From 6dbb716877728ce4eb51619885ef6ef4ada9565f Mon Sep 17 00:00:00 2001 From: Stefan Hajnoczi Date: Fri, 1 May 2020 15:06:43 +0100 Subject: [PATCH] virtiofsd: add --rlimit-nofile=NUM option 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 Reviewed-by: Dr. David Alan Gilbert Message-Id: <20200501140644.220940-2-stefanha@redhat.com> Signed-off-by: Dr. David Alan Gilbert --- tools/virtiofsd/fuse_lowlevel.h | 1 + tools/virtiofsd/helper.c | 23 +++++++++++++++++++++++ tools/virtiofsd/passthrough_ll.c | 22 ++++++++-------------- 3 files changed, 32 insertions(+), 14 deletions(-) diff --git a/tools/virtiofsd/fuse_lowlevel.h b/tools/virtiofsd/fuse_lowlevel.h index 8f6d705b5c..562fd5241e 100644 --- a/tools/virtiofsd/fuse_lowlevel.h +++ b/tools/virtiofsd/fuse_lowlevel.h @@ -1777,6 +1777,7 @@ struct fuse_cmdline_opts { int syslog; int log_level; unsigned int max_idle_threads; + unsigned long rlimit_nofile; }; /** diff --git a/tools/virtiofsd/helper.c b/tools/virtiofsd/helper.c index 819c2bc13c..dc59f38af0 100644 --- a/tools/virtiofsd/helper.c +++ b/tools/virtiofsd/helper.c @@ -23,6 +23,8 @@ #include #include #include +#include +#include #include #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= 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) == diff --git a/tools/virtiofsd/passthrough_ll.c b/tools/virtiofsd/passthrough_ll.c index 4c35c95b25..f7b9c1d20c 100644 --- a/tools/virtiofsd/passthrough_ll.c +++ b/tools/virtiofsd/passthrough_ll.c @@ -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; - - if (getrlimit(RLIMIT_NOFILE, &rlim) < 0) { - fuse_log(FUSE_LOG_ERR, "getrlimit(RLIMIT_NOFILE): %m\n"); - exit(1); - } + struct rlimit rlim = { + .rlim_cur = rlimit_nofile, + .rlim_max = rlimit_nofile, + }; - 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(); -- 2.11.4.GIT