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From 555ec3463b3dbfd6e08eac7840419d176f113e46 Mon Sep 17 00:00:00 2001
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From: "Dr. David Alan Gilbert" <dgilbert@redhat.com>
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Date: Tue, 5 May 2020 16:35:55 +0100
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Subject: [PATCH 4/9] virtiofsd: add --rlimit-nofile=NUM option
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MIME-Version: 1.0
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Content-Type: text/plain; charset=UTF-8
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Content-Transfer-Encoding: 8bit
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RH-Author: Dr. David Alan Gilbert <dgilbert@redhat.com>
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Message-id: <20200505163600.22956-3-dgilbert@redhat.com>
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Patchwork-id: 96270
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O-Subject: [RHEL-AV-8.2.1 qemu-kvm PATCH 2/7] virtiofsd: add --rlimit-nofile=NUM option
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Bugzilla: 1817445
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RH-Acked-by: Stefan Hajnoczi <stefanha@redhat.com>
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RH-Acked-by: Philippe Mathieu-Daudé <philmd@redhat.com>
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RH-Acked-by: Max Reitz <mreitz@redhat.com>
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RH-Acked-by: Michael S. Tsirkin <mst@redhat.com>
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From: Stefan Hajnoczi <stefanha@redhat.com>
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Make it possible to specify the RLIMIT_NOFILE on the command-line.
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Users running multiple virtiofsd processes should allocate a certain
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number to each process so that the system-wide limit can never be
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exhausted.
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When this option is set to 0 the rlimit is left at its current value.
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This is useful when a management tool wants to configure the rlimit
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itself.
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The default behavior remains unchanged: try to set the limit to
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1,000,000 file descriptors if the current rlimit is lower.
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Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
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Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
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Message-Id: <20200501140644.220940-2-stefanha@redhat.com>
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Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
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(cherry picked from commit 6dbb716877728ce4eb51619885ef6ef4ada9565f)
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Signed-off-by: Danilo C. L. de Paula <ddepaula@redhat.com>
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---
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 tools/virtiofsd/fuse_lowlevel.h  |  1 +
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 tools/virtiofsd/helper.c         | 23 +++++++++++++++++++++++
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 tools/virtiofsd/passthrough_ll.c | 22 ++++++++--------------
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 3 files changed, 32 insertions(+), 14 deletions(-)
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diff --git a/tools/virtiofsd/fuse_lowlevel.h b/tools/virtiofsd/fuse_lowlevel.h
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index 8f6d705..562fd52 100644
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--- a/tools/virtiofsd/fuse_lowlevel.h
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+++ b/tools/virtiofsd/fuse_lowlevel.h
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@@ -1777,6 +1777,7 @@ struct fuse_cmdline_opts {
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     int syslog;
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     int log_level;
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     unsigned int max_idle_threads;
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+    unsigned long rlimit_nofile;
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 };
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 /**
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diff --git a/tools/virtiofsd/helper.c b/tools/virtiofsd/helper.c
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index 0801cf7..9b3eddc 100644
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--- a/tools/virtiofsd/helper.c
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+++ b/tools/virtiofsd/helper.c
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@@ -23,6 +23,8 @@
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 #include <stdlib.h>
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 #include <string.h>
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 #include <sys/param.h>
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+#include <sys/time.h>
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+#include <sys/resource.h>
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 #include <unistd.h>
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 #define FUSE_HELPER_OPT(t, p)                       \
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@@ -53,6 +55,7 @@ static const struct fuse_opt fuse_helper_opts[] = {
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     FUSE_HELPER_OPT("subtype=", nodefault_subtype),
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     FUSE_OPT_KEY("subtype=", FUSE_OPT_KEY_KEEP),
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     FUSE_HELPER_OPT("max_idle_threads=%u", max_idle_threads),
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+    FUSE_HELPER_OPT("--rlimit-nofile=%lu", rlimit_nofile),
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     FUSE_HELPER_OPT("--syslog", syslog),
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     FUSE_HELPER_OPT_VALUE("log_level=debug", log_level, FUSE_LOG_DEBUG),
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     FUSE_HELPER_OPT_VALUE("log_level=info", log_level, FUSE_LOG_INFO),
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@@ -171,6 +174,9 @@ void fuse_cmdline_help(void)
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            "                               default: no_writeback\n"
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            "    -o xattr|no_xattr          enable/disable xattr\n"
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            "                               default: no_xattr\n"
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+           "    --rlimit-nofile=<num>      set maximum number of file descriptors\n"
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+           "                               (0 leaves rlimit unchanged)\n"
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+           "                               default: 1,000,000 if the current rlimit is lower\n"
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            );
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 }
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@@ -191,11 +197,28 @@ static int fuse_helper_opt_proc(void *data, const char *arg, int key,
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     }
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 }
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+static unsigned long get_default_rlimit_nofile(void)
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+{
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+    rlim_t max_fds = 1000000; /* our default RLIMIT_NOFILE target */
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+    struct rlimit rlim;
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+
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+    if (getrlimit(RLIMIT_NOFILE, &rlim) < 0) {
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+        fuse_log(FUSE_LOG_ERR, "getrlimit(RLIMIT_NOFILE): %m\n");
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+        exit(1);
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+    }
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+
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+    if (rlim.rlim_cur >= max_fds) {
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+        return 0; /* we have more fds available than required! */
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+    }
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+    return max_fds;
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+}
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+
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 int fuse_parse_cmdline(struct fuse_args *args, struct fuse_cmdline_opts *opts)
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 {
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     memset(opts, 0, sizeof(struct fuse_cmdline_opts));
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     opts->max_idle_threads = 10;
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+    opts->rlimit_nofile = get_default_rlimit_nofile();
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     opts->foreground = 1;
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     if (fuse_opt_parse(args, opts, fuse_helper_opts, fuse_helper_opt_proc) ==
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diff --git a/tools/virtiofsd/passthrough_ll.c b/tools/virtiofsd/passthrough_ll.c
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index 50ff672..184ad0f 100644
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--- a/tools/virtiofsd/passthrough_ll.c
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+++ b/tools/virtiofsd/passthrough_ll.c
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@@ -2711,24 +2711,18 @@ static void setup_sandbox(struct lo_data *lo, struct fuse_session *se,
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     setup_seccomp(enable_syslog);
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 }
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-/* Raise the maximum number of open file descriptors */
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-static void setup_nofile_rlimit(void)
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+/* Set the maximum number of open file descriptors */
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+static void setup_nofile_rlimit(unsigned long rlimit_nofile)
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 {
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-    const rlim_t max_fds = 1000000;
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-    struct rlimit rlim;
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-
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-    if (getrlimit(RLIMIT_NOFILE, &rlim) < 0) {
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-        fuse_log(FUSE_LOG_ERR, "getrlimit(RLIMIT_NOFILE): %m\n");
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-        exit(1);
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-    }
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+    struct rlimit rlim = {
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+        .rlim_cur = rlimit_nofile,
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+        .rlim_max = rlimit_nofile,
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+    };
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-    if (rlim.rlim_cur >= max_fds) {
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+    if (rlimit_nofile == 0) {
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         return; /* nothing to do */
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     }
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-    rlim.rlim_cur = max_fds;
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-    rlim.rlim_max = max_fds;
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-
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     if (setrlimit(RLIMIT_NOFILE, &rlim) < 0) {
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         /* Ignore SELinux denials */
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         if (errno == EPERM) {
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@@ -2981,7 +2975,7 @@ int main(int argc, char *argv[])
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     fuse_daemonize(opts.foreground);
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-    setup_nofile_rlimit();
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+    setup_nofile_rlimit(opts.rlimit_nofile);
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     /* Must be before sandbox since it wants /proc */
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     setup_capng();
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-- 
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1.8.3.1
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