linux-kernel - [PATCH 05/11] fs: refactor new_sync

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Date:   Wed, 24 Jun 2020 18:28:55 +0200
From:   Christoph Hellwig <hch@....de>
To:     Al Viro <viro@...iv.linux.org.uk>,
        Linus Torvalds <torvalds@...ux-foundation.org>
Cc:     Luis Chamberlain <mcgrof@...nel.org>,
        Kees Cook <keescook@...omium.org>,
        Iurii Zaikin <yzaikin@...gle.com>,
        linux-kernel@...r.kernel.org, linux-fsdevel@...r.kernel.org
Subject: [PATCH 05/11] fs: refactor new_sync_read

Pass the read_iter method as a parameter and mark the function
non-static.  This allows reusing it for additional callsites e.g.
in procfs.

Signed-off-by: Christoph Hellwig <hch@....de>
---
 fs/read_write.c    | 8 +++++---
 include/linux/fs.h | 2 ++
 2 files changed, 7 insertions(+), 3 deletions(-)

diff --git a/fs/read_write.c b/fs/read_write.c
index 24ffbf3cbda243..b92c222ca886ca 100644
--- a/fs/read_write.c
+++ b/fs/read_write.c
@@ -401,7 +401,8 @@ int rw_verify_area(int read_write, struct file *file, const loff_t *ppos, size_t
 				read_write == READ ? MAY_READ : MAY_WRITE);
 }
 
-static ssize_t new_sync_read(struct file *filp, char __user *buf, size_t len, loff_t *ppos)
+ssize_t iter_read(struct file *filp, char __user *buf, size_t len, loff_t *ppos,
+		ssize_t (*cb)(struct kiocb *iocb, struct iov_iter *iter))
 {
 	struct iovec iov = { .iov_base = buf, .iov_len = len };
 	struct kiocb kiocb;
@@ -412,7 +413,7 @@ static ssize_t new_sync_read(struct file *filp, char __user *buf, size_t len, lo
 	kiocb.ki_pos = (ppos ? *ppos : 0);
 	iov_iter_init(&iter, READ, &iov, 1, len);
 
-	ret = call_read_iter(filp, &kiocb, &iter);
+	ret = cb(&kiocb, &iter);
 	BUG_ON(ret == -EIOCBQUEUED);
 	if (ppos)
 		*ppos = kiocb.ki_pos;
@@ -492,7 +493,8 @@ ssize_t vfs_read(struct file *file, char __user *buf, size_t count, loff_t *pos)
 	else if (file->f_op->read)
 		ret = file->f_op->read(file, buf, count, pos);
 	else if (file->f_op->read_iter)
-		ret = new_sync_read(file, buf, count, pos);
+		ret = iter_read(file, buf, count, pos,
+				file->f_op->read_iter);
 	else
 		ret = -EINVAL;
 	if (ret > 0) {
diff --git a/include/linux/fs.h b/include/linux/fs.h
index d8fc3015f5a197..d0fea0281ef29b 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -1919,6 +1919,8 @@ ssize_t rw_copy_check_uvector(int type, const struct iovec __user * uvector,
 			      unsigned long nr_segs, unsigned long fast_segs,
 			      struct iovec *fast_pointer,
 			      struct iovec **ret_pointer);
+ssize_t iter_read(struct file *filp, char __user *buf, size_t len, loff_t *ppos,
+		ssize_t (*cb)(struct kiocb *iocb, struct iov_iter *iter));
 
 extern ssize_t vfs_read(struct file *, char __user *, size_t, loff_t *);
 extern ssize_t vfs_write(struct file *, const char __user *, size_t, loff_t *);
-- 
2.26.2