Commit 4fdccaa0 authored by Andreas Gruenbacher's avatar Andreas Gruenbacher
Browse files

iomap: Add done_before argument to iomap_dio_rw 



Add a done_before argument to iomap_dio_rw that indicates how much of
the request has already been transferred.  When the request succeeds, we
report that done_before additional bytes were tranferred.  This is
useful for finishing a request asynchronously when part of the request
has already been completed synchronously.

We'll use that to allow iomap_dio_rw to be used with page faults
disabled: when a page fault occurs while submitting a request, we
synchronously complete the part of the request that has already been
submitted.  The caller can then take care of the page fault and call
iomap_dio_rw again for the rest of the request, passing in the number of
bytes already tranferred.

Signed-off-by: default avatarAndreas Gruenbacher <agruenba@redhat.com>
Reviewed-by: default avatarDarrick J. Wong <djwong@kernel.org>
parent 97308f8b

fs/btrfs/file.c

+3 −2
Original line number Diff line number Diff line
@@ -1957,7 +1957,7 @@ static ssize_t btrfs_direct_write(struct kiocb *iocb, struct iov_iter *from) 
	}



	dio = __iomap_dio_rw(iocb, from, &btrfs_dio_iomap_ops, &btrfs_dio_ops,

			     0);

			     0, 0);



	btrfs_inode_unlock(inode, ilock_flags);
@@ -3658,7 +3658,8 @@ static ssize_t btrfs_direct_read(struct kiocb *iocb, struct iov_iter *to) 
		return 0;



	btrfs_inode_lock(inode, BTRFS_ILOCK_SHARED);

	ret = iomap_dio_rw(iocb, to, &btrfs_dio_iomap_ops, &btrfs_dio_ops, 0);

	ret = iomap_dio_rw(iocb, to, &btrfs_dio_iomap_ops, &btrfs_dio_ops,

			   0, 0);

	btrfs_inode_unlock(inode, BTRFS_ILOCK_SHARED);

	return ret;

}

fs/erofs/data.c

+1 −1
Original line number Diff line number Diff line
@@ -287,7 +287,7 @@ static ssize_t erofs_file_read_iter(struct kiocb *iocb, struct iov_iter *to) 


		if (!err)

			return iomap_dio_rw(iocb, to, &erofs_iomap_ops,

					    NULL, 0);

					    NULL, 0, 0);

		if (err < 0)

			return err;

	}

fs/ext4/file.c

+3 −2
Original line number Diff line number Diff line
@@ -74,7 +74,7 @@ static ssize_t ext4_dio_read_iter(struct kiocb *iocb, struct iov_iter *to) 
		return generic_file_read_iter(iocb, to);

	}



	ret = iomap_dio_rw(iocb, to, &ext4_iomap_ops, NULL, 0);

	ret = iomap_dio_rw(iocb, to, &ext4_iomap_ops, NULL, 0, 0);

	inode_unlock_shared(inode);



	file_accessed(iocb->ki_filp);
@@ -566,7 +566,8 @@ static ssize_t ext4_dio_write_iter(struct kiocb *iocb, struct iov_iter *from) 
	if (ilock_shared)

		iomap_ops = &ext4_iomap_overwrite_ops;

	ret = iomap_dio_rw(iocb, from, iomap_ops, &ext4_dio_write_ops,

			   (unaligned_io || extend) ? IOMAP_DIO_FORCE_WAIT : 0);

			   (unaligned_io || extend) ? IOMAP_DIO_FORCE_WAIT : 0,

			   0);

	if (ret == -ENOTBLK)

		ret = 0;

fs/gfs2/file.c

+2 −2
Original line number Diff line number Diff line
@@ -822,7 +822,7 @@ static ssize_t gfs2_file_direct_read(struct kiocb *iocb, struct iov_iter *to, 
	if (ret)

		goto out_uninit;



	ret = iomap_dio_rw(iocb, to, &gfs2_iomap_ops, NULL, 0);

	ret = iomap_dio_rw(iocb, to, &gfs2_iomap_ops, NULL, 0, 0);

	gfs2_glock_dq(gh);

out_uninit:

	gfs2_holder_uninit(gh);
@@ -856,7 +856,7 @@ static ssize_t gfs2_file_direct_write(struct kiocb *iocb, struct iov_iter *from, 
	if (offset + len > i_size_read(&ip->i_inode))

		goto out;



	ret = iomap_dio_rw(iocb, from, &gfs2_iomap_ops, NULL, 0);

	ret = iomap_dio_rw(iocb, from, &gfs2_iomap_ops, NULL, 0, 0);

	if (ret == -ENOTBLK)

		ret = 0;

out:

fs/iomap/direct-io.c

+16 −3
Original line number Diff line number Diff line
@@ -31,6 +31,7 @@ struct iomap_dio { 
	atomic_t		ref;

	unsigned		flags;

	int			error;

	size_t			done_before;

	bool			wait_for_completion;



	union {
@@ -124,6 +125,9 @@ ssize_t iomap_dio_complete(struct iomap_dio *dio) 
	if (ret > 0 && (dio->flags & IOMAP_DIO_NEED_SYNC))

		ret = generic_write_sync(iocb, ret);



	if (ret > 0)

		ret += dio->done_before;



	kfree(dio);



	return ret;
@@ -450,13 +454,21 @@ static loff_t iomap_dio_iter(const struct iomap_iter *iter, 
 * may be pure data writes. In that case, we still need to do a full data sync

 * completion.

 *

 * When page faults are disabled and @dio_flags includes IOMAP_DIO_PARTIAL,

 * __iomap_dio_rw can return a partial result if it encounters a non-resident

 * page in @iter after preparing a transfer.  In that case, the non-resident

 * pages can be faulted in and the request resumed with @done_before set to the

 * number of bytes previously transferred.  The request will then complete with

 * the correct total number of bytes transferred; this is essential for

 * completing partial requests asynchronously.

 *

 * Returns -ENOTBLK In case of a page invalidation invalidation failure for

 * writes.  The callers needs to fall back to buffered I/O in this case.

 */

struct iomap_dio *

__iomap_dio_rw(struct kiocb *iocb, struct iov_iter *iter,

		const struct iomap_ops *ops, const struct iomap_dio_ops *dops,

		unsigned int dio_flags)

		unsigned int dio_flags, size_t done_before)

{

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

	struct inode *inode = file_inode(iocb->ki_filp);
@@ -486,6 +498,7 @@ __iomap_dio_rw(struct kiocb *iocb, struct iov_iter *iter, 
	dio->dops = dops;

	dio->error = 0;

	dio->flags = 0;

	dio->done_before = done_before;



	dio->submit.iter = iter;

	dio->submit.waiter = current;
@@ -652,11 +665,11 @@ EXPORT_SYMBOL_GPL(__iomap_dio_rw); 
ssize_t

iomap_dio_rw(struct kiocb *iocb, struct iov_iter *iter,

		const struct iomap_ops *ops, const struct iomap_dio_ops *dops,

		unsigned int dio_flags)

		unsigned int dio_flags, size_t done_before)

{

	struct iomap_dio *dio;



	dio = __iomap_dio_rw(iocb, iter, ops, dops, dio_flags);

	dio = __iomap_dio_rw(iocb, iter, ops, dops, dio_flags, done_before);

	if (IS_ERR_OR_NULL(dio))

		return PTR_ERR_OR_ZERO(dio);

	return iomap_dio_complete(dio);