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![Al Viro](/assets/img/avatar_default.png)
Equivalent of single-segment iovec. Initialized by iov_iter_ubuf(), checked for by iter_is_ubuf(), otherwise behaves like ITER_IOVEC ones. We are going to expose the things like ->write_iter() et.al. to those in subsequent commits. New predicate (user_backed_iter()) that is true for ITER_IOVEC and ITER_UBUF; places like direct-IO handling should use that for checking that pages we modify after getting them from iov_iter_get_pages() would need to be dirtied. DO NOT assume that replacing iter_is_iovec() with user_backed_iter() will solve all problems - there's code that uses iter_is_iovec() to decide how to poke around in iov_iter guts and for that the predicate replacement obviously won't suffice. Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
697 lines
17 KiB
C
697 lines
17 KiB
C
// SPDX-License-Identifier: GPL-2.0-only
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/*
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* Copyright (C) 1991, 1992 Linus Torvalds
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* Copyright (C) 2001 Andrea Arcangeli <andrea@suse.de> SuSE
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* Copyright (C) 2016 - 2020 Christoph Hellwig
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*/
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#include <linux/init.h>
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#include <linux/mm.h>
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#include <linux/blkdev.h>
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#include <linux/buffer_head.h>
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#include <linux/mpage.h>
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#include <linux/uio.h>
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#include <linux/namei.h>
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#include <linux/task_io_accounting_ops.h>
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#include <linux/falloc.h>
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#include <linux/suspend.h>
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#include <linux/fs.h>
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#include <linux/module.h>
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#include "blk.h"
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static inline struct inode *bdev_file_inode(struct file *file)
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{
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return file->f_mapping->host;
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}
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static int blkdev_get_block(struct inode *inode, sector_t iblock,
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struct buffer_head *bh, int create)
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{
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bh->b_bdev = I_BDEV(inode);
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bh->b_blocknr = iblock;
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set_buffer_mapped(bh);
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return 0;
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}
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static blk_opf_t dio_bio_write_op(struct kiocb *iocb)
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{
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blk_opf_t opf = REQ_OP_WRITE | REQ_SYNC | REQ_IDLE;
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/* avoid the need for a I/O completion work item */
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if (iocb_is_dsync(iocb))
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opf |= REQ_FUA;
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return opf;
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}
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static bool blkdev_dio_unaligned(struct block_device *bdev, loff_t pos,
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struct iov_iter *iter)
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{
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return pos & (bdev_logical_block_size(bdev) - 1) ||
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!bdev_iter_is_aligned(bdev, iter);
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}
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#define DIO_INLINE_BIO_VECS 4
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static ssize_t __blkdev_direct_IO_simple(struct kiocb *iocb,
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struct iov_iter *iter, unsigned int nr_pages)
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{
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struct block_device *bdev = iocb->ki_filp->private_data;
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struct bio_vec inline_vecs[DIO_INLINE_BIO_VECS], *vecs;
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loff_t pos = iocb->ki_pos;
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bool should_dirty = false;
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struct bio bio;
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ssize_t ret;
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if (blkdev_dio_unaligned(bdev, pos, iter))
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return -EINVAL;
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if (nr_pages <= DIO_INLINE_BIO_VECS)
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vecs = inline_vecs;
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else {
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vecs = kmalloc_array(nr_pages, sizeof(struct bio_vec),
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GFP_KERNEL);
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if (!vecs)
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return -ENOMEM;
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}
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if (iov_iter_rw(iter) == READ) {
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bio_init(&bio, bdev, vecs, nr_pages, REQ_OP_READ);
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if (user_backed_iter(iter))
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should_dirty = true;
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} else {
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bio_init(&bio, bdev, vecs, nr_pages, dio_bio_write_op(iocb));
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}
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bio.bi_iter.bi_sector = pos >> SECTOR_SHIFT;
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bio.bi_ioprio = iocb->ki_ioprio;
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ret = bio_iov_iter_get_pages(&bio, iter);
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if (unlikely(ret))
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goto out;
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ret = bio.bi_iter.bi_size;
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if (iov_iter_rw(iter) == WRITE)
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task_io_account_write(ret);
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if (iocb->ki_flags & IOCB_NOWAIT)
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bio.bi_opf |= REQ_NOWAIT;
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submit_bio_wait(&bio);
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bio_release_pages(&bio, should_dirty);
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if (unlikely(bio.bi_status))
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ret = blk_status_to_errno(bio.bi_status);
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out:
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if (vecs != inline_vecs)
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kfree(vecs);
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bio_uninit(&bio);
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return ret;
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}
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enum {
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DIO_SHOULD_DIRTY = 1,
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DIO_IS_SYNC = 2,
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};
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struct blkdev_dio {
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union {
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struct kiocb *iocb;
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struct task_struct *waiter;
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};
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size_t size;
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atomic_t ref;
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unsigned int flags;
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struct bio bio ____cacheline_aligned_in_smp;
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};
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static struct bio_set blkdev_dio_pool;
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static void blkdev_bio_end_io(struct bio *bio)
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{
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struct blkdev_dio *dio = bio->bi_private;
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bool should_dirty = dio->flags & DIO_SHOULD_DIRTY;
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if (bio->bi_status && !dio->bio.bi_status)
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dio->bio.bi_status = bio->bi_status;
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if (atomic_dec_and_test(&dio->ref)) {
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if (!(dio->flags & DIO_IS_SYNC)) {
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struct kiocb *iocb = dio->iocb;
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ssize_t ret;
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WRITE_ONCE(iocb->private, NULL);
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if (likely(!dio->bio.bi_status)) {
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ret = dio->size;
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iocb->ki_pos += ret;
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} else {
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ret = blk_status_to_errno(dio->bio.bi_status);
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}
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dio->iocb->ki_complete(iocb, ret);
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bio_put(&dio->bio);
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} else {
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struct task_struct *waiter = dio->waiter;
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WRITE_ONCE(dio->waiter, NULL);
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blk_wake_io_task(waiter);
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}
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}
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if (should_dirty) {
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bio_check_pages_dirty(bio);
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} else {
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bio_release_pages(bio, false);
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bio_put(bio);
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}
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}
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static ssize_t __blkdev_direct_IO(struct kiocb *iocb, struct iov_iter *iter,
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unsigned int nr_pages)
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{
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struct block_device *bdev = iocb->ki_filp->private_data;
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struct blk_plug plug;
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struct blkdev_dio *dio;
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struct bio *bio;
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bool is_read = (iov_iter_rw(iter) == READ), is_sync;
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blk_opf_t opf = is_read ? REQ_OP_READ : dio_bio_write_op(iocb);
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loff_t pos = iocb->ki_pos;
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int ret = 0;
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if (blkdev_dio_unaligned(bdev, pos, iter))
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return -EINVAL;
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if (iocb->ki_flags & IOCB_ALLOC_CACHE)
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opf |= REQ_ALLOC_CACHE;
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bio = bio_alloc_bioset(bdev, nr_pages, opf, GFP_KERNEL,
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&blkdev_dio_pool);
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dio = container_of(bio, struct blkdev_dio, bio);
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atomic_set(&dio->ref, 1);
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/*
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* Grab an extra reference to ensure the dio structure which is embedded
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* into the first bio stays around.
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*/
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bio_get(bio);
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is_sync = is_sync_kiocb(iocb);
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if (is_sync) {
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dio->flags = DIO_IS_SYNC;
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dio->waiter = current;
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} else {
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dio->flags = 0;
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dio->iocb = iocb;
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}
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dio->size = 0;
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if (is_read && user_backed_iter(iter))
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dio->flags |= DIO_SHOULD_DIRTY;
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blk_start_plug(&plug);
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for (;;) {
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bio->bi_iter.bi_sector = pos >> SECTOR_SHIFT;
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bio->bi_private = dio;
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bio->bi_end_io = blkdev_bio_end_io;
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bio->bi_ioprio = iocb->ki_ioprio;
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ret = bio_iov_iter_get_pages(bio, iter);
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if (unlikely(ret)) {
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bio->bi_status = BLK_STS_IOERR;
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bio_endio(bio);
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break;
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}
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if (is_read) {
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if (dio->flags & DIO_SHOULD_DIRTY)
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bio_set_pages_dirty(bio);
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} else {
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task_io_account_write(bio->bi_iter.bi_size);
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}
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if (iocb->ki_flags & IOCB_NOWAIT)
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bio->bi_opf |= REQ_NOWAIT;
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dio->size += bio->bi_iter.bi_size;
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pos += bio->bi_iter.bi_size;
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nr_pages = bio_iov_vecs_to_alloc(iter, BIO_MAX_VECS);
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if (!nr_pages) {
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submit_bio(bio);
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break;
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}
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atomic_inc(&dio->ref);
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submit_bio(bio);
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bio = bio_alloc(bdev, nr_pages, opf, GFP_KERNEL);
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}
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blk_finish_plug(&plug);
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if (!is_sync)
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return -EIOCBQUEUED;
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for (;;) {
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set_current_state(TASK_UNINTERRUPTIBLE);
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if (!READ_ONCE(dio->waiter))
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break;
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blk_io_schedule();
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}
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__set_current_state(TASK_RUNNING);
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if (!ret)
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ret = blk_status_to_errno(dio->bio.bi_status);
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if (likely(!ret))
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ret = dio->size;
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bio_put(&dio->bio);
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return ret;
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}
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static void blkdev_bio_end_io_async(struct bio *bio)
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{
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struct blkdev_dio *dio = container_of(bio, struct blkdev_dio, bio);
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struct kiocb *iocb = dio->iocb;
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ssize_t ret;
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WRITE_ONCE(iocb->private, NULL);
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if (likely(!bio->bi_status)) {
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ret = dio->size;
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iocb->ki_pos += ret;
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} else {
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ret = blk_status_to_errno(bio->bi_status);
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}
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iocb->ki_complete(iocb, ret);
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if (dio->flags & DIO_SHOULD_DIRTY) {
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bio_check_pages_dirty(bio);
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} else {
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bio_release_pages(bio, false);
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bio_put(bio);
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}
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}
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static ssize_t __blkdev_direct_IO_async(struct kiocb *iocb,
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struct iov_iter *iter,
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unsigned int nr_pages)
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{
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struct block_device *bdev = iocb->ki_filp->private_data;
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bool is_read = iov_iter_rw(iter) == READ;
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blk_opf_t opf = is_read ? REQ_OP_READ : dio_bio_write_op(iocb);
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struct blkdev_dio *dio;
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struct bio *bio;
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loff_t pos = iocb->ki_pos;
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int ret = 0;
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if (blkdev_dio_unaligned(bdev, pos, iter))
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return -EINVAL;
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if (iocb->ki_flags & IOCB_ALLOC_CACHE)
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opf |= REQ_ALLOC_CACHE;
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bio = bio_alloc_bioset(bdev, nr_pages, opf, GFP_KERNEL,
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&blkdev_dio_pool);
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dio = container_of(bio, struct blkdev_dio, bio);
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dio->flags = 0;
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dio->iocb = iocb;
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bio->bi_iter.bi_sector = pos >> SECTOR_SHIFT;
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bio->bi_end_io = blkdev_bio_end_io_async;
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bio->bi_ioprio = iocb->ki_ioprio;
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if (iov_iter_is_bvec(iter)) {
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/*
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* Users don't rely on the iterator being in any particular
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* state for async I/O returning -EIOCBQUEUED, hence we can
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* avoid expensive iov_iter_advance(). Bypass
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* bio_iov_iter_get_pages() and set the bvec directly.
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*/
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bio_iov_bvec_set(bio, iter);
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} else {
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ret = bio_iov_iter_get_pages(bio, iter);
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if (unlikely(ret)) {
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bio_put(bio);
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return ret;
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}
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}
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dio->size = bio->bi_iter.bi_size;
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if (is_read) {
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if (user_backed_iter(iter)) {
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dio->flags |= DIO_SHOULD_DIRTY;
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bio_set_pages_dirty(bio);
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}
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} else {
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task_io_account_write(bio->bi_iter.bi_size);
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}
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if (iocb->ki_flags & IOCB_HIPRI) {
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bio->bi_opf |= REQ_POLLED | REQ_NOWAIT;
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submit_bio(bio);
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WRITE_ONCE(iocb->private, bio);
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} else {
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if (iocb->ki_flags & IOCB_NOWAIT)
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bio->bi_opf |= REQ_NOWAIT;
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submit_bio(bio);
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}
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return -EIOCBQUEUED;
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}
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static ssize_t blkdev_direct_IO(struct kiocb *iocb, struct iov_iter *iter)
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{
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unsigned int nr_pages;
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if (!iov_iter_count(iter))
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return 0;
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nr_pages = bio_iov_vecs_to_alloc(iter, BIO_MAX_VECS + 1);
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if (likely(nr_pages <= BIO_MAX_VECS)) {
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if (is_sync_kiocb(iocb))
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return __blkdev_direct_IO_simple(iocb, iter, nr_pages);
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return __blkdev_direct_IO_async(iocb, iter, nr_pages);
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}
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return __blkdev_direct_IO(iocb, iter, bio_max_segs(nr_pages));
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}
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static int blkdev_writepage(struct page *page, struct writeback_control *wbc)
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{
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return block_write_full_page(page, blkdev_get_block, wbc);
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}
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static int blkdev_read_folio(struct file *file, struct folio *folio)
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{
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return block_read_full_folio(folio, blkdev_get_block);
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}
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static void blkdev_readahead(struct readahead_control *rac)
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{
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mpage_readahead(rac, blkdev_get_block);
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}
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static int blkdev_write_begin(struct file *file, struct address_space *mapping,
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loff_t pos, unsigned len, struct page **pagep, void **fsdata)
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{
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return block_write_begin(mapping, pos, len, pagep, blkdev_get_block);
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}
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static int blkdev_write_end(struct file *file, struct address_space *mapping,
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loff_t pos, unsigned len, unsigned copied, struct page *page,
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void *fsdata)
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{
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int ret;
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ret = block_write_end(file, mapping, pos, len, copied, page, fsdata);
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unlock_page(page);
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put_page(page);
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return ret;
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}
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static int blkdev_writepages(struct address_space *mapping,
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struct writeback_control *wbc)
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{
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return generic_writepages(mapping, wbc);
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}
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const struct address_space_operations def_blk_aops = {
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.dirty_folio = block_dirty_folio,
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.invalidate_folio = block_invalidate_folio,
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.read_folio = blkdev_read_folio,
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.readahead = blkdev_readahead,
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.writepage = blkdev_writepage,
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.write_begin = blkdev_write_begin,
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.write_end = blkdev_write_end,
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.writepages = blkdev_writepages,
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.direct_IO = blkdev_direct_IO,
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.migrate_folio = buffer_migrate_folio_norefs,
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.is_dirty_writeback = buffer_check_dirty_writeback,
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};
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/*
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* for a block special file file_inode(file)->i_size is zero
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* so we compute the size by hand (just as in block_read/write above)
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*/
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static loff_t blkdev_llseek(struct file *file, loff_t offset, int whence)
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{
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struct inode *bd_inode = bdev_file_inode(file);
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loff_t retval;
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inode_lock(bd_inode);
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retval = fixed_size_llseek(file, offset, whence, i_size_read(bd_inode));
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inode_unlock(bd_inode);
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return retval;
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}
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static int blkdev_fsync(struct file *filp, loff_t start, loff_t end,
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int datasync)
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{
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struct block_device *bdev = filp->private_data;
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int error;
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error = file_write_and_wait_range(filp, start, end);
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if (error)
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return error;
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/*
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* There is no need to serialise calls to blkdev_issue_flush with
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* i_mutex and doing so causes performance issues with concurrent
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* O_SYNC writers to a block device.
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*/
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error = blkdev_issue_flush(bdev);
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if (error == -EOPNOTSUPP)
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error = 0;
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return error;
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}
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static int blkdev_open(struct inode *inode, struct file *filp)
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{
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struct block_device *bdev;
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/*
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* Preserve backwards compatibility and allow large file access
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* even if userspace doesn't ask for it explicitly. Some mkfs
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* binary needs it. We might want to drop this workaround
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* during an unstable branch.
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*/
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filp->f_flags |= O_LARGEFILE;
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filp->f_mode |= FMODE_NOWAIT | FMODE_BUF_RASYNC;
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if (filp->f_flags & O_NDELAY)
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filp->f_mode |= FMODE_NDELAY;
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if (filp->f_flags & O_EXCL)
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filp->f_mode |= FMODE_EXCL;
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if ((filp->f_flags & O_ACCMODE) == 3)
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filp->f_mode |= FMODE_WRITE_IOCTL;
|
|
|
|
bdev = blkdev_get_by_dev(inode->i_rdev, filp->f_mode, filp);
|
|
if (IS_ERR(bdev))
|
|
return PTR_ERR(bdev);
|
|
|
|
filp->private_data = bdev;
|
|
filp->f_mapping = bdev->bd_inode->i_mapping;
|
|
filp->f_wb_err = filemap_sample_wb_err(filp->f_mapping);
|
|
return 0;
|
|
}
|
|
|
|
static int blkdev_close(struct inode *inode, struct file *filp)
|
|
{
|
|
struct block_device *bdev = filp->private_data;
|
|
|
|
blkdev_put(bdev, filp->f_mode);
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* Write data to the block device. Only intended for the block device itself
|
|
* and the raw driver which basically is a fake block device.
|
|
*
|
|
* Does not take i_mutex for the write and thus is not for general purpose
|
|
* use.
|
|
*/
|
|
static ssize_t blkdev_write_iter(struct kiocb *iocb, struct iov_iter *from)
|
|
{
|
|
struct block_device *bdev = iocb->ki_filp->private_data;
|
|
struct inode *bd_inode = bdev->bd_inode;
|
|
loff_t size = bdev_nr_bytes(bdev);
|
|
struct blk_plug plug;
|
|
size_t shorted = 0;
|
|
ssize_t ret;
|
|
|
|
if (bdev_read_only(bdev))
|
|
return -EPERM;
|
|
|
|
if (IS_SWAPFILE(bd_inode) && !is_hibernate_resume_dev(bd_inode->i_rdev))
|
|
return -ETXTBSY;
|
|
|
|
if (!iov_iter_count(from))
|
|
return 0;
|
|
|
|
if (iocb->ki_pos >= size)
|
|
return -ENOSPC;
|
|
|
|
if ((iocb->ki_flags & (IOCB_NOWAIT | IOCB_DIRECT)) == IOCB_NOWAIT)
|
|
return -EOPNOTSUPP;
|
|
|
|
size -= iocb->ki_pos;
|
|
if (iov_iter_count(from) > size) {
|
|
shorted = iov_iter_count(from) - size;
|
|
iov_iter_truncate(from, size);
|
|
}
|
|
|
|
blk_start_plug(&plug);
|
|
ret = __generic_file_write_iter(iocb, from);
|
|
if (ret > 0)
|
|
ret = generic_write_sync(iocb, ret);
|
|
iov_iter_reexpand(from, iov_iter_count(from) + shorted);
|
|
blk_finish_plug(&plug);
|
|
return ret;
|
|
}
|
|
|
|
static ssize_t blkdev_read_iter(struct kiocb *iocb, struct iov_iter *to)
|
|
{
|
|
struct block_device *bdev = iocb->ki_filp->private_data;
|
|
loff_t size = bdev_nr_bytes(bdev);
|
|
loff_t pos = iocb->ki_pos;
|
|
size_t shorted = 0;
|
|
ssize_t ret = 0;
|
|
size_t count;
|
|
|
|
if (unlikely(pos + iov_iter_count(to) > size)) {
|
|
if (pos >= size)
|
|
return 0;
|
|
size -= pos;
|
|
shorted = iov_iter_count(to) - size;
|
|
iov_iter_truncate(to, size);
|
|
}
|
|
|
|
count = iov_iter_count(to);
|
|
if (!count)
|
|
goto reexpand; /* skip atime */
|
|
|
|
if (iocb->ki_flags & IOCB_DIRECT) {
|
|
struct address_space *mapping = iocb->ki_filp->f_mapping;
|
|
|
|
if (iocb->ki_flags & IOCB_NOWAIT) {
|
|
if (filemap_range_needs_writeback(mapping, pos,
|
|
pos + count - 1)) {
|
|
ret = -EAGAIN;
|
|
goto reexpand;
|
|
}
|
|
} else {
|
|
ret = filemap_write_and_wait_range(mapping, pos,
|
|
pos + count - 1);
|
|
if (ret < 0)
|
|
goto reexpand;
|
|
}
|
|
|
|
file_accessed(iocb->ki_filp);
|
|
|
|
ret = blkdev_direct_IO(iocb, to);
|
|
if (ret >= 0) {
|
|
iocb->ki_pos += ret;
|
|
count -= ret;
|
|
}
|
|
iov_iter_revert(to, count - iov_iter_count(to));
|
|
if (ret < 0 || !count)
|
|
goto reexpand;
|
|
}
|
|
|
|
ret = filemap_read(iocb, to, ret);
|
|
|
|
reexpand:
|
|
if (unlikely(shorted))
|
|
iov_iter_reexpand(to, iov_iter_count(to) + shorted);
|
|
return ret;
|
|
}
|
|
|
|
#define BLKDEV_FALLOC_FL_SUPPORTED \
|
|
(FALLOC_FL_KEEP_SIZE | FALLOC_FL_PUNCH_HOLE | \
|
|
FALLOC_FL_ZERO_RANGE | FALLOC_FL_NO_HIDE_STALE)
|
|
|
|
static long blkdev_fallocate(struct file *file, int mode, loff_t start,
|
|
loff_t len)
|
|
{
|
|
struct inode *inode = bdev_file_inode(file);
|
|
struct block_device *bdev = I_BDEV(inode);
|
|
loff_t end = start + len - 1;
|
|
loff_t isize;
|
|
int error;
|
|
|
|
/* Fail if we don't recognize the flags. */
|
|
if (mode & ~BLKDEV_FALLOC_FL_SUPPORTED)
|
|
return -EOPNOTSUPP;
|
|
|
|
/* Don't go off the end of the device. */
|
|
isize = bdev_nr_bytes(bdev);
|
|
if (start >= isize)
|
|
return -EINVAL;
|
|
if (end >= isize) {
|
|
if (mode & FALLOC_FL_KEEP_SIZE) {
|
|
len = isize - start;
|
|
end = start + len - 1;
|
|
} else
|
|
return -EINVAL;
|
|
}
|
|
|
|
/*
|
|
* Don't allow IO that isn't aligned to logical block size.
|
|
*/
|
|
if ((start | len) & (bdev_logical_block_size(bdev) - 1))
|
|
return -EINVAL;
|
|
|
|
filemap_invalidate_lock(inode->i_mapping);
|
|
|
|
/* Invalidate the page cache, including dirty pages. */
|
|
error = truncate_bdev_range(bdev, file->f_mode, start, end);
|
|
if (error)
|
|
goto fail;
|
|
|
|
switch (mode) {
|
|
case FALLOC_FL_ZERO_RANGE:
|
|
case FALLOC_FL_ZERO_RANGE | FALLOC_FL_KEEP_SIZE:
|
|
error = blkdev_issue_zeroout(bdev, start >> SECTOR_SHIFT,
|
|
len >> SECTOR_SHIFT, GFP_KERNEL,
|
|
BLKDEV_ZERO_NOUNMAP);
|
|
break;
|
|
case FALLOC_FL_PUNCH_HOLE | FALLOC_FL_KEEP_SIZE:
|
|
error = blkdev_issue_zeroout(bdev, start >> SECTOR_SHIFT,
|
|
len >> SECTOR_SHIFT, GFP_KERNEL,
|
|
BLKDEV_ZERO_NOFALLBACK);
|
|
break;
|
|
case FALLOC_FL_PUNCH_HOLE | FALLOC_FL_KEEP_SIZE | FALLOC_FL_NO_HIDE_STALE:
|
|
error = blkdev_issue_discard(bdev, start >> SECTOR_SHIFT,
|
|
len >> SECTOR_SHIFT, GFP_KERNEL);
|
|
break;
|
|
default:
|
|
error = -EOPNOTSUPP;
|
|
}
|
|
|
|
fail:
|
|
filemap_invalidate_unlock(inode->i_mapping);
|
|
return error;
|
|
}
|
|
|
|
const struct file_operations def_blk_fops = {
|
|
.open = blkdev_open,
|
|
.release = blkdev_close,
|
|
.llseek = blkdev_llseek,
|
|
.read_iter = blkdev_read_iter,
|
|
.write_iter = blkdev_write_iter,
|
|
.iopoll = iocb_bio_iopoll,
|
|
.mmap = generic_file_mmap,
|
|
.fsync = blkdev_fsync,
|
|
.unlocked_ioctl = blkdev_ioctl,
|
|
#ifdef CONFIG_COMPAT
|
|
.compat_ioctl = compat_blkdev_ioctl,
|
|
#endif
|
|
.splice_read = generic_file_splice_read,
|
|
.splice_write = iter_file_splice_write,
|
|
.fallocate = blkdev_fallocate,
|
|
};
|
|
|
|
static __init int blkdev_init(void)
|
|
{
|
|
return bioset_init(&blkdev_dio_pool, 4,
|
|
offsetof(struct blkdev_dio, bio),
|
|
BIOSET_NEED_BVECS|BIOSET_PERCPU_CACHE);
|
|
}
|
|
module_init(blkdev_init);
|