From 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 Mon Sep 17 00:00:00 2001 From: Linus Torvalds Date: Sat, 16 Apr 2005 15:20:36 -0700 Subject: Linux-2.6.12-rc2 Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip! --- drivers/md/dm-io.c | 426 +++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 426 insertions(+) create mode 100644 drivers/md/dm-io.c (limited to 'drivers/md/dm-io.c') diff --git a/drivers/md/dm-io.c b/drivers/md/dm-io.c new file mode 100644 index 000000000000..45754bb6a799 --- /dev/null +++ b/drivers/md/dm-io.c @@ -0,0 +1,426 @@ +/* + * Copyright (C) 2003 Sistina Software + * + * This file is released under the GPL. + */ + +#include "dm-io.h" + +#include +#include +#include +#include +#include + +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(unsigned int __nocast 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; +} + +/*----------------------------------------------------------------- + * 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_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); -- cgit v1.2.3