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3460cac1ca
If we are doing direct IO writes with datasync semantics, we often have to flush metadata changes along with the data write. However, if we are overwriting existing data, there are no metadata changes that we need to flush. In this case, optimising the IO by using FUA write makes sense. We know from the IOMAP_F_DIRTY flag as to whether a specific inode requires a metadata flush - this is currently used by DAX to ensure extent modification as stable in page fault operations. For direct IO writes, we can use it to determine if we need to flush metadata or not once the data is on disk. Hence if we have been returned a mapped extent that is not new and the IO mapping is not dirty, then we can use a FUA write to provide datasync semantics. This allows us to short-cut the generic_write_sync() call in IO completion and hence avoid unnecessary operations. This makes pure direct IO data write behaviour identical to the way block devices use REQ_FUA to provide datasync semantics. On a FUA enabled device, a synchronous direct IO write workload (sequential 4k overwrites in 32MB file) had the following results: # xfs_io -fd -c "pwrite -V 1 -D 0 32m" /mnt/scratch/boo kernel time write()s write iops Write b/w ------ ---- -------- ---------- --------- (no dsync) 4s 2173/s 2173 8.5MB/s vanilla 22s 370/s 750 1.4MB/s patched 19s 420/s 420 1.6MB/s The patched code clearly doesn't send cache flushes anymore, but instead uses FUA (confirmed via blktrace), and performance improves a bit as a result. However, the benefits will be higher on workloads that mix O_DSYNC overwrites with other write IO as we won't be flushing the entire device cache on every DSYNC overwrite IO anymore. Signed-Off-By: Dave Chinner <dchinner@redhat.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com> Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
1141 lines
28 KiB
C
1141 lines
28 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/task_io_accounting_ops.h>
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#include <linux/dax.h>
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#include <linux/sched/signal.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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const 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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if (WARN_ON(iomap.length == 0))
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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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if (fatal_signal_pending(current))
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return -EINTR;
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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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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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const 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(loff_t, 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, &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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const 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, AOP_FLAG_NOFS, &page,
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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->addr +
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(pos & PAGE_MASK) - iomap->offset) >> 9;
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return __dax_zero_page_range(iomap->bdev, iomap->dax_dev, sector,
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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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|
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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(loff_t, 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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|
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return written;
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}
|
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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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const 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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|
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return 0;
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}
|
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EXPORT_SYMBOL_GPL(iomap_zero_range);
|
|
|
|
int
|
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iomap_truncate_page(struct inode *inode, loff_t pos, bool *did_zero,
|
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const struct iomap_ops *ops)
|
|
{
|
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unsigned int blocksize = i_blocksize(inode);
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unsigned int off = pos & (blocksize - 1);
|
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|
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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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}
|
|
EXPORT_SYMBOL_GPL(iomap_truncate_page);
|
|
|
|
static loff_t
|
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iomap_page_mkwrite_actor(struct inode *inode, loff_t pos, loff_t length,
|
|
void *data, struct iomap *iomap)
|
|
{
|
|
struct page *page = data;
|
|
int ret;
|
|
|
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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_FUA (1 << 28)
|
|
#define IOMAP_DIO_NEED_SYNC (1 << 29)
|
|
#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);
|
|
}
|
|
|
|
/*
|
|
* If this is a DSYNC write, make sure we push it to stable storage now
|
|
* that we've written data.
|
|
*/
|
|
if (ret > 0 && (dio->flags & IOMAP_DIO_NEED_SYNC))
|
|
ret = generic_write_sync(iocb, ret);
|
|
|
|
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;
|
|
|
|
iocb->ki_complete(iocb, iomap_dio_complete(dio), 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;
|
|
bool use_fua = 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;
|
|
} else {
|
|
/*
|
|
* Use a FUA write if we need datasync semantics, this
|
|
* is a pure data IO that doesn't require any metadata
|
|
* updates and the underlying device supports FUA. This
|
|
* allows us to avoid cache flushes on IO completion.
|
|
*/
|
|
if (!(iomap->flags & (IOMAP_F_SHARED|IOMAP_F_DIRTY)) &&
|
|
(dio->flags & IOMAP_DIO_WRITE_FUA) &&
|
|
blk_queue_fua(bdev_get_queue(iomap->bdev)))
|
|
use_fua = 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->bi_opf = REQ_OP_WRITE | REQ_SYNC | REQ_IDLE;
|
|
if (use_fua)
|
|
bio->bi_opf |= REQ_FUA;
|
|
else
|
|
dio->flags &= ~IOMAP_DIO_WRITE_FUA;
|
|
task_io_account_write(n);
|
|
} else {
|
|
bio->bi_opf = REQ_OP_READ;
|
|
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;
|
|
}
|
|
|
|
/*
|
|
* iomap_dio_rw() always completes O_[D]SYNC writes regardless of whether the IO
|
|
* is being issued as AIO or not. This allows us to optimise pure data writes
|
|
* to use REQ_FUA rather than requiring generic_write_sync() to issue a
|
|
* REQ_FLUSH post write. This is slightly tricky because a single request here
|
|
* can be mapped into multiple disjoint IOs and only a subset of the IOs issued
|
|
* may be pure data writes. In that case, we still need to do a full data sync
|
|
* completion.
|
|
*/
|
|
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 {
|
|
flags |= IOMAP_WRITE;
|
|
dio->flags |= IOMAP_DIO_WRITE;
|
|
|
|
/* for data sync or sync, we need sync completion processing */
|
|
if (iocb->ki_flags & IOCB_DSYNC)
|
|
dio->flags |= IOMAP_DIO_NEED_SYNC;
|
|
|
|
/*
|
|
* For datasync only writes, we optimistically try using FUA for
|
|
* this IO. Any non-FUA write that occurs will clear this flag,
|
|
* hence we know before completion whether a cache flush is
|
|
* necessary.
|
|
*/
|
|
if ((iocb->ki_flags & (IOCB_DSYNC | IOCB_SYNC)) == IOCB_DSYNC)
|
|
dio->flags |= IOMAP_DIO_WRITE_FUA;
|
|
}
|
|
|
|
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 all the writes we issued were FUA, we don't need to flush the
|
|
* cache on IO completion. Clear the sync flag for this case.
|
|
*/
|
|
if (dio->flags & IOMAP_DIO_WRITE_FUA)
|
|
dio->flags &= ~IOMAP_DIO_NEED_SYNC;
|
|
|
|
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);
|