[PATCH] cpusets: bitmap and mask remap operators

In the forthcoming task migration support, a key calculation will be
mapping cpu and node numbers from the old set to the new set while
preserving cpuset-relative offset.

For example, if a task and its pages on nodes 8-11 are being migrated to
nodes 24-27, then pages on node 9 (the 2nd node in the old set) should be
moved to node 25 (the 2nd node in the new set.)

As with other bitmap operations, the proper way to code this is to provide
the underlying calculation in lib/bitmap.c, and then to provide the usual
cpumask and nodemask wrappers.

This patch provides that.  These operations are termed 'remap' operations.
Both remapping a single bit and a set of bits is supported.

Signed-off-by: Paul Jackson <pj@sgi.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 6 insertions, 0 deletions

diff --git a/include/linux/bitmap.h b/include/linux/bitmap.h
index 86dd5502b05c..7d8ff97b3e92 100644
--- a/include/linux/bitmap.h
+++ b/include/linux/bitmap.h
@@ -40,6 +40,8 @@
  * bitmap_weight(src, nbits)                    Hamming Weight: number set bits
  * bitmap_shift_right(dst, src, n, nbits)       *dst = *src >> n
  * bitmap_shift_left(dst, src, n, nbits)        *dst = *src << n
+ * bitmap_remap(dst, src, old, new, nbits)      *dst = map(old, new)(src)
+ * bitmap_bitremap(oldbit, old, new, nbits)     newbit = map(old, new)(oldbit)
  * bitmap_scnprintf(buf, len, src, nbits)       Print bitmap src to buf
  * bitmap_parse(ubuf, ulen, dst, nbits)         Parse bitmap dst from user buf
  * bitmap_scnlistprintf(buf, len, src, nbits)   Print bitmap src as list to buf
@@ -104,6 +106,10 @@ extern int bitmap_scnlistprintf(char *buf, unsigned int len,
                         const unsigned long *src, int nbits);
 extern int bitmap_parselist(const char *buf, unsigned long *maskp,
                         int nmaskbits);
+extern void bitmap_remap(unsigned long *dst, const unsigned long *src,
+                const unsigned long *old, const unsigned long *new, int bits);
+extern int bitmap_bitremap(int oldbit,
+                const unsigned long *old, const unsigned long *new, int bits);
 extern int bitmap_find_free_region(unsigned long *bitmap, int bits, int order);
 extern void bitmap_release_region(unsigned long *bitmap, int pos, int order);
 extern int bitmap_allocate_region(unsigned long *bitmap, int pos, int order);