linux-kernel - [PATCH 001/437] fs: split do_loop_readv_writev() into separate read/write side helpers

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Message-ID: <20240411153126.16201-2-axboe@kernel.dk>
Date: Thu, 11 Apr 2024 09:12:21 -0600
From: Jens Axboe <axboe@...nel.dk>
To: linux-kernel@...r.kernel.org
Cc: Jens Axboe <axboe@...nel.dk>
Subject: [PATCH 001/437] fs: split do_loop_readv_writev() into separate read/write side helpers

No functional changes, just in preparation for using these separately.

Signed-off-by: Jens Axboe <axboe@...nel.dk>
---
 fs/read_write.c | 43 +++++++++++++++++++++++++++++++++----------
 1 file changed, 33 insertions(+), 10 deletions(-)

diff --git a/fs/read_write.c b/fs/read_write.c
index d4c036e82b6c..82ec75937b08 100644
--- a/fs/read_write.c
+++ b/fs/read_write.c
@@ -746,8 +746,10 @@ static ssize_t do_iter_readv_writev(struct file *filp, struct iov_iter *iter,
 }
 
 /* Do it by hand, with file-ops */
-static ssize_t do_loop_readv_writev(struct file *filp, struct iov_iter *iter,
-		loff_t *ppos, int type, rwf_t flags)
+static ssize_t do_loop_readv(struct file *file, struct iov_iter *iter,
+			     loff_t *ppos, rwf_t flags,
+			     ssize_t (*read)(struct file *, char __user *,
+					     size_t, loff_t *))
 {
 	ssize_t ret = 0;
 
@@ -757,14 +759,35 @@ static ssize_t do_loop_readv_writev(struct file *filp, struct iov_iter *iter,
 	while (iov_iter_count(iter)) {
 		ssize_t nr;
 
-		if (type == READ) {
-			nr = filp->f_op->read(filp, iter_iov_addr(iter),
-						iter_iov_len(iter), ppos);
-		} else {
-			nr = filp->f_op->write(filp, iter_iov_addr(iter),
-						iter_iov_len(iter), ppos);
+		nr = read(file, iter_iov_addr(iter), iter_iov_len(iter), ppos);
+		if (nr < 0) {
+			if (!ret)
+				ret = nr;
+			break;
 		}
+		ret += nr;
+		if (nr != iter_iov_len(iter))
+			break;
+		iov_iter_advance(iter, nr);
+	}
+
+	return ret;
+}
+
+static ssize_t do_loop_writev(struct file *file, struct iov_iter *iter,
+			      loff_t *ppos, rwf_t flags,
+			      ssize_t (*write)(struct file *, const char __user *,
+					       size_t, loff_t *))
+{
+	ssize_t ret = 0;
+
+	if (flags & ~RWF_HIPRI)
+		return -EOPNOTSUPP;
+
+	while (iov_iter_count(iter)) {
+		ssize_t nr;
 
+		nr = write(file, iter_iov_addr(iter), iter_iov_len(iter), ppos);
 		if (nr < 0) {
 			if (!ret)
 				ret = nr;
@@ -931,7 +954,7 @@ static ssize_t vfs_readv(struct file *file, const struct iovec __user *vec,
 	if (file->f_op->read_iter)
 		ret = do_iter_readv_writev(file, &iter, pos, READ, flags);
 	else
-		ret = do_loop_readv_writev(file, &iter, pos, READ, flags);
+		ret = do_loop_readv(file, &iter, pos, flags, file->f_op->read);
 out:
 	if (ret >= 0)
 		fsnotify_access(file);
@@ -970,7 +993,7 @@ static ssize_t vfs_writev(struct file *file, const struct iovec __user *vec,
 	if (file->f_op->write_iter)
 		ret = do_iter_readv_writev(file, &iter, pos, WRITE, flags);
 	else
-		ret = do_loop_readv_writev(file, &iter, pos, WRITE, flags);
+		ret = do_loop_writev(file, &iter, pos, flags, file->f_op->write);
 	if (ret > 0)
 		fsnotify_modify(file);
 	file_end_write(file);
-- 
2.43.0