[PATCH v22 01/31] splice: Fix filemap_splice_read() to use the correct inode

From: David Howells <dhowells@redhat.com>
To: Jens Axboe <axboe@kernel.dk>, Al Viro <viro@zeniv.linux.org.uk>,
	Christoph Hellwig <hch@infradead.org>
Cc: David Howells <dhowells@redhat.com>,
	Matthew Wilcox <willy@infradead.org>, Jan Kara <jack@suse.cz>,
	Jeff Layton <jlayton@kernel.org>,
	David Hildenbrand <david@redhat.com>,
	Jason Gunthorpe <jgg@nvidia.com>,
	Logan Gunthorpe <logang@deltatee.com>,
	Hillf Danton <hdanton@sina.com>,
	Christian Brauner <brauner@kernel.org>,
	Linus Torvalds <torvalds@linux-foundation.org>,
	linux-fsdevel@vger.kernel.org, linux-block@vger.kernel.org,
	linux-kernel@vger.kernel.org, linux-mm@kvack.org,
	Christoph Hellwig <hch@lst.de>,
	Steve French <stfrench@microsoft.com>,
	John Hubbard <jhubbard@nvidia.com>
Subject: [PATCH v22 01/31] splice: Fix filemap_splice_read() to use the correct inode
Date: Mon, 22 May 2023 14:49:48 +0100	[thread overview]
Message-ID: <20230522135018.2742245-2-dhowells@redhat.com> (raw)
In-Reply-To: <20230522135018.2742245-1-dhowells@redhat.com>

Fix filemap_splice_read() to use file->f_mapping->host, not file->f_inode,
as the source of the file size because in the case of a block device,
file->f_inode points to the block-special file (which is typically 0
length) and not the backing store.

Fixes: 07073eb01c5f ("splice: Add a func to do a splice from a buffered file without ITER_PIPE")
Signed-off-by: David Howells <dhowells@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Christian Brauner <brauner@kernel.org>
cc: Steve French <stfrench@microsoft.com>
cc: Jens Axboe <axboe@kernel.dk>
cc: Al Viro <viro@zeniv.linux.org.uk>
cc: David Hildenbrand <david@redhat.com>
cc: John Hubbard <jhubbard@nvidia.com>
cc: linux-mm@kvack.org
cc: linux-block@vger.kernel.org
cc: linux-fsdevel@vger.kernel.org
---
 mm/filemap.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/mm/filemap.c b/mm/filemap.c
index b4c9bd368b7e..a2006936a6ae 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -2900,7 +2900,7 @@ ssize_t filemap_splice_read(struct file *in, loff_t *ppos,
 	do {
 		cond_resched();
 
-		if (*ppos >= i_size_read(file_inode(in)))
+		if (*ppos >= i_size_read(in->f_mapping->host))
 			break;
 
 		iocb.ki_pos = *ppos;
@@ -2916,7 +2916,7 @@ ssize_t filemap_splice_read(struct file *in, loff_t *ppos,
 		 * part of the page is not copied back to userspace (unless
 		 * another truncate extends the file - this is desired though).
 		 */
-		isize = i_size_read(file_inode(in));
+		isize = i_size_read(in->f_mapping->host);
 		if (unlikely(*ppos >= isize))
 			break;
 		end_offset = min_t(loff_t, isize, *ppos + len);

