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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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