@@ -332,3 +332,34 @@ Each "watch" costs roughly 90 bytes on a 32-bit kernel, and roughly 160 bytes
on a 64-bit one.
The current default value for ``max_user_watches`` is 4% of the
available low memory, divided by the "watch" cost in bytes.
+
+5. /proc/sys/fs/fuse - Configuration options for FUSE filesystems
+=====================================================================
+
+This directory contains the following configuration options for FUSE
+filesystems:
+
+``/proc/sys/fs/fuse/default_request_timeout`` is a read/write file for
+setting/getting the default timeout (in seconds) for a fuse server to
+reply to a kernel-issued request in the event where the server did not
+specify a timeout at mount. If the server set a timeout,
+then default_request_timeout will be ignored. The default
+"default_request_timeout" is set to 0. 0 indicates a no-op (eg
+requests will not have a default request timeout set if no timeout was
+specified by the server).
+
+``/proc/sys/fs/fuse/max_request_timeout`` is a read/write file for
+setting/getting the maximum timeout (in seconds) for a fuse server to
+reply to a kernel-issued request. A value greater than 0 automatically opts
+the server into a timeout that will be at most "max_request_timeout", even if
+the server did not specify a timeout and default_request_timeout is set to 0.
+If max_request_timeout is greater than 0 and the server set a timeout greater
+than max_request_timeout or default_request_timeout is set to greater than
+max_request_timeout, the system will use max_request_timeout as the timeout.
+0 indicates a no-op (eg requests will not have an upper bound on the timeout
+and if the server did not request a timeout and default_request_timeout was not
+set, there will be no timeout).
+
+Please note that for the timeout options, if the server does not respond to
+the request by the time the timeout elapses, then the connection to the fuse
+server will be aborted.
@@ -11,5 +11,6 @@ fuse-y := dev.o dir.o file.o inode.o control.o xattr.o acl.o readdir.o ioctl.o
fuse-y += iomode.o
fuse-$(CONFIG_FUSE_DAX) += dax.o
fuse-$(CONFIG_FUSE_PASSTHROUGH) += passthrough.o
+fuse-$(CONFIG_SYSCTL) += sysctl.o
virtiofs-y := virtio_fs.o
@@ -47,6 +47,14 @@
/** Number of dentries for each connection in the control filesystem */
#define FUSE_CTL_NUM_DENTRIES 5
+/*
+ * Default timeout (in seconds) for the server to reply to a request
+ * if no timeout was specified on mount
+ */
+extern u32 fuse_default_req_timeout;
+/** Max timeout (in seconds) for the server to reply to a request */
+extern u32 fuse_max_req_timeout;
+
/** List of active connections */
extern struct list_head fuse_conn_list;
@@ -1480,4 +1488,12 @@ ssize_t fuse_passthrough_splice_write(struct pipe_inode_info *pipe,
size_t len, unsigned int flags);
ssize_t fuse_passthrough_mmap(struct file *file, struct vm_area_struct *vma);
+#ifdef CONFIG_SYSCTL
+int fuse_sysctl_register(void);
+void fuse_sysctl_unregister(void);
+#else
+static inline int fuse_sysctl_register(void) { return 0; }
+static inline void fuse_sysctl_unregister(void) { return; }
+#endif /* CONFIG_SYSCTL */
+
#endif /* _FS_FUSE_I_H */
@@ -35,6 +35,10 @@ DEFINE_MUTEX(fuse_mutex);
static int set_global_limit(const char *val, const struct kernel_param *kp);
+/* default is no timeout */
+u32 fuse_default_req_timeout = 0;
+u32 fuse_max_req_timeout = 0;
+
unsigned max_user_bgreq;
module_param_call(max_user_bgreq, set_global_limit, param_get_uint,
&max_user_bgreq, 0644);
@@ -1678,6 +1682,7 @@ int fuse_fill_super_common(struct super_block *sb, struct fuse_fs_context *ctx)
struct fuse_conn *fc = fm->fc;
struct inode *root;
struct dentry *root_dentry;
+ u32 req_timeout;
int err;
err = -EINVAL;
@@ -1730,10 +1735,16 @@ int fuse_fill_super_common(struct super_block *sb, struct fuse_fs_context *ctx)
fc->group_id = ctx->group_id;
fc->legacy_opts_show = ctx->legacy_opts_show;
fc->max_read = max_t(unsigned int, 4096, ctx->max_read);
- fc->req_timeout = ctx->req_timeout * HZ;
fc->destroy = ctx->destroy;
fc->no_control = ctx->no_control;
fc->no_force_umount = ctx->no_force_umount;
+ req_timeout = ctx->req_timeout ?: fuse_default_req_timeout;
+ if (!fuse_max_req_timeout)
+ fc->req_timeout = req_timeout * HZ;
+ else if (!req_timeout)
+ fc->req_timeout = fuse_max_req_timeout * HZ;
+ else
+ fc->req_timeout = min(req_timeout, fuse_max_req_timeout) * HZ;
err = -ENOMEM;
root = fuse_get_root_inode(sb, ctx->rootmode);
@@ -2046,8 +2057,14 @@ static int __init fuse_fs_init(void)
if (err)
goto out3;
+ err = fuse_sysctl_register();
+ if (err)
+ goto out4;
+
return 0;
+ out4:
+ unregister_filesystem(&fuse_fs_type);
out3:
unregister_fuseblk();
out2:
new file mode 100644
@@ -0,0 +1,42 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+* linux/fs/fuse/fuse_sysctl.c
+*
+* Sysctl interface to fuse parameters
+*/
+#include <linux/sysctl.h>
+
+#include "fuse_i.h"
+
+static struct ctl_table_header *fuse_table_header;
+
+static struct ctl_table fuse_sysctl_table[] = {
+ {
+ .procname = "default_request_timeout",
+ .data = &fuse_default_req_timeout,
+ .maxlen = sizeof(fuse_default_req_timeout),
+ .mode = 0644,
+ .proc_handler = proc_douintvec,
+ },
+ {
+ .procname = "max_request_timeout",
+ .data = &fuse_max_req_timeout,
+ .maxlen = sizeof(fuse_max_req_timeout),
+ .mode = 0644,
+ .proc_handler = proc_douintvec,
+ },
+};
+
+int fuse_sysctl_register(void)
+{
+ fuse_table_header = register_sysctl("fs/fuse", fuse_sysctl_table);
+ if (!fuse_table_header)
+ return -ENOMEM;
+ return 0;
+}
+
+void fuse_sysctl_unregister(void)
+{
+ unregister_sysctl_table(fuse_table_header);
+ fuse_table_header = NULL;
+}