From 555ec3463b3dbfd6e08eac7840419d176f113e46 Mon Sep 17 00:00:00 2001

From: "Dr. David Alan Gilbert" <dgilbert@redhat.com>

Date: Tue, 5 May 2020 16:35:55 +0100

Subject: [PATCH 4/9] virtiofsd: add --rlimit-nofile=NUM option

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RH-Author: Dr. David Alan Gilbert <dgilbert@redhat.com>

Message-id: <20200505163600.22956-3-dgilbert@redhat.com>

Patchwork-id: 96270

O-Subject: [RHEL-AV-8.2.1 qemu-kvm PATCH 2/7] virtiofsd: add --rlimit-nofile=NUM option

Bugzilla: 1817445

RH-Acked-by: Stefan Hajnoczi <stefanha@redhat.com>

RH-Acked-by: Philippe Mathieu-Daudé <philmd@redhat.com>

RH-Acked-by: Max Reitz <mreitz@redhat.com>

RH-Acked-by: Michael S. Tsirkin <mst@redhat.com>

From: Stefan Hajnoczi <stefanha@redhat.com>

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>

(cherry picked from commit 6dbb716877728ce4eb51619885ef6ef4ada9565f)

Signed-off-by: Danilo C. L. de Paula <ddepaula@redhat.com>

---

 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 8f6d705..562fd52 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 0801cf7..9b3eddc 100644

--- a/tools/virtiofsd/helper.c

+++ b/tools/virtiofsd/helper.c

@@ -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) ==

diff --git a/tools/virtiofsd/passthrough_ll.c b/tools/virtiofsd/passthrough_ll.c

index 50ff672..184ad0f 100644

--- a/tools/virtiofsd/passthrough_ll.c

+++ b/tools/virtiofsd/passthrough_ll.c

@@ -2711,24 +2711,18 @@ 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) {

@@ -2981,7 +2975,7 @@ 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();

-- 

1.8.3.1