dm io: prepare for new interface
Introduce struct dm_io_client to prepare for per-client mempools and bio_sets. Temporary functions bios() and io_pool() choose between the per-client structures and the global ones so the old and new interfaces can co-exist. Make error_bits optional. Signed-off-by: Heinz Mauelshagen <hjm@redhat.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com> Cc: Milan Broz <mbroz@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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891ce20701
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@ -1,5 +1,6 @@
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/*
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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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@ -14,11 +15,17 @@
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static struct bio_set *_bios;
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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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/* FIXME: can we shrink this ? */
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struct io {
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unsigned long error;
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atomic_t count;
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struct task_struct *sleeper;
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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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};
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@ -26,12 +33,24 @@ struct io {
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/*
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* io contexts are only dynamically allocated for asynchronous
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* io. Since async io is likely to be the majority of io we'll
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* have the same number of io contexts as buffer heads ! (FIXME:
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* must reduce this).
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* have the same number of io contexts as bios! (FIXME: must reduce this).
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*/
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static unsigned _num_ios;
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static mempool_t *_io_pool;
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/*
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* Temporary functions to allow old and new interfaces to co-exist.
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*/
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static struct bio_set *bios(struct dm_io_client *client)
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{
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return client ? client->bios : _bios;
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}
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static mempool_t *io_pool(struct dm_io_client *client)
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{
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return client ? client->pool : _io_pool;
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}
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static unsigned int pages_to_ios(unsigned int pages)
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{
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return 4 * pages; /* too many ? */
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@ -118,7 +137,7 @@ static void dec_count(struct io *io, unsigned int region, int error)
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io_notify_fn fn = io->callback;
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void *context = io->context;
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mempool_free(io, _io_pool);
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mempool_free(io, io_pool(io->client));
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fn(r, context);
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}
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}
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@ -241,7 +260,9 @@ static void vm_dp_init(struct dpages *dp, void *data)
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static void dm_bio_destructor(struct bio *bio)
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{
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bio_free(bio, _bios);
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struct io *io = bio->bi_private;
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bio_free(bio, bios(io->client));
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}
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/*-----------------------------------------------------------------
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@ -264,7 +285,7 @@ static void do_region(int rw, unsigned int region, struct io_region *where,
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* to hide it from bio_add_page().
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*/
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num_bvecs = (remaining / (PAGE_SIZE >> SECTOR_SHIFT)) + 2;
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bio = bio_alloc_bioset(GFP_NOIO, num_bvecs, _bios);
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bio = bio_alloc_bioset(GFP_NOIO, num_bvecs, bios(io->client));
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bio->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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@ -319,8 +340,9 @@ static void dispatch_io(int rw, unsigned int num_regions,
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dec_count(io, 0, 0);
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}
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static int sync_io(unsigned int num_regions, struct io_region *where,
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int rw, struct dpages *dp, unsigned long *error_bits)
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static int sync_io(struct dm_io_client *client, unsigned int num_regions,
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struct io_region *where, int rw, struct dpages *dp,
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unsigned long *error_bits)
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{
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struct io io;
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@ -332,6 +354,7 @@ static int sync_io(unsigned int num_regions, struct io_region *where,
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io.error = 0;
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atomic_set(&io.count, 1); /* see dispatch_io() */
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io.sleeper = current;
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io.client = client;
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dispatch_io(rw, num_regions, where, dp, &io, 1);
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@ -348,12 +371,15 @@ static int sync_io(unsigned int num_regions, struct io_region *where,
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if (atomic_read(&io.count))
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return -EINTR;
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*error_bits = io.error;
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if (error_bits)
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*error_bits = io.error;
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return io.error ? -EIO : 0;
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}
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static int async_io(unsigned int num_regions, struct io_region *where, int rw,
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struct dpages *dp, io_notify_fn fn, void *context)
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static int async_io(struct dm_io_client *client, unsigned int num_regions,
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struct io_region *where, int rw, struct dpages *dp,
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io_notify_fn fn, void *context)
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{
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struct io *io;
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@ -363,10 +389,11 @@ static int async_io(unsigned int num_regions, struct io_region *where, int rw,
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return -EIO;
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}
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io = mempool_alloc(_io_pool, GFP_NOIO);
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io = mempool_alloc(io_pool(client), GFP_NOIO);
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io->error = 0;
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atomic_set(&io->count, 1); /* see dispatch_io() */
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io->sleeper = NULL;
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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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@ -380,7 +407,7 @@ int dm_io_sync(unsigned int num_regions, struct io_region *where, int rw,
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{
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struct dpages dp;
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list_dp_init(&dp, pl, offset);
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return sync_io(num_regions, where, rw, &dp, error_bits);
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return sync_io(NULL, num_regions, where, rw, &dp, error_bits);
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}
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int dm_io_sync_bvec(unsigned int num_regions, struct io_region *where, int rw,
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@ -388,7 +415,7 @@ int dm_io_sync_bvec(unsigned int num_regions, struct io_region *where, int rw,
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{
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struct dpages dp;
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bvec_dp_init(&dp, bvec);
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return sync_io(num_regions, where, rw, &dp, error_bits);
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return sync_io(NULL, num_regions, where, rw, &dp, error_bits);
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}
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int dm_io_sync_vm(unsigned int num_regions, struct io_region *where, int rw,
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@ -396,7 +423,7 @@ int dm_io_sync_vm(unsigned int num_regions, struct io_region *where, int rw,
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{
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struct dpages dp;
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vm_dp_init(&dp, data);
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return sync_io(num_regions, where, rw, &dp, error_bits);
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return sync_io(NULL, num_regions, where, rw, &dp, error_bits);
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}
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int dm_io_async(unsigned int num_regions, struct io_region *where, int rw,
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{
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struct dpages dp;
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list_dp_init(&dp, pl, offset);
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return async_io(num_regions, where, rw, &dp, fn, context);
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return async_io(NULL, num_regions, where, rw, &dp, fn, context);
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}
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int dm_io_async_bvec(unsigned int num_regions, struct io_region *where, int rw,
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{
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struct dpages dp;
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bvec_dp_init(&dp, bvec);
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return async_io(num_regions, where, rw, &dp, fn, context);
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return async_io(NULL, num_regions, where, rw, &dp, fn, context);
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}
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int dm_io_async_vm(unsigned int num_regions, struct io_region *where, int rw,
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{
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struct dpages dp;
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vm_dp_init(&dp, data);
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return async_io(num_regions, where, rw, &dp, fn, context);
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return async_io(NULL, num_regions, where, rw, &dp, fn, context);
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}
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EXPORT_SYMBOL(dm_io_get);
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