linux-kernel - [PATCH v22 07/31] splice: Make splice from an O_DIRECT fd use copy_splice

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-Id: <20230522135018.2742245-8-dhowells@redhat.com>
Date:   Mon, 22 May 2023 14:49:54 +0100
From:   David Howells <dhowells@...hat.com>
To:     Jens Axboe <axboe@...nel.dk>, Al Viro <viro@...iv.linux.org.uk>,
        Christoph Hellwig <hch@...radead.org>
Cc:     David Howells <dhowells@...hat.com>,
        Matthew Wilcox <willy@...radead.org>, Jan Kara <jack@...e.cz>,
        Jeff Layton <jlayton@...nel.org>,
        David Hildenbrand <david@...hat.com>,
        Jason Gunthorpe <jgg@...dia.com>,
        Logan Gunthorpe <logang@...tatee.com>,
        Hillf Danton <hdanton@...a.com>,
        Christian Brauner <brauner@...nel.org>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        linux-fsdevel@...r.kernel.org, linux-block@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-mm@...ck.org,
        Christoph Hellwig <hch@....de>
Subject: [PATCH v22 07/31] splice: Make splice from an O_DIRECT fd use copy_splice_read()

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@...hat.com>
Reviewed-by: Christoph Hellwig <hch@....de>
Reviewed-by: Christian Brauner <brauner@...nel.org>
cc: Al Viro <viro@...iv.linux.org.uk>
cc: Jens Axboe <axboe@...nel.dk>
cc: linux-fsdevel@...r.kernel.org
cc: linux-block@...r.kernel.org
cc: linux-mm@...ck.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);