Commit 0a9164cb authored by Gabriel Krisman Bertazi's avatar Gabriel Krisman Bertazi Committed by Jan Kara
Browse files

direct-io: don't force writeback for reads beyond EOF 

If a DIO read starts past EOF, the kernel won't attempt it, so we don't
need to flush dirty pages before failing the syscall.

Link: https://lore.kernel.org/r/20201008062620.2928326-3-krisman@collabora.com


Suggested-by: default avatarJan Kara <jack@suse.cz>
Reviewed-by: default avatarJan Kara <jack@suse.cz>
Reviewed-by: default avatarJens Axboe <axboe@kernel.dk>
Signed-off-by: default avatarGabriel Krisman Bertazi <krisman@collabora.com>
Signed-off-by: default avatarJan Kara <jack@suse.cz>
parent 46d71602

fs/direct-io.c

+11 −13
Original line number Diff line number Diff line
@@ -1188,19 +1188,9 @@ do_blockdev_direct_IO(struct kiocb *iocb, struct inode *inode, 
	memset(dio, 0, offsetof(struct dio, pages));



	dio->flags = flags;

	if (dio->flags & DIO_LOCKING) {

		if (iov_iter_rw(iter) == READ) {

			struct address_space *mapping =

					iocb->ki_filp->f_mapping;



	if (dio->flags & DIO_LOCKING && iov_iter_rw(iter) == READ) {

		/* will be released by direct_io_worker */

		inode_lock(inode);



			retval = filemap_write_and_wait_range(mapping, offset,

							      end - 1);

			if (retval)

				goto fail_dio;

		}

	}



	/* Once we sampled i_size check for reads beyond EOF */
@@ -1210,6 +1200,14 @@ do_blockdev_direct_IO(struct kiocb *iocb, struct inode *inode, 
		goto fail_dio;

	}



	if (dio->flags & DIO_LOCKING && iov_iter_rw(iter) == READ) {

		struct address_space *mapping = iocb->ki_filp->f_mapping;



		retval = filemap_write_and_wait_range(mapping, offset, end - 1);

		if (retval)

			goto fail_dio;

	}



	/*

	 * For file extending writes updating i_size before data writeouts

	 * complete can expose uninitialized blocks in dumb filesystems.

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