lsns: optimize mountinfo use

Let's parse mountinfo only for unknown namespaces or when
namespace Id is not accessible (unprivileged users).

Signed-off-by: Karel Zak <kzak@redhat.com>

diff --git a/misc-utils/lsfd.c b/misc-utils/lsfd.c
index 259640d94d1b51f268f89ed51c9b1c08e7773498..223d008aad64714d3fe6d76cae522171b148b672 100644 (file)
--- a/misc-utils/lsfd.c
+++ b/misc-utils/lsfd.c
@@ -174,6 +174,9 @@ static const int default_threads_columns[] = {
 static int columns[ARRAY_SIZE(infos) * 2] = {-1};
 static size_t ncolumns;
 
+static ino_t *mnt_namespaces;
+static size_t nspaces;
+
 struct lsfd_control {
        struct libscols_table *tb;              /* output */
        struct list_head procs;                 /* list of all processes */
@@ -254,6 +257,31 @@ static struct libscols_column *add_column_by_id_cb(struct libscols_table *tb, in
        return cl;
 }
 
+static int has_mnt_ns(ino_t id)
+{
+       size_t i;
+
+       for (i = 0; i < nspaces; i++) {
+               if (mnt_namespaces[i] == id)
+                       return 1;
+       }
+       return 0;
+}
+
+static void add_mnt_ns(ino_t id)
+{
+       size_t nmax = 0;
+
+       if (nspaces)
+               nmax = (nspaces + 16) / 16 * 16;
+       if (nmax <= nspaces + 1) {
+               nmax += 16;
+               mnt_namespaces = xrealloc(mnt_namespaces,
+                                       sizeof(ino_t) * nmax);
+       }
+       mnt_namespaces[nspaces++] = id;
+}
+
 static const struct file_class *stat2class(struct stat *sb)
 {
        assert(sb);
@@ -417,6 +445,8 @@ static struct file *collect_file_symlink(struct path_cxt *pc,
 
        if (is_association(f, EXE))
                proc->uid = sb.st_uid;
+       if (is_association(f, NS_MNT))
+               proc->ns_mnt = sb.st_ino;
 
        else if (assoc >= 0) {
                /* file-descriptor based association */
@@ -621,6 +651,8 @@ static void finalize_nodevs(void)
 {
        for (int i = 0; i < NODEV_TABLE_SIZE; i++)
                list_free(&nodev_table.tables[i], struct nodev, nodevs, free_nodev);
+
+       free(mnt_namespaces);
 }
 
 const char *get_nodev_filesystem(unsigned long minor)
@@ -818,7 +850,6 @@ static void read_process(struct lsfd_control *ctl, struct path_cxt *pc,
 {
        char buf[BUFSIZ];
        struct proc *proc;
-       FILE *mnt;
 
        if (procfs_process_init_path(pc, pid) != 0)
                return;
@@ -835,14 +866,14 @@ static void read_process(struct lsfd_control *ctl, struct path_cxt *pc,
 
        collect_namespace_files(pc, proc);
 
-       /* TODO: parse mountinfo only when process uses not-yet-known
-        *       mount namespace. Parse mountinfo for each process is
-        *       extremly expensive.
-        */
-       mnt = ul_path_fopen(pc, "r", "mountinfo");
-       if (mnt) {
-               add_nodevs(mnt);
-               fclose(mnt);
+       if (proc->ns_mnt == 0 || !has_mnt_ns(proc->ns_mnt)) {
+               FILE *mnt = ul_path_fopen(pc, "r", "mountinfo");
+               if (mnt) {
+                       add_nodevs(mnt);
+                       if (proc->ns_mnt)
+                               add_mnt_ns(proc->ns_mnt);
+                       fclose(mnt);
+               }
        }
 
        /* If kcmp is not available,

diff --git a/misc-utils/lsfd.h b/misc-utils/lsfd.h
index f9f8bb9097ed6647c9d5aa46ffe195c39bd83f50..368b5be28bf667b523e9c663aa64478276c32de8 100644 (file)
--- a/misc-utils/lsfd.h
+++ b/misc-utils/lsfd.h
@@ -98,6 +98,7 @@ struct proc {
        struct proc * leader;
        char *command;
        uid_t uid;
+       ino_t ns_mnt;
        struct list_head procs;
        struct list_head files;
 };