On 8/14/24 7:22 AM, Joanne Koong wrote: > 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> > Reviewed-by: Josef Bacik <josef@xxxxxxxxxxxxxx> > Reviewed-by: Bernd Schubert <bschubert@xxxxxxx> > --- > 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. "0 indicates no timeout" I think 0 max_request_timeout shall indicate that there's no explicit maximum limitation for request_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 0a2fa487a3bf..dae9977fa050 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 > +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 */ > 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; So if fuse_max_req_timeout is non-zero and req_timeout is zero (either because of 0 fuse_default_req_timeout, or explicit "-o request_timeout = 0" mount option), the final request timeout is exactly fuse_max_req_timeout, which is unexpected as I think 0 fuse_default_req_timeout, or "-o request_timeout=0" shall indicate no timeout. > + 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, > + }, Missing "{}" here? The internal implementation of register_sysctl() depends on an empty last element of the array as the sentinel. > +}; > + > +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; > +} -- Thanks, Jingbo