/* * fs/direct-io.c * * Copyright (C) 2002, Linus Torvalds. * * O_DIRECT * * 04Jul2002 Andrew Morton * Initial version * 11Sep2002 janetinc@us.ibm.com * added readv/writev support. * 29Oct2002 Andrew Morton * rewrote bio_add_page() support. * 30Oct2002 pbadari@us.ibm.com * added support for non-aligned IO. * 06Nov2002 pbadari@us.ibm.com * added asynchronous IO support. * 21Jul2003 nathans@sgi.com * added IO completion notifier. */ #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include /* * How many user pages to map in one call to get_user_pages(). This determines * the size of a structure in the slab cache */ #define DIO_PAGES 64 /* * This code generally works in units of "dio_blocks". A dio_block is * somewhere between the hard sector size and the filesystem block size. it * is determined on a per-invocation basis. When talking to the filesystem * we need to convert dio_blocks to fs_blocks by scaling the dio_block quantity * down by dio->blkfactor. Similarly, fs-blocksize quantities are converted * to bio_block quantities by shifting left by blkfactor. * * If blkfactor is zero then the user's request was aligned to the filesystem's * blocksize. */ /* dio_state only used in the submission path */ struct dio_submit { struct bio *bio; /* bio under assembly */ unsigned blkbits; /* doesn't change */ unsigned blkfactor; /* When we're using an alignment which is finer than the filesystem's soft blocksize, this specifies how much finer. blkfactor=2 means 1/4-block alignment. Does not change */ unsigned start_zero_done; /* flag: sub-blocksize zeroing has been performed at the start of a write */ int pages_in_io; /* approximate total IO pages */ 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 */ int boundary; /* prev block is at a boundary */ get_block_t *get_block; /* block mapping 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 */ /* * Deferred addition of a page to the dio. These variables are * private to dio_send_cur_page(), submit_page_section() and * dio_bio_add_page(). */ struct page *cur_page; /* The page */ 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 */ struct iov_iter *iter; /* * Page queue. These variables belong to dio_refill_pages() and * dio_get_page(). */ unsigned head; /* next page to process */ unsigned tail; /* last valid page + 1 */ size_t from, to; }; /* dio_state communicated between submission path and end_io */ struct dio { int flags; /* doesn't change */ int op; int op_flags; blk_qc_t bio_cookie; struct block_device *bio_bdev; 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? */ bool should_dirty; /* if pages should be dirtied */ 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 */ 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_submit *sdio) { return sdio->tail
/*
 * Old U-boot compatibility for 83xx
 *
 * Author: Scott Wood <scottwood@freescale.com>
 *
 * Copyright (c) 2007 Freescale Semiconductor, Inc.
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 as published
 * by the Free Software Foundation.
 */

#include "ops.h"
#include "stdio.h"
#include "cuboot.h"

#define TARGET_83xx
#include "ppcboot.h"

static bd_t bd;

static void platform_fixups(void)
{
	void *soc;

	dt_fixup_memory(bd.bi_memstart, bd.bi_memsize);
	dt_fixup_mac_address_by_alias("ethernet0", bd.bi_enetaddr);
	dt_fixup_mac_address_by_alias("ethernet1", bd.bi_enet1addr);
	dt_fixup_cpu_clocks(bd.bi_intfreq, bd.bi_busfreq / 4, bd.bi_busfreq);

	/* Unfortunately, the specific model number is encoded in the
	 * soc node name in existing dts files -- once that is fixed,
	 * this can do a simple path lookup.
	 */
	soc = find_node_by_devtype(NULL, "soc");
	if (soc) {
		void *serial = NULL;

		setprop(soc, "bus-frequency", &bd.bi_busfreq,
		        sizeof(bd.bi_busfreq));

		while ((serial = find_node_by_devtype(serial, "serial"))) {
			if (get_parent(serial) != soc)
				continue;

			setprop(serial, "clock-frequency", &bd.bi_busfreq,
			        sizeof(bd.bi_busfreq));
		}
	}
}

void platform_init(unsigned long r3, unsigned long r4, unsigned long r5,
                   unsigned long r6, unsigned long r7)
{
	CUBOOT_INIT();
	fdt_init(_dtb_start);
	serial_console_init();
	platform_ops.fixups = platform_fixups;
}
generated by cgit v1.2.3 (git 2.25.1) at 2024-09-09 19:32:37 +0000
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->op == REQ_OP_WRITE; if (dio->flags & DIO_SKIP_HOLES) { if (fs_startblk <= ((i_size_read(dio->inode) - 1) >> i_blkbits)) create = 0; } 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; } /* * 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_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--; get_page(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_iter.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->op == REQ_OP_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); put_page(sdio->cur_page); sdio->cur_page = NULL; if (ret) return ret; } get_page(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); put_page(sdio->cur_page); sdio->cur_page = NULL; } return ret; } /* * 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 i_blkbits = blkbits + sdio->blkfactor; int ret = 0; while (sdio->block_in_file < sdio->final_block_in_request) { struct page *page; size_t from, to; 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 (from < to) { 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) { put_page(page); goto out; } if (!buffer_mapped(map_bh)) goto do_holes; sdio->blocks_available = map_bh->b_size >> blkbits; sdio->next_block_for_io = map_bh->b_blocknr << sdio->blkfactor; if (buffer_new(map_bh)) { clean_bdev_aliases( map_bh->b_bdev, map_bh->b_blocknr, map_bh->b_size >> i_blkbits); } 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->op == REQ_OP_WRITE) { put_page(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 */ put_page(page); goto out; } zero_user(page, from, 1 << blkbits); sdio->block_in_file++; from += 1 << blkbits; dio->result += 1 << blkbits; 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 = (to - from) >> 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, from, this_chunk_bytes, sdio->next_block_for_io, map_bh); if (ret) { put_page(page); goto out; } sdio->next_block_for_io += 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(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() */ put_page(page); } 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 ->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(struct kiocb *iocb, struct inode *inode, struct block_device *bdev, struct iov_iter *iter, get_block_t get_block, dio_iodone_t end_io, dio_submit_t submit_io, int flags) { 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 offset = iocb->ki_pos; 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); /* * 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 (iov_iter_rw(iter) == 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 (iov_iter_rw(iter) == READ) { struct address_space *mapping = iocb->ki_filp->f_mapping; /* will be released by direct_io_worker */ inode_lock(inode); retval = filemap_write_and_wait_range(mapping, offset, end - 1); if (retval) { inode_unlock(inode); kmem_cache_free(dio_cache, dio); goto out; } } } /* Once we sampled i_size check for reads beyond EOF */ dio->i_size = i_size_read(inode); if (iov_iter_rw(iter) == READ && offset >= dio->i_size) { if (dio->flags & DIO_LOCKING) inode_unlock(inode); kmem_cache_free(dio_cache, dio); retval = 0; 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) && iov_iter_rw(iter) == WRITE && end > i_size_read(inode)) dio->is_async = false; else dio->is_async = true; dio->inode = inode; if (iov_iter_rw(iter) == WRITE) { dio->op = REQ_OP_WRITE; dio->op_flags = REQ_SYNC | REQ_IDLE; } else { dio->op = REQ_OP_READ; } /* * For AIO O_(D)SYNC writes we need to defer completions to a workqueue * so that we can call ->fsync. */ if (dio->is_async && iov_iter_rw(iter) == 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. */ if (!(dio->flags & DIO_SKIP_DIO_COUNT)) inode_dio_begin(inode); 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; sdio.submit_io = submit_io; sdio.final_block_in_bio = -1; sdio.next_block_for_io = -1; dio->iocb = iocb; spin_lock_init(&dio->bio_lock); dio->refcount = 1; dio->should_dirty = (iter->type == ITER_IOVEC); 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(sdio.blkfactor)) sdio.pages_in_io = 2; sdio.pages_in_io += iov_iter_npages(iter, INT_MAX); blk_start_plug(&plug); 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 */ 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; put_page(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 (iov_iter_rw(iter) == READ && (dio->flags & DIO_LOCKING)) inode_unlock(dio->inode); /* * 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 && (iov_iter_rw(iter) == READ || dio->result == count)) retval = -EIOCBQUEUED; else dio_await_completion(dio); if (drop_refcount(dio) == 0) { retval = dio_complete(dio, retval, false); } else BUG_ON(retval != -EIOCBQUEUED); out: return retval; } ssize_t __blockdev_direct_IO(struct kiocb *iocb, struct inode *inode, struct block_device *bdev, struct iov_iter *iter, 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(iocb, inode, bdev, iter, 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)