Commit 6e5e41e2 authored by Andreas Gruenbacher's avatar Andreas Gruenbacher
Browse files

gfs2: fix O_SYNC write handling 



In gfs2_file_write_iter, for direct writes, the error checking in the buffered
write fallback case is incomplete.  This can cause inode write errors to go
undetected.  Fix and clean up gfs2_file_write_iter along the way.

Based on a proposed fix by Christoph Hellwig <hch@lst.de>.

Fixes: 967bcc91 ("gfs2: iomap direct I/O support")
Cc: stable@vger.kernel.org # v4.19+
Signed-off-by: default avatarAndreas Gruenbacher <agruenba@redhat.com>
parent 4c0e8dda

fs/gfs2/file.c

+21 −30
Original line number Diff line number Diff line
@@ -847,7 +847,7 @@ static ssize_t gfs2_file_write_iter(struct kiocb *iocb, struct iov_iter *from) 
	struct file *file = iocb->ki_filp;

	struct inode *inode = file_inode(file);

	struct gfs2_inode *ip = GFS2_I(inode);

	ssize_t written = 0, ret;

	ssize_t ret;



	ret = gfs2_rsqa_alloc(ip);

	if (ret)
@@ -879,55 +879,46 @@ static ssize_t gfs2_file_write_iter(struct kiocb *iocb, struct iov_iter *from) 


	if (iocb->ki_flags & IOCB_DIRECT) {

		struct address_space *mapping = file->f_mapping;

		loff_t pos, endbyte;

		ssize_t buffered;

		ssize_t buffered, ret2;



		written = gfs2_file_direct_write(iocb, from);

		if (written < 0 || !iov_iter_count(from))

		ret = gfs2_file_direct_write(iocb, from);

		if (ret < 0 || !iov_iter_count(from))

			goto out_unlock;



		iocb->ki_flags |= IOCB_DSYNC;

		current->backing_dev_info = inode_to_bdi(inode);

		ret = iomap_file_buffered_write(iocb, from, &gfs2_iomap_ops);

		buffered = iomap_file_buffered_write(iocb, from, &gfs2_iomap_ops);

		current->backing_dev_info = NULL;

		if (unlikely(ret < 0))

		if (unlikely(buffered <= 0))

			goto out_unlock;

		buffered = ret;



		/*

		 * We need to ensure that the page cache pages are written to

		 * disk and invalidated to preserve the expected O_DIRECT

		 * semantics.

		 * semantics.  If the writeback or invalidate fails, only report

		 * the direct I/O range as we don't know if the buffered pages

		 * made it to disk.

		 */

		pos = iocb->ki_pos;

		endbyte = pos + buffered - 1;

		ret = filemap_write_and_wait_range(mapping, pos, endbyte);

		if (!ret) {

		iocb->ki_pos += buffered;

			written += buffered;

		ret2 = generic_write_sync(iocb, buffered);

		invalidate_mapping_pages(mapping,

						 pos >> PAGE_SHIFT,

						 endbyte >> PAGE_SHIFT);

		} else {

			/*

			 * We don't know how much we wrote, so just return

			 * the number of bytes which were direct-written

			 */

		}

				(iocb->ki_pos - buffered) >> PAGE_SHIFT,

				(iocb->ki_pos - 1) >> PAGE_SHIFT);

		if (!ret || ret2 > 0)

			ret += ret2;

	} else {

		current->backing_dev_info = inode_to_bdi(inode);

		ret = iomap_file_buffered_write(iocb, from, &gfs2_iomap_ops);

		current->backing_dev_info = NULL;

		if (likely(ret > 0))

		if (likely(ret > 0)) {

			iocb->ki_pos += ret;

			ret = generic_write_sync(iocb, ret);

		}

	}



out_unlock:

	inode_unlock(inode);

	if (likely(ret > 0)) {

		/* Handle various SYNC-type writes */

		ret = generic_write_sync(iocb, ret);

	}

	return written ? written : ret;

	return ret;

}



static int fallocate_chunk(struct inode *inode, loff_t offset, loff_t len,

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