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Commit 095f1fc4 authored by Lee Schermerhorn's avatar Lee Schermerhorn Committed by Linus Torvalds
Browse files

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: default avatarLee 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: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 2291990a

include/linux/mempolicy.h

+21 −0
Original line number Diff line number Diff line
@@ -214,6 +214,13 @@ static inline void check_highest_zone(enum zone_type k) 
int do_migrate_pages(struct mm_struct *mm,

	const nodemask_t *from_nodes, const nodemask_t *to_nodes, int flags);





#ifdef CONFIG_TMPFS

extern int mpol_parse_str(char *str, unsigned short *mode,

			unsigned short *mode_flags, nodemask_t *policy_nodes);



extern int mpol_to_str(char *buffer, int maxlen, struct mempolicy *pol);

#endif

#else



struct mempolicy {};
@@ -313,6 +320,20 @@ static inline int do_migrate_pages(struct mm_struct *mm, 
static inline void check_highest_zone(int k)

{

}



#ifdef CONFIG_TMPFS

static inline int mpol_parse_str(char *value, unsigned short *policy,

				unsigned short flags, nodemask_t *policy_nodes)

{

	return 1;

}



static inline int mpol_to_str(char *buffer, int maxlen, struct mempolicy *pol)

{

	return 0;

}

#endif



#endif /* CONFIG_NUMA */

#endif /* __KERNEL__ */

mm/mempolicy.c

+102 −2
Original line number Diff line number Diff line
@@ -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;

mm/shmem.c

+13 −105
Original line number Diff line number Diff line
@@ -1079,108 +1079,22 @@ static int shmem_writepage(struct page *page, struct writeback_control *wbc) 


#ifdef CONFIG_NUMA

#ifdef CONFIG_TMPFS

static int shmem_parse_mpol(char *value, unsigned short *policy,

			unsigned short *mode_flags, nodemask_t *policy_nodes)

{

	char *nodelist = strchr(value, ':');

	char *flags = strchr(value, '=');

	int err = 1;



	if (nodelist) {

		/* NUL-terminate policy 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';

	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 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;	/* unrecognized flag */

	}

out:

	/* Restore string for error message */

	if (nodelist)

		*--nodelist = ':';

	if (flags)

		*--flags = '=';

	return err;

}



static void shmem_show_mpol(struct seq_file *seq, unsigned short policy,

static void shmem_show_mpol(struct seq_file *seq, unsigned short mode,

			unsigned short flags, const nodemask_t policy_nodes)

{

	char *policy_string;

	struct mempolicy temp;

	char buffer[64];



	switch (policy) {

	case MPOL_PREFERRED:

		policy_string = "prefer";

		break;

	case MPOL_BIND:

		policy_string = "bind";

		break;

	case MPOL_INTERLEAVE:

		policy_string = "interleave";

		break;

	default:

		/* MPOL_DEFAULT */

		return;

	}

	if (mode == MPOL_DEFAULT)

		return;		/* show nothing */



	seq_printf(seq, ",mpol=%s", policy_string);

	temp.mode = mode;

	temp.flags = flags;

	temp.v.nodes = policy_nodes;



	if (policy != MPOL_INTERLEAVE ||

	    !nodes_equal(policy_nodes, node_states[N_HIGH_MEMORY])) {

		char buffer[64];

		int len;

	mpol_to_str(buffer, sizeof(buffer), &temp);



		len = nodelist_scnprintf(buffer, sizeof(buffer), policy_nodes);

		if (len < sizeof(buffer))

			seq_printf(seq, ":%s", buffer);

		else

			seq_printf(seq, ":?");

	}

	seq_printf(seq, ",mpol=%s", buffer);

}

#endif /* CONFIG_TMPFS */
@@ -1221,12 +1135,6 @@ static struct page *shmem_alloc_page(gfp_t gfp, 
}

#else /* !CONFIG_NUMA */

#ifdef CONFIG_TMPFS

static inline int shmem_parse_mpol(char *value, unsigned short *policy,

			unsigned short *mode_flags, nodemask_t *policy_nodes)

{

	return 1;

}



static inline void shmem_show_mpol(struct seq_file *seq, unsigned short policy,

			unsigned short flags, const nodemask_t policy_nodes)

{
@@ -2231,7 +2139,7 @@ static int shmem_parse_options(char *options, struct shmem_sb_info *sbinfo, 
			if (*rest)

				goto bad_val;

		} else if (!strcmp(this_char,"mpol")) {

			if (shmem_parse_mpol(value, &sbinfo->policy,

			if (mpol_parse_str(value, &sbinfo->policy,

					 &sbinfo->flags, &sbinfo->policy_nodes))

				goto bad_val;

		} else {