linux-next/fs/fuse/sysctl.c
Joanne Koong 2b3933b1e0 fuse: enable dynamic configuration of fuse max pages limit (FUSE_MAX_MAX_PAGES)
Introduce the capability to dynamically configure the max pages limit
(FUSE_MAX_MAX_PAGES) through a sysctl. This allows system administrators
to dynamically set the maximum number of pages that can be used for
servicing requests in fuse.

Previously, this is gated by FUSE_MAX_MAX_PAGES which is statically set
to 256 pages. One result of this is that the buffer size for a write
request is limited to 1 MiB on a 4k-page system.

The default value for this sysctl is the original limit (256 pages).

$ sysctl -a | grep max_pages_limit
fs.fuse.max_pages_limit = 256

$ sysctl -n fs.fuse.max_pages_limit
256

$ echo 1024 | sudo tee /proc/sys/fs/fuse/max_pages_limit
1024

$ sysctl -n fs.fuse.max_pages_limit
1024

$ echo 65536 | sudo tee /proc/sys/fs/fuse/max_pages_limit
tee: /proc/sys/fs/fuse/max_pages_limit: Invalid argument

$ echo 0 | sudo tee /proc/sys/fs/fuse/max_pages_limit
tee: /proc/sys/fs/fuse/max_pages_limit: Invalid argument

$ echo 65535 | sudo tee /proc/sys/fs/fuse/max_pages_limit
65535

$ sysctl -n fs.fuse.max_pages_limit
65535

Signed-off-by: Joanne Koong <joannelkoong@gmail.com>
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: Sweet Tea Dorminy <sweettea-kernel@dorminy.me>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
2024-10-25 17:05:49 +02:00

41 lines
892 B
C

// 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;
/* Bound by fuse_init_out max_pages, which is a u16 */
static unsigned int sysctl_fuse_max_pages_limit = 65535;
static struct ctl_table fuse_sysctl_table[] = {
{
.procname = "max_pages_limit",
.data = &fuse_max_pages_limit,
.maxlen = sizeof(fuse_max_pages_limit),
.mode = 0644,
.proc_handler = proc_douintvec_minmax,
.extra1 = SYSCTL_ONE,
.extra2 = &sysctl_fuse_max_pages_limit,
},
};
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;
}