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virtiofsd: add --rlimit-nofile=NUM option

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Make it possible to specify the RLIMIT_NOFILE on the command-line.
Users running multiple virtiofsd processes should allocate a certain
number to each process so that the system-wide limit can never be
exhausted.

When this option is set to 0 the rlimit is left at its current value.
This is useful when a management tool wants to configure the rlimit
itself.

The default behavior remains unchanged: try to set the limit to
1,000,000 file descriptors if the current rlimit is lower.

Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Message-Id: <20200501140644.220940-2-stefanha@redhat.com>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
This commit is contained in:
Stefan Hajnoczi 2020-05-01 15:06:43 +01:00 committed by Dr. David Alan Gilbert
parent 1c47613588
commit 6dbb716877
3 changed files with 32 additions and 14 deletions
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1
tools/virtiofsd/fuse_lowlevel.h
View File

@ -1777,6 +1777,7 @@ struct fuse_cmdline_opts {
int syslog;
int log_level;
unsigned int max_idle_threads;
unsigned long rlimit_nofile;
};
/**

23
tools/virtiofsd/helper.c
View File

@ -23,6 +23,8 @@
#include <stdlib.h>
#include <string.h>
#include <sys/param.h>
#include <sys/time.h>
#include <sys/resource.h>
#include <unistd.h>
#define FUSE_HELPER_OPT(t, p) \
@ -53,6 +55,7 @@ static const struct fuse_opt fuse_helper_opts[] = {
FUSE_HELPER_OPT("subtype=", nodefault_subtype),
FUSE_OPT_KEY("subtype=", FUSE_OPT_KEY_KEEP),
FUSE_HELPER_OPT("max_idle_threads=%u", max_idle_threads),
FUSE_HELPER_OPT("--rlimit-nofile=%lu", rlimit_nofile),
FUSE_HELPER_OPT("--syslog", syslog),
FUSE_HELPER_OPT_VALUE("log_level=debug", log_level, FUSE_LOG_DEBUG),
FUSE_HELPER_OPT_VALUE("log_level=info", log_level, FUSE_LOG_INFO),
@ -171,6 +174,9 @@ void fuse_cmdline_help(void)
" default: no_writeback\n"
" -o xattr|no_xattr enable/disable xattr\n"
" default: no_xattr\n"
" --rlimit-nofile=<num> set maximum number of file descriptors\n"
" (0 leaves rlimit unchanged)\n"
" default: 1,000,000 if the current rlimit is lower\n"
);
}
@ -191,11 +197,28 @@ static int fuse_helper_opt_proc(void *data, const char *arg, int key,
}
}
static unsigned long get_default_rlimit_nofile(void)
{
rlim_t max_fds = 1000000; /* our default RLIMIT_NOFILE target */
struct rlimit rlim;
if (getrlimit(RLIMIT_NOFILE, &rlim) < 0) {
fuse_log(FUSE_LOG_ERR, "getrlimit(RLIMIT_NOFILE): %m\n");
exit(1);
}
if (rlim.rlim_cur >= max_fds) {
return 0; /* we have more fds available than required! */
}
return max_fds;
}
int fuse_parse_cmdline(struct fuse_args *args, struct fuse_cmdline_opts *opts)
{
memset(opts, 0, sizeof(struct fuse_cmdline_opts));
opts->max_idle_threads = 10;
opts->rlimit_nofile = get_default_rlimit_nofile();
opts->foreground = 1;
if (fuse_opt_parse(args, opts, fuse_helper_opts, fuse_helper_opt_proc) ==

22
tools/virtiofsd/passthrough_ll.c
View File

@ -2707,24 +2707,18 @@ static void setup_sandbox(struct lo_data *lo, struct fuse_session *se,
setup_seccomp(enable_syslog);
}
/* Raise the maximum number of open file descriptors */
static void setup_nofile_rlimit(void)
/* Set the maximum number of open file descriptors */
static void setup_nofile_rlimit(unsigned long rlimit_nofile)
{
const rlim_t max_fds = 1000000;
struct rlimit rlim;
struct rlimit rlim = {
.rlim_cur = rlimit_nofile,
.rlim_max = rlimit_nofile,
};
if (getrlimit(RLIMIT_NOFILE, &rlim) < 0) {
fuse_log(FUSE_LOG_ERR, "getrlimit(RLIMIT_NOFILE): %m\n");
exit(1);
}
if (rlim.rlim_cur >= max_fds) {
if (rlimit_nofile == 0) {
return; /* nothing to do */
}
rlim.rlim_cur = max_fds;
rlim.rlim_max = max_fds;
if (setrlimit(RLIMIT_NOFILE, &rlim) < 0) {
/* Ignore SELinux denials */
if (errno == EPERM) {
@ -2977,7 +2971,7 @@ int main(int argc, char *argv[])
fuse_daemonize(opts.foreground);
setup_nofile_rlimit();
setup_nofile_rlimit(opts.rlimit_nofile);
/* Must be before sandbox since it wants /proc */
setup_capng();