/* * Copyright (C) 2001 Jens Axboe * * 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 #include #include #include #include #include #include #include #include #include #define BIO_POOL_SIZE 256 static mempool_t *bio_pool; 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_pool { int nr_vecs; char *name; kmem_cache_t *slab; mempool_t *pool; }; /* * 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_pool bvec_array[BIOVEC_NR_POOLS] = { BV(1), BV(4), BV(16), BV(64), BV(128), BV(BIO_MAX_PAGES), }; #undef BV static inline struct bio_vec *bvec_alloc(int gfp_mask, int nr, unsigned long *idx) { struct biovec_pool *bp; struct bio_vec *bvl; /* * 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_array + *idx; bvl = mempool_alloc(bp->pool, 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() */ void bio_destructor(struct bio *bio) { const int pool_idx = BIO_POOL_IDX(bio); struct biovec_pool *bp = bvec_array + pool_idx; BIO_BUG_ON(pool_idx >= BIOVEC_NR_POOLS); /* * cloned bio doesn't own the veclist */ if (!bio_flagged(bio, BIO_CLONED)) mempool_free(bio->bi_io_vec, bp->pool); mempool_free(bio, 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_size = 0; bio->bi_max_vecs = 0; bio->bi_end_io = NULL; atomic_set(&bio->bi_cnt, 1); bio->bi_private = NULL; } /** * bio_alloc - 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 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. **/ struct bio *bio_alloc(int gfp_mask, int nr_iovecs) { struct bio_vec *bvl = NULL; unsigned long idx; struct bio *bio; bio = mempool_alloc(bio_pool, gfp_mask); if (unlikely(!bio)) goto out; bio_init(bio); if (unlikely(!nr_iovecs)) goto noiovec; bvl = bvec_alloc(gfp_mask, nr_iovecs, &idx); if (bvl) { bio->bi_flags |= idx << BIO_POOL_OFFSET; bio->bi_max_vecs = bvec_array[idx].nr_vecs; noiovec: bio->bi_io_vec = bvl; bio->bi_destructor = bio_destructor; out: return bio; } mempool_free(bio, bio_pool); bio = NULL; goto out; } /** * 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) { bio->bi_io_vec = bio_src->bi_io_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_idx = bio_src->bi_idx; if (bio_flagged(bio, BIO_SEG_VALID)) { bio->bi_phys_segments = bio_src->bi_phys_segments; bio->bi_hw_segments = bio_src->bi_hw_segments; bio->bi_flags |= (1 << BIO_SEG_VALID); } bio->bi_size = bio_src->bi_size; /* * cloned bio does not own the bio_vec, so users cannot fiddle with * it. clear bi_max_vecs and clear the BIO_POOL_BITS to make this * apparent */ bio->bi_max_vecs = 0; bio->bi_flags &= (BIO_POOL_MASK - 1); } /** * 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, int gfp_mask) { struct bio *b = bio_alloc(gfp_mask, 0); 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_phys_segments(q, bio) >= q->max_phys_segments || bio_hw_segments(q, bio) >= q->max_hw_segments) { if (retried_segments) return 0; bio->bi_flags &= ~(1 << BIO_SEG_VALID); retried_segments = 1; } /* * 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; } } 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); } 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 NULL; bio = bio_alloc(GFP_KERNEL, nr_pages); if (!bio) return NULL; 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); blk_queue_bounce(q, &bio); return bio; out: kfree(pages); bio_put(bio); return NULL; } /** * 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. */ 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 (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) { bio_endio(bio, bio->bi_size, 0); bio_unmap_user(bio, 0); return NULL; } } return bio; } static void __bio_unmap_user(struct bio *bio, int write_to_vm) { struct bio_vec *bvec; int i; /* * find original bio if it was bounced */ if (bio->bi_private) { /* * someone stole our bio, must not happen */ BUG_ON(!bio_flagged(bio, BIO_BOUNCED)); bio = bio->bi_private; } /* * make sure we dirty pages we wrote to */ __bio_for_each_segment(bvec, bio, i, 0) { if (write_to_vm) 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 * @write_to_vm: bool indicating whether pages were written to * * Unmap a bio previously mapped by bio_map_user(). The @write_to_vm * must be the same as passed into bio_map_user(). Must be called with * a process context. * * bio_unmap_user() may sleep. */ void bio_unmap_user(struct bio *bio, int write_to_vm) { __bio_unmap_user(bio, write_to_vm); 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 spinlock_t bio_dirty_lock = SPIN_LOCK_UNLOCKED; 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(int gfp_flags, void *data) { return kmalloc(sizeof(struct bio_pair), gfp_flags); } static void bio_pair_free(void *bp, void *data) { kfree(bp); } static void __init biovec_init_pools(void) { int i, size, megabytes, pool_entries = BIO_POOL_SIZE; int scale = BIOVEC_NR_POOLS; 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 */ pool_entries = megabytes * 2; if (pool_entries > 256) pool_entries = 256; for (i = 0; i < BIOVEC_NR_POOLS; i++) { struct biovec_pool *bp = bvec_array + i; size = bp->nr_vecs * sizeof(struct bio_vec); bp->slab = kmem_cache_create(bp->name, size, 0, SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL, NULL); if (i >= scale) pool_entries >>= 1; bp->pool = mempool_create(pool_entries, mempool_alloc_slab, mempool_free_slab, bp->slab); if (!bp->pool) panic("biovec: can't init mempool\n"); } } static int __init init_bio(void) { bio_slab = kmem_cache_create("bio", sizeof(struct bio), 0, SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL, NULL); bio_pool = mempool_create(BIO_POOL_SIZE, mempool_alloc_slab, mempool_free_slab, bio_slab); if (!bio_pool) panic("bio: can't create mempool\n"); biovec_init_pools(); 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);