linux-kernel - [PATCH v22 14/31] 9p: Add splice

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Message-Id: <20230522135018.2742245-15-dhowells@redhat.com>
Date:   Mon, 22 May 2023 14:50:01 +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>,
        Dominique Martinet <asmadeus@...ewreck.org>,
        Eric Van Hensbergen <ericvh@...nel.org>,
        Latchesar Ionkov <lucho@...kov.net>,
        Christian Schoenebeck <linux_oss@...debyte.com>,
        v9fs@...ts.linux.dev
Subject: [PATCH v22 14/31] 9p:  Add splice_read wrapper

Add a splice_read wrapper for 9p.  We should use copy_splice_read() if
9PL_DIRECT is set and filemap_splice_read() otherwise.  Note that this
doesn't seem to be particularly related to O_DIRECT.

Signed-off-by: David Howells <dhowells@...hat.com>
cc: Christoph Hellwig <hch@....de>
cc: Al Viro <viro@...iv.linux.org.uk>
cc: Jens Axboe <axboe@...nel.dk>
cc: Dominique Martinet <asmadeus@...ewreck.org>
cc: Eric Van Hensbergen <ericvh@...nel.org>
cc: Latchesar Ionkov <lucho@...kov.net>
cc: Christian Schoenebeck <linux_oss@...debyte.com>
cc: v9fs@...ts.linux.dev
cc: linux-fsdevel@...r.kernel.org
cc: linux-block@...r.kernel.org
cc: linux-mm@...ck.org
---
 fs/9p/vfs_file.c | 26 ++++++++++++++++++++++++--
 1 file changed, 24 insertions(+), 2 deletions(-)

diff --git a/fs/9p/vfs_file.c b/fs/9p/vfs_file.c
index 6c31b8c8112d..2996fb00387f 100644
--- a/fs/9p/vfs_file.c
+++ b/fs/9p/vfs_file.c
@@ -374,6 +374,28 @@ v9fs_file_read_iter(struct kiocb *iocb, struct iov_iter *to)
 	return ret;
 }
 
+/*
+ * v9fs_file_splice_read - splice-read from a file
+ * @in: The 9p file to read from
+ * @ppos: Where to find/update the file position
+ * @pipe: The pipe to splice into
+ * @len: The maximum amount of data to splice
+ * @flags: SPLICE_F_* flags
+ */
+static ssize_t v9fs_file_splice_read(struct file *in, loff_t *ppos,
+				     struct pipe_inode_info *pipe,
+				     size_t len, unsigned int flags)
+{
+	struct p9_fid *fid = in->private_data;
+
+	p9_debug(P9_DEBUG_VFS, "fid %d count %zu offset %lld\n",
+		 fid->fid, len, *ppos);
+
+	if (fid->mode & P9L_DIRECT)
+		return copy_splice_read(in, ppos, pipe, len, flags);
+	return filemap_splice_read(in, ppos, pipe, len, flags);
+}
+
 /**
  * v9fs_file_write_iter - write to a file
  * @iocb: The operation parameters
@@ -569,7 +591,7 @@ const struct file_operations v9fs_file_operations = {
 	.release = v9fs_dir_release,
 	.lock = v9fs_file_lock,
 	.mmap = generic_file_readonly_mmap,
-	.splice_read = generic_file_splice_read,
+	.splice_read = v9fs_file_splice_read,
 	.splice_write = iter_file_splice_write,
 	.fsync = v9fs_file_fsync,
 };
@@ -583,7 +605,7 @@ const struct file_operations v9fs_file_operations_dotl = {
 	.lock = v9fs_file_lock_dotl,
 	.flock = v9fs_file_flock_dotl,
 	.mmap = v9fs_file_mmap,
-	.splice_read = generic_file_splice_read,
+	.splice_read = v9fs_file_splice_read,
 	.splice_write = iter_file_splice_write,
 	.fsync = v9fs_file_fsync_dotl,
 };