[PATCH v21 07/30] splice: Make splice from an O_DIRECT fd use copy_splice_read()

David Howells
2023-05-20T00:01:23Z

Make a read splice from a file descriptor that's open O_DIRECT use
copy_splice_read() to do the reading as filemap_splice_read() is unlikely
to find any pagecache to splice.

Signed-off-by: David Howells <dhowells@redhat.com>
cc: Christoph Hellwig <hch@lst.de>
cc: Al Viro <viro@zeniv.linux.org.uk>
cc: Jens Axboe <axboe@kernel.dk>
cc: linux-fsdevel@vger.kernel.org
cc: linux-block@vger.kernel.org
cc: linux-mm@kvack.org
---

Notes:
ver #21)
- Needs to be in vfs_splice_read(), not generic_file_splice_read().

fs/splice.c | 6 ++++++
1 file changed, 6 insertions(+)

diff --git a/fs/splice.c b/fs/splice.c
index fe3309ffeb26..76126b1aafcb 100644
--- a/fs/splice.c
+++ b/fs/splice.c
@@ -907,6 +907,12 @@ long vfs_splice_read(struct file *in, loff_t *ppos,

if (unlikely(!in->f_op->splice_read))
return warn_unsupported(in, "read");
+ /*
+ * O_DIRECT doesn't deal with the pagecache, so we allocate a buffer,
+ * copy into it and splice that into the pipe.
+ */
+ if ((in->f_flags & O_DIRECT))
+ return copy_splice_read(in, ppos, pipe, len, flags);
return in->f_op->splice_read(in, ppos, pipe, len, flags);
}
EXPORT_SYMBOL_GPL(vfs_splice_read);