| /* |
| * Copyright (C) 2003 Sistina Software |
| * |
| * This file is released under the GPL. |
| */ |
| |
| #include "dm-io.h" |
| |
| #include <linux/bio.h> |
| #include <linux/mempool.h> |
| #include <linux/module.h> |
| #include <linux/sched.h> |
| #include <linux/slab.h> |
| |
| static struct bio_set *_bios; |
| |
| /* FIXME: can we shrink this ? */ |
| struct io { |
| unsigned long error; |
| atomic_t count; |
| struct task_struct *sleeper; |
| io_notify_fn callback; |
| void *context; |
| }; |
| |
| /* |
| * io contexts are only dynamically allocated for asynchronous |
| * io. Since async io is likely to be the majority of io we'll |
| * have the same number of io contexts as buffer heads ! (FIXME: |
| * must reduce this). |
| */ |
| static unsigned _num_ios; |
| static mempool_t *_io_pool; |
| |
| static void *alloc_io(gfp_t gfp_mask, void *pool_data) |
| { |
| return kmalloc(sizeof(struct io), gfp_mask); |
| } |
| |
| static void free_io(void *element, void *pool_data) |
| { |
| kfree(element); |
| } |
| |
| static unsigned int pages_to_ios(unsigned int pages) |
| { |
| return 4 * pages; /* too many ? */ |
| } |
| |
| static int resize_pool(unsigned int new_ios) |
| { |
| int r = 0; |
| |
| if (_io_pool) { |
| if (new_ios == 0) { |
| /* free off the pool */ |
| mempool_destroy(_io_pool); |
| _io_pool = NULL; |
| bioset_free(_bios); |
| |
| } else { |
| /* resize the pool */ |
| r = mempool_resize(_io_pool, new_ios, GFP_KERNEL); |
| } |
| |
| } else { |
| /* create new pool */ |
| _io_pool = mempool_create(new_ios, alloc_io, free_io, NULL); |
| if (!_io_pool) |
| return -ENOMEM; |
| |
| _bios = bioset_create(16, 16, 4); |
| if (!_bios) { |
| mempool_destroy(_io_pool); |
| _io_pool = NULL; |
| return -ENOMEM; |
| } |
| } |
| |
| if (!r) |
| _num_ios = new_ios; |
| |
| return r; |
| } |
| |
| int dm_io_get(unsigned int num_pages) |
| { |
| return resize_pool(_num_ios + pages_to_ios(num_pages)); |
| } |
| |
| void dm_io_put(unsigned int num_pages) |
| { |
| resize_pool(_num_ios - pages_to_ios(num_pages)); |
| } |
| |
| /*----------------------------------------------------------------- |
| * We need to keep track of which region a bio is doing io for. |
| * In order to save a memory allocation we store this the last |
| * bvec which we know is unused (blech). |
| * XXX This is ugly and can OOPS with some configs... find another way. |
| *---------------------------------------------------------------*/ |
| static inline void bio_set_region(struct bio *bio, unsigned region) |
| { |
| bio->bi_io_vec[bio->bi_max_vecs - 1].bv_len = region; |
| } |
| |
| static inline unsigned bio_get_region(struct bio *bio) |
| { |
| return bio->bi_io_vec[bio->bi_max_vecs - 1].bv_len; |
| } |
| |
| /*----------------------------------------------------------------- |
| * We need an io object to keep track of the number of bios that |
| * have been dispatched for a particular io. |
| *---------------------------------------------------------------*/ |
| static void dec_count(struct io *io, unsigned int region, int error) |
| { |
| if (error) |
| set_bit(region, &io->error); |
| |
| if (atomic_dec_and_test(&io->count)) { |
| if (io->sleeper) |
| wake_up_process(io->sleeper); |
| |
| else { |
| int r = io->error; |
| io_notify_fn fn = io->callback; |
| void *context = io->context; |
| |
| mempool_free(io, _io_pool); |
| fn(r, context); |
| } |
| } |
| } |
| |
| static int endio(struct bio *bio, unsigned int done, int error) |
| { |
| struct io *io = (struct io *) bio->bi_private; |
| |
| /* keep going until we've finished */ |
| if (bio->bi_size) |
| return 1; |
| |
| if (error && bio_data_dir(bio) == READ) |
| zero_fill_bio(bio); |
| |
| dec_count(io, bio_get_region(bio), error); |
| bio_put(bio); |
| |
| return 0; |
| } |
| |
| /*----------------------------------------------------------------- |
| * These little objects provide an abstraction for getting a new |
| * destination page for io. |
| *---------------------------------------------------------------*/ |
| struct dpages { |
| void (*get_page)(struct dpages *dp, |
| struct page **p, unsigned long *len, unsigned *offset); |
| void (*next_page)(struct dpages *dp); |
| |
| unsigned context_u; |
| void *context_ptr; |
| }; |
| |
| /* |
| * Functions for getting the pages from a list. |
| */ |
| static void list_get_page(struct dpages *dp, |
| struct page **p, unsigned long *len, unsigned *offset) |
| { |
| unsigned o = dp->context_u; |
| struct page_list *pl = (struct page_list *) dp->context_ptr; |
| |
| *p = pl->page; |
| *len = PAGE_SIZE - o; |
| *offset = o; |
| } |
| |
| static void list_next_page(struct dpages *dp) |
| { |
| struct page_list *pl = (struct page_list *) dp->context_ptr; |
| dp->context_ptr = pl->next; |
| dp->context_u = 0; |
| } |
| |
| static void list_dp_init(struct dpages *dp, struct page_list *pl, unsigned offset) |
| { |
| dp->get_page = list_get_page; |
| dp->next_page = list_next_page; |
| dp->context_u = offset; |
| dp->context_ptr = pl; |
| } |
| |
| /* |
| * Functions for getting the pages from a bvec. |
| */ |
| static void bvec_get_page(struct dpages *dp, |
| struct page **p, unsigned long *len, unsigned *offset) |
| { |
| struct bio_vec *bvec = (struct bio_vec *) dp->context_ptr; |
| *p = bvec->bv_page; |
| *len = bvec->bv_len; |
| *offset = bvec->bv_offset; |
| } |
| |
| static void bvec_next_page(struct dpages *dp) |
| { |
| struct bio_vec *bvec = (struct bio_vec *) dp->context_ptr; |
| dp->context_ptr = bvec + 1; |
| } |
| |
| static void bvec_dp_init(struct dpages *dp, struct bio_vec *bvec) |
| { |
| dp->get_page = bvec_get_page; |
| dp->next_page = bvec_next_page; |
| dp->context_ptr = bvec; |
| } |
| |
| static void vm_get_page(struct dpages *dp, |
| struct page **p, unsigned long *len, unsigned *offset) |
| { |
| *p = vmalloc_to_page(dp->context_ptr); |
| *offset = dp->context_u; |
| *len = PAGE_SIZE - dp->context_u; |
| } |
| |
| static void vm_next_page(struct dpages *dp) |
| { |
| dp->context_ptr += PAGE_SIZE - dp->context_u; |
| dp->context_u = 0; |
| } |
| |
| static void vm_dp_init(struct dpages *dp, void *data) |
| { |
| dp->get_page = vm_get_page; |
| dp->next_page = vm_next_page; |
| dp->context_u = ((unsigned long) data) & (PAGE_SIZE - 1); |
| dp->context_ptr = data; |
| } |
| |
| static void dm_bio_destructor(struct bio *bio) |
| { |
| bio_free(bio, _bios); |
| } |
| |
| /*----------------------------------------------------------------- |
| * IO routines that accept a list of pages. |
| *---------------------------------------------------------------*/ |
| static void do_region(int rw, unsigned int region, struct io_region *where, |
| struct dpages *dp, struct io *io) |
| { |
| struct bio *bio; |
| struct page *page; |
| unsigned long len; |
| unsigned offset; |
| unsigned num_bvecs; |
| sector_t remaining = where->count; |
| |
| while (remaining) { |
| /* |
| * Allocate a suitably sized bio, we add an extra |
| * bvec for bio_get/set_region(). |
| */ |
| num_bvecs = (remaining / (PAGE_SIZE >> 9)) + 2; |
| bio = bio_alloc_bioset(GFP_NOIO, num_bvecs, _bios); |
| bio->bi_sector = where->sector + (where->count - remaining); |
| bio->bi_bdev = where->bdev; |
| bio->bi_end_io = endio; |
| bio->bi_private = io; |
| bio->bi_destructor = dm_bio_destructor; |
| bio_set_region(bio, region); |
| |
| /* |
| * Try and add as many pages as possible. |
| */ |
| while (remaining) { |
| dp->get_page(dp, &page, &len, &offset); |
| len = min(len, to_bytes(remaining)); |
| if (!bio_add_page(bio, page, len, offset)) |
| break; |
| |
| offset = 0; |
| remaining -= to_sector(len); |
| dp->next_page(dp); |
| } |
| |
| atomic_inc(&io->count); |
| submit_bio(rw, bio); |
| } |
| } |
| |
| static void dispatch_io(int rw, unsigned int num_regions, |
| struct io_region *where, struct dpages *dp, |
| struct io *io, int sync) |
| { |
| int i; |
| struct dpages old_pages = *dp; |
| |
| if (sync) |
| rw |= (1 << BIO_RW_SYNC); |
| |
| /* |
| * For multiple regions we need to be careful to rewind |
| * the dp object for each call to do_region. |
| */ |
| for (i = 0; i < num_regions; i++) { |
| *dp = old_pages; |
| if (where[i].count) |
| do_region(rw, i, where + i, dp, io); |
| } |
| |
| /* |
| * Drop the extra refence that we were holding to avoid |
| * the io being completed too early. |
| */ |
| dec_count(io, 0, 0); |
| } |
| |
| static int sync_io(unsigned int num_regions, struct io_region *where, |
| int rw, struct dpages *dp, unsigned long *error_bits) |
| { |
| struct io io; |
| |
| if (num_regions > 1 && rw != WRITE) { |
| WARN_ON(1); |
| return -EIO; |
| } |
| |
| io.error = 0; |
| atomic_set(&io.count, 1); /* see dispatch_io() */ |
| io.sleeper = current; |
| |
| dispatch_io(rw, num_regions, where, dp, &io, 1); |
| |
| while (1) { |
| set_current_state(TASK_UNINTERRUPTIBLE); |
| |
| if (!atomic_read(&io.count) || signal_pending(current)) |
| break; |
| |
| io_schedule(); |
| } |
| set_current_state(TASK_RUNNING); |
| |
| if (atomic_read(&io.count)) |
| return -EINTR; |
| |
| *error_bits = io.error; |
| return io.error ? -EIO : 0; |
| } |
| |
| static int async_io(unsigned int num_regions, struct io_region *where, int rw, |
| struct dpages *dp, io_notify_fn fn, void *context) |
| { |
| struct io *io; |
| |
| if (num_regions > 1 && rw != WRITE) { |
| WARN_ON(1); |
| fn(1, context); |
| return -EIO; |
| } |
| |
| io = mempool_alloc(_io_pool, GFP_NOIO); |
| io->error = 0; |
| atomic_set(&io->count, 1); /* see dispatch_io() */ |
| io->sleeper = NULL; |
| io->callback = fn; |
| io->context = context; |
| |
| dispatch_io(rw, num_regions, where, dp, io, 0); |
| return 0; |
| } |
| |
| int dm_io_sync(unsigned int num_regions, struct io_region *where, int rw, |
| struct page_list *pl, unsigned int offset, |
| unsigned long *error_bits) |
| { |
| struct dpages dp; |
| list_dp_init(&dp, pl, offset); |
| return sync_io(num_regions, where, rw, &dp, error_bits); |
| } |
| |
| int dm_io_sync_bvec(unsigned int num_regions, struct io_region *where, int rw, |
| struct bio_vec *bvec, unsigned long *error_bits) |
| { |
| struct dpages dp; |
| bvec_dp_init(&dp, bvec); |
| return sync_io(num_regions, where, rw, &dp, error_bits); |
| } |
| |
| int dm_io_sync_vm(unsigned int num_regions, struct io_region *where, int rw, |
| void *data, unsigned long *error_bits) |
| { |
| struct dpages dp; |
| vm_dp_init(&dp, data); |
| return sync_io(num_regions, where, rw, &dp, error_bits); |
| } |
| |
| int dm_io_async(unsigned int num_regions, struct io_region *where, int rw, |
| struct page_list *pl, unsigned int offset, |
| io_notify_fn fn, void *context) |
| { |
| struct dpages dp; |
| list_dp_init(&dp, pl, offset); |
| return async_io(num_regions, where, rw, &dp, fn, context); |
| } |
| |
| int dm_io_async_bvec(unsigned int num_regions, struct io_region *where, int rw, |
| struct bio_vec *bvec, io_notify_fn fn, void *context) |
| { |
| struct dpages dp; |
| bvec_dp_init(&dp, bvec); |
| return async_io(num_regions, where, rw, &dp, fn, context); |
| } |
| |
| int dm_io_async_vm(unsigned int num_regions, struct io_region *where, int rw, |
| void *data, io_notify_fn fn, void *context) |
| { |
| struct dpages dp; |
| vm_dp_init(&dp, data); |
| return async_io(num_regions, where, rw, &dp, fn, context); |
| } |
| |
| EXPORT_SYMBOL(dm_io_get); |
| EXPORT_SYMBOL(dm_io_put); |
| EXPORT_SYMBOL(dm_io_sync); |
| EXPORT_SYMBOL(dm_io_async); |
| EXPORT_SYMBOL(dm_io_sync_bvec); |
| EXPORT_SYMBOL(dm_io_async_bvec); |
| EXPORT_SYMBOL(dm_io_sync_vm); |
| EXPORT_SYMBOL(dm_io_async_vm); |