/* * 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 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_kmalloc_pool(new_ios, sizeof(struct io)); 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);