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c663e29f88
iomap_page_mkwrite_actor() calls __block_write_begin_int() with position masked as pos & ~PAGE_MASK which is equivalent to pos & (PAGE_SIZE-1). Thus it masks off high bits of file position. However __block_write_begin_int() expects full file position on input. This does not cause any visible issues because all __block_write_begin_int() really cares about are low file position bits but still it is a bug waiting to happen. Signed-off-by: Jan Kara <jack@suse.cz> Reviewed-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Dave Chinner <david@fromorbit.com>
586 lines
14 KiB
C
586 lines
14 KiB
C
/*
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* Copyright (C) 2010 Red Hat, Inc.
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* Copyright (c) 2016 Christoph Hellwig.
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*
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* This program is free software; you can redistribute it and/or modify it
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* under the terms and conditions of the GNU General Public License,
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* version 2, as published by the Free Software Foundation.
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*
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* This program is distributed in the hope it will be useful, but WITHOUT
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
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* more details.
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*/
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#include <linux/module.h>
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#include <linux/compiler.h>
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#include <linux/fs.h>
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#include <linux/iomap.h>
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#include <linux/uaccess.h>
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#include <linux/gfp.h>
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#include <linux/mm.h>
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#include <linux/swap.h>
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#include <linux/pagemap.h>
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#include <linux/file.h>
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#include <linux/uio.h>
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#include <linux/backing-dev.h>
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#include <linux/buffer_head.h>
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#include <linux/dax.h>
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#include "internal.h"
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/*
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* Execute a iomap write on a segment of the mapping that spans a
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* contiguous range of pages that have identical block mapping state.
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*
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* This avoids the need to map pages individually, do individual allocations
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* for each page and most importantly avoid the need for filesystem specific
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* locking per page. Instead, all the operations are amortised over the entire
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* range of pages. It is assumed that the filesystems will lock whatever
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* resources they require in the iomap_begin call, and release them in the
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* iomap_end call.
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*/
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loff_t
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iomap_apply(struct inode *inode, loff_t pos, loff_t length, unsigned flags,
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struct iomap_ops *ops, void *data, iomap_actor_t actor)
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{
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struct iomap iomap = { 0 };
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loff_t written = 0, ret;
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/*
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* Need to map a range from start position for length bytes. This can
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* span multiple pages - it is only guaranteed to return a range of a
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* single type of pages (e.g. all into a hole, all mapped or all
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* unwritten). Failure at this point has nothing to undo.
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*
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* If allocation is required for this range, reserve the space now so
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* that the allocation is guaranteed to succeed later on. Once we copy
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* the data into the page cache pages, then we cannot fail otherwise we
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* expose transient stale data. If the reserve fails, we can safely
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* back out at this point as there is nothing to undo.
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*/
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ret = ops->iomap_begin(inode, pos, length, flags, &iomap);
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if (ret)
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return ret;
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if (WARN_ON(iomap.offset > pos))
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return -EIO;
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/*
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* Cut down the length to the one actually provided by the filesystem,
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* as it might not be able to give us the whole size that we requested.
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*/
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if (iomap.offset + iomap.length < pos + length)
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length = iomap.offset + iomap.length - pos;
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/*
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* Now that we have guaranteed that the space allocation will succeed.
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* we can do the copy-in page by page without having to worry about
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* failures exposing transient data.
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*/
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written = actor(inode, pos, length, data, &iomap);
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/*
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* Now the data has been copied, commit the range we've copied. This
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* should not fail unless the filesystem has had a fatal error.
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*/
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if (ops->iomap_end) {
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ret = ops->iomap_end(inode, pos, length,
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written > 0 ? written : 0,
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flags, &iomap);
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}
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return written ? written : ret;
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}
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static void
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iomap_write_failed(struct inode *inode, loff_t pos, unsigned len)
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{
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loff_t i_size = i_size_read(inode);
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/*
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* Only truncate newly allocated pages beyoned EOF, even if the
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* write started inside the existing inode size.
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*/
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if (pos + len > i_size)
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truncate_pagecache_range(inode, max(pos, i_size), pos + len);
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}
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static int
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iomap_write_begin(struct inode *inode, loff_t pos, unsigned len, unsigned flags,
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struct page **pagep, struct iomap *iomap)
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{
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pgoff_t index = pos >> PAGE_SHIFT;
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struct page *page;
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int status = 0;
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BUG_ON(pos + len > iomap->offset + iomap->length);
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page = grab_cache_page_write_begin(inode->i_mapping, index, flags);
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if (!page)
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return -ENOMEM;
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status = __block_write_begin_int(page, pos, len, NULL, iomap);
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if (unlikely(status)) {
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unlock_page(page);
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put_page(page);
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page = NULL;
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iomap_write_failed(inode, pos, len);
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}
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*pagep = page;
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return status;
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}
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static int
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iomap_write_end(struct inode *inode, loff_t pos, unsigned len,
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unsigned copied, struct page *page)
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{
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int ret;
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ret = generic_write_end(NULL, inode->i_mapping, pos, len,
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copied, page, NULL);
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if (ret < len)
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iomap_write_failed(inode, pos, len);
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return ret;
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}
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static loff_t
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iomap_write_actor(struct inode *inode, loff_t pos, loff_t length, void *data,
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struct iomap *iomap)
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{
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struct iov_iter *i = data;
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long status = 0;
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ssize_t written = 0;
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unsigned int flags = AOP_FLAG_NOFS;
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/*
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* Copies from kernel address space cannot fail (NFSD is a big user).
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*/
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if (!iter_is_iovec(i))
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flags |= AOP_FLAG_UNINTERRUPTIBLE;
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do {
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struct page *page;
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unsigned long offset; /* Offset into pagecache page */
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unsigned long bytes; /* Bytes to write to page */
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size_t copied; /* Bytes copied from user */
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offset = (pos & (PAGE_SIZE - 1));
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bytes = min_t(unsigned long, PAGE_SIZE - offset,
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iov_iter_count(i));
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again:
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if (bytes > length)
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bytes = length;
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/*
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* Bring in the user page that we will copy from _first_.
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* Otherwise there's a nasty deadlock on copying from the
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* same page as we're writing to, without it being marked
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* up-to-date.
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*
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* Not only is this an optimisation, but it is also required
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* to check that the address is actually valid, when atomic
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* usercopies are used, below.
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*/
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if (unlikely(iov_iter_fault_in_readable(i, bytes))) {
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status = -EFAULT;
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break;
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}
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status = iomap_write_begin(inode, pos, bytes, flags, &page,
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iomap);
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if (unlikely(status))
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break;
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if (mapping_writably_mapped(inode->i_mapping))
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flush_dcache_page(page);
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copied = iov_iter_copy_from_user_atomic(page, i, offset, bytes);
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flush_dcache_page(page);
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status = iomap_write_end(inode, pos, bytes, copied, page);
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if (unlikely(status < 0))
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break;
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copied = status;
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cond_resched();
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iov_iter_advance(i, copied);
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if (unlikely(copied == 0)) {
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/*
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* If we were unable to copy any data at all, we must
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* fall back to a single segment length write.
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*
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* If we didn't fallback here, we could livelock
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* because not all segments in the iov can be copied at
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* once without a pagefault.
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*/
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bytes = min_t(unsigned long, PAGE_SIZE - offset,
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iov_iter_single_seg_count(i));
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goto again;
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}
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pos += copied;
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written += copied;
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length -= copied;
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balance_dirty_pages_ratelimited(inode->i_mapping);
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} while (iov_iter_count(i) && length);
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return written ? written : status;
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}
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ssize_t
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iomap_file_buffered_write(struct kiocb *iocb, struct iov_iter *iter,
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struct iomap_ops *ops)
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{
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struct inode *inode = iocb->ki_filp->f_mapping->host;
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loff_t pos = iocb->ki_pos, ret = 0, written = 0;
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while (iov_iter_count(iter)) {
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ret = iomap_apply(inode, pos, iov_iter_count(iter),
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IOMAP_WRITE, ops, iter, iomap_write_actor);
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if (ret <= 0)
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break;
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pos += ret;
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written += ret;
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}
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return written ? written : ret;
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}
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EXPORT_SYMBOL_GPL(iomap_file_buffered_write);
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static struct page *
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__iomap_read_page(struct inode *inode, loff_t offset)
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{
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struct address_space *mapping = inode->i_mapping;
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struct page *page;
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page = read_mapping_page(mapping, offset >> PAGE_SHIFT, NULL);
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if (IS_ERR(page))
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return page;
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if (!PageUptodate(page)) {
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put_page(page);
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return ERR_PTR(-EIO);
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}
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return page;
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}
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static loff_t
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iomap_dirty_actor(struct inode *inode, loff_t pos, loff_t length, void *data,
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struct iomap *iomap)
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{
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long status = 0;
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ssize_t written = 0;
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do {
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struct page *page, *rpage;
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unsigned long offset; /* Offset into pagecache page */
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unsigned long bytes; /* Bytes to write to page */
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offset = (pos & (PAGE_SIZE - 1));
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bytes = min_t(unsigned long, PAGE_SIZE - offset, length);
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rpage = __iomap_read_page(inode, pos);
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if (IS_ERR(rpage))
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return PTR_ERR(rpage);
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status = iomap_write_begin(inode, pos, bytes,
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AOP_FLAG_NOFS | AOP_FLAG_UNINTERRUPTIBLE,
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&page, iomap);
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put_page(rpage);
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if (unlikely(status))
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return status;
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WARN_ON_ONCE(!PageUptodate(page));
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status = iomap_write_end(inode, pos, bytes, bytes, page);
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if (unlikely(status <= 0)) {
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if (WARN_ON_ONCE(status == 0))
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return -EIO;
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return status;
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}
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cond_resched();
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pos += status;
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written += status;
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length -= status;
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balance_dirty_pages_ratelimited(inode->i_mapping);
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} while (length);
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return written;
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}
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int
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iomap_file_dirty(struct inode *inode, loff_t pos, loff_t len,
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struct iomap_ops *ops)
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{
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loff_t ret;
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while (len) {
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ret = iomap_apply(inode, pos, len, IOMAP_WRITE, ops, NULL,
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iomap_dirty_actor);
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if (ret <= 0)
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return ret;
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pos += ret;
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len -= ret;
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}
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return 0;
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}
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EXPORT_SYMBOL_GPL(iomap_file_dirty);
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static int iomap_zero(struct inode *inode, loff_t pos, unsigned offset,
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unsigned bytes, struct iomap *iomap)
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{
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struct page *page;
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int status;
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status = iomap_write_begin(inode, pos, bytes,
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AOP_FLAG_UNINTERRUPTIBLE | AOP_FLAG_NOFS, &page, iomap);
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if (status)
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return status;
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zero_user(page, offset, bytes);
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mark_page_accessed(page);
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return iomap_write_end(inode, pos, bytes, bytes, page);
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}
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static int iomap_dax_zero(loff_t pos, unsigned offset, unsigned bytes,
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struct iomap *iomap)
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{
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sector_t sector = iomap->blkno +
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(((pos & ~(PAGE_SIZE - 1)) - iomap->offset) >> 9);
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return __dax_zero_page_range(iomap->bdev, sector, offset, bytes);
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}
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static loff_t
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iomap_zero_range_actor(struct inode *inode, loff_t pos, loff_t count,
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void *data, struct iomap *iomap)
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{
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bool *did_zero = data;
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loff_t written = 0;
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int status;
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/* already zeroed? we're done. */
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if (iomap->type == IOMAP_HOLE || iomap->type == IOMAP_UNWRITTEN)
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return count;
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do {
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unsigned offset, bytes;
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offset = pos & (PAGE_SIZE - 1); /* Within page */
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bytes = min_t(unsigned, PAGE_SIZE - offset, count);
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if (IS_DAX(inode))
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status = iomap_dax_zero(pos, offset, bytes, iomap);
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else
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status = iomap_zero(inode, pos, offset, bytes, iomap);
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if (status < 0)
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return status;
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pos += bytes;
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count -= bytes;
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written += bytes;
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if (did_zero)
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*did_zero = true;
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} while (count > 0);
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return written;
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}
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int
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iomap_zero_range(struct inode *inode, loff_t pos, loff_t len, bool *did_zero,
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struct iomap_ops *ops)
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{
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loff_t ret;
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while (len > 0) {
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ret = iomap_apply(inode, pos, len, IOMAP_ZERO,
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ops, did_zero, iomap_zero_range_actor);
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if (ret <= 0)
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return ret;
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pos += ret;
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len -= ret;
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}
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return 0;
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}
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EXPORT_SYMBOL_GPL(iomap_zero_range);
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int
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iomap_truncate_page(struct inode *inode, loff_t pos, bool *did_zero,
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struct iomap_ops *ops)
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{
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unsigned blocksize = (1 << inode->i_blkbits);
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unsigned off = pos & (blocksize - 1);
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/* Block boundary? Nothing to do */
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if (!off)
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return 0;
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return iomap_zero_range(inode, pos, blocksize - off, did_zero, ops);
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}
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EXPORT_SYMBOL_GPL(iomap_truncate_page);
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static loff_t
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iomap_page_mkwrite_actor(struct inode *inode, loff_t pos, loff_t length,
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void *data, struct iomap *iomap)
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{
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struct page *page = data;
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int ret;
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ret = __block_write_begin_int(page, pos, length, NULL, iomap);
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if (ret)
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return ret;
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block_commit_write(page, 0, length);
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return length;
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}
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int iomap_page_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf,
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struct iomap_ops *ops)
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{
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struct page *page = vmf->page;
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struct inode *inode = file_inode(vma->vm_file);
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unsigned long length;
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loff_t offset, size;
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ssize_t ret;
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lock_page(page);
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size = i_size_read(inode);
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if ((page->mapping != inode->i_mapping) ||
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(page_offset(page) > size)) {
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/* We overload EFAULT to mean page got truncated */
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ret = -EFAULT;
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goto out_unlock;
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}
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/* page is wholly or partially inside EOF */
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if (((page->index + 1) << PAGE_SHIFT) > size)
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length = size & ~PAGE_MASK;
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else
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length = PAGE_SIZE;
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offset = page_offset(page);
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while (length > 0) {
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ret = iomap_apply(inode, offset, length, IOMAP_WRITE,
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ops, page, iomap_page_mkwrite_actor);
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if (unlikely(ret <= 0))
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goto out_unlock;
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offset += ret;
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length -= ret;
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}
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set_page_dirty(page);
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wait_for_stable_page(page);
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return 0;
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out_unlock:
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unlock_page(page);
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return ret;
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}
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EXPORT_SYMBOL_GPL(iomap_page_mkwrite);
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struct fiemap_ctx {
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struct fiemap_extent_info *fi;
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struct iomap prev;
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};
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static int iomap_to_fiemap(struct fiemap_extent_info *fi,
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struct iomap *iomap, u32 flags)
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{
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switch (iomap->type) {
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case IOMAP_HOLE:
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/* skip holes */
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return 0;
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case IOMAP_DELALLOC:
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flags |= FIEMAP_EXTENT_DELALLOC | FIEMAP_EXTENT_UNKNOWN;
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break;
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case IOMAP_UNWRITTEN:
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flags |= FIEMAP_EXTENT_UNWRITTEN;
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break;
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case IOMAP_MAPPED:
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break;
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}
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if (iomap->flags & IOMAP_F_MERGED)
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flags |= FIEMAP_EXTENT_MERGED;
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if (iomap->flags & IOMAP_F_SHARED)
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flags |= FIEMAP_EXTENT_SHARED;
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return fiemap_fill_next_extent(fi, iomap->offset,
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iomap->blkno != IOMAP_NULL_BLOCK ? iomap->blkno << 9: 0,
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iomap->length, flags);
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}
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static loff_t
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iomap_fiemap_actor(struct inode *inode, loff_t pos, loff_t length, void *data,
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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);
|