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Commit b00dc3ad authored by Hugh Dickins's avatar Hugh Dickins Committed by Linus Torvalds
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[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: default avatarHugh Dickins <hugh@veritas.com>
Acked-by: default avatarRobin Holt <holt@sgi.com>
Acked-by: default avatarAndi Kleen <ak@suse.de>
Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
parent 808c783e

Documentation/filesystems/tmpfs.txt

+12 −9
Original line number Diff line number Diff line
@@ -79,15 +79,18 @@ that instance in a system with many cpus making intensive use of it. 




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

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=bind		prefers to allocate from mpol_nodelist

mpol=preferred		prefers to allocate from first node in mpol_nodelist

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



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.

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 accessible by root. 
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

mm/shmem.c

+69 −12
Original line number Diff line number Diff line
@@ -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_inode_info *info, 
	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 *options, int *mode, uid_t *uid, 
{

	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 *options, int *mode, uid_t *uid, 
			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);