Commit d4120d87 authored by David Howells's avatar David Howells Committed by Jens Axboe
Browse files

overlayfs: Implement splice-read 



Implement splice-read for overlayfs by passing the request down a layer
rather than going through generic_file_splice_read() which is going to be
changed to assume that ->read_folio() is present on buffered files.

Signed-off-by: default avatarDavid Howells <dhowells@redhat.com>
Acked-by: default avatarChristian Brauner <brauner@kernel.org>
cc: Christoph Hellwig <hch@lst.de>
cc: Jens Axboe <axboe@kernel.dk>
cc: Al Viro <viro@zeniv.linux.org.uk>
cc: John Hubbard <jhubbard@nvidia.com>
cc: David Hildenbrand <david@redhat.com>
cc: Matthew Wilcox <willy@infradead.org>
cc: Miklos Szeredi <miklos@szeredi.hu>
cc: Amir Goldstein <amir73il@gmail.com>
cc: linux-unionfs@vger.kernel.org
cc: linux-block@vger.kernel.org
cc: linux-fsdevel@vger.kernel.org
cc: linux-mm@kvack.org
Link: https://lore.kernel.org/r/20230522135018.2742245-11-dhowells@redhat.com


Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent bd194b18

fs/overlayfs/file.c

+22 −1
Original line number Diff line number Diff line
@@ -419,6 +419,27 @@ static ssize_t ovl_write_iter(struct kiocb *iocb, struct iov_iter *iter) 
	return ret;

}



static ssize_t ovl_splice_read(struct file *in, loff_t *ppos,

			       struct pipe_inode_info *pipe, size_t len,

			       unsigned int flags)

{

	const struct cred *old_cred;

	struct fd real;

	ssize_t ret;



	ret = ovl_real_fdget(in, &real);

	if (ret)

		return ret;



	old_cred = ovl_override_creds(file_inode(in)->i_sb);

	ret = vfs_splice_read(real.file, ppos, pipe, len, flags);

	revert_creds(old_cred);

	ovl_file_accessed(in);



	fdput(real);

	return ret;

}



/*

 * Calling iter_file_splice_write() directly from overlay's f_op may deadlock

 * due to lock order inversion between pipe->mutex in iter_file_splice_write()
@@ -695,7 +716,7 @@ const struct file_operations ovl_file_operations = { 
	.fallocate	= ovl_fallocate,

	.fadvise	= ovl_fadvise,

	.flush		= ovl_flush,

	.splice_read    = generic_file_splice_read,

	.splice_read    = ovl_splice_read,

	.splice_write   = ovl_splice_write,



	.copy_file_range	= ovl_copy_file_range,