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571 lines
14 KiB
571 lines
14 KiB
/* |
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* Copyright (C) 2003 Sistina Software |
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* Copyright (C) 2006 Red Hat GmbH |
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* |
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* This file is released under the GPL. |
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*/ |
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#include "dm-core.h" |
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#include <linux/device-mapper.h> |
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#include <linux/bio.h> |
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#include <linux/completion.h> |
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#include <linux/mempool.h> |
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#include <linux/module.h> |
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#include <linux/sched.h> |
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#include <linux/slab.h> |
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#include <linux/dm-io.h> |
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#define DM_MSG_PREFIX "io" |
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#define DM_IO_MAX_REGIONS BITS_PER_LONG |
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struct dm_io_client { |
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mempool_t pool; |
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struct bio_set bios; |
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}; |
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/* |
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* Aligning 'struct io' reduces the number of bits required to store |
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* its address. Refer to store_io_and_region_in_bio() below. |
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*/ |
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struct io { |
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unsigned long error_bits; |
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atomic_t count; |
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struct dm_io_client *client; |
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io_notify_fn callback; |
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void *context; |
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void *vma_invalidate_address; |
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unsigned long vma_invalidate_size; |
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} __attribute__((aligned(DM_IO_MAX_REGIONS))); |
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static struct kmem_cache *_dm_io_cache; |
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/* |
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* Create a client with mempool and bioset. |
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*/ |
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struct dm_io_client *dm_io_client_create(void) |
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{ |
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struct dm_io_client *client; |
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unsigned min_ios = dm_get_reserved_bio_based_ios(); |
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int ret; |
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client = kzalloc(sizeof(*client), GFP_KERNEL); |
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if (!client) |
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return ERR_PTR(-ENOMEM); |
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ret = mempool_init_slab_pool(&client->pool, min_ios, _dm_io_cache); |
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if (ret) |
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goto bad; |
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ret = bioset_init(&client->bios, min_ios, 0, BIOSET_NEED_BVECS); |
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if (ret) |
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goto bad; |
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return client; |
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bad: |
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mempool_exit(&client->pool); |
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kfree(client); |
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return ERR_PTR(ret); |
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} |
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EXPORT_SYMBOL(dm_io_client_create); |
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void dm_io_client_destroy(struct dm_io_client *client) |
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{ |
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mempool_exit(&client->pool); |
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bioset_exit(&client->bios); |
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kfree(client); |
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} |
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EXPORT_SYMBOL(dm_io_client_destroy); |
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/*----------------------------------------------------------------- |
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* We need to keep track of which region a bio is doing io for. |
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* To avoid a memory allocation to store just 5 or 6 bits, we |
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* ensure the 'struct io' pointer is aligned so enough low bits are |
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* always zero and then combine it with the region number directly in |
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* bi_private. |
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*---------------------------------------------------------------*/ |
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static void store_io_and_region_in_bio(struct bio *bio, struct io *io, |
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unsigned region) |
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{ |
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if (unlikely(!IS_ALIGNED((unsigned long)io, DM_IO_MAX_REGIONS))) { |
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DMCRIT("Unaligned struct io pointer %p", io); |
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BUG(); |
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} |
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bio->bi_private = (void *)((unsigned long)io | region); |
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} |
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static void retrieve_io_and_region_from_bio(struct bio *bio, struct io **io, |
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unsigned *region) |
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{ |
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unsigned long val = (unsigned long)bio->bi_private; |
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*io = (void *)(val & -(unsigned long)DM_IO_MAX_REGIONS); |
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*region = val & (DM_IO_MAX_REGIONS - 1); |
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} |
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/*----------------------------------------------------------------- |
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* We need an io object to keep track of the number of bios that |
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* have been dispatched for a particular io. |
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*---------------------------------------------------------------*/ |
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static void complete_io(struct io *io) |
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{ |
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unsigned long error_bits = io->error_bits; |
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io_notify_fn fn = io->callback; |
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void *context = io->context; |
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if (io->vma_invalidate_size) |
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invalidate_kernel_vmap_range(io->vma_invalidate_address, |
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io->vma_invalidate_size); |
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mempool_free(io, &io->client->pool); |
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fn(error_bits, context); |
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} |
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static void dec_count(struct io *io, unsigned int region, blk_status_t error) |
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{ |
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if (error) |
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set_bit(region, &io->error_bits); |
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if (atomic_dec_and_test(&io->count)) |
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complete_io(io); |
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} |
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static void endio(struct bio *bio) |
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{ |
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struct io *io; |
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unsigned region; |
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blk_status_t error; |
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if (bio->bi_status && bio_data_dir(bio) == READ) |
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zero_fill_bio(bio); |
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/* |
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* The bio destructor in bio_put() may use the io object. |
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*/ |
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retrieve_io_and_region_from_bio(bio, &io, ®ion); |
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error = bio->bi_status; |
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bio_put(bio); |
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dec_count(io, region, error); |
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} |
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/*----------------------------------------------------------------- |
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* These little objects provide an abstraction for getting a new |
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* destination page for io. |
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*---------------------------------------------------------------*/ |
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struct dpages { |
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void (*get_page)(struct dpages *dp, |
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struct page **p, unsigned long *len, unsigned *offset); |
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void (*next_page)(struct dpages *dp); |
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union { |
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unsigned context_u; |
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struct bvec_iter context_bi; |
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}; |
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void *context_ptr; |
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void *vma_invalidate_address; |
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unsigned long vma_invalidate_size; |
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}; |
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/* |
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* Functions for getting the pages from a list. |
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*/ |
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static void list_get_page(struct dpages *dp, |
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struct page **p, unsigned long *len, unsigned *offset) |
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{ |
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unsigned o = dp->context_u; |
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struct page_list *pl = (struct page_list *) dp->context_ptr; |
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*p = pl->page; |
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*len = PAGE_SIZE - o; |
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*offset = o; |
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} |
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static void list_next_page(struct dpages *dp) |
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{ |
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struct page_list *pl = (struct page_list *) dp->context_ptr; |
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dp->context_ptr = pl->next; |
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dp->context_u = 0; |
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} |
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static void list_dp_init(struct dpages *dp, struct page_list *pl, unsigned offset) |
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{ |
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dp->get_page = list_get_page; |
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dp->next_page = list_next_page; |
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dp->context_u = offset; |
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dp->context_ptr = pl; |
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} |
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/* |
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* Functions for getting the pages from a bvec. |
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*/ |
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static void bio_get_page(struct dpages *dp, struct page **p, |
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unsigned long *len, unsigned *offset) |
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{ |
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struct bio_vec bvec = bvec_iter_bvec((struct bio_vec *)dp->context_ptr, |
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dp->context_bi); |
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*p = bvec.bv_page; |
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*len = bvec.bv_len; |
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*offset = bvec.bv_offset; |
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/* avoid figuring it out again in bio_next_page() */ |
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dp->context_bi.bi_sector = (sector_t)bvec.bv_len; |
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} |
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static void bio_next_page(struct dpages *dp) |
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{ |
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unsigned int len = (unsigned int)dp->context_bi.bi_sector; |
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bvec_iter_advance((struct bio_vec *)dp->context_ptr, |
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&dp->context_bi, len); |
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} |
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static void bio_dp_init(struct dpages *dp, struct bio *bio) |
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{ |
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dp->get_page = bio_get_page; |
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dp->next_page = bio_next_page; |
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/* |
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* We just use bvec iterator to retrieve pages, so it is ok to |
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* access the bvec table directly here |
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*/ |
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dp->context_ptr = bio->bi_io_vec; |
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dp->context_bi = bio->bi_iter; |
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} |
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/* |
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* Functions for getting the pages from a VMA. |
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*/ |
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static void vm_get_page(struct dpages *dp, |
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struct page **p, unsigned long *len, unsigned *offset) |
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{ |
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*p = vmalloc_to_page(dp->context_ptr); |
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*offset = dp->context_u; |
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*len = PAGE_SIZE - dp->context_u; |
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} |
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static void vm_next_page(struct dpages *dp) |
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{ |
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dp->context_ptr += PAGE_SIZE - dp->context_u; |
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dp->context_u = 0; |
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} |
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static void vm_dp_init(struct dpages *dp, void *data) |
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{ |
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dp->get_page = vm_get_page; |
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dp->next_page = vm_next_page; |
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dp->context_u = offset_in_page(data); |
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dp->context_ptr = data; |
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} |
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/* |
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* Functions for getting the pages from kernel memory. |
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*/ |
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static void km_get_page(struct dpages *dp, struct page **p, unsigned long *len, |
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unsigned *offset) |
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{ |
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*p = virt_to_page(dp->context_ptr); |
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*offset = dp->context_u; |
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*len = PAGE_SIZE - dp->context_u; |
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} |
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static void km_next_page(struct dpages *dp) |
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{ |
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dp->context_ptr += PAGE_SIZE - dp->context_u; |
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dp->context_u = 0; |
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} |
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static void km_dp_init(struct dpages *dp, void *data) |
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{ |
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dp->get_page = km_get_page; |
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dp->next_page = km_next_page; |
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dp->context_u = offset_in_page(data); |
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dp->context_ptr = data; |
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} |
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/*----------------------------------------------------------------- |
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* IO routines that accept a list of pages. |
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*---------------------------------------------------------------*/ |
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static void do_region(int op, int op_flags, unsigned region, |
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struct dm_io_region *where, struct dpages *dp, |
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struct io *io) |
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{ |
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struct bio *bio; |
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struct page *page; |
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unsigned long len; |
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unsigned offset; |
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unsigned num_bvecs; |
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sector_t remaining = where->count; |
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struct request_queue *q = bdev_get_queue(where->bdev); |
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unsigned short logical_block_size = queue_logical_block_size(q); |
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sector_t num_sectors; |
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unsigned int special_cmd_max_sectors; |
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/* |
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* Reject unsupported discard and write same requests. |
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*/ |
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if (op == REQ_OP_DISCARD) |
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special_cmd_max_sectors = q->limits.max_discard_sectors; |
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else if (op == REQ_OP_WRITE_ZEROES) |
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special_cmd_max_sectors = q->limits.max_write_zeroes_sectors; |
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else if (op == REQ_OP_WRITE_SAME) |
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special_cmd_max_sectors = q->limits.max_write_same_sectors; |
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if ((op == REQ_OP_DISCARD || op == REQ_OP_WRITE_ZEROES || |
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op == REQ_OP_WRITE_SAME) && special_cmd_max_sectors == 0) { |
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atomic_inc(&io->count); |
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dec_count(io, region, BLK_STS_NOTSUPP); |
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return; |
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} |
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/* |
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* where->count may be zero if op holds a flush and we need to |
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* send a zero-sized flush. |
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*/ |
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do { |
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/* |
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* Allocate a suitably sized-bio. |
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*/ |
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switch (op) { |
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case REQ_OP_DISCARD: |
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case REQ_OP_WRITE_ZEROES: |
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num_bvecs = 0; |
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break; |
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case REQ_OP_WRITE_SAME: |
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num_bvecs = 1; |
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break; |
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default: |
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num_bvecs = bio_max_segs(dm_sector_div_up(remaining, |
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(PAGE_SIZE >> SECTOR_SHIFT))); |
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} |
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bio = bio_alloc_bioset(GFP_NOIO, num_bvecs, &io->client->bios); |
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bio->bi_iter.bi_sector = where->sector + (where->count - remaining); |
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bio_set_dev(bio, where->bdev); |
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bio->bi_end_io = endio; |
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bio_set_op_attrs(bio, op, op_flags); |
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store_io_and_region_in_bio(bio, io, region); |
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if (op == REQ_OP_DISCARD || op == REQ_OP_WRITE_ZEROES) { |
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num_sectors = min_t(sector_t, special_cmd_max_sectors, remaining); |
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bio->bi_iter.bi_size = num_sectors << SECTOR_SHIFT; |
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remaining -= num_sectors; |
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} else if (op == REQ_OP_WRITE_SAME) { |
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/* |
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* WRITE SAME only uses a single page. |
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*/ |
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dp->get_page(dp, &page, &len, &offset); |
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bio_add_page(bio, page, logical_block_size, offset); |
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num_sectors = min_t(sector_t, special_cmd_max_sectors, remaining); |
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bio->bi_iter.bi_size = num_sectors << SECTOR_SHIFT; |
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offset = 0; |
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remaining -= num_sectors; |
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dp->next_page(dp); |
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} else while (remaining) { |
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/* |
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* Try and add as many pages as possible. |
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*/ |
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dp->get_page(dp, &page, &len, &offset); |
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len = min(len, to_bytes(remaining)); |
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if (!bio_add_page(bio, page, len, offset)) |
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break; |
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offset = 0; |
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remaining -= to_sector(len); |
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dp->next_page(dp); |
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} |
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atomic_inc(&io->count); |
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submit_bio(bio); |
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} while (remaining); |
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} |
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static void dispatch_io(int op, int op_flags, unsigned int num_regions, |
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struct dm_io_region *where, struct dpages *dp, |
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struct io *io, int sync) |
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{ |
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int i; |
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struct dpages old_pages = *dp; |
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BUG_ON(num_regions > DM_IO_MAX_REGIONS); |
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if (sync) |
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op_flags |= REQ_SYNC; |
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/* |
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* For multiple regions we need to be careful to rewind |
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* the dp object for each call to do_region. |
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*/ |
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for (i = 0; i < num_regions; i++) { |
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*dp = old_pages; |
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if (where[i].count || (op_flags & REQ_PREFLUSH)) |
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do_region(op, op_flags, i, where + i, dp, io); |
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} |
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/* |
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* Drop the extra reference that we were holding to avoid |
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* the io being completed too early. |
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*/ |
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dec_count(io, 0, 0); |
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} |
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struct sync_io { |
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unsigned long error_bits; |
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struct completion wait; |
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}; |
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static void sync_io_complete(unsigned long error, void *context) |
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{ |
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struct sync_io *sio = context; |
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sio->error_bits = error; |
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complete(&sio->wait); |
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} |
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static int sync_io(struct dm_io_client *client, unsigned int num_regions, |
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struct dm_io_region *where, int op, int op_flags, |
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struct dpages *dp, unsigned long *error_bits) |
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{ |
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struct io *io; |
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struct sync_io sio; |
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if (num_regions > 1 && !op_is_write(op)) { |
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WARN_ON(1); |
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return -EIO; |
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} |
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init_completion(&sio.wait); |
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io = mempool_alloc(&client->pool, GFP_NOIO); |
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io->error_bits = 0; |
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atomic_set(&io->count, 1); /* see dispatch_io() */ |
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io->client = client; |
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io->callback = sync_io_complete; |
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io->context = &sio; |
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io->vma_invalidate_address = dp->vma_invalidate_address; |
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io->vma_invalidate_size = dp->vma_invalidate_size; |
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dispatch_io(op, op_flags, num_regions, where, dp, io, 1); |
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wait_for_completion_io(&sio.wait); |
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if (error_bits) |
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*error_bits = sio.error_bits; |
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return sio.error_bits ? -EIO : 0; |
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} |
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static int async_io(struct dm_io_client *client, unsigned int num_regions, |
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struct dm_io_region *where, int op, int op_flags, |
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struct dpages *dp, io_notify_fn fn, void *context) |
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{ |
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struct io *io; |
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if (num_regions > 1 && !op_is_write(op)) { |
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WARN_ON(1); |
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fn(1, context); |
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return -EIO; |
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} |
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io = mempool_alloc(&client->pool, GFP_NOIO); |
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io->error_bits = 0; |
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atomic_set(&io->count, 1); /* see dispatch_io() */ |
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io->client = client; |
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io->callback = fn; |
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io->context = context; |
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io->vma_invalidate_address = dp->vma_invalidate_address; |
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io->vma_invalidate_size = dp->vma_invalidate_size; |
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dispatch_io(op, op_flags, num_regions, where, dp, io, 0); |
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return 0; |
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} |
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static int dp_init(struct dm_io_request *io_req, struct dpages *dp, |
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unsigned long size) |
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{ |
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/* Set up dpages based on memory type */ |
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dp->vma_invalidate_address = NULL; |
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dp->vma_invalidate_size = 0; |
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switch (io_req->mem.type) { |
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case DM_IO_PAGE_LIST: |
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list_dp_init(dp, io_req->mem.ptr.pl, io_req->mem.offset); |
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break; |
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case DM_IO_BIO: |
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bio_dp_init(dp, io_req->mem.ptr.bio); |
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break; |
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case DM_IO_VMA: |
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flush_kernel_vmap_range(io_req->mem.ptr.vma, size); |
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if (io_req->bi_op == REQ_OP_READ) { |
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dp->vma_invalidate_address = io_req->mem.ptr.vma; |
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dp->vma_invalidate_size = size; |
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} |
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vm_dp_init(dp, io_req->mem.ptr.vma); |
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break; |
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case DM_IO_KMEM: |
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km_dp_init(dp, io_req->mem.ptr.addr); |
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break; |
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default: |
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return -EINVAL; |
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} |
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return 0; |
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} |
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/* |
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* New collapsed (a)synchronous interface. |
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* |
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* If the IO is asynchronous (i.e. it has notify.fn), you must either unplug |
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* the queue with blk_unplug() some time later or set REQ_SYNC in |
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* io_req->bi_opf. If you fail to do one of these, the IO will be submitted to |
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* the disk after q->unplug_delay, which defaults to 3ms in blk-settings.c. |
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*/ |
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int dm_io(struct dm_io_request *io_req, unsigned num_regions, |
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struct dm_io_region *where, unsigned long *sync_error_bits) |
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{ |
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int r; |
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struct dpages dp; |
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r = dp_init(io_req, &dp, (unsigned long)where->count << SECTOR_SHIFT); |
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if (r) |
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return r; |
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if (!io_req->notify.fn) |
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return sync_io(io_req->client, num_regions, where, |
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io_req->bi_op, io_req->bi_op_flags, &dp, |
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sync_error_bits); |
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return async_io(io_req->client, num_regions, where, io_req->bi_op, |
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io_req->bi_op_flags, &dp, io_req->notify.fn, |
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io_req->notify.context); |
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} |
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EXPORT_SYMBOL(dm_io); |
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int __init dm_io_init(void) |
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{ |
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_dm_io_cache = KMEM_CACHE(io, 0); |
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if (!_dm_io_cache) |
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return -ENOMEM; |
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return 0; |
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} |
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void dm_io_exit(void) |
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{ |
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kmem_cache_destroy(_dm_io_cache); |
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_dm_io_cache = NULL; |
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}
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