[v2,055/109] virtiofsd: set maximum RLIMIT_NOFILE limit

Commit Message

Dr. David Alan Gilbert Jan. 21, 2020, 12:23 p.m. UTC

From: Stefan Hajnoczi <[e-mail]>

virtiofsd can exceed the default open file descriptor limit easily on
most systems.  Take advantage of the fact that it runs as root to raise
the limit.

Signed-off-by: Stefan Hajnoczi <[e-mail]>
Reviewed-by: Daniel P. Berrangé <[e-mail]>
Reviewed-by: Philippe Mathieu-Daudé <[e-mail]>
---
 tools/virtiofsd/passthrough_ll.c | 32 ++++++++++++++++++++++++++++++++
 1 file changed, 32 insertions(+)

Patch

diff --git a/tools/virtiofsd/passthrough_ll.c b/tools/virtiofsd/passthrough_ll.c
index 3f7ec85938..7257a4a512 100644
--- a/tools/virtiofsd/passthrough_ll.c
+++ b/tools/virtiofsd/passthrough_ll.c
@@ -52,6 +52,7 @@ 
 #include <sys/file.h>
 #include <sys/mount.h>
 #include <sys/prctl.h>
+#include <sys/resource.h>
 #include <sys/syscall.h>
 #include <sys/types.h>
 #include <sys/wait.h>
@@ -2267,6 +2268,35 @@  static void setup_sandbox(struct lo_data *lo, struct fuse_session *se)
     setup_seccomp();
 }
 
+/* Raise the maximum number of open file descriptors */
+static void setup_nofile_rlimit(void)
+{
+    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);
+    }
+
+    if (rlim.rlim_cur >= max_fds) {
+        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) {
+            return;
+        }
+
+        fuse_log(FUSE_LOG_ERR, "setrlimit(RLIMIT_NOFILE): %m\n");
+        exit(1);
+    }
+}
+
 int main(int argc, char *argv[])
 {
     struct fuse_args args = FUSE_ARGS_INIT(argc, argv);
@@ -2388,6 +2418,8 @@  int main(int argc, char *argv[])
 
     fuse_daemonize(opts.foreground);
 
+    setup_nofile_rlimit();
+
     /* Must be before sandbox since it wants /proc */
     setup_capng();