[RFC PATCH 1/2] fuse: Add "timeout" sysfs attribute for each fuse connection

[Yafang Shao <laoar.shao@gmail.com>]

A dedicated "timeout" sysfs attribute has been introduced for each fuse
connection, empowering users to manage and control the timeout duration for
individual connections.

This is a preparation for the followup patch.

Signed-off-by: Yafang Shao <laoar.shao@gmail.com>
---
 fs/fuse/control.c | 50 ++++++++++++++++++++++++++++++++++++++++++++++-
 fs/fuse/fuse_i.h  |  5 ++++-
 2 files changed, 53 insertions(+), 2 deletions(-)

diff --git a/fs/fuse/control.c b/fs/fuse/control.c
index 97ac994ff78f..247fbec72cda 100644
--- a/fs/fuse/control.c
+++ b/fs/fuse/control.c
@@ -180,6 +180,44 @@ static ssize_t fuse_conn_congestion_threshold_write(struct file *file,
 	return ret;
 }
 
+static ssize_t fuse_conn_timeout_read(struct file *file,
+				      char __user *buf, size_t len,
+				      loff_t *ppos)
+{
+	struct fuse_conn *fc;
+	u32 val;
+
+	fc = fuse_ctl_file_conn_get(file);
+	if (!fc)
+		return 0;
+
+	val = READ_ONCE(fc->timeout);
+	fuse_conn_put(fc);
+	return fuse_conn_limit_read(file, buf, len, ppos, val);
+}
+
+static ssize_t fuse_conn_timeout_write(struct file *file,
+				       const char __user *buf,
+				       size_t count, loff_t *ppos)
+{
+	struct fuse_conn *fc;
+	ssize_t ret;
+	u32 val;
+
+	ret = fuse_conn_limit_write(file, buf, count, ppos, &val,
+				    3600);
+	if (ret <= 0)
+		goto out;
+	fc = fuse_ctl_file_conn_get(file);
+	if (!fc)
+		goto out;
+
+	WRITE_ONCE(fc->timeout, val);
+	fuse_conn_put(fc);
+out:
+	return ret;
+}
+
 static const struct file_operations fuse_ctl_abort_ops = {
 	.open = nonseekable_open,
 	.write = fuse_conn_abort_write,
@@ -206,6 +244,13 @@ static const struct file_operations fuse_conn_congestion_threshold_ops = {
 	.llseek = no_llseek,
 };
 
+static const struct file_operations fuse_conn_timeout_ops = {
+	.open = nonseekable_open,
+	.read = fuse_conn_timeout_read,
+	.write = fuse_conn_timeout_write,
+	.llseek = no_llseek,
+};
+
 static struct dentry *fuse_ctl_add_dentry(struct dentry *parent,
 					  struct fuse_conn *fc,
 					  const char *name,
@@ -274,7 +319,10 @@ int fuse_ctl_add_conn(struct fuse_conn *fc)
 				 1, NULL, &fuse_conn_max_background_ops) ||
 	    !fuse_ctl_add_dentry(parent, fc, "congestion_threshold",
 				 S_IFREG | 0600, 1, NULL,
-				 &fuse_conn_congestion_threshold_ops))
+				 &fuse_conn_congestion_threshold_ops) ||
+	    !fuse_ctl_add_dentry(parent, fc, "timeout",
+				 S_IFREG | 0600, 1, NULL,
+				 &fuse_conn_timeout_ops))
 		goto err;
 
 	return 0;
diff --git a/fs/fuse/fuse_i.h b/fs/fuse/fuse_i.h
index f23919610313..367601bf7285 100644
--- a/fs/fuse/fuse_i.h
+++ b/fs/fuse/fuse_i.h
@@ -45,7 +45,7 @@
 #define FUSE_NAME_MAX 1024
 
 /** Number of dentries for each connection in the control filesystem */
-#define FUSE_CTL_NUM_DENTRIES 5
+#define FUSE_CTL_NUM_DENTRIES 6
 
 /** List of active connections */
 extern struct list_head fuse_conn_list;
@@ -917,6 +917,9 @@ struct fuse_conn {
 	/** IDR for backing files ids */
 	struct idr backing_files_map;
 #endif
+
+	/* fuse request timeout */
+	u32 timeout;
 };
 
 /*
-- 
2.43.5