mempolicy: rework shmem mpol parsing and display

[net-next-2.6.git] / mm / mempolicy.c

diff --git a/mm/mempolicy.c b/mm/mempolicy.c
index 3c8ee31572ec5c0dbbc1ee88a05c65642369d9ce..155bb284dbf1b8c5f0b8e10b6ee2088d9abbb2d9 100644 (file)
--- a/mm/mempolicy.c
+++ b/mm/mempolicy.c
@@ -88,6 +88,7 @@
 #include <linux/rmap.h>
 #include <linux/security.h>
 #include <linux/syscalls.h>
+#include <linux/ctype.h>
 
 #include <asm/tlbflush.h>
 #include <asm/uaccess.h>
@@ -1944,6 +1945,10 @@ void numa_default_policy(void)
        do_set_mempolicy(MPOL_DEFAULT, 0, NULL);
 }
 
+/*
+ * Parse and format mempolicy from/to strings
+ */
+
 /*
  * "local" is pseudo-policy:  MPOL_PREFERRED with MPOL_F_LOCAL flag
  * Used only for mpol_to_str()
@@ -1952,12 +1957,107 @@ void numa_default_policy(void)
 static const char * const policy_types[] =
        { "default", "prefer", "bind", "interleave", "local" };
 
+
+#ifdef CONFIG_TMPFS
+/**
+ * mpol_parse_str - parse string to mempolicy
+ * @str:  string containing mempolicy to parse
+ * @mode:  pointer to returned policy mode
+ * @mode_flags:  pointer to returned flags
+ * @policy_nodes:  pointer to returned nodemask
+ *
+ * Format of input:
+ *     <mode>[=<flags>][:<nodelist>]
+ *
+ * Currently only used for tmpfs/shmem mount options
+ */
+int mpol_parse_str(char *str, unsigned short *mode, unsigned short *mode_flags,
+                       nodemask_t *policy_nodes)
+{
+       char *nodelist = strchr(str, ':');
+       char *flags = strchr(str, '=');
+       int i;
+       int err = 1;
+
+       if (nodelist) {
+               /* NUL-terminate mode or flags string */
+               *nodelist++ = '\0';
+               if (nodelist_parse(nodelist, *policy_nodes))
+                       goto out;
+               if (!nodes_subset(*policy_nodes, node_states[N_HIGH_MEMORY]))
+                       goto out;
+       }
+       if (flags)
+               *flags++ = '\0';        /* terminate mode string */
+
+       for (i = 0; i < MPOL_MAX; i++) {
+               if (!strcmp(str, policy_types[i])) {
+                       *mode = i;
+                       break;
+               }
+       }
+       if (i == MPOL_MAX)
+               goto out;
+
+       switch (*mode) {
+       case MPOL_DEFAULT:
+               /* Don't allow a nodelist nor flags */
+               if (!nodelist && !flags)
+                       err = 0;
+               break;
+       case MPOL_PREFERRED:
+               /* Insist on a nodelist of one node only */
+               if (nodelist) {
+                       char *rest = nodelist;
+                       while (isdigit(*rest))
+                               rest++;
+                       if (!*rest)
+                               err = 0;
+               }
+               break;
+       case MPOL_BIND:
+               /* Insist on a nodelist */
+               if (nodelist)
+                       err = 0;
+               break;
+       case MPOL_INTERLEAVE:
+               /*
+                * Default to online nodes with memory if no nodelist
+                */
+               if (!nodelist)
+                       *policy_nodes = node_states[N_HIGH_MEMORY];
+               err = 0;
+       }
+
+       *mode_flags = 0;
+       if (flags) {
+               /*
+                * Currently, we only support two mutually exclusive
+                * mode flags.
+                */
+               if (!strcmp(flags, "static"))
+                       *mode_flags |= MPOL_F_STATIC_NODES;
+               else if (!strcmp(flags, "relative"))
+                       *mode_flags |= MPOL_F_RELATIVE_NODES;
+               else
+                       err = 1;
+       }
+out:
+       /* Restore string for error message */
+       if (nodelist)
+               *--nodelist = ':';
+       if (flags)
+               *--flags = '=';
+       return err;
+}
+#endif /* CONFIG_TMPFS */
+
 /*
  * Convert a mempolicy into a string.
  * Returns the number of characters in buffer (if positive)
  * or an error (negative)
  */
-static inline int mpol_to_str(char *buffer, int maxlen, struct mempolicy *pol)
+int mpol_to_str(char *buffer, int maxlen, struct mempolicy *pol)
 {
        char *p = buffer;
        int l;
@@ -2022,7 +2122,7 @@ static inline int mpol_to_str(char *buffer, int maxlen, struct mempolicy *pol)
        if (!nodes_empty(nodes)) {
                if (buffer + maxlen < p + 2)
                        return -ENOSPC;
-               *p++ = '=';
+               *p++ = ':';
                p += nodelist_scnprintf(p, buffer + maxlen - p, nodes);
        }
        return p - buffer;