On Tue, Oct 29, 2024 at 12:40 PM Bernd Schubert
<bernd.schubert@xxxxxxxxxxx> wrote:
>
> On 10/11/24 21:13, Joanne Koong wrote:
> > Introduce two new sysctls, "default_request_timeout" and
> > "max_request_timeout". These control how long (in minutes) a server can
> > take to reply to a request. If the server does not reply by the timeout,
> > then the connection will be aborted.
> >
> > "default_request_timeout" sets the default timeout if no timeout is
> > specified by the fuse server on mount. 0 (default) indicates no default
> > timeout should be enforced. If the server did specify a timeout, then
> > default_request_timeout will be ignored.
> >
> > "max_request_timeout" sets the max amount of time the server may take to
> > reply to a request. 0 (default) indicates no maximum timeout. If
> > max_request_timeout is set and the fuse server attempts to set a
> > timeout greater than max_request_timeout, the system will use
> > max_request_timeout as the timeout. Similarly, if default_request_timeout
> > is greater than max_request_timeout, the system will use
> > max_request_timeout as the timeout. If the server does not request a
> > timeout and default_request_timeout is set to 0 but max_request_timeout
> > is set, then the timeout will be max_request_timeout.
> >
> > Please note that these timeouts are not 100% precise. The request may
> > take an extra FUSE_TIMEOUT_TIMER_FREQ seconds beyond the set max timeout
> > due to how it's internally implemented.
> >
> > $ sysctl -a | grep fuse.default_request_timeout
> > fs.fuse.default_request_timeout = 0
> >
> > $ echo 65536 | sudo tee /proc/sys/fs/fuse/default_request_timeout
> > tee: /proc/sys/fs/fuse/default_request_timeout: Invalid argument
> >
> > $ echo 65535 | sudo tee /proc/sys/fs/fuse/default_request_timeout
> > 65535
> >
> > $ sysctl -a | grep fuse.default_request_timeout
> > fs.fuse.default_request_timeout = 65535
> >
> > $ echo 0 | sudo tee /proc/sys/fs/fuse/default_request_timeout
> > 0
> >
> > $ sysctl -a | grep fuse.default_request_timeout
> > fs.fuse.default_request_timeout = 0
> >
> > Signed-off-by: Joanne Koong <joannelkoong@xxxxxxxxx>
> > ---
> > Documentation/admin-guide/sysctl/fs.rst | 27 +++++++++++++++++++++++++
> > fs/fuse/fuse_i.h | 10 +++++++++
> > fs/fuse/inode.c | 16 +++++++++++++--
> > fs/fuse/sysctl.c | 20 ++++++++++++++++++
> > 4 files changed, 71 insertions(+), 2 deletions(-)
> >
> > diff --git a/Documentation/admin-guide/sysctl/fs.rst b/Documentation/admin-guide/sysctl/fs.rst
> > index fa25d7e718b3..790a34291467 100644
> > --- a/Documentation/admin-guide/sysctl/fs.rst
> > +++ b/Documentation/admin-guide/sysctl/fs.rst
> > @@ -342,3 +342,30 @@ filesystems:
> > ``/proc/sys/fs/fuse/max_pages_limit`` is a read/write file for
> > setting/getting the maximum number of pages that can be used for servicing
> > requests in FUSE.
> > +
> > +``/proc/sys/fs/fuse/default_request_timeout`` is a read/write file for
> > +setting/getting the default timeout (in minutes) 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 minutes) 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 a value 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. Please also note that the timeouts are not 100%
> > +precise (eg you may set 10 minutes but the timeout may kick in after 11
> > +minutes).
> > diff --git a/fs/fuse/fuse_i.h b/fs/fuse/fuse_i.h
> > index ef4558c2c44e..28d9230f4fcb 100644
> > --- a/fs/fuse/fuse_i.h
> > +++ b/fs/fuse/fuse_i.h
> > @@ -46,6 +46,16 @@
> >
> > /** Maximum of max_pages received in init_out */
> > extern unsigned int fuse_max_pages_limit;
> > +/*
> > + * Default timeout (in minutes) for the server to reply to a request
> > + * before the connection is aborted, if no timeout was specified on mount.
> > + */
> > +extern unsigned int fuse_default_req_timeout;
> > +/*
> > + * Max timeout (in minutes) for the server to reply to a request before
> > + * the connection is aborted.
> > + */
> > +extern unsigned int fuse_max_req_timeout;
> >
> > /** List of active connections */
> > extern struct list_head fuse_conn_list;
> > diff --git a/fs/fuse/inode.c b/fs/fuse/inode.c
> > index a78aac76b942..d97dde59eac3 100644
> > --- a/fs/fuse/inode.c
> > +++ b/fs/fuse/inode.c
> > @@ -36,6 +36,9 @@ DEFINE_MUTEX(fuse_mutex);
> > static int set_global_limit(const char *val, const struct kernel_param *kp);
> >
> > unsigned int fuse_max_pages_limit = 256;
> > +/* default is no timeout */
> > +unsigned int fuse_default_req_timeout = 0;
> > +unsigned int fuse_max_req_timeout = 0;
> >
> > unsigned max_user_bgreq;
> > module_param_call(max_user_bgreq, set_global_limit, param_get_uint,
> > @@ -1701,8 +1704,17 @@ EXPORT_SYMBOL_GPL(fuse_init_fs_context_submount);
> >
> > static void fuse_init_fc_timeout(struct fuse_conn *fc, struct fuse_fs_context *ctx)
> > {
> > - if (ctx->req_timeout) {
> > - if (check_mul_overflow(ctx->req_timeout * 60, HZ, &fc->timeout.req_timeout))
> > + unsigned int timeout = ctx->req_timeout ?: fuse_default_req_timeout;
> > +
> > + if (fuse_max_req_timeout) {
> > + if (!timeout)
> > + timeout = fuse_max_req_timeout;
>
> Hmm, so 'max' might be used as 'min' as well. Isn't that a bit confusing?
Interesting. Yeah, i don't think there's a good name that encapsulates
the behavior of this (eg sets a min timeout if no timeout is set but
sets the max timeout if a timeout is set). in my head, I think of it
more as "max timeout that is automatically enforced if there's no timeout".
Thanks,
Joanne
>
>
> > + else
> > + timeout = min(timeout, fuse_max_req_timeout)> + }
> > +
> > + if (timeout) {
> > + if (check_mul_overflow(timeout * 60, HZ, &fc->timeout.req_timeout))
> > fc->timeout.req_timeout = U32_MAX;
> > timer_setup(&fc->timeout.timer, fuse_check_timeout, 0);
> > mod_timer(&fc->timeout.timer, jiffies + FUSE_TIMEOUT_TIMER_FREQ);
> > diff --git a/fs/fuse/sysctl.c b/fs/fuse/sysctl.c
> > index b272bb333005..e70b5269c16d 100644
> > --- a/fs/fuse/sysctl.c
> > +++ b/fs/fuse/sysctl.c
> > @@ -13,6 +13,8 @@ static struct ctl_table_header *fuse_table_header;
> > /* Bound by fuse_init_out max_pages, which is a u16 */
> > static unsigned int sysctl_fuse_max_pages_limit = 65535;
> >
> > +static unsigned int sysctl_fuse_max_req_timeout_limit = U16_MAX;
> > +
> > static struct ctl_table fuse_sysctl_table[] = {
> > {
> > .procname = "max_pages_limit",
> > @@ -23,6 +25,24 @@ static struct ctl_table fuse_sysctl_table[] = {
> > .extra1 = SYSCTL_ONE,
> > .extra2 = &sysctl_fuse_max_pages_limit,
> > },
> > + {
> > + .procname = "default_request_timeout",
> > + .data = &fuse_default_req_timeout,
> > + .maxlen = sizeof(fuse_default_req_timeout),
> > + .mode = 0644,
> > + .proc_handler = proc_douintvec_minmax,
> > + .extra1 = SYSCTL_ZERO,
>
> There is slight whitespace issue here - spaces instead of tabs.
Thanks for noting - I'll fix this and the one below.
>
>
> > + .extra2 = &sysctl_fuse_max_req_timeout_limit,
> > + },
> > + {
> > + .procname = "max_request_timeout",
> > + .data = &fuse_max_req_timeout,
> > + .maxlen = sizeof(fuse_max_req_timeout),
> > + .mode = 0644,
> > + .proc_handler = proc_douintvec_minmax,
> > + .extra1 = SYSCTL_ZERO,
>
> And here.
>
> > + .extra2 = &sysctl_fuse_max_req_timeout_limit,
> > + },
> > };
> >
> > int fuse_sysctl_register(void)
>
> Reviewed-by: Bernd Schubert <bschubert@xxxxxxx>
