4de13d7aa8
Pull block core updates from Jens Axboe: - Major bit is Kents prep work for immutable bio vecs. - Stable candidate fix for a scheduling-while-atomic in the queue bypass operation. - Fix for the hang on exceeded rq->datalen 32-bit unsigned when merging discard bios. - Tejuns changes to convert the writeback thread pool to the generic workqueue mechanism. - Runtime PM framework, SCSI patches exists on top of these in James' tree. - A few random fixes. * 'for-3.10/core' of git://git.kernel.dk/linux-block: (40 commits) relay: move remove_buf_file inside relay_close_buf partitions/efi.c: replace useless kzalloc's by kmalloc's fs/block_dev.c: fix iov_shorten() criteria in blkdev_aio_read() block: fix max discard sectors limit blkcg: fix "scheduling while atomic" in blk_queue_bypass_start Documentation: cfq-iosched: update documentation help for cfq tunables writeback: expose the bdi_wq workqueue writeback: replace custom worker pool implementation with unbound workqueue writeback: remove unused bdi_pending_list aoe: Fix unitialized var usage bio-integrity: Add explicit field for owner of bip_buf block: Add an explicit bio flag for bios that own their bvec block: Add bio_alloc_pages() block: Convert some code to bio_for_each_segment_all() block: Add bio_for_each_segment_all() bounce: Refactor __blk_queue_bounce to not use bi_io_vec raid1: use bio_copy_data() pktcdvd: Use bio_reset() in disabled code to kill bi_idx usage pktcdvd: use bio_copy_data() block: Add bio_copy_data() ...
1310 lines
37 KiB
C
1310 lines
37 KiB
C
/*
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* fs/direct-io.c
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*
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* Copyright (C) 2002, Linus Torvalds.
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*
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* O_DIRECT
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*
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* 04Jul2002 Andrew Morton
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* Initial version
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* 11Sep2002 janetinc@us.ibm.com
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* added readv/writev support.
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* 29Oct2002 Andrew Morton
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* rewrote bio_add_page() support.
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* 30Oct2002 pbadari@us.ibm.com
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* added support for non-aligned IO.
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* 06Nov2002 pbadari@us.ibm.com
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* added asynchronous IO support.
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* 21Jul2003 nathans@sgi.com
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* added IO completion notifier.
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*/
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#include <linux/kernel.h>
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#include <linux/module.h>
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#include <linux/types.h>
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#include <linux/fs.h>
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#include <linux/mm.h>
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#include <linux/slab.h>
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#include <linux/highmem.h>
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#include <linux/pagemap.h>
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#include <linux/task_io_accounting_ops.h>
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#include <linux/bio.h>
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#include <linux/wait.h>
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#include <linux/err.h>
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#include <linux/blkdev.h>
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#include <linux/buffer_head.h>
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#include <linux/rwsem.h>
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#include <linux/uio.h>
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#include <linux/atomic.h>
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#include <linux/prefetch.h>
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#include <linux/aio.h>
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/*
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* How many user pages to map in one call to get_user_pages(). This determines
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* the size of a structure in the slab cache
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*/
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#define DIO_PAGES 64
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/*
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* This code generally works in units of "dio_blocks". A dio_block is
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* somewhere between the hard sector size and the filesystem block size. it
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* is determined on a per-invocation basis. When talking to the filesystem
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* we need to convert dio_blocks to fs_blocks by scaling the dio_block quantity
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* down by dio->blkfactor. Similarly, fs-blocksize quantities are converted
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* to bio_block quantities by shifting left by blkfactor.
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*
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* If blkfactor is zero then the user's request was aligned to the filesystem's
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* blocksize.
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*/
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/* dio_state only used in the submission path */
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struct dio_submit {
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struct bio *bio; /* bio under assembly */
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unsigned blkbits; /* doesn't change */
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unsigned blkfactor; /* When we're using an alignment which
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is finer than the filesystem's soft
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blocksize, this specifies how much
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finer. blkfactor=2 means 1/4-block
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alignment. Does not change */
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unsigned start_zero_done; /* flag: sub-blocksize zeroing has
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been performed at the start of a
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write */
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int pages_in_io; /* approximate total IO pages */
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size_t size; /* total request size (doesn't change)*/
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sector_t block_in_file; /* Current offset into the underlying
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file in dio_block units. */
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unsigned blocks_available; /* At block_in_file. changes */
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int reap_counter; /* rate limit reaping */
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sector_t final_block_in_request;/* doesn't change */
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unsigned first_block_in_page; /* doesn't change, Used only once */
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int boundary; /* prev block is at a boundary */
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get_block_t *get_block; /* block mapping function */
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dio_submit_t *submit_io; /* IO submition function */
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loff_t logical_offset_in_bio; /* current first logical block in bio */
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sector_t final_block_in_bio; /* current final block in bio + 1 */
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sector_t next_block_for_io; /* next block to be put under IO,
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in dio_blocks units */
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/*
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* Deferred addition of a page to the dio. These variables are
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* private to dio_send_cur_page(), submit_page_section() and
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* dio_bio_add_page().
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*/
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struct page *cur_page; /* The page */
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unsigned cur_page_offset; /* Offset into it, in bytes */
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unsigned cur_page_len; /* Nr of bytes at cur_page_offset */
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sector_t cur_page_block; /* Where it starts */
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loff_t cur_page_fs_offset; /* Offset in file */
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/*
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* Page fetching state. These variables belong to dio_refill_pages().
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*/
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int curr_page; /* changes */
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int total_pages; /* doesn't change */
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unsigned long curr_user_address;/* changes */
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/*
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* Page queue. These variables belong to dio_refill_pages() and
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* dio_get_page().
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*/
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unsigned head; /* next page to process */
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unsigned tail; /* last valid page + 1 */
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};
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/* dio_state communicated between submission path and end_io */
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struct dio {
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int flags; /* doesn't change */
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int rw;
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struct inode *inode;
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loff_t i_size; /* i_size when submitted */
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dio_iodone_t *end_io; /* IO completion function */
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void *private; /* copy from map_bh.b_private */
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/* BIO completion state */
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spinlock_t bio_lock; /* protects BIO fields below */
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int page_errors; /* errno from get_user_pages() */
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int is_async; /* is IO async ? */
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int io_error; /* IO error in completion path */
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unsigned long refcount; /* direct_io_worker() and bios */
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struct bio *bio_list; /* singly linked via bi_private */
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struct task_struct *waiter; /* waiting task (NULL if none) */
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/* AIO related stuff */
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struct kiocb *iocb; /* kiocb */
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ssize_t result; /* IO result */
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/*
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* pages[] (and any fields placed after it) are not zeroed out at
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* allocation time. Don't add new fields after pages[] unless you
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* wish that they not be zeroed.
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*/
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struct page *pages[DIO_PAGES]; /* page buffer */
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} ____cacheline_aligned_in_smp;
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static struct kmem_cache *dio_cache __read_mostly;
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/*
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* How many pages are in the queue?
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*/
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static inline unsigned dio_pages_present(struct dio_submit *sdio)
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{
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return sdio->tail - sdio->head;
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}
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/*
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* Go grab and pin some userspace pages. Typically we'll get 64 at a time.
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*/
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static inline int dio_refill_pages(struct dio *dio, struct dio_submit *sdio)
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{
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int ret;
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int nr_pages;
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nr_pages = min(sdio->total_pages - sdio->curr_page, DIO_PAGES);
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ret = get_user_pages_fast(
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sdio->curr_user_address, /* Where from? */
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nr_pages, /* How many pages? */
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dio->rw == READ, /* Write to memory? */
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&dio->pages[0]); /* Put results here */
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if (ret < 0 && sdio->blocks_available && (dio->rw & WRITE)) {
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struct page *page = ZERO_PAGE(0);
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/*
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* A memory fault, but the filesystem has some outstanding
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* mapped blocks. We need to use those blocks up to avoid
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* leaking stale data in the file.
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*/
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if (dio->page_errors == 0)
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dio->page_errors = ret;
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page_cache_get(page);
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dio->pages[0] = page;
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sdio->head = 0;
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sdio->tail = 1;
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ret = 0;
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goto out;
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}
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if (ret >= 0) {
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sdio->curr_user_address += ret * PAGE_SIZE;
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sdio->curr_page += ret;
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sdio->head = 0;
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sdio->tail = ret;
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ret = 0;
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}
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out:
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return ret;
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}
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/*
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* Get another userspace page. Returns an ERR_PTR on error. Pages are
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* buffered inside the dio so that we can call get_user_pages() against a
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* decent number of pages, less frequently. To provide nicer use of the
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* L1 cache.
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*/
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static inline struct page *dio_get_page(struct dio *dio,
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struct dio_submit *sdio)
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{
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if (dio_pages_present(sdio) == 0) {
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int ret;
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ret = dio_refill_pages(dio, sdio);
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if (ret)
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return ERR_PTR(ret);
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BUG_ON(dio_pages_present(sdio) == 0);
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}
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return dio->pages[sdio->head++];
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}
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/**
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* dio_complete() - called when all DIO BIO I/O has been completed
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* @offset: the byte offset in the file of the completed operation
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*
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* This releases locks as dictated by the locking type, lets interested parties
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* know that a DIO operation has completed, and calculates the resulting return
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* code for the operation.
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*
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* It lets the filesystem know if it registered an interest earlier via
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* get_block. Pass the private field of the map buffer_head so that
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* filesystems can use it to hold additional state between get_block calls and
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* dio_complete.
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*/
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static ssize_t dio_complete(struct dio *dio, loff_t offset, ssize_t ret, bool is_async)
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{
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ssize_t transferred = 0;
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/*
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* AIO submission can race with bio completion to get here while
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* expecting to have the last io completed by bio completion.
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* In that case -EIOCBQUEUED is in fact not an error we want
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* to preserve through this call.
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*/
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if (ret == -EIOCBQUEUED)
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ret = 0;
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if (dio->result) {
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transferred = dio->result;
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/* Check for short read case */
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if ((dio->rw == READ) && ((offset + transferred) > dio->i_size))
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transferred = dio->i_size - offset;
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}
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if (ret == 0)
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ret = dio->page_errors;
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if (ret == 0)
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ret = dio->io_error;
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if (ret == 0)
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ret = transferred;
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if (dio->end_io && dio->result) {
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dio->end_io(dio->iocb, offset, transferred,
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dio->private, ret, is_async);
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} else {
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inode_dio_done(dio->inode);
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if (is_async)
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aio_complete(dio->iocb, ret, 0);
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}
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return ret;
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}
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static int dio_bio_complete(struct dio *dio, struct bio *bio);
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/*
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* Asynchronous IO callback.
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*/
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static void dio_bio_end_aio(struct bio *bio, int error)
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{
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struct dio *dio = bio->bi_private;
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unsigned long remaining;
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unsigned long flags;
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/* cleanup the bio */
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dio_bio_complete(dio, bio);
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spin_lock_irqsave(&dio->bio_lock, flags);
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remaining = --dio->refcount;
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if (remaining == 1 && dio->waiter)
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wake_up_process(dio->waiter);
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spin_unlock_irqrestore(&dio->bio_lock, flags);
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if (remaining == 0) {
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dio_complete(dio, dio->iocb->ki_pos, 0, true);
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kmem_cache_free(dio_cache, dio);
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}
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}
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/*
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* The BIO completion handler simply queues the BIO up for the process-context
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* handler.
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*
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* During I/O bi_private points at the dio. After I/O, bi_private is used to
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* implement a singly-linked list of completed BIOs, at dio->bio_list.
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*/
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static void dio_bio_end_io(struct bio *bio, int error)
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{
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struct dio *dio = bio->bi_private;
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unsigned long flags;
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spin_lock_irqsave(&dio->bio_lock, flags);
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bio->bi_private = dio->bio_list;
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dio->bio_list = bio;
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if (--dio->refcount == 1 && dio->waiter)
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wake_up_process(dio->waiter);
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spin_unlock_irqrestore(&dio->bio_lock, flags);
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}
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/**
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* dio_end_io - handle the end io action for the given bio
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* @bio: The direct io bio thats being completed
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* @error: Error if there was one
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*
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* This is meant to be called by any filesystem that uses their own dio_submit_t
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* so that the DIO specific endio actions are dealt with after the filesystem
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* has done it's completion work.
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*/
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void dio_end_io(struct bio *bio, int error)
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{
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struct dio *dio = bio->bi_private;
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if (dio->is_async)
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dio_bio_end_aio(bio, error);
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else
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dio_bio_end_io(bio, error);
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}
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EXPORT_SYMBOL_GPL(dio_end_io);
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static inline void
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dio_bio_alloc(struct dio *dio, struct dio_submit *sdio,
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struct block_device *bdev,
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sector_t first_sector, int nr_vecs)
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{
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struct bio *bio;
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/*
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* bio_alloc() is guaranteed to return a bio when called with
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* __GFP_WAIT and we request a valid number of vectors.
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*/
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bio = bio_alloc(GFP_KERNEL, nr_vecs);
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bio->bi_bdev = bdev;
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bio->bi_sector = first_sector;
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if (dio->is_async)
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bio->bi_end_io = dio_bio_end_aio;
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else
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bio->bi_end_io = dio_bio_end_io;
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sdio->bio = bio;
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sdio->logical_offset_in_bio = sdio->cur_page_fs_offset;
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}
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|
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/*
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* In the AIO read case we speculatively dirty the pages before starting IO.
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* During IO completion, any of these pages which happen to have been written
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* back will be redirtied by bio_check_pages_dirty().
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*
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* bios hold a dio reference between submit_bio and ->end_io.
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*/
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static inline void dio_bio_submit(struct dio *dio, struct dio_submit *sdio)
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{
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struct bio *bio = sdio->bio;
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unsigned long flags;
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bio->bi_private = dio;
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spin_lock_irqsave(&dio->bio_lock, flags);
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dio->refcount++;
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spin_unlock_irqrestore(&dio->bio_lock, flags);
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if (dio->is_async && dio->rw == READ)
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bio_set_pages_dirty(bio);
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if (sdio->submit_io)
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sdio->submit_io(dio->rw, bio, dio->inode,
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sdio->logical_offset_in_bio);
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else
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submit_bio(dio->rw, bio);
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sdio->bio = NULL;
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sdio->boundary = 0;
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sdio->logical_offset_in_bio = 0;
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}
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|
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/*
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* Release any resources in case of a failure
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*/
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static inline void dio_cleanup(struct dio *dio, struct dio_submit *sdio)
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{
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while (dio_pages_present(sdio))
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page_cache_release(dio_get_page(dio, sdio));
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}
|
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|
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/*
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* Wait for the next BIO to complete. Remove it and return it. NULL is
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* returned once all BIOs have been completed. This must only be called once
|
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* all bios have been issued so that dio->refcount can only decrease. This
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* requires that that the caller hold a reference on the dio.
|
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*/
|
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static struct bio *dio_await_one(struct dio *dio)
|
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{
|
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unsigned long flags;
|
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struct bio *bio = NULL;
|
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|
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spin_lock_irqsave(&dio->bio_lock, flags);
|
|
|
|
/*
|
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* Wait as long as the list is empty and there are bios in flight. bio
|
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* completion drops the count, maybe adds to the list, and wakes while
|
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* holding the bio_lock so we don't need set_current_state()'s barrier
|
|
* and can call it after testing our condition.
|
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*/
|
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while (dio->refcount > 1 && dio->bio_list == NULL) {
|
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__set_current_state(TASK_UNINTERRUPTIBLE);
|
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dio->waiter = current;
|
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spin_unlock_irqrestore(&dio->bio_lock, flags);
|
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io_schedule();
|
|
/* wake up sets us TASK_RUNNING */
|
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spin_lock_irqsave(&dio->bio_lock, flags);
|
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dio->waiter = NULL;
|
|
}
|
|
if (dio->bio_list) {
|
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bio = dio->bio_list;
|
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dio->bio_list = bio->bi_private;
|
|
}
|
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spin_unlock_irqrestore(&dio->bio_lock, flags);
|
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return bio;
|
|
}
|
|
|
|
/*
|
|
* Process one completed BIO. No locks are held.
|
|
*/
|
|
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;
|
|
unsigned i;
|
|
|
|
if (!uptodate)
|
|
dio->io_error = -EIO;
|
|
|
|
if (dio->is_async && dio->rw == READ) {
|
|
bio_check_pages_dirty(bio); /* transfers ownership */
|
|
} else {
|
|
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);
|
|
page_cache_release(page);
|
|
}
|
|
bio_put(bio);
|
|
}
|
|
return uptodate ? 0 : -EIO;
|
|
}
|
|
|
|
/*
|
|
* Wait on and process all in-flight BIOs. This must only be called once
|
|
* all bios have been issued so that the refcount can only decrease.
|
|
* This just waits for all bios to make it through dio_bio_complete. IO
|
|
* errors are propagated through dio->io_error and should be propagated via
|
|
* dio_complete().
|
|
*/
|
|
static void dio_await_completion(struct dio *dio)
|
|
{
|
|
struct bio *bio;
|
|
do {
|
|
bio = dio_await_one(dio);
|
|
if (bio)
|
|
dio_bio_complete(dio, bio);
|
|
} while (bio);
|
|
}
|
|
|
|
/*
|
|
* A really large O_DIRECT read or write can generate a lot of BIOs. So
|
|
* to keep the memory consumption sane we periodically reap any completed BIOs
|
|
* during the BIO generation phase.
|
|
*
|
|
* This also helps to limit the peak amount of pinned userspace memory.
|
|
*/
|
|
static inline int dio_bio_reap(struct dio *dio, struct dio_submit *sdio)
|
|
{
|
|
int ret = 0;
|
|
|
|
if (sdio->reap_counter++ >= 64) {
|
|
while (dio->bio_list) {
|
|
unsigned long flags;
|
|
struct bio *bio;
|
|
int ret2;
|
|
|
|
spin_lock_irqsave(&dio->bio_lock, flags);
|
|
bio = dio->bio_list;
|
|
dio->bio_list = bio->bi_private;
|
|
spin_unlock_irqrestore(&dio->bio_lock, flags);
|
|
ret2 = dio_bio_complete(dio, bio);
|
|
if (ret == 0)
|
|
ret = ret2;
|
|
}
|
|
sdio->reap_counter = 0;
|
|
}
|
|
return ret;
|
|
}
|
|
|
|
/*
|
|
* Call into the fs to map some more disk blocks. We record the current number
|
|
* 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,
|
|
* it uses the passed inode-relative block number as the file offset, as usual.
|
|
*
|
|
* get_block() is passed the number of i_blkbits-sized blocks which direct_io
|
|
* has remaining to do. The fs should not map more than this number of blocks.
|
|
*
|
|
* If the fs has mapped a lot of blocks, it should populate bh->b_size to
|
|
* indicate how much contiguous disk space has been made available at
|
|
* bh->b_blocknr.
|
|
*
|
|
* If *any* of the mapped blocks are new, then the fs must set buffer_new().
|
|
* This isn't very efficient...
|
|
*
|
|
* In the case of filesystem holes: the fs may return an arbitrarily-large
|
|
* hole by returning an appropriate value in b_size and by clearing
|
|
* 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, struct dio_submit *sdio,
|
|
struct buffer_head *map_bh)
|
|
{
|
|
int ret;
|
|
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 */
|
|
int create;
|
|
unsigned int i_blkbits = sdio->blkbits + sdio->blkfactor;
|
|
|
|
/*
|
|
* If there was a memory error and we've overwritten all the
|
|
* mapped blocks then we can now return that memory error
|
|
*/
|
|
ret = dio->page_errors;
|
|
if (ret == 0) {
|
|
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 << 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->flags & DIO_SKIP_HOLES) {
|
|
if (sdio->block_in_file < (i_size_read(dio->inode) >>
|
|
sdio->blkbits))
|
|
create = 0;
|
|
}
|
|
|
|
ret = (*sdio->get_block)(dio->inode, fs_startblk,
|
|
map_bh, create);
|
|
|
|
/* Store for completion */
|
|
dio->private = map_bh->b_private;
|
|
}
|
|
return ret;
|
|
}
|
|
|
|
/*
|
|
* There is no bio. Make one now.
|
|
*/
|
|
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, sdio);
|
|
if (ret)
|
|
goto out;
|
|
sector = start_sector << (sdio->blkbits - 9);
|
|
nr_pages = min(sdio->pages_in_io, bio_get_nr_vecs(map_bh->b_bdev));
|
|
nr_pages = min(nr_pages, BIO_MAX_PAGES);
|
|
BUG_ON(nr_pages <= 0);
|
|
dio_bio_alloc(dio, sdio, map_bh->b_bdev, sector, nr_pages);
|
|
sdio->boundary = 0;
|
|
out:
|
|
return ret;
|
|
}
|
|
|
|
/*
|
|
* Attempt to put the current chunk of 'cur_page' into the current BIO. If
|
|
* that was successful then update final_block_in_bio and take a ref against
|
|
* the just-added page.
|
|
*
|
|
* Return zero on success. Non-zero means the caller needs to start a new BIO.
|
|
*/
|
|
static inline int dio_bio_add_page(struct dio_submit *sdio)
|
|
{
|
|
int ret;
|
|
|
|
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 ((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;
|
|
}
|
|
return ret;
|
|
}
|
|
|
|
/*
|
|
* Put cur_page under IO. The section of cur_page which is described by
|
|
* cur_page_offset,cur_page_len is put into a BIO. The section of cur_page
|
|
* starts on-disk at cur_page_block.
|
|
*
|
|
* We take a ref against the page here (on behalf of its presence in the bio).
|
|
*
|
|
* 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 inline int dio_send_cur_page(struct dio *dio, struct dio_submit *sdio,
|
|
struct buffer_head *map_bh)
|
|
{
|
|
int ret = 0;
|
|
|
|
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_size;
|
|
|
|
/*
|
|
* 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 (sdio->final_block_in_bio != sdio->cur_page_block ||
|
|
cur_offset != bio_next_offset)
|
|
dio_bio_submit(dio, sdio);
|
|
}
|
|
|
|
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(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(sdio);
|
|
BUG_ON(ret != 0);
|
|
}
|
|
}
|
|
out:
|
|
return ret;
|
|
}
|
|
|
|
/*
|
|
* An autonomous function to put a chunk of a page under deferred IO.
|
|
*
|
|
* The caller doesn't actually know (or care) whether this piece of page is in
|
|
* a BIO, or is under IO or whatever. We just take care of all possible
|
|
* situations here. The separation between the logic of do_direct_IO() and
|
|
* that of submit_page_section() is important for clarity. Please don't break.
|
|
*
|
|
* The chunk of page starts on-disk at blocknr.
|
|
*
|
|
* We perform deferred IO, by recording the last-submitted page inside our
|
|
* private part of the dio structure. If possible, we just expand the IO
|
|
* across that page here.
|
|
*
|
|
* If that doesn't work out then we put the old page into the bio and add this
|
|
* page to the dio instead.
|
|
*/
|
|
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;
|
|
|
|
if (dio->rw & WRITE) {
|
|
/*
|
|
* Read accounting is performed in submit_bio()
|
|
*/
|
|
task_io_account_write(len);
|
|
}
|
|
|
|
/*
|
|
* Can we just grow the current page's presence in the dio?
|
|
*/
|
|
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 (sdio->cur_page) {
|
|
ret = dio_send_cur_page(dio, sdio, map_bh);
|
|
page_cache_release(sdio->cur_page);
|
|
sdio->cur_page = NULL;
|
|
if (ret)
|
|
return ret;
|
|
}
|
|
|
|
page_cache_get(page); /* It is in dio */
|
|
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;
|
|
}
|
|
|
|
/*
|
|
* Clean any dirty buffers in the blockdev mapping which alias newly-created
|
|
* file blocks. Only called for S_ISREG files - blockdevs do not set
|
|
* buffer_new
|
|
*/
|
|
static void clean_blockdev_aliases(struct dio *dio, struct buffer_head *map_bh)
|
|
{
|
|
unsigned i;
|
|
unsigned nblocks;
|
|
|
|
nblocks = map_bh->b_size >> dio->inode->i_blkbits;
|
|
|
|
for (i = 0; i < nblocks; i++) {
|
|
unmap_underlying_metadata(map_bh->b_bdev,
|
|
map_bh->b_blocknr + i);
|
|
}
|
|
}
|
|
|
|
/*
|
|
* If we are not writing the entire block and get_block() allocated
|
|
* the block for us, we need to fill-in the unused portion of the
|
|
* block with zeros. This happens only if user-buffer, fileoffset or
|
|
* io length is not filesystem block-size multiple.
|
|
*
|
|
* `end' is zero if we're doing the start of the IO, 1 at the end of the
|
|
* IO.
|
|
*/
|
|
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;
|
|
|
|
sdio->start_zero_done = 1;
|
|
if (!sdio->blkfactor || !buffer_new(map_bh))
|
|
return;
|
|
|
|
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;
|
|
|
|
/*
|
|
* We need to zero out part of an fs block. It is either at the
|
|
* beginning or the end of the fs block.
|
|
*/
|
|
if (end)
|
|
this_chunk_blocks = dio_blocks_per_fs_block - this_chunk_blocks;
|
|
|
|
this_chunk_bytes = this_chunk_blocks << sdio->blkbits;
|
|
|
|
page = ZERO_PAGE(0);
|
|
if (submit_page_section(dio, sdio, page, 0, this_chunk_bytes,
|
|
sdio->next_block_for_io, map_bh))
|
|
return;
|
|
|
|
sdio->next_block_for_io += this_chunk_blocks;
|
|
}
|
|
|
|
/*
|
|
* Walk the user pages, and the file, mapping blocks to disk and generating
|
|
* a sequence of (page,offset,len,block) mappings. These mappings are injected
|
|
* into submit_page_section(), which takes care of the next stage of submission
|
|
*
|
|
* Direct IO against a blockdev is different from a file. Because we can
|
|
* happily perform page-sized but 512-byte aligned IOs. It is important that
|
|
* blockdev IO be able to have fine alignment and large sizes.
|
|
*
|
|
* So what we do is to permit the ->get_block function to populate bh.b_size
|
|
* with the size of IO which is permitted at this offset and this i_blkbits.
|
|
*
|
|
* For best results, the blockdev should be set up with 512-byte i_blkbits and
|
|
* 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, struct dio_submit *sdio,
|
|
struct buffer_head *map_bh)
|
|
{
|
|
const unsigned blkbits = sdio->blkbits;
|
|
const unsigned blocks_per_page = PAGE_SIZE >> blkbits;
|
|
struct page *page;
|
|
unsigned block_in_page;
|
|
int ret = 0;
|
|
|
|
/* The I/O can start at any block offset within the first page */
|
|
block_in_page = sdio->first_block_in_page;
|
|
|
|
while (sdio->block_in_file < sdio->final_block_in_request) {
|
|
page = dio_get_page(dio, sdio);
|
|
if (IS_ERR(page)) {
|
|
ret = PTR_ERR(page);
|
|
goto out;
|
|
}
|
|
|
|
while (block_in_page < blocks_per_page) {
|
|
unsigned offset_in_page = block_in_page << blkbits;
|
|
unsigned this_chunk_bytes; /* # of bytes mapped */
|
|
unsigned this_chunk_blocks; /* # of blocks */
|
|
unsigned u;
|
|
|
|
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, sdio, map_bh);
|
|
if (ret) {
|
|
page_cache_release(page);
|
|
goto out;
|
|
}
|
|
if (!buffer_mapped(map_bh))
|
|
goto do_holes;
|
|
|
|
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, map_bh);
|
|
|
|
if (!sdio->blkfactor)
|
|
goto do_holes;
|
|
|
|
blkmask = (1 << sdio->blkfactor) - 1;
|
|
dio_remainder = (sdio->block_in_file & blkmask);
|
|
|
|
/*
|
|
* If we are at the start of IO and that IO
|
|
* starts partway into a fs-block,
|
|
* dio_remainder will be non-zero. If the IO
|
|
* is a read then we can simply advance the IO
|
|
* cursor to the first block which is to be
|
|
* read. But if the IO is a write and the
|
|
* block was newly allocated we cannot do that;
|
|
* the start of the fs block must be zeroed out
|
|
* on-disk
|
|
*/
|
|
if (!buffer_new(map_bh))
|
|
sdio->next_block_for_io += dio_remainder;
|
|
sdio->blocks_available -= dio_remainder;
|
|
}
|
|
do_holes:
|
|
/* Handle holes */
|
|
if (!buffer_mapped(map_bh)) {
|
|
loff_t i_size_aligned;
|
|
|
|
/* AKPM: eargh, -ENOTBLK is a hack */
|
|
if (dio->rw & WRITE) {
|
|
page_cache_release(page);
|
|
return -ENOTBLK;
|
|
}
|
|
|
|
/*
|
|
* Be sure to account for a partial block as the
|
|
* last block in the file
|
|
*/
|
|
i_size_aligned = ALIGN(i_size_read(dio->inode),
|
|
1 << blkbits);
|
|
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);
|
|
sdio->block_in_file++;
|
|
block_in_page++;
|
|
goto next_block;
|
|
}
|
|
|
|
/*
|
|
* If we're performing IO which has an alignment which
|
|
* is finer than the underlying fs, go check to see if
|
|
* we must zero out the start of this block.
|
|
*/
|
|
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 = sdio->blocks_available;
|
|
u = (PAGE_SIZE - offset_in_page) >> blkbits;
|
|
if (this_chunk_blocks > u)
|
|
this_chunk_blocks = u;
|
|
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);
|
|
|
|
if (this_chunk_blocks == sdio->blocks_available)
|
|
sdio->boundary = buffer_boundary(map_bh);
|
|
ret = submit_page_section(dio, sdio, page,
|
|
offset_in_page,
|
|
this_chunk_bytes,
|
|
sdio->next_block_for_io,
|
|
map_bh);
|
|
if (ret) {
|
|
page_cache_release(page);
|
|
goto out;
|
|
}
|
|
sdio->next_block_for_io += this_chunk_blocks;
|
|
|
|
sdio->block_in_file += this_chunk_blocks;
|
|
block_in_page += this_chunk_blocks;
|
|
sdio->blocks_available -= this_chunk_blocks;
|
|
next_block:
|
|
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;
|
|
}
|
|
|
|
/*
|
|
* 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 inline ssize_t
|
|
do_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,
|
|
dio_submit_t submit_io, int flags)
|
|
{
|
|
int seg;
|
|
size_t size;
|
|
unsigned long addr;
|
|
unsigned i_blkbits = ACCESS_ONCE(inode->i_blkbits);
|
|
unsigned blkbits = i_blkbits;
|
|
unsigned blocksize_mask = (1 << blkbits) - 1;
|
|
ssize_t retval = -EINVAL;
|
|
loff_t end = offset;
|
|
struct dio *dio;
|
|
struct dio_submit sdio = { 0, };
|
|
unsigned long user_addr;
|
|
size_t bytes;
|
|
struct buffer_head map_bh = { 0, };
|
|
struct blk_plug plug;
|
|
|
|
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 (offset & blocksize_mask) {
|
|
if (bdev)
|
|
blkbits = blksize_bits(bdev_logical_block_size(bdev));
|
|
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 (unlikely((addr & blocksize_mask) ||
|
|
(size & blocksize_mask))) {
|
|
if (bdev)
|
|
blkbits = blksize_bits(
|
|
bdev_logical_block_size(bdev));
|
|
blocksize_mask = (1 << blkbits) - 1;
|
|
if ((addr & blocksize_mask) || (size & blocksize_mask))
|
|
goto out;
|
|
}
|
|
}
|
|
|
|
/* watch out for a 0 len io from a tricksy fs */
|
|
if (rw == READ && end == offset)
|
|
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;
|
|
}
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Will be decremented at I/O completion time.
|
|
*/
|
|
atomic_inc(&inode->i_dio_count);
|
|
|
|
/*
|
|
* 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.
|
|
*/
|
|
dio->is_async = !is_sync_kiocb(iocb) && !((rw & WRITE) &&
|
|
(end > i_size_read(inode)));
|
|
|
|
retval = 0;
|
|
|
|
dio->inode = inode;
|
|
dio->rw = rw;
|
|
sdio.blkbits = blkbits;
|
|
sdio.blkfactor = i_blkbits - blkbits;
|
|
sdio.block_in_file = offset >> blkbits;
|
|
|
|
sdio.get_block = get_block;
|
|
dio->end_io = end_io;
|
|
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);
|
|
|
|
spin_lock_init(&dio->bio_lock);
|
|
dio->refcount = 1;
|
|
|
|
/*
|
|
* In case of non-aligned buffers, we may need 2 more
|
|
* pages since we need to zero out first and last block.
|
|
*/
|
|
if (unlikely(sdio.blkfactor))
|
|
sdio.pages_in_io = 2;
|
|
|
|
for (seg = 0; seg < nr_segs; seg++) {
|
|
user_addr = (unsigned long)iov[seg].iov_base;
|
|
sdio.pages_in_io +=
|
|
((user_addr + iov[seg].iov_len + PAGE_SIZE-1) /
|
|
PAGE_SIZE - user_addr / PAGE_SIZE);
|
|
}
|
|
|
|
blk_start_plug(&plug);
|
|
|
|
for (seg = 0; seg < nr_segs; seg++) {
|
|
user_addr = (unsigned long)iov[seg].iov_base;
|
|
sdio.size += bytes = iov[seg].iov_len;
|
|
|
|
/* Index into the first page of the first block */
|
|
sdio.first_block_in_page = (user_addr & ~PAGE_MASK) >> blkbits;
|
|
sdio.final_block_in_request = sdio.block_in_file +
|
|
(bytes >> blkbits);
|
|
/* Page fetching state */
|
|
sdio.head = 0;
|
|
sdio.tail = 0;
|
|
sdio.curr_page = 0;
|
|
|
|
sdio.total_pages = 0;
|
|
if (user_addr & (PAGE_SIZE-1)) {
|
|
sdio.total_pages++;
|
|
bytes -= PAGE_SIZE - (user_addr & (PAGE_SIZE - 1));
|
|
}
|
|
sdio.total_pages += (bytes + PAGE_SIZE - 1) / PAGE_SIZE;
|
|
sdio.curr_user_address = user_addr;
|
|
|
|
retval = do_direct_IO(dio, &sdio, &map_bh);
|
|
|
|
dio->result += iov[seg].iov_len -
|
|
((sdio.final_block_in_request - sdio.block_in_file) <<
|
|
blkbits);
|
|
|
|
if (retval) {
|
|
dio_cleanup(dio, &sdio);
|
|
break;
|
|
}
|
|
} /* end iovec loop */
|
|
|
|
if (retval == -ENOTBLK) {
|
|
/*
|
|
* The remaining part of the request will be
|
|
* be handled by buffered I/O when we return
|
|
*/
|
|
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, &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 (sdio.bio)
|
|
dio_bio_submit(dio, &sdio);
|
|
|
|
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, &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->flags & DIO_LOCKING))
|
|
mutex_unlock(&dio->inode->i_mutex);
|
|
|
|
/*
|
|
* The only time we want to leave bios in flight is when a successful
|
|
* partial aio read or full aio write have been setup. In that case
|
|
* bio completion will call aio_complete. The only time it's safe to
|
|
* 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(retval == -EIOCBQUEUED);
|
|
if (dio->is_async && retval == 0 && dio->result &&
|
|
((rw == READ) || (dio->result == sdio.size)))
|
|
retval = -EIOCBQUEUED;
|
|
|
|
if (retval != -EIOCBQUEUED)
|
|
dio_await_completion(dio);
|
|
|
|
if (drop_refcount(dio) == 0) {
|
|
retval = dio_complete(dio, offset, retval, false);
|
|
kmem_cache_free(dio_cache, dio);
|
|
} else
|
|
BUG_ON(retval != -EIOCBQUEUED);
|
|
|
|
out:
|
|
return retval;
|
|
}
|
|
|
|
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,
|
|
dio_submit_t submit_io, int flags)
|
|
{
|
|
/*
|
|
* 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.
|
|
*/
|
|
prefetch(&bdev->bd_disk->part_tbl);
|
|
prefetch(bdev->bd_queue);
|
|
prefetch((char *)bdev->bd_queue + SMP_CACHE_BYTES);
|
|
|
|
return do_blockdev_direct_IO(rw, iocb, inode, bdev, iov, offset,
|
|
nr_segs, get_block, end_io,
|
|
submit_io, flags);
|
|
}
|
|
|
|
EXPORT_SYMBOL(__blockdev_direct_IO);
|
|
|
|
static __init int dio_init(void)
|
|
{
|
|
dio_cache = KMEM_CACHE(dio, SLAB_PANIC);
|
|
return 0;
|
|
}
|
|
module_init(dio_init)
|