[PATCH v16 04/13] coda: Implement splice-read

[David Howells <dhowells@redhat.com>]

Implement splice-read for coda by passing the request down a layer rather
than going through generic_file_splice_read() which is going to be changed
to assume that ->read_folio() is present on buffered files.

Signed-off-by: David Howells <dhowells@redhat.com>
Acked-by: Jan Harkes <jaharkes@cs.cmu.edu>
cc: Christoph Hellwig <hch@lst.de>
cc: Jens Axboe <axboe@kernel.dk>
cc: Al Viro <viro@zeniv.linux.org.uk>
cc: John Hubbard <jhubbard@nvidia.com>
cc: David Hildenbrand <david@redhat.com>
cc: Matthew Wilcox <willy@infradead.org>
cc: coda@cs.cmu.edu
cc: codalist@coda.cs.cmu.edu
cc: linux-unionfs@vger.kernel.org
cc: linux-block@vger.kernel.org
cc: linux-fsdevel@vger.kernel.org
cc: linux-mm@kvack.org
---
 fs/coda/file.c | 36 +++++++++++++++++++++++++++++++++++-
 1 file changed, 35 insertions(+), 1 deletion(-)

diff --git a/fs/coda/file.c b/fs/coda/file.c
index 3f3c81e6b1ab..33cd7880d30e 100644
--- a/fs/coda/file.c
+++ b/fs/coda/file.c
@@ -23,6 +23,7 @@
 #include <linux/slab.h>
 #include <linux/uaccess.h>
 #include <linux/uio.h>
+#include <linux/splice.h>
 
 #include <linux/coda.h>
 #include "coda_psdev.h"
@@ -94,6 +95,39 @@ coda_file_write_iter(struct kiocb *iocb, struct iov_iter *to)
 	return ret;
 }
 
+static ssize_t
+coda_file_splice_read(struct file *coda_file, loff_t *ppos,
+		      struct pipe_inode_info *pipe,
+		      size_t len, unsigned int flags)
+{
+	struct inode *coda_inode = file_inode(coda_file);
+	struct coda_file_info *cfi = coda_ftoc(coda_file);
+	struct file *in = cfi->cfi_container;
+	loff_t ki_pos = *ppos;
+	ssize_t ret;
+
+	if (!in->f_op->splice_read)
+		return -EINVAL;
+
+	ret = rw_verify_area(READ, in, ppos, len);
+	if (unlikely(ret < 0))
+		return ret;
+
+	ret = venus_access_intent(coda_inode->i_sb, coda_i2f(coda_inode),
+				  &cfi->cfi_access_intent,
+				  len, ki_pos, CODA_ACCESS_TYPE_READ);
+	if (ret)
+		goto finish_read;
+
+	ret = in->f_op->splice_read(in, ppos, pipe, len, flags);
+
+finish_read:
+	venus_access_intent(coda_inode->i_sb, coda_i2f(coda_inode),
+			    &cfi->cfi_access_intent,
+			    len, ki_pos, CODA_ACCESS_TYPE_READ_FINISH);
+	return ret;
+}
+
 static void
 coda_vm_open(struct vm_area_struct *vma)
 {
@@ -302,5 +336,5 @@ const struct file_operations coda_file_operations = {
 	.open		= coda_open,
 	.release	= coda_release,
 	.fsync		= coda_fsync,
-	.splice_read	= generic_file_splice_read,
+	.splice_read	= coda_file_splice_read,
 };