Introduce two new sysctls, "default_request_timeout" and
"max_request_timeout". These control timeouts on replies by the
server to kernel-issued fuse requests.
"default_request_timeout" sets a timeout if no timeout is specified by
the fuse server on mount. 0 (default) indicates no timeout should be enforced.
"max_request_timeout" sets a maximum timeout for fuse requests. If the
fuse server attempts to set a timeout greater than max_request_timeout,
the system will default to max_request_timeout. Similarly, if the max
default timeout is greater than the max request timeout, the system will
default to the max request timeout. 0 (default) indicates no timeout should
be enforced.
$ sysctl -a | grep fuse
fs.fuse.default_request_timeout = 0
fs.fuse.max_request_timeout = 0
$ echo 0x100000000 | sudo tee /proc/sys/fs/fuse/default_request_timeout
tee: /proc/sys/fs/fuse/default_request_timeout: Invalid argument
$ echo 0xFFFFFFFF | sudo tee /proc/sys/fs/fuse/default_request_timeout
0xFFFFFFFF
$ sysctl -a | grep fuse
fs.fuse.default_request_timeout = 4294967295
fs.fuse.max_request_timeout = 0
Signed-off-by: Joanne Koong <joannelkoong@xxxxxxxxx>
---
Documentation/admin-guide/sysctl/fs.rst | 17 ++++++++++
fs/fuse/Makefile | 2 +-
fs/fuse/fuse_i.h | 16 ++++++++++
fs/fuse/inode.c | 19 ++++++++++-
fs/fuse/sysctl.c | 42 +++++++++++++++++++++++++
5 files changed, 94 insertions(+), 2 deletions(-)
create mode 100644 fs/fuse/sysctl.c
diff --git a/Documentation/admin-guide/sysctl/fs.rst b/Documentation/admin-guide/sysctl/fs.rst
index 47499a1742bd..44fd495f69b4 100644
--- a/Documentation/admin-guide/sysctl/fs.rst
+++ b/Documentation/admin-guide/sysctl/fs.rst
@@ -332,3 +332,20 @@ 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. 0 indicates no timeout.
+
+``/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. If the server attempts to set a
+timeout greater than max_request_timeout, the system will use
+max_request_timeout as the timeout. 0 indicates no timeout.
diff --git a/fs/fuse/Makefile b/fs/fuse/Makefile
index 6e0228c6d0cb..cd4ef3e08ebf 100644
--- a/fs/fuse/Makefile
+++ b/fs/fuse/Makefile
@@ -7,7 +7,7 @@ obj-$(CONFIG_FUSE_FS) += fuse.o
obj-$(CONFIG_CUSE) += cuse.o
obj-$(CONFIG_VIRTIO_FS) += virtiofs.o
-fuse-y := dev.o dir.o file.o inode.o control.o xattr.o acl.o readdir.o ioctl.o
+fuse-y := dev.o dir.o file.o inode.o control.o xattr.o acl.o readdir.o ioctl.o sysctl.o
fuse-y += iomode.o
fuse-$(CONFIG_FUSE_DAX) += dax.o
fuse-$(CONFIG_FUSE_PASSTHROUGH) += passthrough.o
diff --git a/fs/fuse/fuse_i.h b/fs/fuse/fuse_i.h
index 2b616c5977b4..1a3a3b8a83ae 100644
--- a/fs/fuse/fuse_i.h
+++ b/fs/fuse/fuse_i.h
@@ -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;
@@ -1486,4 +1494,12 @@ 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
+extern int fuse_sysctl_register(void);
+extern void fuse_sysctl_unregister(void);
+#else
+#define fuse_sysctl_register() (0)
+#define fuse_sysctl_unregister() do { } while (0)
+#endif /* CONFIG_SYSCTL */
+
#endif /* _FS_FUSE_I_H */
diff --git a/fs/fuse/inode.c b/fs/fuse/inode.c
index 9e69006fc026..cf333448f2d3 100644
--- a/fs/fuse/inode.c
+++ b/fs/fuse/inode.c
@@ -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:
diff --git a/fs/fuse/sysctl.c b/fs/fuse/sysctl.c
new file mode 100644
index 000000000000..c87bb0ecbfa9
--- /dev/null
+++ b/fs/fuse/sysctl.c
@@ -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;
+}
--
2.43.0
