| /* |
| * 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/dax.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, |
| 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; |
| |
| /* |
| * 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; |
| |
| /* |
| * Copies from kernel address space cannot fail (NFSD is a big user). |
| */ |
| if (!iter_is_iovec(i)) |
| flags |= AOP_FLAG_UNINTERRUPTIBLE; |
| |
| 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, |
| 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 | AOP_FLAG_UNINTERRUPTIBLE, |
| &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, |
| 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_UNINTERRUPTIBLE | 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->blkno + |
| (((pos & ~(PAGE_SIZE - 1)) - iomap->offset) >> 9); |
| |
| return __dax_zero_page_range(iomap->bdev, 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, |
| 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, |
| 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_area_struct *vma, struct vm_fault *vmf, |
| struct iomap_ops *ops) |
| { |
| struct page *page = vmf->page; |
| struct inode *inode = file_inode(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, |
| 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 0; |
| out_unlock: |
| unlock_page(page); |
| 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; |
| |
| return fiemap_fill_next_extent(fi, iomap->offset, |
| iomap->blkno != IOMAP_NULL_BLOCK ? iomap->blkno << 9: 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, 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); |