mempolicy: rework shmem mpol parsing and display
mm/shmem.c currently contains functions to parse and display memory policy
strings for the tmpfs 'mpol' mount option. Move this to mm/mempolicy.c with
the rest of the mempolicy support. With subsequent patches, we'll be able to
remove knowledge of the details [mode, flags, policy, ...] completely from
shmem.c
1) replace shmem_parse_mpol() in mm/shmem.c with mpol_parse_str() in
mm/mempolicy.c. Rework to use the policy_types[] array [used by
mpol_to_str()] to look up mode by name.
2) use mpol_to_str() to format policy for shmem_show_mpol(). mpol_to_str()
expects a pointer to a struct mempolicy, so temporarily construct one.
This will be replaced with a reference to a struct mempolicy in the tmpfs
superblock in a subsequent patch.
NOTE 1: I changed mpol_to_str() to use a colon ':' rather than an equal
sign '=' as the nodemask delimiter to match mpol_parse_str() and the
tmpfs/shmem mpol mount option formatting that now uses mpol_to_str(). This
is a user visible change to numa_maps, but then the addition of the mode
flags already changed the display. It makes sense to me to have the mounts
and numa_maps display the policy in the same format. However, if anyone
objects strongly, I can pass the desired nodemask delimeter as an arg to
mpol_to_str().
Note 2: Like show_numa_map(), I don't check the return code from
mpol_to_str(). I do use a longer buffer than the one provided by
show_numa_map(), which seems to have sufficed so far.
Signed-off-by: Lee Schermerhorn <lee.schermerhorn@hp.com>
Cc: Christoph Lameter <clameter@sgi.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Mel Gorman <mel@csn.ul.ie>
Cc: Andi Kleen <ak@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/mm/mempolicy.c b/mm/mempolicy.c
index 3c8ee31..155bb28 100644
--- 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>
@@ -1945,6 +1946,10 @@
}
/*
+ * 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 @@
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 @@
if (!nodes_empty(nodes)) {
if (buffer + maxlen < p + 2)
return -ENOSPC;
- *p++ = '=';
+ *p++ = ':';
p += nodelist_scnprintf(p, buffer + maxlen - p, nodes);
}
return p - buffer;