[PATCH 6.4 018/800] splice: Fix filemap_splice_read() to use the correct inode

Greg Kroah-Hartman
2023-07-16T19:53:38Z

From: David Howells <dhowells@redhat.com>

[ Upstream commit c37222082f23c456664d1c3182a714670ab8f9a4 ]

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
Link: https://lore.kernel.org/r/20230522135018.2742245-2-dhowells@redhat.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
mm/filemap.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/mm/filemap.c b/mm/filemap.c
index 83dda76d1fc36..8abce63b259c9 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -2906,7 +2906,7 @@ 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;
@@ -2922,7 +2922,7 @@ 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);
--
2.39.2