// SPDX-License-Identifier: GPL-2.0-only /* * Copyright (C) 1991, 1992 Linus Torvalds * Copyright (C) 2001 Andrea Arcangeli <andrea@suse.de> SuSE * Copyright (C) 2016 - 2020 Christoph Hellwig */ #include <linux/init.h> #include <linux/mm.h> #include <linux/blkdev.h> #include <linux/buffer_head.h> #include <linux/mpage.h> #include <linux/uio.h> #include <linux/namei.h> #include <linux/task_io_accounting_ops.h> #include <linux/falloc.h> #include <linux/suspend.h> #include <linux/fs.h> #include <linux/module.h> #include "blk.h" static inline struct inode *bdev_file_inode(struct file *file) { return file->f_mapping->host; } static int blkdev_get_block(struct inode *inode, sector_t iblock, struct buffer_head *bh, int create) { bh->b_bdev = I_BDEV(inode); bh->b_blocknr = iblock; set_buffer_mapped(bh); return 0; } static unsigned int dio_bio_write_op(struct kiocb *iocb) { unsigned int op = REQ_OP_WRITE | REQ_SYNC | REQ_IDLE; /* avoid the need for a I/O completion work item */ if (iocb->ki_flags & IOCB_DSYNC) op |= REQ_FUA; return op; } #define DIO_INLINE_BIO_VECS 4 static void blkdev_bio_end_io_simple(struct bio *bio) { struct task_struct *waiter = bio->bi_private; WRITE_ONCE(bio->bi_private, NULL); blk_wake_io_task(waiter); } static ssize_t __blkdev_direct_IO_simple(struct kiocb *iocb, struct iov_iter *iter, unsigned int nr_pages) { struct block_device *bdev = iocb->ki_filp->private_data; struct bio_vec inline_vecs[DIO_INLINE_BIO_VECS], *vecs; loff_t pos = iocb->ki_pos; bool should_dirty = false; struct bio bio; ssize_t ret; if ((pos | iov_iter_alignment(iter)) & (bdev_logical_block_size(bdev) - 1)) return -EINVAL; if (nr_pages <= DIO_INLINE_BIO_VECS) vecs = inline_vecs; else { vecs = kmalloc_array(nr_pages, sizeof(struct bio_vec), GFP_KERNEL); if (!vecs) return -ENOMEM; } bio_init(&bio, vecs, nr_pages); bio_set_dev(&bio, bdev); bio.bi_iter.bi_sector = pos >> SECTOR_SHIFT; bio.bi_write_hint = iocb->ki_hint; bio.bi_private = current; bio.bi_end_io = blkdev_bio_end_io_simple; bio.bi_ioprio = iocb->ki_ioprio; ret = bio_iov_iter_get_pages(&bio, iter); if (unlikely(ret)) goto out; ret = bio.bi_iter.bi_size; if (iov_iter_rw(iter) == READ) { bio.bi_opf = REQ_OP_READ; if (iter_is_iovec(iter)) should_dirty = true; } else { bio.bi_opf = dio_bio_write_op(iocb); task_io_account_write(ret); } if (iocb->ki_flags & IOCB_NOWAIT) bio.bi_opf |= REQ_NOWAIT; if (iocb->ki_flags & IOCB_HIPRI) bio_set_polled(&bio, iocb); submit_bio(&bio); for (;;) { set_current_state(TASK_UNINTERRUPTIBLE); if (!READ_ONCE(bio.bi_private)) break; if (!(iocb->ki_flags & IOCB_HIPRI) || !bio_poll(&bio, NULL, 0)) blk_io_schedule(); } __set_current_state(TASK_RUNNING); bio_release_pages(&bio, should_dirty); if (unlikely(bio.bi_status)) ret = blk_status_to_errno(bio.bi_status); out: if (vecs != inline_vecs) kfree(vecs); bio_uninit(&bio); return ret; } enum { DIO_SHOULD_DIRTY = 1, DIO_IS_SYNC = 2, }; struct blkdev_dio { union { struct kiocb *iocb; struct task_struct *waiter; }; size_t size; atomic_t ref; unsigned int flags; struct bio bio ____cacheline_aligned_in_smp; }; static struct bio_set blkdev_dio_pool; static void blkdev_bio_end_io(struct bio *bio) { struct blkdev_dio *dio = bio->bi_private; bool should_dirty = dio->flags & DIO_SHOULD_DIRTY; if (bio->bi_status && !dio->bio.bi_status) dio->bio.bi_status = bio->bi_status; if (atomic_dec_and_test(&dio->ref)) { if (!(dio->flags & DIO_IS_SYNC)) { struct kiocb *iocb = dio->iocb; ssize_t ret; WRITE_ONCE(iocb->private, NULL); if (likely(!dio->bio.bi_status)) { ret = dio->size; iocb->ki_pos += ret; } else { ret = blk_status_to_errno(dio->bio.bi_status); } dio->iocb->ki_complete(iocb, ret); bio_put(&dio->bio); } else { struct task_struct *waiter = dio->waiter; WRITE_ONCE(dio->waiter, NULL); blk_wake_io_task(waiter); } } if (should_dirty) { bio_check_pages_dirty(bio); } else { bio_release_pages(bio, false); bio_put(bio); } } static ssize_t __blkdev_direct_IO(struct kiocb *iocb, struct iov_iter *iter, unsigned int nr_pages) { struct block_device *bdev = iocb->ki_filp->private_data; struct blk_plug plug; struct blkdev_dio *dio; struct bio *bio; bool is_read = (iov_iter_rw(iter) == READ), is_sync; loff_t pos = iocb->ki_pos; int ret = 0; if ((pos | iov_iter_alignment(iter)) & (bdev_logical_block_size(bdev) - 1)) return -EINVAL; bio = bio_alloc_kiocb(iocb, nr_pages, &blkdev_dio_pool); dio = container_of(bio, struct blkdev_dio, bio); atomic_set(&dio->ref, 1); /* * Grab an extra reference to ensure the dio structure which is embedded * into the first bio stays around. */ bio_get(bio); is_sync = is_sync_kiocb(iocb); if (is_sync) { dio->flags = DIO_IS_SYNC; dio->waiter = current; } else { dio->flags = 0; dio->iocb = iocb; } dio->size = 0; if (is_read && iter_is_iovec(iter)) dio->flags |= DIO_SHOULD_DIRTY; blk_start_plug(&plug); for (;;) { bio_set_dev(bio, bdev); bio->bi_iter.bi_sector = pos >> SECTOR_SHIFT; bio->bi_write_hint = iocb->ki_hint; bio->bi_private = dio; bio->bi_end_io = blkdev_bio_end_io; bio->bi_ioprio = iocb->ki_ioprio; ret = bio_iov_iter_get_pages(bio, iter); if (unlikely(ret)) { bio->bi_status = BLK_STS_IOERR; bio_endio(bio); break; } if (is_read) { bio->bi_opf = REQ_OP_READ; if (dio->flags & DIO_SHOULD_DIRTY) bio_set_pages_dirty(bio); } else { bio->bi_opf = dio_bio_write_op(iocb); task_io_account_write(bio->bi_iter.bi_size); } if (iocb->ki_flags & IOCB_NOWAIT) bio->bi_opf |= REQ_NOWAIT; dio->size += bio->bi_iter.bi_size; pos += bio->bi_iter.bi_size; nr_pages = bio_iov_vecs_to_alloc(iter, BIO_MAX_VECS); if (!nr_pages) { submit_bio(bio); break; } atomic_inc(&dio->ref); submit_bio(bio); bio = bio_alloc(GFP_KERNEL, nr_pages); } blk_finish_plug(&plug); if (!is_sync) return -EIOCBQUEUED; for (;;) { set_current_state(TASK_UNINTERRUPTIBLE); if (!READ_ONCE(dio->waiter)) break; blk_io_schedule(); } __set_current_state(TASK_RUNNING); if (!ret) ret = blk_status_to_errno(dio->bio.bi_status); if (likely(!ret)) ret = dio->size; bio_put(&dio->bio); return ret; } static void blkdev_bio_end_io_async(struct bio *bio) { struct blkdev_dio *dio = container_of(bio, struct blkdev_dio, bio); struct kiocb *iocb = dio->iocb; ssize_t ret; if (likely(!bio->bi_status)) { ret = dio->size; iocb->ki_pos += ret; } else { ret = blk_status_to_errno(bio->bi_status); } iocb->ki_complete(iocb, ret); if (dio->flags & DIO_SHOULD_DIRTY) { bio_check_pages_dirty(bio); } else { bio_release_pages(bio, false); bio_put(bio); } } static ssize_t __blkdev_direct_IO_async(struct kiocb *iocb, struct iov_iter *iter, unsigned int nr_pages) { struct block_device *bdev = iocb->ki_filp->private_data; struct blkdev_dio *dio; struct bio *bio; loff_t pos = iocb->ki_pos; int ret = 0; if ((pos | iov_iter_alignment(iter)) & (bdev_logical_block_size(bdev) - 1)) return -EINVAL; bio = bio_alloc_kiocb(iocb, nr_pages, &blkdev_dio_pool); dio = container_of(bio, struct blkdev_dio, bio); dio->flags = 0; dio->iocb = iocb; bio_set_dev(bio, bdev); bio->bi_iter.bi_sector = pos >> SECTOR_SHIFT; bio->bi_write_hint = iocb->ki_hint; bio->bi_end_io = blkdev_bio_end_io_async; bio->bi_ioprio = iocb->ki_ioprio; if (iov_iter_is_bvec(iter)) { /* * Users don't rely on the iterator being in any particular * state for async I/O returning -EIOCBQUEUED, hence we can * avoid expensive iov_iter_advance(). Bypass * bio_iov_iter_get_pages() and set the bvec directly. */ bio_iov_bvec_set(bio, iter); } else { ret = bio_iov_iter_get_pages(bio, iter); if (unlikely(ret)) { bio_put(bio); return ret; } } dio->size = bio->bi_iter.bi_size; if (iov_iter_rw(iter) == READ) { bio->bi_opf = REQ_OP_READ; if (iter_is_iovec(iter)) { dio->flags |= DIO_SHOULD_DIRTY; bio_set_pages_dirty(bio); } } else { bio->bi_opf = dio_bio_write_op(iocb); task_io_account_write(bio->bi_iter.bi_size); } if (iocb->ki_flags & IOCB_HIPRI) { bio->bi_opf |= REQ_POLLED | REQ_NOWAIT; submit_bio(bio); WRITE_ONCE(iocb->private, bio); } else { if (iocb->ki_flags & IOCB_NOWAIT) bio->bi_opf |= REQ_NOWAIT; submit_bio(bio); } return -EIOCBQUEUED; } static ssize_t blkdev_direct_IO(struct kiocb *iocb, struct iov_iter *iter) { unsigned int nr_pages; if (!iov_iter_count(iter)) return 0; nr_pages = bio_iov_vecs_to_alloc(iter, BIO_MAX_VECS + 1); if (likely(nr_pages <= BIO_MAX_VECS)) { if (is_sync_kiocb(iocb)) return __blkdev_direct_IO_simple(iocb, iter, nr_pages); return __blkdev_direct_IO_async(iocb, iter, nr_pages); } return __blkdev_direct_IO(iocb, iter, bio_max_segs(nr_pages)); } static int blkdev_writepage(struct page *page, struct writeback_control *wbc) { return block_write_full_page(page, blkdev_get_block, wbc); } static int blkdev_readpage(struct file * file, struct page * page) { return block_read_full_page(page, blkdev_get_block); } static void blkdev_readahead(struct readahead_control *rac) { mpage_readahead(rac, blkdev_get_block); } static int blkdev_write_begin(struct file *file, struct address_space *mapping, loff_t pos, unsigned len, unsigned flags, struct page **pagep, void **fsdata) { return block_write_begin(mapping, pos, len, flags, pagep, blkdev_get_block); } static int blkdev_write_end(struct file *file, struct address_space *mapping, loff_t pos, unsigned len, unsigned copied, struct page *page, void *fsdata) { int ret; ret = block_write_end(file, mapping, pos, len, copied, page, fsdata); unlock_page(page); put_page(page); return ret; } static int blkdev_writepages(struct address_space *mapping, struct writeback_control *wbc) { return generic_writepages(mapping, wbc); } const struct address_space_operations def_blk_aops = { .set_page_dirty = __set_page_dirty_buffers, .readpage = blkdev_readpage, .readahead = blkdev_readahead, .writepage = blkdev_writepage, .write_begin = blkdev_write_begin, .write_end = blkdev_write_end, .writepages = blkdev_writepages, .direct_IO = blkdev_direct_IO, .migratepage = buffer_migrate_page_norefs, .is_dirty_writeback = buffer_check_dirty_writeback, }; /* * for a block special file file_inode(file)->i_size is zero * so we compute the size by hand (just as in block_read/write above) */ static loff_t blkdev_llseek(struct file *file, loff_t offset, int whence) { struct inode *bd_inode = bdev_file_inode(file); loff_t retval; inode_lock(bd_inode); retval = fixed_size_llseek(file, offset, whence, i_size_read(bd_inode)); inode_unlock(bd_inode); return retval; } static int blkdev_fsync(struct file *filp, loff_t start, loff_t end, int datasync) { struct block_device *bdev = filp->private_data; int error; error = file_write_and_wait_range(filp, start, end); if (error) return error; /* * There is no need to serialise calls to blkdev_issue_flush with * i_mutex and doing so causes performance issues with concurrent * O_SYNC writers to a block device. */ error = blkdev_issue_flush(bdev); if (error == -EOPNOTSUPP) error = 0; return error; } static int blkdev_open(struct inode *inode, struct file *filp) { struct block_device *bdev; /* * Preserve backwards compatibility and allow large file access * even if userspace doesn't ask for it explicitly. Some mkfs * binary needs it. We might want to drop this workaround * during an unstable branch. */ filp->f_flags |= O_LARGEFILE; filp->f_mode |= FMODE_NOWAIT | FMODE_BUF_RASYNC; if (filp->f_flags & O_NDELAY) filp->f_mode |= FMODE_NDELAY; if (filp->f_flags & O_EXCL) filp->f_mode |= FMODE_EXCL; if ((filp->f_flags & O_ACCMODE) == 3) 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); size_t count = iov_iter_count(to); loff_t pos = iocb->ki_pos; size_t shorted = 0; ssize_t ret = 0; if (unlikely(pos + count > size)) { if (pos >= size) return 0; size -= pos; if (count > size) { shorted = count - size; iov_iter_truncate(to, size); } } 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, iocb->ki_pos, iocb->ki_pos + count - 1)) return -EAGAIN; } else { ret = filemap_write_and_wait_range(mapping, iocb->ki_pos, iocb->ki_pos + count - 1); if (ret < 0) return ret; } file_accessed(iocb->ki_filp); ret = blkdev_direct_IO(iocb, to); if (ret >= 0) { iocb->ki_pos += ret; count -= ret; } if (ret < 0 || !count) return ret; } ret = filemap_read(iocb, to, ret); 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, 0); 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);