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author | Linus Torvalds <torvalds@ppc970.osdl.org> | 2005-04-16 22:20:36 (GMT) |
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committer | Linus Torvalds <torvalds@ppc970.osdl.org> | 2005-04-16 22:20:36 (GMT) |
commit | 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 (patch) | |
tree | 0bba044c4ce775e45a88a51686b5d9f90697ea9d /fs/bio.c | |
download | linux-fsl-qoriq-1da177e4c3f41524e886b7f1b8a0c1fc7321cac2.tar.xz |
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!
Diffstat (limited to 'fs/bio.c')
-rw-r--r-- | fs/bio.c | 1096 |
1 files changed, 1096 insertions, 0 deletions
diff --git a/fs/bio.c b/fs/bio.c new file mode 100644 index 0000000..e5349e8 --- /dev/null +++ b/fs/bio.c @@ -0,0 +1,1096 @@ +/* + * Copyright (C) 2001 Jens Axboe <axboe@suse.de> + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License version 2 as + * published by the Free Software Foundation. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + * + * You should have received a copy of the GNU General Public Licens + * along with this program; if not, write to the Free Software + * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111- + * + */ +#include <linux/mm.h> +#include <linux/swap.h> +#include <linux/bio.h> +#include <linux/blkdev.h> +#include <linux/slab.h> +#include <linux/init.h> +#include <linux/kernel.h> +#include <linux/module.h> +#include <linux/mempool.h> +#include <linux/workqueue.h> + +#define BIO_POOL_SIZE 256 + +static kmem_cache_t *bio_slab; + +#define BIOVEC_NR_POOLS 6 + +/* + * a small number of entries is fine, not going to be performance critical. + * basically we just need to survive + */ +#define BIO_SPLIT_ENTRIES 8 +mempool_t *bio_split_pool; + +struct biovec_slab { + int nr_vecs; + char *name; + kmem_cache_t *slab; +}; + +/* + * if you change this list, also change bvec_alloc or things will + * break badly! cannot be bigger than what you can fit into an + * unsigned short + */ + +#define BV(x) { .nr_vecs = x, .name = "biovec-"__stringify(x) } +static struct biovec_slab bvec_slabs[BIOVEC_NR_POOLS] = { + BV(1), BV(4), BV(16), BV(64), BV(128), BV(BIO_MAX_PAGES), +}; +#undef BV + +/* + * bio_set is used to allow other portions of the IO system to + * allocate their own private memory pools for bio and iovec structures. + * These memory pools in turn all allocate from the bio_slab + * and the bvec_slabs[]. + */ +struct bio_set { + mempool_t *bio_pool; + mempool_t *bvec_pools[BIOVEC_NR_POOLS]; +}; + +/* + * fs_bio_set is the bio_set containing bio and iovec memory pools used by + * IO code that does not need private memory pools. + */ +static struct bio_set *fs_bio_set; + +static inline struct bio_vec *bvec_alloc_bs(unsigned int __nocast gfp_mask, int nr, unsigned long *idx, struct bio_set *bs) +{ + struct bio_vec *bvl; + struct biovec_slab *bp; + + /* + * see comment near bvec_array define! + */ + switch (nr) { + case 1 : *idx = 0; break; + case 2 ... 4: *idx = 1; break; + case 5 ... 16: *idx = 2; break; + case 17 ... 64: *idx = 3; break; + case 65 ... 128: *idx = 4; break; + case 129 ... BIO_MAX_PAGES: *idx = 5; break; + default: + return NULL; + } + /* + * idx now points to the pool we want to allocate from + */ + + bp = bvec_slabs + *idx; + bvl = mempool_alloc(bs->bvec_pools[*idx], gfp_mask); + if (bvl) + memset(bvl, 0, bp->nr_vecs * sizeof(struct bio_vec)); + + return bvl; +} + +/* + * default destructor for a bio allocated with bio_alloc_bioset() + */ +static void bio_destructor(struct bio *bio) +{ + const int pool_idx = BIO_POOL_IDX(bio); + struct bio_set *bs = bio->bi_set; + + BIO_BUG_ON(pool_idx >= BIOVEC_NR_POOLS); + + mempool_free(bio->bi_io_vec, bs->bvec_pools[pool_idx]); + mempool_free(bio, bs->bio_pool); +} + +inline void bio_init(struct bio *bio) +{ + bio->bi_next = NULL; + bio->bi_flags = 1 << BIO_UPTODATE; + bio->bi_rw = 0; + bio->bi_vcnt = 0; + bio->bi_idx = 0; + bio->bi_phys_segments = 0; + bio->bi_hw_segments = 0; + bio->bi_hw_front_size = 0; + bio->bi_hw_back_size = 0; + bio->bi_size = 0; + bio->bi_max_vecs = 0; + bio->bi_end_io = NULL; + atomic_set(&bio->bi_cnt, 1); + bio->bi_private = NULL; +} + +/** + * bio_alloc_bioset - allocate a bio for I/O + * @gfp_mask: the GFP_ mask given to the slab allocator + * @nr_iovecs: number of iovecs to pre-allocate + * + * Description: + * bio_alloc_bioset will first try it's on mempool to satisfy the allocation. + * If %__GFP_WAIT is set then we will block on the internal pool waiting + * for a &struct bio to become free. + * + * allocate bio and iovecs from the memory pools specified by the + * bio_set structure. + **/ +struct bio *bio_alloc_bioset(unsigned int __nocast gfp_mask, int nr_iovecs, struct bio_set *bs) +{ + struct bio *bio = mempool_alloc(bs->bio_pool, gfp_mask); + + if (likely(bio)) { + struct bio_vec *bvl = NULL; + + bio_init(bio); + if (likely(nr_iovecs)) { + unsigned long idx; + + bvl = bvec_alloc_bs(gfp_mask, nr_iovecs, &idx, bs); + if (unlikely(!bvl)) { + mempool_free(bio, bs->bio_pool); + bio = NULL; + goto out; + } + bio->bi_flags |= idx << BIO_POOL_OFFSET; + bio->bi_max_vecs = bvec_slabs[idx].nr_vecs; + } + bio->bi_io_vec = bvl; + bio->bi_destructor = bio_destructor; + bio->bi_set = bs; + } +out: + return bio; +} + +struct bio *bio_alloc(unsigned int __nocast gfp_mask, int nr_iovecs) +{ + return bio_alloc_bioset(gfp_mask, nr_iovecs, fs_bio_set); +} + +void zero_fill_bio(struct bio *bio) +{ + unsigned long flags; + struct bio_vec *bv; + int i; + + bio_for_each_segment(bv, bio, i) { + char *data = bvec_kmap_irq(bv, &flags); + memset(data, 0, bv->bv_len); + flush_dcache_page(bv->bv_page); + bvec_kunmap_irq(data, &flags); + } +} +EXPORT_SYMBOL(zero_fill_bio); + +/** + * bio_put - release a reference to a bio + * @bio: bio to release reference to + * + * Description: + * Put a reference to a &struct bio, either one you have gotten with + * bio_alloc or bio_get. The last put of a bio will free it. + **/ +void bio_put(struct bio *bio) +{ + BIO_BUG_ON(!atomic_read(&bio->bi_cnt)); + + /* + * last put frees it + */ + if (atomic_dec_and_test(&bio->bi_cnt)) { + bio->bi_next = NULL; + bio->bi_destructor(bio); + } +} + +inline int bio_phys_segments(request_queue_t *q, struct bio *bio) +{ + if (unlikely(!bio_flagged(bio, BIO_SEG_VALID))) + blk_recount_segments(q, bio); + + return bio->bi_phys_segments; +} + +inline int bio_hw_segments(request_queue_t *q, struct bio *bio) +{ + if (unlikely(!bio_flagged(bio, BIO_SEG_VALID))) + blk_recount_segments(q, bio); + + return bio->bi_hw_segments; +} + +/** + * __bio_clone - clone a bio + * @bio: destination bio + * @bio_src: bio to clone + * + * Clone a &bio. Caller will own the returned bio, but not + * the actual data it points to. Reference count of returned + * bio will be one. + */ +inline void __bio_clone(struct bio *bio, struct bio *bio_src) +{ + request_queue_t *q = bdev_get_queue(bio_src->bi_bdev); + + memcpy(bio->bi_io_vec, bio_src->bi_io_vec, bio_src->bi_max_vecs * sizeof(struct bio_vec)); + + bio->bi_sector = bio_src->bi_sector; + bio->bi_bdev = bio_src->bi_bdev; + bio->bi_flags |= 1 << BIO_CLONED; + bio->bi_rw = bio_src->bi_rw; + + /* + * notes -- maybe just leave bi_idx alone. assume identical mapping + * for the clone + */ + bio->bi_vcnt = bio_src->bi_vcnt; + bio->bi_size = bio_src->bi_size; + bio_phys_segments(q, bio); + bio_hw_segments(q, bio); +} + +/** + * bio_clone - clone a bio + * @bio: bio to clone + * @gfp_mask: allocation priority + * + * Like __bio_clone, only also allocates the returned bio + */ +struct bio *bio_clone(struct bio *bio, unsigned int __nocast gfp_mask) +{ + struct bio *b = bio_alloc_bioset(gfp_mask, bio->bi_max_vecs, fs_bio_set); + + if (b) + __bio_clone(b, bio); + + return b; +} + +/** + * bio_get_nr_vecs - return approx number of vecs + * @bdev: I/O target + * + * Return the approximate number of pages we can send to this target. + * There's no guarantee that you will be able to fit this number of pages + * into a bio, it does not account for dynamic restrictions that vary + * on offset. + */ +int bio_get_nr_vecs(struct block_device *bdev) +{ + request_queue_t *q = bdev_get_queue(bdev); + int nr_pages; + + nr_pages = ((q->max_sectors << 9) + PAGE_SIZE - 1) >> PAGE_SHIFT; + if (nr_pages > q->max_phys_segments) + nr_pages = q->max_phys_segments; + if (nr_pages > q->max_hw_segments) + nr_pages = q->max_hw_segments; + + return nr_pages; +} + +static int __bio_add_page(request_queue_t *q, struct bio *bio, struct page + *page, unsigned int len, unsigned int offset) +{ + int retried_segments = 0; + struct bio_vec *bvec; + + /* + * cloned bio must not modify vec list + */ + if (unlikely(bio_flagged(bio, BIO_CLONED))) + return 0; + + if (bio->bi_vcnt >= bio->bi_max_vecs) + return 0; + + if (((bio->bi_size + len) >> 9) > q->max_sectors) + return 0; + + /* + * we might lose a segment or two here, but rather that than + * make this too complex. + */ + + while (bio->bi_phys_segments >= q->max_phys_segments + || bio->bi_hw_segments >= q->max_hw_segments + || BIOVEC_VIRT_OVERSIZE(bio->bi_size)) { + + if (retried_segments) + return 0; + + retried_segments = 1; + blk_recount_segments(q, bio); + } + + /* + * setup the new entry, we might clear it again later if we + * cannot add the page + */ + bvec = &bio->bi_io_vec[bio->bi_vcnt]; + bvec->bv_page = page; + bvec->bv_len = len; + bvec->bv_offset = offset; + + /* + * if queue has other restrictions (eg varying max sector size + * depending on offset), it can specify a merge_bvec_fn in the + * queue to get further control + */ + if (q->merge_bvec_fn) { + /* + * merge_bvec_fn() returns number of bytes it can accept + * at this offset + */ + if (q->merge_bvec_fn(q, bio, bvec) < len) { + bvec->bv_page = NULL; + bvec->bv_len = 0; + bvec->bv_offset = 0; + return 0; + } + } + + /* If we may be able to merge these biovecs, force a recount */ + if (bio->bi_vcnt && (BIOVEC_PHYS_MERGEABLE(bvec-1, bvec) || + BIOVEC_VIRT_MERGEABLE(bvec-1, bvec))) + bio->bi_flags &= ~(1 << BIO_SEG_VALID); + + bio->bi_vcnt++; + bio->bi_phys_segments++; + bio->bi_hw_segments++; + bio->bi_size += len; + return len; +} + +/** + * bio_add_page - attempt to add page to bio + * @bio: destination bio + * @page: page to add + * @len: vec entry length + * @offset: vec entry offset + * + * Attempt to add a page to the bio_vec maplist. This can fail for a + * number of reasons, such as the bio being full or target block + * device limitations. The target block device must allow bio's + * smaller than PAGE_SIZE, so it is always possible to add a single + * page to an empty bio. + */ +int bio_add_page(struct bio *bio, struct page *page, unsigned int len, + unsigned int offset) +{ + return __bio_add_page(bdev_get_queue(bio->bi_bdev), bio, page, + len, offset); +} + +struct bio_map_data { + struct bio_vec *iovecs; + void __user *userptr; +}; + +static void bio_set_map_data(struct bio_map_data *bmd, struct bio *bio) +{ + memcpy(bmd->iovecs, bio->bi_io_vec, sizeof(struct bio_vec) * bio->bi_vcnt); + bio->bi_private = bmd; +} + +static void bio_free_map_data(struct bio_map_data *bmd) +{ + kfree(bmd->iovecs); + kfree(bmd); +} + +static struct bio_map_data *bio_alloc_map_data(int nr_segs) +{ + struct bio_map_data *bmd = kmalloc(sizeof(*bmd), GFP_KERNEL); + + if (!bmd) + return NULL; + + bmd->iovecs = kmalloc(sizeof(struct bio_vec) * nr_segs, GFP_KERNEL); + if (bmd->iovecs) + return bmd; + + kfree(bmd); + return NULL; +} + +/** + * bio_uncopy_user - finish previously mapped bio + * @bio: bio being terminated + * + * Free pages allocated from bio_copy_user() and write back data + * to user space in case of a read. + */ +int bio_uncopy_user(struct bio *bio) +{ + struct bio_map_data *bmd = bio->bi_private; + const int read = bio_data_dir(bio) == READ; + struct bio_vec *bvec; + int i, ret = 0; + + __bio_for_each_segment(bvec, bio, i, 0) { + char *addr = page_address(bvec->bv_page); + unsigned int len = bmd->iovecs[i].bv_len; + + if (read && !ret && copy_to_user(bmd->userptr, addr, len)) + ret = -EFAULT; + + __free_page(bvec->bv_page); + bmd->userptr += len; + } + bio_free_map_data(bmd); + bio_put(bio); + return ret; +} + +/** + * bio_copy_user - copy user data to bio + * @q: destination block queue + * @uaddr: start of user address + * @len: length in bytes + * @write_to_vm: bool indicating writing to pages or not + * + * Prepares and returns a bio for indirect user io, bouncing data + * to/from kernel pages as necessary. Must be paired with + * call bio_uncopy_user() on io completion. + */ +struct bio *bio_copy_user(request_queue_t *q, unsigned long uaddr, + unsigned int len, int write_to_vm) +{ + unsigned long end = (uaddr + len + PAGE_SIZE - 1) >> PAGE_SHIFT; + unsigned long start = uaddr >> PAGE_SHIFT; + struct bio_map_data *bmd; + struct bio_vec *bvec; + struct page *page; + struct bio *bio; + int i, ret; + + bmd = bio_alloc_map_data(end - start); + if (!bmd) + return ERR_PTR(-ENOMEM); + + bmd->userptr = (void __user *) uaddr; + + ret = -ENOMEM; + bio = bio_alloc(GFP_KERNEL, end - start); + if (!bio) + goto out_bmd; + + bio->bi_rw |= (!write_to_vm << BIO_RW); + + ret = 0; + while (len) { + unsigned int bytes = PAGE_SIZE; + + if (bytes > len) + bytes = len; + + page = alloc_page(q->bounce_gfp | GFP_KERNEL); + if (!page) { + ret = -ENOMEM; + break; + } + + if (__bio_add_page(q, bio, page, bytes, 0) < bytes) { + ret = -EINVAL; + break; + } + + len -= bytes; + } + + if (ret) + goto cleanup; + + /* + * success + */ + if (!write_to_vm) { + char __user *p = (char __user *) uaddr; + + /* + * for a write, copy in data to kernel pages + */ + ret = -EFAULT; + bio_for_each_segment(bvec, bio, i) { + char *addr = page_address(bvec->bv_page); + + if (copy_from_user(addr, p, bvec->bv_len)) + goto cleanup; + p += bvec->bv_len; + } + } + + bio_set_map_data(bmd, bio); + return bio; +cleanup: + bio_for_each_segment(bvec, bio, i) + __free_page(bvec->bv_page); + + bio_put(bio); +out_bmd: + bio_free_map_data(bmd); + return ERR_PTR(ret); +} + +static struct bio *__bio_map_user(request_queue_t *q, struct block_device *bdev, + unsigned long uaddr, unsigned int len, + int write_to_vm) +{ + unsigned long end = (uaddr + len + PAGE_SIZE - 1) >> PAGE_SHIFT; + unsigned long start = uaddr >> PAGE_SHIFT; + const int nr_pages = end - start; + int ret, offset, i; + struct page **pages; + struct bio *bio; + + /* + * transfer and buffer must be aligned to at least hardsector + * size for now, in the future we can relax this restriction + */ + if ((uaddr & queue_dma_alignment(q)) || (len & queue_dma_alignment(q))) + return ERR_PTR(-EINVAL); + + bio = bio_alloc(GFP_KERNEL, nr_pages); + if (!bio) + return ERR_PTR(-ENOMEM); + + ret = -ENOMEM; + pages = kmalloc(nr_pages * sizeof(struct page *), GFP_KERNEL); + if (!pages) + goto out; + + down_read(¤t->mm->mmap_sem); + ret = get_user_pages(current, current->mm, uaddr, nr_pages, + write_to_vm, 0, pages, NULL); + up_read(¤t->mm->mmap_sem); + + if (ret < nr_pages) + goto out; + + bio->bi_bdev = bdev; + + offset = uaddr & ~PAGE_MASK; + for (i = 0; i < nr_pages; i++) { + unsigned int bytes = PAGE_SIZE - offset; + + if (len <= 0) + break; + + if (bytes > len) + bytes = len; + + /* + * sorry... + */ + if (__bio_add_page(q, bio, pages[i], bytes, offset) < bytes) + break; + + len -= bytes; + offset = 0; + } + + /* + * release the pages we didn't map into the bio, if any + */ + while (i < nr_pages) + page_cache_release(pages[i++]); + + kfree(pages); + + /* + * set data direction, and check if mapped pages need bouncing + */ + if (!write_to_vm) + bio->bi_rw |= (1 << BIO_RW); + + bio->bi_flags |= (1 << BIO_USER_MAPPED); + return bio; +out: + kfree(pages); + bio_put(bio); + return ERR_PTR(ret); +} + +/** + * bio_map_user - map user address into bio + * @bdev: destination block device + * @uaddr: start of user address + * @len: length in bytes + * @write_to_vm: bool indicating writing to pages or not + * + * Map the user space address into a bio suitable for io to a block + * device. Returns an error pointer in case of error. + */ +struct bio *bio_map_user(request_queue_t *q, struct block_device *bdev, + unsigned long uaddr, unsigned int len, int write_to_vm) +{ + struct bio *bio; + + bio = __bio_map_user(q, bdev, uaddr, len, write_to_vm); + + if (IS_ERR(bio)) + return bio; + + /* + * subtle -- if __bio_map_user() ended up bouncing a bio, + * it would normally disappear when its bi_end_io is run. + * however, we need it for the unmap, so grab an extra + * reference to it + */ + bio_get(bio); + + if (bio->bi_size == len) + return bio; + + /* + * don't support partial mappings + */ + bio_endio(bio, bio->bi_size, 0); + bio_unmap_user(bio); + return ERR_PTR(-EINVAL); +} + +static void __bio_unmap_user(struct bio *bio) +{ + struct bio_vec *bvec; + int i; + + /* + * make sure we dirty pages we wrote to + */ + __bio_for_each_segment(bvec, bio, i, 0) { + if (bio_data_dir(bio) == READ) + set_page_dirty_lock(bvec->bv_page); + + page_cache_release(bvec->bv_page); + } + + bio_put(bio); +} + +/** + * bio_unmap_user - unmap a bio + * @bio: the bio being unmapped + * + * Unmap a bio previously mapped by bio_map_user(). Must be called with + * a process context. + * + * bio_unmap_user() may sleep. + */ +void bio_unmap_user(struct bio *bio) +{ + __bio_unmap_user(bio); + bio_put(bio); +} + +/* + * bio_set_pages_dirty() and bio_check_pages_dirty() are support functions + * for performing direct-IO in BIOs. + * + * The problem is that we cannot run set_page_dirty() from interrupt context + * because the required locks are not interrupt-safe. So what we can do is to + * mark the pages dirty _before_ performing IO. And in interrupt context, + * check that the pages are still dirty. If so, fine. If not, redirty them + * in process context. + * + * We special-case compound pages here: normally this means reads into hugetlb + * pages. The logic in here doesn't really work right for compound pages + * because the VM does not uniformly chase down the head page in all cases. + * But dirtiness of compound pages is pretty meaningless anyway: the VM doesn't + * handle them at all. So we skip compound pages here at an early stage. + * + * Note that this code is very hard to test under normal circumstances because + * direct-io pins the pages with get_user_pages(). This makes + * is_page_cache_freeable return false, and the VM will not clean the pages. + * But other code (eg, pdflush) could clean the pages if they are mapped + * pagecache. + * + * Simply disabling the call to bio_set_pages_dirty() is a good way to test the + * deferred bio dirtying paths. + */ + +/* + * bio_set_pages_dirty() will mark all the bio's pages as dirty. + */ +void bio_set_pages_dirty(struct bio *bio) +{ + struct bio_vec *bvec = bio->bi_io_vec; + int i; + + for (i = 0; i < bio->bi_vcnt; i++) { + struct page *page = bvec[i].bv_page; + + if (page && !PageCompound(page)) + set_page_dirty_lock(page); + } +} + +static void bio_release_pages(struct bio *bio) +{ + struct bio_vec *bvec = bio->bi_io_vec; + int i; + + for (i = 0; i < bio->bi_vcnt; i++) { + struct page *page = bvec[i].bv_page; + + if (page) + put_page(page); + } +} + +/* + * bio_check_pages_dirty() will check that all the BIO's pages are still dirty. + * If they are, then fine. If, however, some pages are clean then they must + * have been written out during the direct-IO read. So we take another ref on + * the BIO and the offending pages and re-dirty the pages in process context. + * + * It is expected that bio_check_pages_dirty() will wholly own the BIO from + * here on. It will run one page_cache_release() against each page and will + * run one bio_put() against the BIO. + */ + +static void bio_dirty_fn(void *data); + +static DECLARE_WORK(bio_dirty_work, bio_dirty_fn, NULL); +static DEFINE_SPINLOCK(bio_dirty_lock); +static struct bio *bio_dirty_list; + +/* + * This runs in process context + */ +static void bio_dirty_fn(void *data) +{ + unsigned long flags; + struct bio *bio; + + spin_lock_irqsave(&bio_dirty_lock, flags); + bio = bio_dirty_list; + bio_dirty_list = NULL; + spin_unlock_irqrestore(&bio_dirty_lock, flags); + + while (bio) { + struct bio *next = bio->bi_private; + + bio_set_pages_dirty(bio); + bio_release_pages(bio); + bio_put(bio); + bio = next; + } +} + +void bio_check_pages_dirty(struct bio *bio) +{ + struct bio_vec *bvec = bio->bi_io_vec; + int nr_clean_pages = 0; + int i; + + for (i = 0; i < bio->bi_vcnt; i++) { + struct page *page = bvec[i].bv_page; + + if (PageDirty(page) || PageCompound(page)) { + page_cache_release(page); + bvec[i].bv_page = NULL; + } else { + nr_clean_pages++; + } + } + + if (nr_clean_pages) { + unsigned long flags; + + spin_lock_irqsave(&bio_dirty_lock, flags); + bio->bi_private = bio_dirty_list; + bio_dirty_list = bio; + spin_unlock_irqrestore(&bio_dirty_lock, flags); + schedule_work(&bio_dirty_work); + } else { + bio_put(bio); + } +} + +/** + * bio_endio - end I/O on a bio + * @bio: bio + * @bytes_done: number of bytes completed + * @error: error, if any + * + * Description: + * bio_endio() will end I/O on @bytes_done number of bytes. This may be + * just a partial part of the bio, or it may be the whole bio. bio_endio() + * is the preferred way to end I/O on a bio, it takes care of decrementing + * bi_size and clearing BIO_UPTODATE on error. @error is 0 on success, and + * and one of the established -Exxxx (-EIO, for instance) error values in + * case something went wrong. Noone should call bi_end_io() directly on + * a bio unless they own it and thus know that it has an end_io function. + **/ +void bio_endio(struct bio *bio, unsigned int bytes_done, int error) +{ + if (error) + clear_bit(BIO_UPTODATE, &bio->bi_flags); + + if (unlikely(bytes_done > bio->bi_size)) { + printk("%s: want %u bytes done, only %u left\n", __FUNCTION__, + bytes_done, bio->bi_size); + bytes_done = bio->bi_size; + } + + bio->bi_size -= bytes_done; + bio->bi_sector += (bytes_done >> 9); + + if (bio->bi_end_io) + bio->bi_end_io(bio, bytes_done, error); +} + +void bio_pair_release(struct bio_pair *bp) +{ + if (atomic_dec_and_test(&bp->cnt)) { + struct bio *master = bp->bio1.bi_private; + + bio_endio(master, master->bi_size, bp->error); + mempool_free(bp, bp->bio2.bi_private); + } +} + +static int bio_pair_end_1(struct bio * bi, unsigned int done, int err) +{ + struct bio_pair *bp = container_of(bi, struct bio_pair, bio1); + + if (err) + bp->error = err; + + if (bi->bi_size) + return 1; + + bio_pair_release(bp); + return 0; +} + +static int bio_pair_end_2(struct bio * bi, unsigned int done, int err) +{ + struct bio_pair *bp = container_of(bi, struct bio_pair, bio2); + + if (err) + bp->error = err; + + if (bi->bi_size) + return 1; + + bio_pair_release(bp); + return 0; +} + +/* + * split a bio - only worry about a bio with a single page + * in it's iovec + */ +struct bio_pair *bio_split(struct bio *bi, mempool_t *pool, int first_sectors) +{ + struct bio_pair *bp = mempool_alloc(pool, GFP_NOIO); + + if (!bp) + return bp; + + BUG_ON(bi->bi_vcnt != 1); + BUG_ON(bi->bi_idx != 0); + atomic_set(&bp->cnt, 3); + bp->error = 0; + bp->bio1 = *bi; + bp->bio2 = *bi; + bp->bio2.bi_sector += first_sectors; + bp->bio2.bi_size -= first_sectors << 9; + bp->bio1.bi_size = first_sectors << 9; + + bp->bv1 = bi->bi_io_vec[0]; + bp->bv2 = bi->bi_io_vec[0]; + bp->bv2.bv_offset += first_sectors << 9; + bp->bv2.bv_len -= first_sectors << 9; + bp->bv1.bv_len = first_sectors << 9; + + bp->bio1.bi_io_vec = &bp->bv1; + bp->bio2.bi_io_vec = &bp->bv2; + + bp->bio1.bi_end_io = bio_pair_end_1; + bp->bio2.bi_end_io = bio_pair_end_2; + + bp->bio1.bi_private = bi; + bp->bio2.bi_private = pool; + + return bp; +} + +static void *bio_pair_alloc(unsigned int __nocast gfp_flags, void *data) +{ + return kmalloc(sizeof(struct bio_pair), gfp_flags); +} + +static void bio_pair_free(void *bp, void *data) +{ + kfree(bp); +} + + +/* + * create memory pools for biovec's in a bio_set. + * use the global biovec slabs created for general use. + */ +static int biovec_create_pools(struct bio_set *bs, int pool_entries, int scale) +{ + int i; + + for (i = 0; i < BIOVEC_NR_POOLS; i++) { + struct biovec_slab *bp = bvec_slabs + i; + mempool_t **bvp = bs->bvec_pools + i; + + if (i >= scale) + pool_entries >>= 1; + + *bvp = mempool_create(pool_entries, mempool_alloc_slab, + mempool_free_slab, bp->slab); + if (!*bvp) + return -ENOMEM; + } + return 0; +} + +static void biovec_free_pools(struct bio_set *bs) +{ + int i; + + for (i = 0; i < BIOVEC_NR_POOLS; i++) { + mempool_t *bvp = bs->bvec_pools[i]; + + if (bvp) + mempool_destroy(bvp); + } + +} + +void bioset_free(struct bio_set *bs) +{ + if (bs->bio_pool) + mempool_destroy(bs->bio_pool); + + biovec_free_pools(bs); + + kfree(bs); +} + +struct bio_set *bioset_create(int bio_pool_size, int bvec_pool_size, int scale) +{ + struct bio_set *bs = kmalloc(sizeof(*bs), GFP_KERNEL); + + if (!bs) + return NULL; + + memset(bs, 0, sizeof(*bs)); + bs->bio_pool = mempool_create(bio_pool_size, mempool_alloc_slab, + mempool_free_slab, bio_slab); + + if (!bs->bio_pool) + goto bad; + + if (!biovec_create_pools(bs, bvec_pool_size, scale)) + return bs; + +bad: + bioset_free(bs); + return NULL; +} + +static void __init biovec_init_slabs(void) +{ + int i; + + for (i = 0; i < BIOVEC_NR_POOLS; i++) { + int size; + struct biovec_slab *bvs = bvec_slabs + i; + + size = bvs->nr_vecs * sizeof(struct bio_vec); + bvs->slab = kmem_cache_create(bvs->name, size, 0, + SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL, NULL); + } +} + +static int __init init_bio(void) +{ + int megabytes, bvec_pool_entries; + int scale = BIOVEC_NR_POOLS; + + bio_slab = kmem_cache_create("bio", sizeof(struct bio), 0, + SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL, NULL); + + biovec_init_slabs(); + + megabytes = nr_free_pages() >> (20 - PAGE_SHIFT); + + /* + * find out where to start scaling + */ + if (megabytes <= 16) + scale = 0; + else if (megabytes <= 32) + scale = 1; + else if (megabytes <= 64) + scale = 2; + else if (megabytes <= 96) + scale = 3; + else if (megabytes <= 128) + scale = 4; + + /* + * scale number of entries + */ + bvec_pool_entries = megabytes * 2; + if (bvec_pool_entries > 256) + bvec_pool_entries = 256; + + fs_bio_set = bioset_create(BIO_POOL_SIZE, bvec_pool_entries, scale); + if (!fs_bio_set) + panic("bio: can't allocate bios\n"); + + bio_split_pool = mempool_create(BIO_SPLIT_ENTRIES, + bio_pair_alloc, bio_pair_free, NULL); + if (!bio_split_pool) + panic("bio: can't create split pool\n"); + + return 0; +} + +subsys_initcall(init_bio); + +EXPORT_SYMBOL(bio_alloc); +EXPORT_SYMBOL(bio_put); +EXPORT_SYMBOL(bio_endio); +EXPORT_SYMBOL(bio_init); +EXPORT_SYMBOL(__bio_clone); +EXPORT_SYMBOL(bio_clone); +EXPORT_SYMBOL(bio_phys_segments); +EXPORT_SYMBOL(bio_hw_segments); +EXPORT_SYMBOL(bio_add_page); +EXPORT_SYMBOL(bio_get_nr_vecs); +EXPORT_SYMBOL(bio_map_user); +EXPORT_SYMBOL(bio_unmap_user); +EXPORT_SYMBOL(bio_pair_release); +EXPORT_SYMBOL(bio_split); +EXPORT_SYMBOL(bio_split_pool); +EXPORT_SYMBOL(bio_copy_user); +EXPORT_SYMBOL(bio_uncopy_user); +EXPORT_SYMBOL(bioset_create); +EXPORT_SYMBOL(bioset_free); +EXPORT_SYMBOL(bio_alloc_bioset); |