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Subject[PATCH] tmpfs: fix mount mpol nodelist parsing
I've been dissatisfied with the mpol_nodelist mount option which was
added to tmpfs earlier in -rc. Replace it by mpol=policy:nodelist.

And it was broken: a nodelist is a comma-separated list of numbers and
ranges; the mount options are a comma-separated list of token=values.
Whoops, blindly strsep'ing on commas doesn't work so well: since we've
no numeric tokens, and unlikely to add them, use that to distinguish.

Move the mpol= parsing to shmem_parse_mpol under CONFIG_NUMA, reject
all its options as invalid if not NUMA. /proc shows MPOL_PREFERRED
as "prefer", so use that name for the policy instead of "preferred".

Enforce that mpol=default has no nodelist; that mpol=prefer has one
node only; that mpol=bind has a nodelist; but let mpol=interleave use
node_online_map if no nodelist given. Describe this in tmpfs.txt.

Signed-off-by: Hugh Dickins <hugh@veritas.com>
Acked-by: Robin Holt <holt@sgi.com>
---
Documentation/filesystems/tmpfs.txt | 23 +++++-----
mm/shmem.c | 81 ++++++++++++++++++++++++++++++------
2 files changed, 82 insertions(+), 22 deletions(-)
--- 2.6.16-rc4/Documentation/filesystems/tmpfs.txt 2006-02-18 12:27:18.000000000 +0000
+++ linux/Documentation/filesystems/tmpfs.txt 2006-02-19 19:49:36.000000000 +0000
@@ -79,15 +79,18 @@ that instance in a system with many cpus


tmpfs has a mount option to set the NUMA memory allocation policy for
-all files in that instance:
-mpol=interleave prefers to allocate memory from each node in turn
-mpol=default prefers to allocate memory from the local node
-mpol=bind prefers to allocate from mpol_nodelist
-mpol=preferred prefers to allocate from first node in mpol_nodelist
-
-The following mount option is used in conjunction with mpol=interleave,
-mpol=bind or mpol=preferred:
-mpol_nodelist: nodelist suitable for parsing with nodelist_parse.
+all files in that instance (if CONFIG_NUMA is enabled) - which can be
+adjusted on the fly via 'mount -o remount ...'
+
+mpol=default prefers to allocate memory from the local node
+mpol=prefer:Node prefers to allocate memory from the given Node
+mpol=bind:NodeList allocates memory only from nodes in NodeList
+mpol=interleave prefers to allocate from each node in turn
+mpol=interleave:NodeList allocates from each node of NodeList in turn
+
+NodeList format is a comma-separated list of decimal numbers and ranges,
+a range being two hyphen-separated decimal numbers, the smallest and
+largest node numbers in the range. For example, mpol=bind:0-3,5,7,9-15


To specify the initial root directory you can use the following mount
@@ -109,4 +112,4 @@ RAM/SWAP in 10240 inodes and it is only
Author:
Christoph Rohland <cr@sap.com>, 1.12.01
Updated:
- Hugh Dickins <hugh@veritas.com>, 13 March 2005
+ Hugh Dickins <hugh@veritas.com>, 19 February 2006
--- 2.6.16-rc4/mm/shmem.c 2006-02-18 12:28:19.000000000 +0000
+++ linux/mm/shmem.c 2006-02-19 19:49:36.000000000 +0000
@@ -45,6 +45,7 @@
#include <linux/swapops.h>
#include <linux/mempolicy.h>
#include <linux/namei.h>
+#include <linux/ctype.h>
#include <asm/uaccess.h>
#include <asm/div64.h>
#include <asm/pgtable.h>
@@ -874,6 +875,51 @@ redirty:
}

#ifdef CONFIG_NUMA
+static int shmem_parse_mpol(char *value, int *policy, nodemask_t *policy_nodes)
+{
+ char *nodelist = strchr(value, ':');
+ int err = 1;
+
+ if (nodelist) {
+ /* NUL-terminate policy string */
+ *nodelist++ = '\0';
+ if (nodelist_parse(nodelist, *policy_nodes))
+ goto out;
+ }
+ if (!strcmp(value, "default")) {
+ *policy = MPOL_DEFAULT;
+ /* Don't allow a nodelist */
+ if (!nodelist)
+ err = 0;
+ } else if (!strcmp(value, "prefer")) {
+ *policy = MPOL_PREFERRED;
+ /* Insist on a nodelist of one node only */
+ if (nodelist) {
+ char *rest = nodelist;
+ while (isdigit(*rest))
+ rest++;
+ if (!*rest)
+ err = 0;
+ }
+ } else if (!strcmp(value, "bind")) {
+ *policy = MPOL_BIND;
+ /* Insist on a nodelist */
+ if (nodelist)
+ err = 0;
+ } else if (!strcmp(value, "interleave")) {
+ *policy = MPOL_INTERLEAVE;
+ /* Default to nodes online if no nodelist */
+ if (!nodelist)
+ *policy_nodes = node_online_map;
+ err = 0;
+ }
+out:
+ /* Restore string for error message */
+ if (nodelist)
+ *--nodelist = ':';
+ return err;
+}
+
static struct page *shmem_swapin_async(struct shared_policy *p,
swp_entry_t entry, unsigned long idx)
{
@@ -926,6 +972,11 @@ shmem_alloc_page(gfp_t gfp, struct shmem
return page;
}
#else
+static inline int shmem_parse_mpol(char *value, int *policy, nodemask_t *policy_nodes)
+{
+ return 1;
+}
+
static inline struct page *
shmem_swapin(struct shmem_inode_info *info,swp_entry_t entry,unsigned long idx)
{
@@ -1859,7 +1910,23 @@ static int shmem_parse_options(char *opt
{
char *this_char, *value, *rest;

- while ((this_char = strsep(&options, ",")) != NULL) {
+ while (options != NULL) {
+ this_char = options;
+ for (;;) {
+ /*
+ * NUL-terminate this option: unfortunately,
+ * mount options form a comma-separated list,
+ * but mpol's nodelist may also contain commas.
+ */
+ options = strchr(options, ',');
+ if (options == NULL)
+ break;
+ options++;
+ if (!isdigit(*options)) {
+ options[-1] = '\0';
+ break;
+ }
+ }
if (!*this_char)
continue;
if ((value = strchr(this_char,'=')) != NULL) {
@@ -1910,18 +1977,8 @@ static int shmem_parse_options(char *opt
if (*rest)
goto bad_val;
} else if (!strcmp(this_char,"mpol")) {
- if (!strcmp(value,"default"))
- *policy = MPOL_DEFAULT;
- else if (!strcmp(value,"preferred"))
- *policy = MPOL_PREFERRED;
- else if (!strcmp(value,"bind"))
- *policy = MPOL_BIND;
- else if (!strcmp(value,"interleave"))
- *policy = MPOL_INTERLEAVE;
- else
+ if (shmem_parse_mpol(value,policy,policy_nodes))
goto bad_val;
- } else if (!strcmp(this_char,"mpol_nodelist")) {
- nodelist_parse(value, *policy_nodes);
} else {
printk(KERN_ERR "tmpfs: Bad mount option %s\n",
this_char);
-
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