drop the extra reference that we were holding to avoid
347 * the io being completed too early.
352 static int sync_io(struct dm_io_client
*client
, unsigned int num_regions
,
353 struct dm_io_region
*where
, int rw
, struct dpages
*dp
,
354 unsigned long *error_bits
)
358 if (num_regions
> 1 && (rw
& RW_MASK
) != WRITE
) {
364 atomic_set(&io
.count
, 1); /* see dispatch_io() */
365 io
.sleeper
= current
;
368 dispatch_io(rw
, num_regions
, where
, dp
, &io
, 1);
371 set_current_state(TASK_UNINTERRUPTIBLE
);
373 if (!atomic_read(&io
.count
))
378 set_current_state(TASK_RUNNING
);
381 *error_bits
= io
.error_bits
;
383 return io
.error_bits
? -EIO
: 0;
386 static int async_io(struct dm_io_client
*client
, unsigned int num_regions
,
387 struct dm_io_region
*where
, int rw
, struct dpages
*dp
,
388 io_notify_fn fn
, void *context
)
392 if (num_regions
> 1 && (rw
& RW_MASK
) != WRITE
) {
398 io
= mempool_alloc(client
->pool
, GFP_NOIO
);
400 atomic_set(&io
->count
, 1); /* see dispatch_io() */
404 io
->context
= context
;
406 dispatch_io(rw
, num_regions
, where
, dp
, io
, 0);
410 static int dp_init(struct dm_io_request
*io_req
, struct dpages
*dp
)
412 /* Set up dpages based on memory type */
413 switch (io_req
->mem
.type
) {
414 case DM_IO_PAGE_LIST
:
415 list_dp_init(dp
, io_req
->mem
.ptr
.pl
, io_req
->mem
.offset
);
419 bvec_dp_init(dp
, io_req
->mem
.ptr
.bvec
);
423 vm_dp_init(dp
, io_req
->mem
.ptr
.vma
);
427 km_dp_init(dp
, io_req
->mem
.ptr
.addr
);
438 * New collapsed (a)synchronous interface.
440 * If the IO is asynchronous (i.e. it has notify.fn), you must either unplug
441 * the queue with blk_unplug() some time later or set the BIO_RW_SYNC bit in
442 * io_req->bi_rw. If you fail to do one of these, the IO will be submitted to
443 * the disk after q->unplug_delay, which defaults to 3ms in blk-settings.c.
445 int dm_io(struct dm_io_request
*io_req
, unsigned num_regions
,
446 struct dm_io_region
*where
, unsigned long *sync_error_bits
)
451 r
= dp_init(io_req
, &dp
);
455 if (!io_req
->notify
.fn
)
456 return sync_io(io_req
->client
, num_regions
, where
,
457 io_req
->bi_rw
, &dp
, sync_error_bits
);
459 return async_io(io_req
->client
, num_regions
, where
, io_req
->bi_rw
,
460 &dp
, io_req
->notify
.fn
, io_req
->notify
.context
);
462 EXPORT_SYMBOL(dm_io
);
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