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/include/linux/mempolicy.h b/include/linux/mempolicy.h
index b0fab9e..dcc1737 100644
--- a/include/linux/mempolicy.h
+++ b/include/linux/mempolicy.h
@@ -214,6 +214,13 @@
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 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__ */