diff options
Diffstat (limited to 'fs/direct-io.c')
| -rw-r--r-- | fs/direct-io.c | 1051 |
1 files changed, 578 insertions, 473 deletions
diff --git a/fs/direct-io.c b/fs/direct-io.c index 9e81addbd6e..17e39b047de 100644 --- a/fs/direct-io.c +++ b/fs/direct-io.c @@ -5,11 +5,11 @@ * * O_DIRECT * - * 04Jul2002 akpm@zip.com.au + * 04Jul2002 Andrew Morton * Initial version * 11Sep2002 janetinc@us.ibm.com * added readv/writev support. - * 29Oct2002 akpm@zip.com.au + * 29Oct2002 Andrew Morton * rewrote bio_add_page() support. * 30Oct2002 pbadari@us.ibm.com * added support for non-aligned IO. @@ -35,11 +35,13 @@ #include <linux/buffer_head.h> #include <linux/rwsem.h> #include <linux/uio.h> -#include <asm/atomic.h> +#include <linux/atomic.h> +#include <linux/prefetch.h> +#include <linux/aio.h> /* * How many user pages to map in one call to get_user_pages(). This determines - * the size of a structure on the stack. + * the size of a structure in the slab cache */ #define DIO_PAGES 64 @@ -53,22 +55,12 @@ * * If blkfactor is zero then the user's request was aligned to the filesystem's * blocksize. - * - * lock_type is DIO_LOCKING for regular files on direct-IO-naive filesystems. - * This determines whether we need to do the fancy locking which prevents - * direct-IO from being able to read uninitialised disk blocks. If its zero - * (blockdev) this locking is not done, and if it is DIO_OWN_LOCKING i_mutex is - * not held for the entire direct write (taken briefly, initially, during a - * direct read though, but its never held for the duration of a direct-IO). */ -struct dio { - /* BIO submission state */ +/* dio_state only used in the submission path */ + +struct dio_submit { struct bio *bio; /* bio under assembly */ - struct inode *inode; - int rw; - loff_t i_size; /* i_size when submitted */ - int lock_type; /* doesn't change */ unsigned blkbits; /* doesn't change */ unsigned blkfactor; /* When we're using an alignment which is finer than the filesystem's soft @@ -79,20 +71,19 @@ struct dio { been performed at the start of a write */ int pages_in_io; /* approximate total IO pages */ - size_t size; /* total request size (doesn't change)*/ sector_t block_in_file; /* Current offset into the underlying file in dio_block units. */ unsigned blocks_available; /* At block_in_file. changes */ + int reap_counter; /* rate limit reaping */ sector_t final_block_in_request;/* doesn't change */ - unsigned first_block_in_page; /* doesn't change, Used only once */ int boundary; /* prev block is at a boundary */ - int reap_counter; /* rate limit reaping */ get_block_t *get_block; /* block mapping function */ - dio_iodone_t *end_io; /* IO completion function */ + dio_submit_t *submit_io; /* IO submition function */ + + loff_t logical_offset_in_bio; /* current first logical block in bio */ sector_t final_block_in_bio; /* current final block in bio + 1 */ sector_t next_block_for_io; /* next block to be put under IO, in dio_blocks units */ - struct buffer_head map_bh; /* last get_block() result */ /* * Deferred addition of a page to the dio. These variables are @@ -103,66 +94,74 @@ struct dio { unsigned cur_page_offset; /* Offset into it, in bytes */ unsigned cur_page_len; /* Nr of bytes at cur_page_offset */ sector_t cur_page_block; /* Where it starts */ + loff_t cur_page_fs_offset; /* Offset in file */ - /* - * Page fetching state. These variables belong to dio_refill_pages(). - */ - int curr_page; /* changes */ - int total_pages; /* doesn't change */ - unsigned long curr_user_address;/* changes */ - + struct iov_iter *iter; /* * Page queue. These variables belong to dio_refill_pages() and * dio_get_page(). */ - struct page *pages[DIO_PAGES]; /* page buffer */ unsigned head; /* next page to process */ unsigned tail; /* last valid page + 1 */ - int page_errors; /* errno from get_user_pages() */ + size_t from, to; +}; + +/* dio_state communicated between submission path and end_io */ +struct dio { + int flags; /* doesn't change */ + int rw; + struct inode *inode; + loff_t i_size; /* i_size when submitted */ + dio_iodone_t *end_io; /* IO completion function */ + + void *private; /* copy from map_bh.b_private */ /* BIO completion state */ spinlock_t bio_lock; /* protects BIO fields below */ + int page_errors; /* errno from get_user_pages() */ + int is_async; /* is IO async ? */ + bool defer_completion; /* defer AIO completion to workqueue? */ + int io_error; /* IO error in completion path */ unsigned long refcount; /* direct_io_worker() and bios */ struct bio *bio_list; /* singly linked via bi_private */ struct task_struct *waiter; /* waiting task (NULL if none) */ /* AIO related stuff */ struct kiocb *iocb; /* kiocb */ - int is_async; /* is IO async ? */ - int io_error; /* IO error in completion path */ ssize_t result; /* IO result */ -}; + + /* + * pages[] (and any fields placed after it) are not zeroed out at + * allocation time. Don't add new fields after pages[] unless you + * wish that they not be zeroed. + */ + union { + struct page *pages[DIO_PAGES]; /* page buffer */ + struct work_struct complete_work;/* deferred AIO completion */ + }; +} ____cacheline_aligned_in_smp; + +static struct kmem_cache *dio_cache __read_mostly; /* * How many pages are in the queue? */ -static inline unsigned dio_pages_present(struct dio *dio) +static inline unsigned dio_pages_present(struct dio_submit *sdio) { - return dio->tail - dio->head; + return sdio->tail - sdio->head; } /* * Go grab and pin some userspace pages. Typically we'll get 64 at a time. */ -static int dio_refill_pages(struct dio *dio) +static inline int dio_refill_pages(struct dio *dio, struct dio_submit *sdio) { - int ret; - int nr_pages; - - nr_pages = min(dio->total_pages - dio->curr_page, DIO_PAGES); - down_read(¤t->mm->mmap_sem); - ret = get_user_pages( - current, /* Task for fault acounting */ - current->mm, /* whose pages? */ - dio->curr_user_address, /* Where from? */ - nr_pages, /* How many pages? */ - dio->rw == READ, /* Write to memory? */ - 0, /* force (?) */ - &dio->pages[0], - NULL); /* vmas */ - up_read(¤t->mm->mmap_sem); - - if (ret < 0 && dio->blocks_available && (dio->rw & WRITE)) { + ssize_t ret; + + ret = iov_iter_get_pages(sdio->iter, dio->pages, DIO_PAGES * PAGE_SIZE, + &sdio->from); + + if (ret < 0 && sdio->blocks_available && (dio->rw & WRITE)) { struct page *page = ZERO_PAGE(0); /* * A memory fault, but the filesystem has some outstanding @@ -173,20 +172,21 @@ static int dio_refill_pages(struct dio *dio) dio->page_errors = ret; page_cache_get(page); dio->pages[0] = page; - dio->head = 0; - dio->tail = 1; - ret = 0; - goto out; + sdio->head = 0; + sdio->tail = 1; + sdio->from = 0; + sdio->to = PAGE_SIZE; + return 0; } if (ret >= 0) { - dio->curr_user_address += ret * PAGE_SIZE; - dio->curr_page += ret; - dio->head = 0; - dio->tail = ret; - ret = 0; + iov_iter_advance(sdio->iter, ret); + ret += sdio->from; + sdio->head = 0; + sdio->tail = (ret + PAGE_SIZE - 1) / PAGE_SIZE; + sdio->to = ((ret - 1) & (PAGE_SIZE - 1)) + 1; + return 0; } -out: return ret; } @@ -196,33 +196,34 @@ out: * decent number of pages, less frequently. To provide nicer use of the * L1 cache. */ -static struct page *dio_get_page(struct dio *dio) +static inline struct page *dio_get_page(struct dio *dio, + struct dio_submit *sdio) { - if (dio_pages_present(dio) == 0) { + if (dio_pages_present(sdio) == 0) { int ret; - ret = dio_refill_pages(dio); + ret = dio_refill_pages(dio, sdio); if (ret) return ERR_PTR(ret); - BUG_ON(dio_pages_present(dio) == 0); + BUG_ON(dio_pages_present(sdio) == 0); } - return dio->pages[dio->head++]; + return dio->pages[sdio->head]; } /** * dio_complete() - called when all DIO BIO I/O has been completed * @offset: the byte offset in the file of the completed operation * - * This releases locks as dictated by the locking type, lets interested parties - * know that a DIO operation has completed, and calculates the resulting return - * code for the operation. + * This drops i_dio_count, lets interested parties know that a DIO operation + * has completed, and calculates the resulting return code for the operation. * * It lets the filesystem know if it registered an interest earlier via * get_block. Pass the private field of the map buffer_head so that * filesystems can use it to hold additional state between get_block calls and * dio_complete. */ -static int dio_complete(struct dio *dio, loff_t offset, int ret) +static ssize_t dio_complete(struct dio *dio, loff_t offset, ssize_t ret, + bool is_async) { ssize_t transferred = 0; @@ -243,13 +244,6 @@ static int dio_complete(struct dio *dio, loff_t offset, int ret) transferred = dio->i_size - offset; } - if (dio->end_io && dio->result) - dio->end_io(dio->iocb, offset, transferred, - dio->map_bh.b_private); - if (dio->lock_type == DIO_LOCKING) - /* lockdep: non-owner release */ - up_read_non_owner(&dio->inode->i_alloc_sem); - if (ret == 0) ret = dio->page_errors; if (ret == 0) @@ -257,10 +251,36 @@ static int dio_complete(struct dio *dio, loff_t offset, int ret) if (ret == 0) ret = transferred; + if (dio->end_io && dio->result) + dio->end_io(dio->iocb, offset, transferred, dio->private); + + inode_dio_done(dio->inode); + if (is_async) { + if (dio->rw & WRITE) { + int err; + + err = generic_write_sync(dio->iocb->ki_filp, offset, + transferred); + if (err < 0 && ret > 0) + ret = err; + } + + aio_complete(dio->iocb, ret, 0); + } + + kmem_cache_free(dio_cache, dio); return ret; } +static void dio_aio_complete_work(struct work_struct *work) +{ + struct dio *dio = container_of(work, struct dio, complete_work); + + dio_complete(dio, dio->iocb->ki_pos, 0, true); +} + static int dio_bio_complete(struct dio *dio, struct bio *bio); + /* * Asynchronous IO callback. */ @@ -280,9 +300,13 @@ static void dio_bio_end_aio(struct bio *bio, int error) spin_unlock_irqrestore(&dio->bio_lock, flags); if (remaining == 0) { - int ret = dio_complete(dio, dio->iocb->ki_pos, 0); - aio_complete(dio->iocb, ret, 0); - kfree(dio); + if (dio->result && dio->defer_completion) { + INIT_WORK(&dio->complete_work, dio_aio_complete_work); + queue_work(dio->inode->i_sb->s_dio_done_wq, + &dio->complete_work); + } else { + dio_complete(dio, dio->iocb->ki_pos, 0, true); + } } } @@ -306,25 +330,48 @@ static void dio_bio_end_io(struct bio *bio, int error) spin_unlock_irqrestore(&dio->bio_lock, flags); } -static int -dio_bio_alloc(struct dio *dio, struct block_device *bdev, - sector_t first_sector, int nr_vecs) +/** + * dio_end_io - handle the end io action for the given bio + * @bio: The direct io bio thats being completed + * @error: Error if there was one + * + * This is meant to be called by any filesystem that uses their own dio_submit_t + * so that the DIO specific endio actions are dealt with after the filesystem + * has done it's completion work. + */ +void dio_end_io(struct bio *bio, int error) +{ + struct dio *dio = bio->bi_private; + + if (dio->is_async) + dio_bio_end_aio(bio, error); + else + dio_bio_end_io(bio, error); +} +EXPORT_SYMBOL_GPL(dio_end_io); + +static inline void +dio_bio_alloc(struct dio *dio, struct dio_submit *sdio, + struct block_device *bdev, + sector_t first_sector, int nr_vecs) { struct bio *bio; + /* + * bio_alloc() is guaranteed to return a bio when called with + * __GFP_WAIT and we request a valid number of vectors. + */ bio = bio_alloc(GFP_KERNEL, nr_vecs); - if (bio == NULL) - return -ENOMEM; bio->bi_bdev = bdev; - bio->bi_sector = first_sector; + bio->bi_iter.bi_sector = first_sector; if (dio->is_async) bio->bi_end_io = dio_bio_end_aio; else bio->bi_end_io = dio_bio_end_io; - dio->bio = bio; - return 0; + sdio->bio = bio; + sdio->logical_offset_in_bio = sdio->cur_page_fs_offset; } /* @@ -334,9 +381,9 @@ dio_bio_alloc(struct dio *dio, struct block_device *bdev, * * bios hold a dio reference between submit_bio and ->end_io. */ -static void dio_bio_submit(struct dio *dio) +static inline void dio_bio_submit(struct dio *dio, struct dio_submit *sdio) { - struct bio *bio = dio->bio; + struct bio *bio = sdio->bio; unsigned long flags; bio->bi_private = dio; @@ -348,19 +395,24 @@ static void dio_bio_submit(struct dio *dio) if (dio->is_async && dio->rw == READ) bio_set_pages_dirty(bio); - submit_bio(dio->rw, bio); + if (sdio->submit_io) + sdio->submit_io(dio->rw, bio, dio->inode, + sdio->logical_offset_in_bio); + else + submit_bio(dio->rw, bio); - dio->bio = NULL; - dio->boundary = 0; + sdio->bio = NULL; + sdio->boundary = 0; + sdio->logical_offset_in_bio = 0; } /* * Release any resources in case of a failure */ -static void dio_cleanup(struct dio *dio) +static inline void dio_cleanup(struct dio *dio, struct dio_submit *sdio) { - while (dio_pages_present(dio)) - page_cache_release(dio_get_page(dio)); + while (sdio->head < sdio->tail) + page_cache_release(dio->pages[sdio->head++]); } /* @@ -405,8 +457,8 @@ static struct bio *dio_await_one(struct dio *dio) static int dio_bio_complete(struct dio *dio, struct bio *bio) { const int uptodate = test_bit(BIO_UPTODATE, &bio->bi_flags); - struct bio_vec *bvec = bio->bi_io_vec; - int page_no; + struct bio_vec *bvec; + unsigned i; if (!uptodate) dio->io_error = -EIO; @@ -414,8 +466,8 @@ static int dio_bio_complete(struct dio *dio, struct bio *bio) if (dio->is_async && dio->rw == READ) { bio_check_pages_dirty(bio); /* transfers ownership */ } else { - for (page_no = 0; page_no < bio->bi_vcnt; page_no++) { - struct page *page = bvec[page_no].bv_page; + bio_for_each_segment_all(bvec, bio, i) { + struct page *page = bvec->bv_page; if (dio->rw == READ && !PageCompound(page)) set_page_dirty_lock(page); @@ -450,11 +502,11 @@ static void dio_await_completion(struct dio *dio) * * This also helps to limit the peak amount of pinned userspace memory. */ -static int dio_bio_reap(struct dio *dio) +static inline int dio_bio_reap(struct dio *dio, struct dio_submit *sdio) { int ret = 0; - if (dio->reap_counter++ >= 64) { + if (sdio->reap_counter++ >= 64) { while (dio->bio_list) { unsigned long flags; struct bio *bio; @@ -468,14 +520,50 @@ static int dio_bio_reap(struct dio *dio) if (ret == 0) ret = ret2; } - dio->reap_counter = 0; + sdio->reap_counter = 0; } return ret; } /* + * Create workqueue for deferred direct IO completions. We allocate the + * workqueue when it's first needed. This avoids creating workqueue for + * filesystems that don't need it and also allows us to create the workqueue + * late enough so the we can include s_id in the name of the workqueue. + */ +static int sb_init_dio_done_wq(struct super_block *sb) +{ + struct workqueue_struct *old; + struct workqueue_struct *wq = alloc_workqueue("dio/%s", + WQ_MEM_RECLAIM, 0, + sb->s_id); + if (!wq) + return -ENOMEM; + /* + * This has to be atomic as more DIOs can race to create the workqueue + */ + old = cmpxchg(&sb->s_dio_done_wq, NULL, wq); + /* Someone created workqueue before us? Free ours... */ + if (old) + destroy_workqueue(wq); + return 0; +} + +static int dio_set_defer_completion(struct dio *dio) +{ + struct super_block *sb = dio->inode->i_sb; + + if (dio->defer_completion) + return 0; + dio->defer_completion = true; + if (!sb->s_dio_done_wq) + return sb_init_dio_done_wq(sb); + return 0; +} + +/* * Call into the fs to map some more disk blocks. We record the current number - * of available blocks at dio->blocks_available. These are in units of the + * of available blocks at sdio->blocks_available. These are in units of the * fs blocksize, (1 << inode->i_blkbits). * * The fs is allowed to map lots of blocks at once. If it wants to do that, @@ -496,15 +584,15 @@ static int dio_bio_reap(struct dio *dio) * buffer_mapped(). However the direct-io code will only process holes one * block at a time - it will repeatedly call get_block() as it walks the hole. */ -static int get_more_blocks(struct dio *dio) +static int get_more_blocks(struct dio *dio, struct dio_submit *sdio, + struct buffer_head *map_bh) { int ret; - struct buffer_head *map_bh = &dio->map_bh; sector_t fs_startblk; /* Into file, in filesystem-sized blocks */ + sector_t fs_endblk; /* Into file, in filesystem-sized blocks */ unsigned long fs_count; /* Number of filesystem-sized blocks */ - unsigned long dio_count;/* Number of dio_block-sized blocks */ - unsigned long blkmask; int create; + unsigned int i_blkbits = sdio->blkbits + sdio->blkfactor; /* * If there was a memory error and we've overwritten all the @@ -512,34 +600,41 @@ static int get_more_blocks(struct dio *dio) */ ret = dio->page_errors; if (ret == 0) { - BUG_ON(dio->block_in_file >= dio->final_block_in_request); - fs_startblk = dio->block_in_file >> dio->blkfactor; - dio_count = dio->final_block_in_request - dio->block_in_file; - fs_count = dio_count >> dio->blkfactor; - blkmask = (1 << dio->blkfactor) - 1; - if (dio_count & blkmask) - fs_count++; + BUG_ON(sdio->block_in_file >= sdio->final_block_in_request); + fs_startblk = sdio->block_in_file >> sdio->blkfactor; + fs_endblk = (sdio->final_block_in_request - 1) >> + sdio->blkfactor; + fs_count = fs_endblk - fs_startblk + 1; map_bh->b_state = 0; - map_bh->b_size = fs_count << dio->inode->i_blkbits; + map_bh->b_size = fs_count << i_blkbits; + /* + * For writes inside i_size on a DIO_SKIP_HOLES filesystem we + * forbid block creations: only overwrites are permitted. + * We will return early to the caller once we see an + * unmapped buffer head returned, and the caller will fall + * back to buffered I/O. + * + * Otherwise the decision is left to the get_blocks method, + * which may decide to handle it or also return an unmapped + * buffer head. + */ create = dio->rw & WRITE; - if (dio->lock_type == DIO_LOCKING) { - if (dio->block_in_file < (i_size_read(dio->inode) >> - dio->blkbits)) + if (dio->flags & DIO_SKIP_HOLES) { + if (sdio->block_in_file < (i_size_read(dio->inode) >> + sdio->blkbits)) create = 0; - } else if (dio->lock_type == DIO_NO_LOCKING) { - create = 0; } - /* - * For writes inside i_size we forbid block creations: only - * overwrites are permitted. We fall back to buffered writes - * at a higher level for inside-i_size block-instantiating - * writes. - */ - ret = (*dio->get_block)(dio->inode, fs_startblk, + ret = (*sdio->get_block)(dio->inode, fs_startblk, map_bh, create); + + /* Store for completion */ + dio->private = map_bh->b_private; + + if (ret == 0 && buffer_defer_completion(map_bh)) + ret = dio_set_defer_completion(dio); } return ret; } @@ -547,19 +642,20 @@ static int get_more_blocks(struct dio *dio) /* * There is no bio. Make one now. */ -static int dio_new_bio(struct dio *dio, sector_t start_sector) +static inline int dio_new_bio(struct dio *dio, struct dio_submit *sdio, + sector_t start_sector, struct buffer_head *map_bh) { sector_t sector; int ret, nr_pages; - ret = dio_bio_reap(dio); + ret = dio_bio_reap(dio, sdio); if (ret) goto out; - sector = start_sector << (dio->blkbits - 9); - nr_pages = min(dio->pages_in_io, bio_get_nr_vecs(dio->map_bh.b_bdev)); + sector = start_sector << (sdio->blkbits - 9); + nr_pages = min(sdio->pages_in_io, bio_get_nr_vecs(map_bh->b_bdev)); BUG_ON(nr_pages <= 0); - ret = dio_bio_alloc(dio, dio->map_bh.b_bdev, sector, nr_pages); - dio->boundary = 0; + dio_bio_alloc(dio, sdio, map_bh->b_bdev, sector, nr_pages); + sdio->boundary = 0; out: return ret; } @@ -571,21 +667,21 @@ out: * * Return zero on success. Non-zero means the caller needs to start a new BIO. */ -static int dio_bio_add_page(struct dio *dio) +static inline int dio_bio_add_page(struct dio_submit *sdio) { int ret; - ret = bio_add_page(dio->bio, dio->cur_page, - dio->cur_page_len, dio->cur_page_offset); - if (ret == dio->cur_page_len) { + ret = bio_add_page(sdio->bio, sdio->cur_page, + sdio->cur_page_len, sdio->cur_page_offset); + if (ret == sdio->cur_page_len) { /* * Decrement count only, if we are done with this page */ - if ((dio->cur_page_len + dio->cur_page_offset) == PAGE_SIZE) - dio->pages_in_io--; - page_cache_get(dio->cur_page); - dio->final_block_in_bio = dio->cur_page_block + - (dio->cur_page_len >> dio->blkbits); + if ((sdio->cur_page_len + sdio->cur_page_offset) == PAGE_SIZE) + sdio->pages_in_io--; + page_cache_get(sdio->cur_page); + sdio->final_block_in_bio = sdio->cur_page_block + + (sdio->cur_page_len >> sdio->blkbits); ret = 0; } else { ret = 1; @@ -603,35 +699,46 @@ static int dio_bio_add_page(struct dio *dio) * The caller of this function is responsible for removing cur_page from the * dio, and for dropping the refcount which came from that presence. */ -static int dio_send_cur_page(struct dio *dio) +static inline int dio_send_cur_page(struct dio *dio, struct dio_submit *sdio, + struct buffer_head *map_bh) { int ret = 0; - if (dio->bio) { - /* - * See whether this new request is contiguous with the old - */ - if (dio->final_block_in_bio != dio->cur_page_block) - dio_bio_submit(dio); + if (sdio->bio) { + loff_t cur_offset = sdio->cur_page_fs_offset; + loff_t bio_next_offset = sdio->logical_offset_in_bio + + sdio->bio->bi_iter.bi_size; + /* - * Submit now if the underlying fs is about to perform a - * metadata read + * See whether this new request is contiguous with the old. + * + * Btrfs cannot handle having logically non-contiguous requests + * submitted. For example if you have + * + * Logical: [0-4095][HOLE][8192-12287] + * Physical: [0-4095] [4096-8191] + * + * We cannot submit those pages together as one BIO. So if our + * current logical offset in the file does not equal what would + * be the next logical offset in the bio, submit the bio we + * have. */ - if (dio->boundary) - dio_bio_submit(dio); + if (sdio->final_block_in_bio != sdio->cur_page_block || + cur_offset != bio_next_offset) + dio_bio_submit(dio, sdio); } - if (dio->bio == NULL) { - ret = dio_new_bio(dio, dio->cur_page_block); + if (sdio->bio == NULL) { + ret = dio_new_bio(dio, sdio, sdio->cur_page_block, map_bh); if (ret) goto out; } - if (dio_bio_add_page(dio) != 0) { - dio_bio_submit(dio); - ret = dio_new_bio(dio, dio->cur_page_block); + if (dio_bio_add_page(sdio) != 0) { + dio_bio_submit(dio, sdio); + ret = dio_new_bio(dio, sdio, sdio->cur_page_block, map_bh); if (ret == 0) { - ret = dio_bio_add_page(dio); + ret = dio_bio_add_page(sdio); BUG_ON(ret != 0); } } @@ -656,9 +763,10 @@ out: * If that doesn't work out then we put the old page into the bio and add this * page to the dio instead. */ -static int -submit_page_section(struct dio *dio, struct page *page, - unsigned offset, unsigned len, sector_t blocknr) +static inline int +submit_page_section(struct dio *dio, struct dio_submit *sdio, struct page *page, + unsigned offset, unsigned len, sector_t blocknr, + struct buffer_head *map_bh) { int ret = 0; @@ -672,41 +780,42 @@ submit_page_section(struct dio *dio, struct page *page, /* * Can we just grow the current page's presence in the dio? */ - if ( (dio->cur_page == page) && - (dio->cur_page_offset + dio->cur_page_len == offset) && - (dio->cur_page_block + - (dio->cur_page_len >> dio->blkbits) == blocknr)) { - dio->cur_page_len += len; - - /* - * If dio->boundary then we want to schedule the IO now to - * avoid metadata seeks. - */ - if (dio->boundary) { - ret = dio_send_cur_page(dio); - page_cache_release(dio->cur_page); - dio->cur_page = NULL; - } + if (sdio->cur_page == page && + sdio->cur_page_offset + sdio->cur_page_len == offset && + sdio->cur_page_block + + (sdio->cur_page_len >> sdio->blkbits) == blocknr) { + sdio->cur_page_len += len; goto out; } /* * If there's a deferred page already there then send it. */ - if (dio->cur_page) { - ret = dio_send_cur_page(dio); - page_cache_release(dio->cur_page); - dio->cur_page = NULL; + if (sdio->cur_page) { + ret = dio_send_cur_page(dio, sdio, map_bh); + page_cache_release(sdio->cur_page); + sdio->cur_page = NULL; if (ret) - goto out; + return ret; } page_cache_get(page); /* It is in dio */ - dio->cur_page = page; - dio->cur_page_offset = offset; - dio->cur_page_len = len; - dio->cur_page_block = blocknr; + sdio->cur_page = page; + sdio->cur_page_offset = offset; + sdio->cur_page_len = len; + sdio->cur_page_block = blocknr; + sdio->cur_page_fs_offset = sdio->block_in_file << sdio->blkbits; out: + /* + * If sdio->boundary then we want to schedule the IO now to + * avoid metadata seeks. + */ + if (sdio->boundary) { + ret = dio_send_cur_page(dio, sdio, map_bh); + dio_bio_submit(dio, sdio); + page_cache_release(sdio->cur_page); + sdio->cur_page = NULL; + } return ret; } @@ -715,16 +824,16 @@ out: * file blocks. Only called for S_ISREG files - blockdevs do not set * buffer_new */ -static void clean_blockdev_aliases(struct dio *dio) +static void clean_blockdev_aliases(struct dio *dio, struct buffer_head *map_bh) { unsigned i; unsigned nblocks; - nblocks = dio->map_bh.b_size >> dio->inode->i_blkbits; + nblocks = map_bh->b_size >> dio->inode->i_blkbits; for (i = 0; i < nblocks; i++) { - unmap_underlying_metadata(dio->map_bh.b_bdev, - dio->map_bh.b_blocknr + i); + unmap_underlying_metadata(map_bh->b_bdev, + map_bh->b_blocknr + i); } } @@ -737,19 +846,20 @@ static void clean_blockdev_aliases(struct dio *dio) * `end' is zero if we're doing the start of the IO, 1 at the end of the * IO. */ -static void dio_zero_block(struct dio *dio, int end) +static inline void dio_zero_block(struct dio *dio, struct dio_submit *sdio, + int end, struct buffer_head *map_bh) { unsigned dio_blocks_per_fs_block; unsigned this_chunk_blocks; /* In dio_blocks */ unsigned this_chunk_bytes; struct page *page; - dio->start_zero_done = 1; - if (!dio->blkfactor || !buffer_new(&dio->map_bh)) + sdio->start_zero_done = 1; + if (!sdio->blkfactor || !buffer_new(map_bh)) return; - dio_blocks_per_fs_block = 1 << dio->blkfactor; - this_chunk_blocks = dio->block_in_file & (dio_blocks_per_fs_block - 1); + dio_blocks_per_fs_block = 1 << sdio->blkfactor; + this_chunk_blocks = sdio->block_in_file & (dio_blocks_per_fs_block - 1); if (!this_chunk_blocks) return; @@ -761,14 +871,14 @@ static void dio_zero_block(struct dio *dio, int end) if (end) this_chunk_blocks = dio_blocks_per_fs_block - this_chunk_blocks; - this_chunk_bytes = this_chunk_blocks << dio->blkbits; + this_chunk_bytes = this_chunk_blocks << sdio->blkbits; page = ZERO_PAGE(0); - if (submit_page_section(dio, page, 0, this_chunk_bytes, - dio->next_block_for_io)) + if (submit_page_section(dio, sdio, page, 0, this_chunk_bytes, + sdio->next_block_for_io, map_bh)) return; - dio->next_block_for_io += this_chunk_blocks; + sdio->next_block_for_io += this_chunk_blocks; } /* @@ -787,39 +897,38 @@ static void dio_zero_block(struct dio *dio, int end) * it should set b_size to PAGE_SIZE or more inside get_block(). This gives * fine alignment but still allows this function to work in PAGE_SIZE units. */ -static int do_direct_IO(struct dio *dio) +static int do_direct_IO(struct dio *dio, struct dio_submit *sdio, + struct buffer_head *map_bh) { - const unsigned blkbits = dio->blkbits; - const unsigned blocks_per_page = PAGE_SIZE >> blkbits; - struct page *page; - unsigned block_in_page; - struct buffer_head *map_bh = &dio->map_bh; + const unsigned blkbits = sdio->blkbits; int ret = 0; - /* The I/O can start at any block offset within the first page */ - block_in_page = dio->first_block_in_page; + while (sdio->block_in_file < sdio->final_block_in_request) { + struct page *page; + size_t from, to; - while (dio->block_in_file < dio->final_block_in_request) { - page = dio_get_page(dio); + page = dio_get_page(dio, sdio); if (IS_ERR(page)) { ret = PTR_ERR(page); goto out; } + from = sdio->head ? 0 : sdio->from; + to = (sdio->head == sdio->tail - 1) ? sdio->to : PAGE_SIZE; + sdio->head++; - while (block_in_page < blocks_per_page) { - unsigned offset_in_page = block_in_page << blkbits; + while (from < to) { unsigned this_chunk_bytes; /* # of bytes mapped */ unsigned this_chunk_blocks; /* # of blocks */ unsigned u; - if (dio->blocks_available == 0) { + if (sdio->blocks_available == 0) { /* * Need to go and map some more disk */ unsigned long blkmask; unsigned long dio_remainder; - ret = get_more_blocks(dio); + ret = get_more_blocks(dio, sdio, map_bh); if (ret) { page_cache_release(page); goto out; @@ -827,18 +936,18 @@ static int do_direct_IO(struct dio *dio) if (!buffer_mapped(map_bh)) goto do_holes; - dio->blocks_available = - map_bh->b_size >> dio->blkbits; - dio->next_block_for_io = - map_bh->b_blocknr << dio->blkfactor; + sdio->blocks_available = + map_bh->b_size >> sdio->blkbits; + sdio->next_block_for_io = + map_bh->b_blocknr << sdio->blkfactor; if (buffer_new(map_bh)) - clean_blockdev_aliases(dio); + clean_blockdev_aliases(dio, map_bh); - if (!dio->blkfactor) + if (!sdio->blkfactor) goto do_holes; - blkmask = (1 << dio->blkfactor) - 1; - dio_remainder = (dio->block_in_file & blkmask); + blkmask = (1 << sdio->blkfactor) - 1; + dio_remainder = (sdio->block_in_file & blkmask); /* * If we are at the start of IO and that IO @@ -852,8 +961,8 @@ static int do_direct_IO(struct dio *dio) * on-disk */ if (!buffer_new(map_bh)) - dio->next_block_for_io += dio_remainder; - dio->blocks_available -= dio_remainder; + sdio->next_block_for_io += dio_remainder; + sdio->blocks_available -= dio_remainder; } do_holes: /* Handle holes */ @@ -872,16 +981,16 @@ do_holes: */ i_size_aligned = ALIGN(i_size_read(dio->inode), 1 << blkbits); - if (dio->block_in_file >= + if (sdio->block_in_file >= i_size_aligned >> blkbits) { /* We hit eof */ page_cache_release(page); goto out; } - zero_user(page, block_in_page << blkbits, - 1 << blkbits); - dio->block_in_file++; - block_in_page++; + zero_user(page, from, 1 << blkbits); + sdio->block_in_file++; + from += 1 << blkbits; + dio->result += 1 << blkbits; goto next_block; } @@ -890,75 +999,218 @@ do_holes: * is finer than the underlying fs, go check to see if * we must zero out the start of this block. */ - if (unlikely(dio->blkfactor && !dio->start_zero_done)) - dio_zero_block(dio, 0); + if (unlikely(sdio->blkfactor && !sdio->start_zero_done)) + dio_zero_block(dio, sdio, 0, map_bh); /* * Work out, in this_chunk_blocks, how much disk we * can add to this page */ - this_chunk_blocks = dio->blocks_available; - u = (PAGE_SIZE - offset_in_page) >> blkbits; + this_chunk_blocks = sdio->blocks_available; + u = (to - from) >> blkbits; if (this_chunk_blocks > u) this_chunk_blocks = u; - u = dio->final_block_in_request - dio->block_in_file; + u = sdio->final_block_in_request - sdio->block_in_file; if (this_chunk_blocks > u) this_chunk_blocks = u; this_chunk_bytes = this_chunk_blocks << blkbits; BUG_ON(this_chunk_bytes == 0); - dio->boundary = buffer_boundary(map_bh); - ret = submit_page_section(dio, page, offset_in_page, - this_chunk_bytes, dio->next_block_for_io); + if (this_chunk_blocks == sdio->blocks_available) + sdio->boundary = buffer_boundary(map_bh); + ret = submit_page_section(dio, sdio, page, + from, + this_chunk_bytes, + sdio->next_block_for_io, + map_bh); if (ret) { page_cache_release(page); goto out; } - dio->next_block_for_io += this_chunk_blocks; + sdio->next_block_for_io += this_chunk_blocks; - dio->block_in_file += this_chunk_blocks; - block_in_page += this_chunk_blocks; - dio->blocks_available -= this_chunk_blocks; + sdio->block_in_file += this_chunk_blocks; + from += this_chunk_bytes; + dio->result += this_chunk_bytes; + sdio->blocks_available -= this_chunk_blocks; next_block: - BUG_ON(dio->block_in_file > dio->final_block_in_request); - if (dio->block_in_file == dio->final_block_in_request) + BUG_ON(sdio->block_in_file > sdio->final_block_in_request); + if (sdio->block_in_file == sdio->final_block_in_request) break; } /* Drop the ref which was taken in get_user_pages() */ page_cache_release(page); - block_in_page = 0; } out: return ret; } +static inline int drop_refcount(struct dio *dio) +{ + int ret2; + unsigned long flags; + + /* + * Sync will always be dropping the final ref and completing the + * operation. AIO can if it was a broken operation described above or + * in fact if all the bios race to complete before we get here. In + * that case dio_complete() translates the EIOCBQUEUED into the proper + * return code that the caller will hand to aio_complete(). + * + * This is managed by the bio_lock instead of being an atomic_t so that + * completion paths can drop their ref and use the remaining count to + * decide to wake the submission path atomically. + */ + spin_lock_irqsave(&dio->bio_lock, flags); + ret2 = --dio->refcount; + spin_unlock_irqrestore(&dio->bio_lock, flags); + return ret2; +} + /* - * Releases both i_mutex and i_alloc_sem + * This is a library function for use by filesystem drivers. + * + * The locking rules are governed by the flags parameter: + * - if the flags value contains DIO_LOCKING we use a fancy locking + * scheme for dumb filesystems. + * For writes this function is called under i_mutex and returns with + * i_mutex held, for reads, i_mutex is not held on entry, but it is + * taken and dropped again before returning. + * - if the flags value does NOT contain DIO_LOCKING we don't use any + * internal locking but rather rely on the filesystem to synchronize + * direct I/O reads/writes versus each other and truncate. + * + * To help with locking against truncate we incremented the i_dio_count + * counter before starting direct I/O, and decrement it once we are done. + * Truncate can wait for it to reach zero to provide exclusion. It is + * expected that filesystem provide exclusion between new direct I/O + * and truncates. For DIO_LOCKING filesystems this is done by i_mutex, + * but other filesystems need to take care of this on their own. + * + * NOTE: if you pass "sdio" to anything by pointer make sure that function + * is always inlined. Otherwise gcc is unable to split the structure into + * individual fields and will generate much worse code. This is important + * for the whole file. */ -static ssize_t -direct_io_worker(int rw, struct kiocb *iocb, struct inode *inode, - const struct iovec *iov, loff_t offset, unsigned long nr_segs, - unsigned blkbits, get_block_t get_block, dio_iodone_t end_io, - struct dio *dio) +static inline ssize_t +do_blockdev_direct_IO(int rw, struct kiocb *iocb, struct inode *inode, + struct block_device *bdev, struct iov_iter *iter, loff_t offset, + get_block_t get_block, dio_iodone_t end_io, + dio_submit_t submit_io, int flags) { - unsigned long user_addr; - unsigned long flags; - int seg; - ssize_t ret = 0; - ssize_t ret2; - size_t bytes; + unsigned i_blkbits = ACCESS_ONCE(inode->i_blkbits); + unsigned blkbits = i_blkbits; + unsigned blocksize_mask = (1 << blkbits) - 1; + ssize_t retval = -EINVAL; + size_t count = iov_iter_count(iter); + loff_t end = offset + count; + struct dio *dio; + struct dio_submit sdio = { 0, }; + struct buffer_head map_bh = { 0, }; + struct blk_plug plug; + unsigned long align = offset | iov_iter_alignment(iter); + + if (rw & WRITE) + rw = WRITE_ODIRECT; + + /* + * Avoid references to bdev if not absolutely needed to give + * the early prefetch in the caller enough time. + */ + + if (align & blocksize_mask) { + if (bdev) + blkbits = blksize_bits(bdev_logical_block_size(bdev)); + blocksize_mask = (1 << blkbits) - 1; + if (align & blocksize_mask) + goto out; + } + + /* watch out for a 0 len io from a tricksy fs */ + if (rw == READ && !iov_iter_count(iter)) + return 0; + + dio = kmem_cache_alloc(dio_cache, GFP_KERNEL); + retval = -ENOMEM; + if (!dio) + goto out; + /* + * Believe it or not, zeroing out the page array caused a .5% + * performance regression in a database benchmark. So, we take + * care to only zero out what's needed. + */ + memset(dio, 0, offsetof(struct dio, pages)); + + dio->flags = flags; + if (dio->flags & DIO_LOCKING) { + if (rw == READ) { + struct address_space *mapping = + iocb->ki_filp->f_mapping; + + /* will be released by direct_io_worker */ + mutex_lock(&inode->i_mutex); + + retval = filemap_write_and_wait_range(mapping, offset, + end - 1); + if (retval) { + mutex_unlock(&inode->i_mutex); + kmem_cache_free(dio_cache, dio); + goto out; + } + } + } + + /* + * For file extending writes updating i_size before data writeouts + * complete can expose uninitialized blocks in dumb filesystems. + * In that case we need to wait for I/O completion even if asked + * for an asynchronous write. + */ + if (is_sync_kiocb(iocb)) + dio->is_async = false; + else if (!(dio->flags & DIO_ASYNC_EXTEND) && + (rw & WRITE) && end > i_size_read(inode)) + dio->is_async = false; + else + dio->is_async = true; dio->inode = inode; dio->rw = rw; - dio->blkbits = blkbits; - dio->blkfactor = inode->i_blkbits - blkbits; - dio->block_in_file = offset >> blkbits; - dio->get_block = get_block; + /* + * For AIO O_(D)SYNC writes we need to defer completions to a workqueue + * so that we can call ->fsync. + */ + if (dio->is_async && (rw & WRITE) && + ((iocb->ki_filp->f_flags & O_DSYNC) || + IS_SYNC(iocb->ki_filp->f_mapping->host))) { + retval = dio_set_defer_completion(dio); + if (retval) { + /* + * We grab i_mutex only for reads so we don't have + * to release it here + */ + kmem_cache_free(dio_cache, dio); + goto out; + } + } + + /* + * Will be decremented at I/O completion time. + */ + atomic_inc(&inode->i_dio_count); + + retval = 0; + sdio.blkbits = blkbits; + sdio.blkfactor = i_blkbits - blkbits; + sdio.block_in_file = offset >> blkbits; + + sdio.get_block = get_block; dio->end_io = end_io; - dio->final_block_in_bio = -1; - dio->next_block_for_io = -1; + sdio.submit_io = submit_io; + sdio.final_block_in_bio = -1; + sdio.next_block_for_io = -1; dio->iocb = iocb; dio->i_size = i_size_read(inode); @@ -966,91 +1218,64 @@ direct_io_worker(int rw, struct kiocb *iocb, struct inode *inode, spin_lock_init(&dio->bio_lock); dio->refcount = 1; + sdio.iter = iter; + sdio.final_block_in_request = + (offset + iov_iter_count(iter)) >> blkbits; + /* * In case of non-aligned buffers, we may need 2 more * pages since we need to zero out first and last block. */ - if (unlikely(dio->blkfactor)) - dio->pages_in_io = 2; - - for (seg = 0; seg < nr_segs; seg++) { - user_addr = (unsigned long)iov[seg].iov_base; - dio->pages_in_io += - ((user_addr+iov[seg].iov_len +PAGE_SIZE-1)/PAGE_SIZE - - user_addr/PAGE_SIZE); - } + if (unlikely(sdio.blkfactor)) + sdio.pages_in_io = 2; - for (seg = 0; seg < nr_segs; seg++) { - user_addr = (unsigned long)iov[seg].iov_base; - dio->size += bytes = iov[seg].iov_len; - - /* Index into the first page of the first block */ - dio->first_block_in_page = (user_addr & ~PAGE_MASK) >> blkbits; - dio->final_block_in_request = dio->block_in_file + - (bytes >> blkbits); - /* Page fetching state */ - dio->head = 0; - dio->tail = 0; - dio->curr_page = 0; - - dio->total_pages = 0; - if (user_addr & (PAGE_SIZE-1)) { - dio->total_pages++; - bytes -= PAGE_SIZE - (user_addr & (PAGE_SIZE - 1)); - } - dio->total_pages += (bytes + PAGE_SIZE - 1) / PAGE_SIZE; - dio->curr_user_address = user_addr; - - ret = do_direct_IO(dio); - - dio->result += iov[seg].iov_len - - ((dio->final_block_in_request - dio->block_in_file) << - blkbits); - - if (ret) { - dio_cleanup(dio); - break; - } - } /* end iovec loop */ + sdio.pages_in_io += iov_iter_npages(iter, INT_MAX); + + blk_start_plug(&plug); - if (ret == -ENOTBLK && (rw & WRITE)) { + retval = do_direct_IO(dio, &sdio, &map_bh); + if (retval) + dio_cleanup(dio, &sdio); + + if (retval == -ENOTBLK) { /* * The remaining part of the request will be * be handled by buffered I/O when we return */ - ret = 0; + retval = 0; } /* * There may be some unwritten disk at the end of a part-written * fs-block-sized block. Go zero that now. */ - dio_zero_block(dio, 1); - - if (dio->cur_page) { - ret2 = dio_send_cur_page(dio); - if (ret == 0) - ret = ret2; - page_cache_release(dio->cur_page); - dio->cur_page = NULL; + dio_zero_block(dio, &sdio, 1, &map_bh); + + if (sdio.cur_page) { + ssize_t ret2; + + ret2 = dio_send_cur_page(dio, &sdio, &map_bh); + if (retval == 0) + retval = ret2; + page_cache_release(sdio.cur_page); + sdio.cur_page = NULL; } - if (dio->bio) - dio_bio_submit(dio); + if (sdio.bio) + dio_bio_submit(dio, &sdio); - /* All IO is now issued, send it on its way */ - blk_run_address_space(inode->i_mapping); + blk_finish_plug(&plug); /* * It is possible that, we return short IO due to end of file. * In that case, we need to release all the pages we got hold on. */ - dio_cleanup(dio); + dio_cleanup(dio, &sdio); /* * All block lookups have been performed. For READ requests * we can let i_mutex go now that its achieved its purpose * of protecting us from looking up uninitialized blocks. */ - if ((rw == READ) && (dio->lock_type == DIO_LOCKING)) + if (rw == READ && (dio->flags & DIO_LOCKING)) mutex_unlock(&dio->inode->i_mutex); /* @@ -1060,169 +1285,49 @@ direct_io_worker(int rw, struct kiocb *iocb, struct inode *inode, * call aio_complete is when we return -EIOCBQUEUED, so we key on that. * This had *better* be the only place that raises -EIOCBQUEUED. */ - BUG_ON(ret == -EIOCBQUEUED); - if (dio->is_async && ret == 0 && dio->result && - ((rw & READ) || (dio->result == dio->size))) - ret = -EIOCBQUEUED; - - if (ret != -EIOCBQUEUED) + BUG_ON(retval == -EIOCBQUEUED); + if (dio->is_async && retval == 0 && dio->result && + (rw == READ || dio->result == count)) + retval = -EIOCBQUEUED; + else dio_await_completion(dio); - /* - * Sync will always be dropping the final ref and completing the - * operation. AIO can if it was a broken operation described above or - * in fact if all the bios race to complete before we get here. In - * that case dio_complete() translates the EIOCBQUEUED into the proper - * return code that the caller will hand to aio_complete(). - * - * This is managed by the bio_lock instead of being an atomic_t so that - * completion paths can drop their ref and use the remaining count to - * decide to wake the submission path atomically. - */ - spin_lock_irqsave(&dio->bio_lock, flags); - ret2 = --dio->refcount; - spin_unlock_irqrestore(&dio->bio_lock, flags); - - if (ret2 == 0) { - ret = dio_complete(dio, offset, ret); - kfree(dio); + if (drop_refcount(dio) == 0) { + retval = dio_complete(dio, offset, retval, false); } else - BUG_ON(ret != -EIOCBQUEUED); + BUG_ON(retval != -EIOCBQUEUED); - return ret; +out: + return retval; } -/* - * This is a library function for use by filesystem drivers. - * The locking rules are governed by the dio_lock_type parameter. - * - * DIO_NO_LOCKING (no locking, for raw block device access) - * For writes, i_mutex is not held on entry; it is never taken. - * - * DIO_LOCKING (simple locking for regular files) - * For writes we are called under i_mutex and return with i_mutex held, even - * though it is internally dropped. - * For reads, i_mutex is not held on entry, but it is taken and dropped before - * returning. - * - * DIO_OWN_LOCKING (filesystem provides synchronisation and handling of - * uninitialised data, allowing parallel direct readers and writers) - * For writes we are called without i_mutex, return without it, never touch it. - * For reads we are called under i_mutex and return with i_mutex held, even - * though it may be internally dropped. - * - * Additional i_alloc_sem locking requirements described inline below. - */ ssize_t __blockdev_direct_IO(int rw, struct kiocb *iocb, struct inode *inode, - struct block_device *bdev, const struct iovec *iov, loff_t offset, - unsigned long nr_segs, get_block_t get_block, dio_iodone_t end_io, - int dio_lock_type) + struct block_device *bdev, struct iov_iter *iter, loff_t offset, + get_block_t get_block, dio_iodone_t end_io, + dio_submit_t submit_io, int flags) { - int seg; - size_t size; - unsigned long addr; - unsigned blkbits = inode->i_blkbits; - unsigned bdev_blkbits = 0; - unsigned blocksize_mask = (1 << blkbits) - 1; - ssize_t retval = -EINVAL; - loff_t end = offset; - struct dio *dio; - int release_i_mutex = 0; - int acquire_i_mutex = 0; - - if (rw & WRITE) - rw = WRITE_SYNC; - - if (bdev) - bdev_blkbits = blksize_bits(bdev_hardsect_size(bdev)); - - if (offset & blocksize_mask) { - if (bdev) - blkbits = bdev_blkbits; - blocksize_mask = (1 << blkbits) - 1; - if (offset & blocksize_mask) - goto out; - } - - /* Check the memory alignment. Blocks cannot straddle pages */ - for (seg = 0; seg < nr_segs; seg++) { - addr = (unsigned long)iov[seg].iov_base; - size = iov[seg].iov_len; - end += size; - if ((addr & blocksize_mask) || (size & blocksize_mask)) { - if (bdev) - blkbits = bdev_blkbits; - blocksize_mask = (1 << blkbits) - 1; - if ((addr & blocksize_mask) || (size & blocksize_mask)) - goto out; - } - } - - dio = kzalloc(sizeof(*dio), GFP_KERNEL); - retval = -ENOMEM; - if (!dio) - goto out; - /* - * For block device access DIO_NO_LOCKING is used, - * neither readers nor writers do any locking at all - * For regular files using DIO_LOCKING, - * readers need to grab i_mutex and i_alloc_sem - * writers need to grab i_alloc_sem only (i_mutex is already held) - * For regular files using DIO_OWN_LOCKING, - * neither readers nor writers take any locks here - */ - dio->lock_type = dio_lock_type; - if (dio_lock_type != DIO_NO_LOCKING) { - /* watch out for a 0 len io from a tricksy fs */ - if (rw == READ && end > offset) { - struct address_space *mapping; - - mapping = iocb->ki_filp->f_mapping; - if (dio_lock_type != DIO_OWN_LOCKING) { - mutex_lock(&inode->i_mutex); - release_i_mutex = 1; - } - - retval = filemap_write_and_wait_range(mapping, offset, - end - 1); - if (retval) { - kfree(dio); - goto out; - } - - if (dio_lock_type == DIO_OWN_LOCKING) { - mutex_unlock(&inode->i_mutex); - acquire_i_mutex = 1; - } - } - - if (dio_lock_type == DIO_LOCKING) - /* lockdep: not the owner will release it */ - down_read_non_owner(&inode->i_alloc_sem); - } - - /* - * For file extending writes updating i_size before data - * writeouts complete can expose uninitialized blocks. So - * even for AIO, we need to wait for i/o to complete before - * returning in this case. + * The block device state is needed in the end to finally + * submit everything. Since it's likely to be cache cold + * prefetch it here as first thing to hide some of the + * latency. + * + * Attempt to prefetch the pieces we likely need later. */ - dio->is_async = !is_sync_kiocb(iocb) && !((rw & WRITE) && - (end > i_size_read(inode))); + prefetch(&bdev->bd_disk->part_tbl); + prefetch(bdev->bd_queue); + prefetch((char *)bdev->bd_queue + SMP_CACHE_BYTES); - retval = direct_io_worker(rw, iocb, inode, iov, offset, - nr_segs, blkbits, get_block, end_io, dio); + return do_blockdev_direct_IO(rw, iocb, inode, bdev, iter, offset, + get_block, end_io, submit_io, flags); +} - if (rw == READ && dio_lock_type == DIO_LOCKING) - release_i_mutex = 0; +EXPORT_SYMBOL(__blockdev_direct_IO); -out: - if (release_i_mutex) - mutex_unlock(&inode->i_mutex); - else if (acquire_i_mutex) - mutex_lock(&inode->i_mutex); - return retval; +static __init int dio_init(void) +{ + dio_cache = KMEM_CACHE(dio, SLAB_PANIC); + return 0; } -EXPORT_SYMBOL(__blockdev_direct_IO); +module_init(dio_init) |