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https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
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cacc7b0556
Firstly we have mature bvec/bio iterator helper for iterate each page in one bio, not necessary to reinvent a wheel to do that. Secondly the coming multipage bvecs requires this patch. Also add comments about the direct access to bvec table. Signed-off-by: Ming Lei <tom.leiming@gmail.com> Signed-off-by: Mike Snitzer <snitzer@redhat.com>
560 lines
14 KiB
C
560 lines
14 KiB
C
/*
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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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client = kmalloc(sizeof(*client), GFP_KERNEL);
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if (!client)
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return ERR_PTR(-ENOMEM);
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client->pool = mempool_create_slab_pool(min_ios, _dm_io_cache);
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if (!client->pool)
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goto bad;
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client->bios = bioset_create(min_ios, 0);
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if (!client->bios)
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goto bad;
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return client;
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bad:
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mempool_destroy(client->pool);
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kfree(client);
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return ERR_PTR(-ENOMEM);
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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_destroy(client->pool);
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bioset_free(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, int 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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int error;
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if (bio->bi_error && 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_error;
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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 uninitialized_var(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_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_SAME) &&
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special_cmd_max_sectors == 0) {
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dec_count(io, region, -EOPNOTSUPP);
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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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if ((op == REQ_OP_DISCARD) || (op == REQ_OP_WRITE_SAME))
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num_bvecs = 1;
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else
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num_bvecs = min_t(int, BIO_MAX_PAGES,
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dm_sector_div_up(remaining, (PAGE_SIZE >> SECTOR_SHIFT)));
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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->bi_bdev = 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) {
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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
|
|
* the disk after q->unplug_delay, which defaults to 3ms in blk-settings.c.
|
|
*/
|
|
int dm_io(struct dm_io_request *io_req, unsigned num_regions,
|
|
struct dm_io_region *where, unsigned long *sync_error_bits)
|
|
{
|
|
int r;
|
|
struct dpages dp;
|
|
|
|
r = dp_init(io_req, &dp, (unsigned long)where->count << SECTOR_SHIFT);
|
|
if (r)
|
|
return r;
|
|
|
|
if (!io_req->notify.fn)
|
|
return sync_io(io_req->client, num_regions, where,
|
|
io_req->bi_op, io_req->bi_op_flags, &dp,
|
|
sync_error_bits);
|
|
|
|
return async_io(io_req->client, num_regions, where, io_req->bi_op,
|
|
io_req->bi_op_flags, &dp, io_req->notify.fn,
|
|
io_req->notify.context);
|
|
}
|
|
EXPORT_SYMBOL(dm_io);
|
|
|
|
int __init dm_io_init(void)
|
|
{
|
|
_dm_io_cache = KMEM_CACHE(io, 0);
|
|
if (!_dm_io_cache)
|
|
return -ENOMEM;
|
|
|
|
return 0;
|
|
}
|
|
|
|
void dm_io_exit(void)
|
|
{
|
|
kmem_cache_destroy(_dm_io_cache);
|
|
_dm_io_cache = NULL;
|
|
}
|