/* * Copyright (C) 2010 Red Hat, Inc. * Copyright (c) 2016 Christoph Hellwig. * * This program is free software; you can redistribute it and/or modify it * under the terms and conditions of the GNU General Public License, * version 2, as published by the Free Software Foundation. * * This program is distributed in the hope it will be useful, but WITHOUT * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for * more details. */ #include <linux/module.h> #include <linux/compiler.h> #include <linux/fs.h> #include <linux/iomap.h> #include <linux/uaccess.h> #include <linux/gfp.h> #include <linux/mm.h> #include <linux/swap.h> #include <linux/pagemap.h> #include <linux/file.h> #include <linux/uio.h> #include <linux/backing-dev.h> #include <linux/buffer_head.h> #include <linux/task_io_accounting_ops.h> #include <linux/dax.h> #include <linux/sched/signal.h> #include "internal.h" /* * Execute a iomap write on a segment of the mapping that spans a * contiguous range of pages that have identical block mapping state. * * This avoids the need to map pages individually, do individual allocations * for each page and most importantly avoid the need for filesystem specific * locking per page. Instead, all the operations are amortised over the entire * range of pages. It is assumed that the filesystems will lock whatever * resources they require in the iomap_begin call, and release them in the * iomap_end call. */ loff_t iomap_apply(struct inode *inode, loff_t pos, loff_t length, unsigned flags, const struct iomap_ops *ops, void *data, iomap_actor_t actor) { struct iomap iomap = { 0 }; loff_t written = 0, ret; /* * Need to map a range from start position for length bytes. This can * span multiple pages - it is only guaranteed to return a range of a * single type of pages (e.g. all into a hole, all mapped or all * unwritten). Failure at this point has nothing to undo. * * If allocation is required for this range, reserve the space now so * that the allocation is guaranteed to succeed later on. Once we copy * the data into the page cache pages, then we cannot fail otherwise we * expose transient stale data. If the reserve fails, we can safely * back out at this point as there is nothing to undo. */ ret = ops->iomap_begin(inode, pos, length, flags, &iomap); if (ret) return ret; if (WARN_ON(iomap.offset > pos)) return -EIO; if (WARN_ON(iomap.length == 0)) return -EIO; /* * Cut down the length to the one actually provided by the filesystem, * as it might not be able to give us the whole size that we requested. */ if (iomap.offset + iomap.length < pos + length) length = iomap.offset + iomap.length - pos; /* * Now that we have guaranteed that the space allocation will succeed. * we can do the copy-in page by page without having to worry about * failures exposing transient data. */ written = actor(inode, pos, length, data, &iomap); /* * Now the data has been copied, commit the range we've copied. This * should not fail unless the filesystem has had a fatal error. */ if (ops->iomap_end) { ret = ops->iomap_end(inode, pos, length, written > 0 ? written : 0, flags, &iomap); } return written ? written : ret; } static void iomap_write_failed(struct inode *inode, loff_t pos, unsigned len) { loff_t i_size = i_size_read(inode); /* * Only truncate newly allocated pages beyoned EOF, even if the * write started inside the existing inode size. */ if (pos + len > i_size) truncate_pagecache_range(inode, max(pos, i_size), pos + len); } static int iomap_write_begin(struct inode *inode, loff_t pos, unsigned len, unsigned flags, struct page **pagep, struct iomap *iomap) { pgoff_t index = pos >> PAGE_SHIFT; struct page *page; int status = 0; BUG_ON(pos + len > iomap->offset + iomap->length); if (fatal_signal_pending(current)) return -EINTR; page = grab_cache_page_write_begin(inode->i_mapping, index, flags); if (!page) return -ENOMEM; status = __block_write_begin_int(page, pos, len, NULL, iomap); if (unlikely(status)) { unlock_page(page); put_page(page); page = NULL; iomap_write_failed(inode, pos, len); } *pagep = page; return status; } static int iomap_write_end(struct inode *inode, loff_t pos, unsigned len, unsigned copied, struct page *page) { int ret; ret = generic_write_end(NULL, inode->i_mapping, pos, len, copied, page, NULL); if (ret < len) iomap_write_failed(inode, pos, len); return ret; } static loff_t iomap_write_actor(struct inode *inode, loff_t pos, loff_t length, void *data, struct iomap *iomap) { struct iov_iter *i = data; long status = 0; ssize_t written = 0; unsigned int flags = AOP_FLAG_NOFS; do { struct page *page; unsigned long offset; /* Offset into pagecache page */ unsigned long bytes; /* Bytes to write to page */ size_t copied; /* Bytes copied from user */ offset = (pos & (PAGE_SIZE - 1)); bytes = min_t(unsigned long, PAGE_SIZE - offset, iov_iter_count(i)); again: if (bytes > length) bytes = length; /* * Bring in the user page that we will copy from _first_. * Otherwise there's a nasty deadlock on copying from the * same page as we're writing to, without it being marked * up-to-date. * * Not only is this an optimisation, but it is also required * to check that the address is actually valid, when atomic * usercopies are used, below. */ if (unlikely(iov_iter_fault_in_readable(i, bytes))) { status = -EFAULT; break; } status = iomap_write_begin(inode, pos, bytes, flags, &page, iomap); if (unlikely(status)) break; if (mapping_writably_mapped(inode->i_mapping)) flush_dcache_page(page); copied = iov_iter_copy_from_user_atomic(page, i, offset, bytes); flush_dcache_page(page); status = iomap_write_end(inode, pos, bytes, copied, page); if (unlikely(status < 0)) break; copied = status; cond_resched(); iov_iter_advance(i, copied); if (unlikely(copied == 0)) { /* * If we were unable to copy any data at all, we must * fall back to a single segment length write. * * If we didn't fallback here, we could livelock * because not all segments in the iov can be copied at * once without a pagefault. */ bytes = min_t(unsigned long, PAGE_SIZE - offset, iov_iter_single_seg_count(i)); goto again; } pos += copied; written += copied; length -= copied; balance_dirty_pages_ratelimited(inode->i_mapping); } while (iov_iter_count(i) && length); return written ? written : status; } ssize_t iomap_file_buffered_write(struct kiocb *iocb, struct iov_iter *iter, const struct iomap_ops *ops) { struct inode *inode = iocb->ki_filp->f_mapping->host; loff_t pos = iocb->ki_pos, ret = 0, written = 0; while (iov_iter_count(iter)) { ret = iomap_apply(inode, pos, iov_iter_count(iter), IOMAP_WRITE, ops, iter, iomap_write_actor); if (ret <= 0) break; pos += ret; written += ret; } return written ? written : ret; } EXPORT_SYMBOL_GPL(iomap_file_buffered_write); static struct page * __iomap_read_page(struct inode *inode, loff_t offset) { struct address_space *mapping = inode->i_mapping; struct page *page; page = read_mapping_page(mapping, offset >> PAGE_SHIFT, NULL); if (IS_ERR(page)) return page; if (!PageUptodate(page)) { put_page(page); return ERR_PTR(-EIO); } return page; } static loff_t iomap_dirty_actor(struct inode *inode, loff_t pos, loff_t length, void *data, struct iomap *iomap) { long status = 0; ssize_t written = 0; do { struct page *page, *rpage; unsigned long offset; /* Offset into pagecache page */ unsigned long bytes; /* Bytes to write to page */ offset = (pos & (PAGE_SIZE - 1)); bytes = min_t(loff_t, PAGE_SIZE - offset, length); rpage = __iomap_read_page(inode, pos); if (IS_ERR(rpage)) return PTR_ERR(rpage); status = iomap_write_begin(inode, pos, bytes, AOP_FLAG_NOFS, &page, iomap); put_page(rpage); if (unlikely(status)) return status; WARN_ON_ONCE(!PageUptodate(page)); status = iomap_write_end(inode, pos, bytes, bytes, page); if (unlikely(status <= 0)) { if (WARN_ON_ONCE(status == 0)) return -EIO; return status; } cond_resched(); pos += status; written += status; length -= status; balance_dirty_pages_ratelimited(inode->i_mapping); } while (length); return written; } int iomap_file_dirty(struct inode *inode, loff_t pos, loff_t len, const struct iomap_ops *ops) { loff_t ret; while (len) { ret = iomap_apply(inode, pos, len, IOMAP_WRITE, ops, NULL, iomap_dirty_actor); if (ret <= 0) return ret; pos += ret; len -= ret; } return 0; } EXPORT_SYMBOL_GPL(iomap_file_dirty); static int iomap_zero(struct inode *inode, loff_t pos, unsigned offset, unsigned bytes, struct iomap *iomap) { struct page *page; int status; status = iomap_write_begin(inode, pos, bytes, AOP_FLAG_NOFS, &page, iomap); if (status) return status; zero_user(page, offset, bytes); mark_page_accessed(page); return iomap_write_end(inode, pos, bytes, bytes, page); } static int iomap_dax_zero(loff_t pos, unsigned offset, unsigned bytes, struct iomap *iomap) { sector_t sector = (iomap->addr + (pos & PAGE_MASK) - iomap->offset) >> 9; return __dax_zero_page_range(iomap->bdev, iomap->dax_dev, sector, offset, bytes); } static loff_t iomap_zero_range_actor(struct inode *inode, loff_t pos, loff_t count, void *data, struct iomap *iomap) { bool *did_zero = data; loff_t written = 0; int status; /* already zeroed? we're done. */ if (iomap->type == IOMAP_HOLE || iomap->type == IOMAP_UNWRITTEN) return count; do { unsigned offset, bytes; offset = pos & (PAGE_SIZE - 1); /* Within page */ bytes = min_t(loff_t, PAGE_SIZE - offset, count); if (IS_DAX(inode)) status = iomap_dax_zero(pos, offset, bytes, iomap); else status = iomap_zero(inode, pos, offset, bytes, iomap); if (status < 0) return status; pos += bytes; count -= bytes; written += bytes; if (did_zero) *did_zero = true; } while (count > 0); return written; } int iomap_zero_range(struct inode *inode, loff_t pos, loff_t len, bool *did_zero, const struct iomap_ops *ops) { loff_t ret; while (len > 0) { ret = iomap_apply(inode, pos, len, IOMAP_ZERO, ops, did_zero, iomap_zero_range_actor); if (ret <= 0) return ret; pos += ret; len -= ret; } return 0; } EXPORT_SYMBOL_GPL(iomap_zero_range); int iomap_truncate_page(struct inode *inode, loff_t pos, bool *did_zero, const struct iomap_ops *ops) { unsigned int blocksize = i_blocksize(inode); unsigned int off = pos & (blocksize - 1); /* Block boundary? Nothing to do */ if (!off) return 0; return iomap_zero_range(inode, pos, blocksize - off, did_zero, ops); } EXPORT_SYMBOL_GPL(iomap_truncate_page); static loff_t iomap_page_mkwrite_actor(struct inode *inode, loff_t pos, loff_t length, void *data, struct iomap *iomap) { struct page *page = data; int ret; ret = __block_write_begin_int(page, pos, length, NULL, iomap); if (ret) return ret; block_commit_write(page, 0, length); return length; } int iomap_page_mkwrite(struct vm_fault *vmf, const struct iomap_ops *ops) { struct page *page = vmf->page; struct inode *inode = file_inode(vmf->vma->vm_file); unsigned long length; loff_t offset, size; ssize_t ret; lock_page(page); size = i_size_read(inode); if ((page->mapping != inode->i_mapping) || (page_offset(page) > size)) { /* We overload EFAULT to mean page got truncated */ ret = -EFAULT; goto out_unlock; } /* page is wholly or partially inside EOF */ if (((page->index + 1) << PAGE_SHIFT) > size) length = size & ~PAGE_MASK; else length = PAGE_SIZE; offset = page_offset(page); while (length > 0) { ret = iomap_apply(inode, offset, length, IOMAP_WRITE | IOMAP_FAULT, ops, page, iomap_page_mkwrite_actor); if (unlikely(ret <= 0)) goto out_unlock; offset += ret; length -= ret; } set_page_dirty(page); wait_for_stable_page(page); return VM_FAULT_LOCKED; out_unlock: unlock_page(page); return block_page_mkwrite_return(ret); } EXPORT_SYMBOL_GPL(iomap_page_mkwrite); struct fiemap_ctx { struct fiemap_extent_info *fi; struct iomap prev; }; static int iomap_to_fiemap(struct fiemap_extent_info *fi, struct iomap *iomap, u32 flags) { switch (iomap->type) { case IOMAP_HOLE: /* skip holes */ return 0; case IOMAP_DELALLOC: flags |= FIEMAP_EXTENT_DELALLOC | FIEMAP_EXTENT_UNKNOWN; break; case IOMAP_UNWRITTEN: flags |= FIEMAP_EXTENT_UNWRITTEN; break; case IOMAP_MAPPED: break; } if (iomap->flags & IOMAP_F_MERGED) flags |= FIEMAP_EXTENT_MERGED; if (iomap->flags & IOMAP_F_SHARED) flags |= FIEMAP_EXTENT_SHARED; if (iomap->flags & IOMAP_F_DATA_INLINE) flags |= FIEMAP_EXTENT_DATA_INLINE; return fiemap_fill_next_extent(fi, iomap->offset, iomap->addr != IOMAP_NULL_ADDR ? iomap->addr : 0, iomap->length, flags); } static loff_t iomap_fiemap_actor(struct inode *inode, loff_t pos, loff_t length, void *data, struct iomap *iomap) { struct fiemap_ctx *ctx = data; loff_t ret = length; if (iomap->type == IOMAP_HOLE) return length; ret = iomap_to_fiemap(ctx->fi, &ctx->prev, 0); ctx->prev = *iomap; switch (ret) { case 0: /* success */ return length; case 1: /* extent array full */ return 0; default: return ret; } } int iomap_fiemap(struct inode *inode, struct fiemap_extent_info *fi, loff_t start, loff_t len, const struct iomap_ops *ops) { struct fiemap_ctx ctx; loff_t ret; memset(&ctx, 0, sizeof(ctx)); ctx.fi = fi; ctx.prev.type = IOMAP_HOLE; ret = fiemap_check_flags(fi, FIEMAP_FLAG_SYNC); if (ret) return ret; if (fi->fi_flags & FIEMAP_FLAG_SYNC) { ret = filemap_write_and_wait(inode->i_mapping); if (ret) return ret; } while (len > 0) { ret = iomap_apply(inode, start, len, IOMAP_REPORT, ops, &ctx, iomap_fiemap_actor); /* inode with no (attribute) mapping will give ENOENT */ if (ret == -ENOENT) break; if (ret < 0) return ret; if (ret == 0) break; start += ret; len -= ret; } if (ctx.prev.type != IOMAP_HOLE) { ret = iomap_to_fiemap(fi, &ctx.prev, FIEMAP_EXTENT_LAST); if (ret < 0) return ret; } return 0; } EXPORT_SYMBOL_GPL(iomap_fiemap); static loff_t iomap_seek_hole_actor(struct inode *inode, loff_t offset, loff_t length, void *data, struct iomap *iomap) { switch (iomap->type) { case IOMAP_UNWRITTEN: offset = page_cache_seek_hole_data(inode, offset, length, SEEK_HOLE); if (offset < 0) return length; /* fall through */ case IOMAP_HOLE: *(loff_t *)data = offset; return 0; default: return length; } } loff_t iomap_seek_hole(struct inode *inode, loff_t offset, const struct iomap_ops *ops) { loff_t size = i_size_read(inode); loff_t length = size - offset; loff_t ret; /* Nothing to be found before or beyond the end of the file. */ if (offset < 0 || offset >= size) return -ENXIO; while (length > 0) { ret = iomap_apply(inode, offset, length, IOMAP_REPORT, ops, &offset, iomap_seek_hole_actor); if (ret < 0) return ret; if (ret == 0) break; offset += ret; length -= ret; } return offset; } EXPORT_SYMBOL_GPL(iomap_seek_hole); static loff_t iomap_seek_data_actor(struct inode *inode, loff_t offset, loff_t length, void *data, struct iomap *iomap) { switch (iomap->type) { case IOMAP_HOLE: return length; case IOMAP_UNWRITTEN: offset = page_cache_seek_hole_data(inode, offset, length, SEEK_DATA); if (offset < 0) return length; /*FALLTHRU*/ default: *(loff_t *)data = offset; return 0; } } loff_t iomap_seek_data(struct inode *inode, loff_t offset, const struct iomap_ops *ops) { loff_t size = i_size_read(inode); loff_t length = size - offset; loff_t ret; /* Nothing to be found before or beyond the end of the file. */ if (offset < 0 || offset >= size) return -ENXIO; while (length > 0) { ret = iomap_apply(inode, offset, length, IOMAP_REPORT, ops, &offset, iomap_seek_data_actor); if (ret < 0) return ret; if (ret == 0) break; offset += ret; length -= ret; } if (length <= 0) return -ENXIO; return offset; } EXPORT_SYMBOL_GPL(iomap_seek_data); /* * Private flags for iomap_dio, must not overlap with the public ones in * iomap.h: */ #define IOMAP_DIO_WRITE (1 << 30) #define IOMAP_DIO_DIRTY (1 << 31) struct iomap_dio { struct kiocb *iocb; iomap_dio_end_io_t *end_io; loff_t i_size; loff_t size; atomic_t ref; unsigned flags; int error; union { /* used during submission and for synchronous completion: */ struct { struct iov_iter *iter; struct task_struct *waiter; struct request_queue *last_queue; blk_qc_t cookie; } submit; /* used for aio completion: */ struct { struct work_struct work; } aio; }; }; static ssize_t iomap_dio_complete(struct iomap_dio *dio) { struct kiocb *iocb = dio->iocb; struct inode *inode = file_inode(iocb->ki_filp); loff_t offset = iocb->ki_pos; ssize_t ret; if (dio->end_io) { ret = dio->end_io(iocb, dio->error ? dio->error : dio->size, dio->flags); } else { ret = dio->error; } if (likely(!ret)) { ret = dio->size; /* check for short read */ if (offset + ret > dio->i_size && !(dio->flags & IOMAP_DIO_WRITE)) ret = dio->i_size - offset; iocb->ki_pos += ret; } /* * Try again to invalidate clean pages which might have been cached by * non-direct readahead, or faulted in by get_user_pages() if the source * of the write was an mmap'ed region of the file we're writing. Either * one is a pretty crazy thing to do, so we don't support it 100%. If * this invalidation fails, tough, the write still worked... * * And this page cache invalidation has to be after dio->end_io(), as * some filesystems convert unwritten extents to real allocations in * end_io() when necessary, otherwise a racing buffer read would cache * zeros from unwritten extents. */ if (!dio->error && (dio->flags & IOMAP_DIO_WRITE) && inode->i_mapping->nrpages) { int err; err = invalidate_inode_pages2_range(inode->i_mapping, offset >> PAGE_SHIFT, (offset + dio->size - 1) >> PAGE_SHIFT); if (err) dio_warn_stale_pagecache(iocb->ki_filp); } inode_dio_end(file_inode(iocb->ki_filp)); kfree(dio); return ret; } static void iomap_dio_complete_work(struct work_struct *work) { struct iomap_dio *dio = container_of(work, struct iomap_dio, aio.work); struct kiocb *iocb = dio->iocb; bool is_write = (dio->flags & IOMAP_DIO_WRITE); ssize_t ret; ret = iomap_dio_complete(dio); if (is_write && ret > 0) ret = generic_write_sync(iocb, ret); iocb->ki_complete(iocb, ret, 0); } /* * Set an error in the dio if none is set yet. We have to use cmpxchg * as the submission context and the completion context(s) can race to * update the error. */ static inline void iomap_dio_set_error(struct iomap_dio *dio, int ret) { cmpxchg(&dio->error, 0, ret); } static void iomap_dio_bio_end_io(struct bio *bio) { struct iomap_dio *dio = bio->bi_private; bool should_dirty = (dio->flags & IOMAP_DIO_DIRTY); if (bio->bi_status) iomap_dio_set_error(dio, blk_status_to_errno(bio->bi_status)); if (atomic_dec_and_test(&dio->ref)) { if (is_sync_kiocb(dio->iocb)) { struct task_struct *waiter = dio->submit.waiter; WRITE_ONCE(dio->submit.waiter, NULL); wake_up_process(waiter); } else if (dio->flags & IOMAP_DIO_WRITE) { struct inode *inode = file_inode(dio->iocb->ki_filp); INIT_WORK(&dio->aio.work, iomap_dio_complete_work); queue_work(inode->i_sb->s_dio_done_wq, &dio->aio.work); } else { iomap_dio_complete_work(&dio->aio.work); } } if (should_dirty) { bio_check_pages_dirty(bio); } else { struct bio_vec *bvec; int i; bio_for_each_segment_all(bvec, bio, i) put_page(bvec->bv_page); bio_put(bio); } } static blk_qc_t iomap_dio_zero(struct iomap_dio *dio, struct iomap *iomap, loff_t pos, unsigned len) { struct page *page = ZERO_PAGE(0); struct bio *bio; bio = bio_alloc(GFP_KERNEL, 1); bio_set_dev(bio, iomap->bdev); bio->bi_iter.bi_sector = (iomap->addr + pos - iomap->offset) >> 9; bio->bi_private = dio; bio->bi_end_io = iomap_dio_bio_end_io; get_page(page); if (bio_add_page(bio, page, len, 0) != len) BUG(); bio_set_op_attrs(bio, REQ_OP_WRITE, REQ_SYNC | REQ_IDLE); atomic_inc(&dio->ref); return submit_bio(bio); } static loff_t iomap_dio_actor(struct inode *inode, loff_t pos, loff_t length, void *data, struct iomap *iomap) { struct iomap_dio *dio = data; unsigned int blkbits = blksize_bits(bdev_logical_block_size(iomap->bdev)); unsigned int fs_block_size = i_blocksize(inode), pad; unsigned int align = iov_iter_alignment(dio->submit.iter); struct iov_iter iter; struct bio *bio; bool need_zeroout = false; int nr_pages, ret; size_t copied = 0; if ((pos | length | align) & ((1 << blkbits) - 1)) return -EINVAL; switch (iomap->type) { case IOMAP_HOLE: if (WARN_ON_ONCE(dio->flags & IOMAP_DIO_WRITE)) return -EIO; /*FALLTHRU*/ case IOMAP_UNWRITTEN: if (!(dio->flags & IOMAP_DIO_WRITE)) { length = iov_iter_zero(length, dio->submit.iter); dio->size += length; return length; } dio->flags |= IOMAP_DIO_UNWRITTEN; need_zeroout = true; break; case IOMAP_MAPPED: if (iomap->flags & IOMAP_F_SHARED) dio->flags |= IOMAP_DIO_COW; if (iomap->flags & IOMAP_F_NEW) need_zeroout = true; break; default: WARN_ON_ONCE(1); return -EIO; } /* * Operate on a partial iter trimmed to the extent we were called for. * We'll update the iter in the dio once we're done with this extent. */ iter = *dio->submit.iter; iov_iter_truncate(&iter, length); nr_pages = iov_iter_npages(&iter, BIO_MAX_PAGES); if (nr_pages <= 0) return nr_pages; if (need_zeroout) { /* zero out from the start of the block to the write offset */ pad = pos & (fs_block_size - 1); if (pad) iomap_dio_zero(dio, iomap, pos - pad, pad); } do { size_t n; if (dio->error) { iov_iter_revert(dio->submit.iter, copied); return 0; } bio = bio_alloc(GFP_KERNEL, nr_pages); bio_set_dev(bio, iomap->bdev); bio->bi_iter.bi_sector = (iomap->addr + pos - iomap->offset) >> 9; bio->bi_write_hint = dio->iocb->ki_hint; bio->bi_private = dio; bio->bi_end_io = iomap_dio_bio_end_io; ret = bio_iov_iter_get_pages(bio, &iter); if (unlikely(ret)) { bio_put(bio); return copied ? copied : ret; } n = bio->bi_iter.bi_size; if (dio->flags & IOMAP_DIO_WRITE) { bio_set_op_attrs(bio, REQ_OP_WRITE, REQ_SYNC | REQ_IDLE); task_io_account_write(n); } else { bio_set_op_attrs(bio, REQ_OP_READ, 0); if (dio->flags & IOMAP_DIO_DIRTY) bio_set_pages_dirty(bio); } iov_iter_advance(dio->submit.iter, n); dio->size += n; pos += n; copied += n; nr_pages = iov_iter_npages(&iter, BIO_MAX_PAGES); atomic_inc(&dio->ref); dio->submit.last_queue = bdev_get_queue(iomap->bdev); dio->submit.cookie = submit_bio(bio); } while (nr_pages); if (need_zeroout) { /* zero out from the end of the write to the end of the block */ pad = pos & (fs_block_size - 1); if (pad) iomap_dio_zero(dio, iomap, pos, fs_block_size - pad); } return copied; } ssize_t iomap_dio_rw(struct kiocb *iocb, struct iov_iter *iter, const struct iomap_ops *ops, iomap_dio_end_io_t end_io) { struct address_space *mapping = iocb->ki_filp->f_mapping; struct inode *inode = file_inode(iocb->ki_filp); size_t count = iov_iter_count(iter); loff_t pos = iocb->ki_pos, start = pos; loff_t end = iocb->ki_pos + count - 1, ret = 0; unsigned int flags = IOMAP_DIRECT; struct blk_plug plug; struct iomap_dio *dio; lockdep_assert_held(&inode->i_rwsem); if (!count) return 0; dio = kmalloc(sizeof(*dio), GFP_KERNEL); if (!dio) return -ENOMEM; dio->iocb = iocb; atomic_set(&dio->ref, 1); dio->size = 0; dio->i_size = i_size_read(inode); dio->end_io = end_io; dio->error = 0; dio->flags = 0; dio->submit.iter = iter; if (is_sync_kiocb(iocb)) { dio->submit.waiter = current; dio->submit.cookie = BLK_QC_T_NONE; dio->submit.last_queue = NULL; } if (iov_iter_rw(iter) == READ) { if (pos >= dio->i_size) goto out_free_dio; if (iter->type == ITER_IOVEC) dio->flags |= IOMAP_DIO_DIRTY; } else { dio->flags |= IOMAP_DIO_WRITE; flags |= IOMAP_WRITE; } if (iocb->ki_flags & IOCB_NOWAIT) { if (filemap_range_has_page(mapping, start, end)) { ret = -EAGAIN; goto out_free_dio; } flags |= IOMAP_NOWAIT; } ret = filemap_write_and_wait_range(mapping, start, end); if (ret) goto out_free_dio; /* * Try to invalidate cache pages for the range we're direct * writing. If this invalidation fails, tough, the write will * still work, but racing two incompatible write paths is a * pretty crazy thing to do, so we don't support it 100%. */ ret = invalidate_inode_pages2_range(mapping, start >> PAGE_SHIFT, end >> PAGE_SHIFT); if (ret) dio_warn_stale_pagecache(iocb->ki_filp); ret = 0; if (iov_iter_rw(iter) == WRITE && !is_sync_kiocb(iocb) && !inode->i_sb->s_dio_done_wq) { ret = sb_init_dio_done_wq(inode->i_sb); if (ret < 0) goto out_free_dio; } inode_dio_begin(inode); blk_start_plug(&plug); do { ret = iomap_apply(inode, pos, count, flags, ops, dio, iomap_dio_actor); if (ret <= 0) { /* magic error code to fall back to buffered I/O */ if (ret == -ENOTBLK) ret = 0; break; } pos += ret; if (iov_iter_rw(iter) == READ && pos >= dio->i_size) break; } while ((count = iov_iter_count(iter)) > 0); blk_finish_plug(&plug); if (ret < 0) iomap_dio_set_error(dio, ret); if (!atomic_dec_and_test(&dio->ref)) { if (!is_sync_kiocb(iocb)) return -EIOCBQUEUED; for (;;) { set_current_state(TASK_UNINTERRUPTIBLE); if (!READ_ONCE(dio->submit.waiter)) break; if (!(iocb->ki_flags & IOCB_HIPRI) || !dio->submit.last_queue || !blk_poll(dio->submit.last_queue, dio->submit.cookie)) io_schedule(); } __set_current_state(TASK_RUNNING); } ret = iomap_dio_complete(dio); return ret; out_free_dio: kfree(dio); return ret; } EXPORT_SYMBOL_GPL(iomap_dio_rw);