[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>

[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>
Paul Jackson · Linus Torvalds
1 parent 28a42b9ea7
Showing 4 changed files with 212 additions and 0 deletions Side-by-side Diff
include/linux/bitmap.h
include/linux/cpumask.h
include/linux/nodemask.h
lib/bitmap.c
@@ -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 @@
 			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);
@@ -12,6 +12,8 @@
  * see bitmap_scnprintf() and bitmap_parse() in lib/bitmap.c.
  * For details of cpulist_scnprintf() and cpulist_parse(), see
  * bitmap_scnlistprintf() and bitmap_parselist(), also in bitmap.c.
+ * For details of cpu_remap(), see bitmap_bitremap in lib/bitmap.c
+ * For details of cpus_remap(), see bitmap_remap in lib/bitmap.c.
  *
  * The available cpumask operations are:
  *
@@ -50,6 +52,8 @@
  * int cpumask_parse(ubuf, ulen, mask)	Parse ascii string as cpumask
  * int cpulist_scnprintf(buf, len, mask) Format cpumask as list for printing
  * int cpulist_parse(buf, map)		Parse ascii string as cpulist
+ * int cpu_remap(oldbit, old, new)	newbit = map(old, new)(oldbit)
+ * int cpus_remap(dst, src, old, new)	*dst = map(old, new)(src)
  *
  * for_each_cpu_mask(cpu, mask)		for-loop cpu over mask
  *
@@ -292,6 +296,22 @@
 static inline int __cpulist_parse(const char *buf, cpumask_t *dstp, int nbits)
 {
 	return bitmap_parselist(buf, dstp->bits, nbits);
+}
+
+#define cpu_remap(oldbit, old, new) \
+		__cpu_remap((oldbit), &(old), &(new), NR_CPUS)
+static inline int __cpu_remap(int oldbit,
+		const cpumask_t *oldp, const cpumask_t *newp, int nbits)
+{
+	return bitmap_bitremap(oldbit, oldp->bits, newp->bits, nbits);
+}
+
+#define cpus_remap(dst, src, old, new) \
+		__cpus_remap(&(dst), &(src), &(old), &(new), NR_CPUS)
+static inline void __cpus_remap(cpumask_t *dstp, const cpumask_t *srcp,
+		const cpumask_t *oldp, const cpumask_t *newp, int nbits)
+{
+	bitmap_remap(dstp->bits, srcp->bits, oldp->bits, newp->bits, nbits);
 }
  
 #if NR_CPUS > 1
@@ -12,6 +12,8 @@
  * see bitmap_scnprintf() and bitmap_parse() in lib/bitmap.c.
  * For details of nodelist_scnprintf() and nodelist_parse(), see
  * bitmap_scnlistprintf() and bitmap_parselist(), also in bitmap.c.
+ * For details of node_remap(), see bitmap_bitremap in lib/bitmap.c.
+ * For details of nodes_remap(), see bitmap_remap in lib/bitmap.c.
  *
  * The available nodemask operations are:
  *
@@ -52,6 +54,8 @@
  * int nodemask_parse(ubuf, ulen, mask)	Parse ascii string as nodemask
  * int nodelist_scnprintf(buf, len, mask) Format nodemask as list for printing
  * int nodelist_parse(buf, map)		Parse ascii string as nodelist
+ * int node_remap(oldbit, old, new)	newbit = map(old, new)(oldbit)
+ * int nodes_remap(dst, src, old, new)	*dst = map(old, new)(dst)
  *
  * for_each_node_mask(node, mask)	for-loop node over mask
  *
@@ -305,6 +309,22 @@
 static inline int __nodelist_parse(const char *buf, nodemask_t *dstp, int nbits)
 {
 	return bitmap_parselist(buf, dstp->bits, nbits);
+}
+
+#define node_remap(oldbit, old, new) \
+		__node_remap((oldbit), &(old), &(new), MAX_NUMNODES)
+static inline int __node_remap(int oldbit,
+		const nodemask_t *oldp, const nodemask_t *newp, int nbits)
+{
+	return bitmap_bitremap(oldbit, oldp->bits, newp->bits, nbits);
+}
+
+#define nodes_remap(dst, src, old, new) \
+		__nodes_remap(&(dst), &(src), &(old), &(new), MAX_NUMNODES)
+static inline void __nodes_remap(nodemask_t *dstp, const nodemask_t *srcp,
+		const nodemask_t *oldp, const nodemask_t *newp, int nbits)
+{
+	bitmap_remap(dstp->bits, srcp->bits, oldp->bits, newp->bits, nbits);
 }
  
 #if MAX_NUMNODES > 1
@@ -511,6 +511,172 @@
 }
 EXPORT_SYMBOL(bitmap_parselist);
  
+/*
+ * bitmap_pos_to_ord(buf, pos, bits)
+ *	@buf: pointer to a bitmap
+ *	@pos: a bit position in @buf (0 <= @pos < @bits)
+ *	@bits: number of valid bit positions in @buf
+ *
+ * Map the bit at position @pos in @buf (of length @bits) to the
+ * ordinal of which set bit it is.  If it is not set or if @pos
+ * is not a valid bit position, map to zero (0).
+ *
+ * If for example, just bits 4 through 7 are set in @buf, then @pos
+ * values 4 through 7 will get mapped to 0 through 3, respectively,
+ * and other @pos values will get mapped to 0.  When @pos value 7
+ * gets mapped to (returns) @ord value 3 in this example, that means
+ * that bit 7 is the 3rd (starting with 0th) set bit in @buf.
+ *
+ * The bit positions 0 through @bits are valid positions in @buf.
+ */
+static int bitmap_pos_to_ord(const unsigned long *buf, int pos, int bits)
+{
+	int ord = 0;
+
+	if (pos >= 0 && pos < bits) {
+		int i;
+
+		for (i = find_first_bit(buf, bits);
+		     i < pos;
+		     i = find_next_bit(buf, bits, i + 1))
+	     		ord++;
+		if (i > pos)
+			ord = 0;
+	}
+	return ord;
+}
+
+/**
+ * bitmap_ord_to_pos(buf, ord, bits)
+ *	@buf: pointer to bitmap
+ *	@ord: ordinal bit position (n-th set bit, n >= 0)
+ *	@bits: number of valid bit positions in @buf
+ *
+ * Map the ordinal offset of bit @ord in @buf to its position in @buf.
+ * If @ord is not the ordinal offset of a set bit in @buf, map to zero (0).
+ *
+ * If for example, just bits 4 through 7 are set in @buf, then @ord
+ * values 0 through 3 will get mapped to 4 through 7, respectively,
+ * and all other @ord valuds will get mapped to 0.  When @ord value 3
+ * gets mapped to (returns) @pos value 7 in this example, that means
+ * that the 3rd set bit (starting with 0th) is at position 7 in @buf.
+ *
+ * The bit positions 0 through @bits are valid positions in @buf.
+ */
+static int bitmap_ord_to_pos(const unsigned long *buf, int ord, int bits)
+{
+	int pos = 0;
+
+	if (ord >= 0 && ord < bits) {
+		int i;
+
+		for (i = find_first_bit(buf, bits);
+		     i < bits && ord > 0;
+		     i = find_next_bit(buf, bits, i + 1))
+	     		ord--;
+		if (i < bits && ord == 0)
+			pos = i;
+	}
+
+	return pos;
+}
+
+/**
+ * bitmap_remap - Apply map defined by a pair of bitmaps to another bitmap
+ *	@src: subset to be remapped
+ *	@dst: remapped result
+ *	@old: defines domain of map
+ *	@new: defines range of map
+ *	@bits: number of bits in each of these bitmaps
+ *
+ * Let @old and @new define a mapping of bit positions, such that
+ * whatever position is held by the n-th set bit in @old is mapped
+ * to the n-th set bit in @new.  In the more general case, allowing
+ * for the possibility that the weight 'w' of @new is less than the
+ * weight of @old, map the position of the n-th set bit in @old to
+ * the position of the m-th set bit in @new, where m == n % w.
+ *
+ * If either of the @old and @new bitmaps are empty, or if@src and @dst
+ * point to the same location, then this routine does nothing.
+ *
+ * The positions of unset bits in @old are mapped to the position of
+ * the first set bit in @new.
+ *
+ * Apply the above specified mapping to @src, placing the result in
+ * @dst, clearing any bits previously set in @dst.
+ *
+ * The resulting value of @dst will have either the same weight as
+ * @src, or less weight in the general case that the mapping wasn't
+ * injective due to the weight of @new being less than that of @old.
+ * The resulting value of @dst will never have greater weight than
+ * that of @src, except perhaps in the case that one of the above
+ * conditions was not met and this routine just returned.
+ *
+ * For example, lets say that @old has bits 4 through 7 set, and
+ * @new has bits 12 through 15 set.  This defines the mapping of bit
+ * position 4 to 12, 5 to 13, 6 to 14 and 7 to 15, and of all other
+ * bit positions to 12 (the first set bit in @new.  So if say @src
+ * comes into this routine with bits 1, 5 and 7 set, then @dst should
+ * leave with bits 12, 13 and 15 set.
+ */
+void bitmap_remap(unsigned long *dst, const unsigned long *src,
+		const unsigned long *old, const unsigned long *new,
+		int bits)
+{
+	int s;
+
+	if (bitmap_weight(old, bits) == 0)
+		return;
+	if (bitmap_weight(new, bits) == 0)
+		return;
+	if (dst == src)		/* following doesn't handle inplace remaps */
+		return;
+
+	bitmap_zero(dst, bits);
+	for (s = find_first_bit(src, bits);
+	     s < bits;
+	     s = find_next_bit(src, bits, s + 1)) {
+	     	int x = bitmap_pos_to_ord(old, s, bits);
+		int y = bitmap_ord_to_pos(new, x, bits);
+		set_bit(y, dst);
+	}
+}
+EXPORT_SYMBOL(bitmap_remap);
+
+/**
+ * bitmap_bitremap - Apply map defined by a pair of bitmaps to a single bit
+ *	@oldbit - bit position to be mapped
+ *      @old: defines domain of map
+ *      @new: defines range of map
+ *      @bits: number of bits in each of these bitmaps
+ *
+ * Let @old and @new define a mapping of bit positions, such that
+ * whatever position is held by the n-th set bit in @old is mapped
+ * to the n-th set bit in @new.  In the more general case, allowing
+ * for the possibility that the weight 'w' of @new is less than the
+ * weight of @old, map the position of the n-th set bit in @old to
+ * the position of the m-th set bit in @new, where m == n % w.
+ *
+ * The positions of unset bits in @old are mapped to the position of
+ * the first set bit in @new.
+ *
+ * Apply the above specified mapping to bit position @oldbit, returning
+ * the new bit position.
+ *
+ * For example, lets say that @old has bits 4 through 7 set, and
+ * @new has bits 12 through 15 set.  This defines the mapping of bit
+ * position 4 to 12, 5 to 13, 6 to 14 and 7 to 15, and of all other
+ * bit positions to 12 (the first set bit in @new.  So if say @oldbit
+ * is 5, then this routine returns 13.
+ */
+int bitmap_bitremap(int oldbit, const unsigned long *old,
+				const unsigned long *new, int bits)
+{
+	int x = bitmap_pos_to_ord(old, oldbit, bits);
+	return bitmap_ord_to_pos(new, x, bits);
+}
+EXPORT_SYMBOL(bitmap_bitremap);
+
 /**
  *	bitmap_find_free_region - find a contiguous aligned mem region
  *	@bitmap: an array of unsigned longs corresponding to the bitmap
...	...	@@ -40,6 +40,8 @@
40	40	* bitmap_weight(src, nbits) Hamming Weight: number set bits
41	41	* bitmap_shift_right(dst, src, n, nbits) dst = src >> n
42	42	* bitmap_shift_left(dst, src, n, nbits) dst = src << n
	43	+ * bitmap_remap(dst, src, old, new, nbits) *dst = map(old, new)(src)
	44	+ * bitmap_bitremap(oldbit, old, new, nbits) newbit = map(old, new)(oldbit)
43	45	* bitmap_scnprintf(buf, len, src, nbits) Print bitmap src to buf
44	46	* bitmap_parse(ubuf, ulen, dst, nbits) Parse bitmap dst from user buf
45	47	* bitmap_scnlistprintf(buf, len, src, nbits) Print bitmap src as list to buf
...	...	@@ -104,6 +106,10 @@
104	106	const unsigned long *src, int nbits);
105	107	extern int bitmap_parselist(const char buf, unsigned long maskp,
106	108	int nmaskbits);
	109	+extern void bitmap_remap(unsigned long dst, const unsigned long src,
	110	+ const unsigned long old, const unsigned long new, int bits);
	111	+extern int bitmap_bitremap(int oldbit,
	112	+ const unsigned long old, const unsigned long new, int bits);
107	113	extern int bitmap_find_free_region(unsigned long *bitmap, int bits, int order);
108	114	extern void bitmap_release_region(unsigned long *bitmap, int pos, int order);
109	115	extern int bitmap_allocate_region(unsigned long *bitmap, int pos, int order);
...	...	@@ -12,6 +12,8 @@
12	12	* see bitmap_scnprintf() and bitmap_parse() in lib/bitmap.c.
13	13	* For details of cpulist_scnprintf() and cpulist_parse(), see
14	14	* bitmap_scnlistprintf() and bitmap_parselist(), also in bitmap.c.
	15	+ * For details of cpu_remap(), see bitmap_bitremap in lib/bitmap.c
	16	+ * For details of cpus_remap(), see bitmap_remap in lib/bitmap.c.
15	17	*
16	18	* The available cpumask operations are:
17	19	*
...	...	@@ -50,6 +52,8 @@
50	52	* int cpumask_parse(ubuf, ulen, mask) Parse ascii string as cpumask
51	53	* int cpulist_scnprintf(buf, len, mask) Format cpumask as list for printing
52	54	* int cpulist_parse(buf, map) Parse ascii string as cpulist
	55	+ * int cpu_remap(oldbit, old, new) newbit = map(old, new)(oldbit)
	56	+ * int cpus_remap(dst, src, old, new) *dst = map(old, new)(src)
53	57	*
54	58	* for_each_cpu_mask(cpu, mask) for-loop cpu over mask
55	59	*
...	...	@@ -292,6 +296,22 @@
292	296	static inline int __cpulist_parse(const char buf, cpumask_t dstp, int nbits)
293	297	{
294	298	return bitmap_parselist(buf, dstp->bits, nbits);
	299	+}
	300	+
	301	+#define cpu_remap(oldbit, old, new) \
	302	+ __cpu_remap((oldbit), &(old), &(new), NR_CPUS)
	303	+static inline int __cpu_remap(int oldbit,
	304	+ const cpumask_t oldp, const cpumask_t newp, int nbits)
	305	+{
	306	+ return bitmap_bitremap(oldbit, oldp->bits, newp->bits, nbits);
	307	+}
	308	+
	309	+#define cpus_remap(dst, src, old, new) \
	310	+ __cpus_remap(&(dst), &(src), &(old), &(new), NR_CPUS)
	311	+static inline void __cpus_remap(cpumask_t dstp, const cpumask_t srcp,
	312	+ const cpumask_t oldp, const cpumask_t newp, int nbits)
	313	+{
	314	+ bitmap_remap(dstp->bits, srcp->bits, oldp->bits, newp->bits, nbits);
295	315	}
296	316
297	317	#if NR_CPUS > 1
...	...	@@ -12,6 +12,8 @@
12	12	* see bitmap_scnprintf() and bitmap_parse() in lib/bitmap.c.
13	13	* For details of nodelist_scnprintf() and nodelist_parse(), see
14	14	* bitmap_scnlistprintf() and bitmap_parselist(), also in bitmap.c.
	15	+ * For details of node_remap(), see bitmap_bitremap in lib/bitmap.c.
	16	+ * For details of nodes_remap(), see bitmap_remap in lib/bitmap.c.
15	17	*
16	18	* The available nodemask operations are:
17	19	*
...	...	@@ -52,6 +54,8 @@
52	54	* int nodemask_parse(ubuf, ulen, mask) Parse ascii string as nodemask
53	55	* int nodelist_scnprintf(buf, len, mask) Format nodemask as list for printing
54	56	* int nodelist_parse(buf, map) Parse ascii string as nodelist
	57	+ * int node_remap(oldbit, old, new) newbit = map(old, new)(oldbit)
	58	+ * int nodes_remap(dst, src, old, new) *dst = map(old, new)(dst)
55	59	*
56	60	* for_each_node_mask(node, mask) for-loop node over mask
57	61	*
...	...	@@ -305,6 +309,22 @@
305	309	static inline int __nodelist_parse(const char buf, nodemask_t dstp, int nbits)
306	310	{
307	311	return bitmap_parselist(buf, dstp->bits, nbits);
	312	+}
	313	+
	314	+#define node_remap(oldbit, old, new) \
	315	+ __node_remap((oldbit), &(old), &(new), MAX_NUMNODES)
	316	+static inline int __node_remap(int oldbit,
	317	+ const nodemask_t oldp, const nodemask_t newp, int nbits)
	318	+{
	319	+ return bitmap_bitremap(oldbit, oldp->bits, newp->bits, nbits);
	320	+}
	321	+
	322	+#define nodes_remap(dst, src, old, new) \
	323	+ __nodes_remap(&(dst), &(src), &(old), &(new), MAX_NUMNODES)
	324	+static inline void __nodes_remap(nodemask_t dstp, const nodemask_t srcp,
	325	+ const nodemask_t oldp, const nodemask_t newp, int nbits)
	326	+{
	327	+ bitmap_remap(dstp->bits, srcp->bits, oldp->bits, newp->bits, nbits);
308	328	}
309	329
310	330	#if MAX_NUMNODES > 1
...	...	@@ -511,6 +511,172 @@
511	511	}
512	512	EXPORT_SYMBOL(bitmap_parselist);
513	513
	514	+/*
	515	+ * bitmap_pos_to_ord(buf, pos, bits)
	516	+ * @buf: pointer to a bitmap
	517	+ * @pos: a bit position in @buf (0 <= @pos < @bits)
	518	+ * @bits: number of valid bit positions in @buf
	519	+ *
	520	+ * Map the bit at position @pos in @buf (of length @bits) to the
	521	+ * ordinal of which set bit it is. If it is not set or if @pos
	522	+ * is not a valid bit position, map to zero (0).
	523	+ *
	524	+ * If for example, just bits 4 through 7 are set in @buf, then @pos
	525	+ * values 4 through 7 will get mapped to 0 through 3, respectively,
	526	+ * and other @pos values will get mapped to 0. When @pos value 7
	527	+ * gets mapped to (returns) @ord value 3 in this example, that means
	528	+ * that bit 7 is the 3rd (starting with 0th) set bit in @buf.
	529	+ *
	530	+ * The bit positions 0 through @bits are valid positions in @buf.
	531	+ */
	532	+static int bitmap_pos_to_ord(const unsigned long *buf, int pos, int bits)
	533	+{
	534	+ int ord = 0;
	535	+
	536	+ if (pos >= 0 && pos < bits) {
	537	+ int i;
	538	+
	539	+ for (i = find_first_bit(buf, bits);
	540	+ i < pos;
	541	+ i = find_next_bit(buf, bits, i + 1))
	542	+ ord++;
	543	+ if (i > pos)
	544	+ ord = 0;
	545	+ }
	546	+ return ord;
	547	+}
	548	+
	549	+/**
	550	+ * bitmap_ord_to_pos(buf, ord, bits)
	551	+ * @buf: pointer to bitmap
	552	+ * @ord: ordinal bit position (n-th set bit, n >= 0)
	553	+ * @bits: number of valid bit positions in @buf
	554	+ *
	555	+ * Map the ordinal offset of bit @ord in @buf to its position in @buf.
	556	+ * If @ord is not the ordinal offset of a set bit in @buf, map to zero (0).
	557	+ *
	558	+ * If for example, just bits 4 through 7 are set in @buf, then @ord
	559	+ * values 0 through 3 will get mapped to 4 through 7, respectively,
	560	+ * and all other @ord valuds will get mapped to 0. When @ord value 3
	561	+ * gets mapped to (returns) @pos value 7 in this example, that means
	562	+ * that the 3rd set bit (starting with 0th) is at position 7 in @buf.
	563	+ *
	564	+ * The bit positions 0 through @bits are valid positions in @buf.
	565	+ */
	566	+static int bitmap_ord_to_pos(const unsigned long *buf, int ord, int bits)
	567	+{
	568	+ int pos = 0;
	569	+
	570	+ if (ord >= 0 && ord < bits) {
	571	+ int i;
	572	+
	573	+ for (i = find_first_bit(buf, bits);
	574	+ i < bits && ord > 0;
	575	+ i = find_next_bit(buf, bits, i + 1))
	576	+ ord--;
	577	+ if (i < bits && ord == 0)
	578	+ pos = i;
	579	+ }
	580	+
	581	+ return pos;
	582	+}
	583	+
	584	+/**
	585	+ * bitmap_remap - Apply map defined by a pair of bitmaps to another bitmap
	586	+ * @src: subset to be remapped
	587	+ * @dst: remapped result
	588	+ * @old: defines domain of map
	589	+ * @new: defines range of map
	590	+ * @bits: number of bits in each of these bitmaps
	591	+ *
	592	+ * Let @old and @new define a mapping of bit positions, such that
	593	+ * whatever position is held by the n-th set bit in @old is mapped
	594	+ * to the n-th set bit in @new. In the more general case, allowing
	595	+ * for the possibility that the weight 'w' of @new is less than the
	596	+ * weight of @old, map the position of the n-th set bit in @old to
	597	+ * the position of the m-th set bit in @new, where m == n % w.
	598	+ *
	599	+ * If either of the @old and @new bitmaps are empty, or if@src and @dst
	600	+ * point to the same location, then this routine does nothing.
	601	+ *
	602	+ * The positions of unset bits in @old are mapped to the position of
	603	+ * the first set bit in @new.
	604	+ *
	605	+ * Apply the above specified mapping to @src, placing the result in
	606	+ * @dst, clearing any bits previously set in @dst.
	607	+ *
	608	+ * The resulting value of @dst will have either the same weight as
	609	+ * @src, or less weight in the general case that the mapping wasn't
	610	+ * injective due to the weight of @new being less than that of @old.
	611	+ * The resulting value of @dst will never have greater weight than
	612	+ * that of @src, except perhaps in the case that one of the above
	613	+ * conditions was not met and this routine just returned.
	614	+ *
	615	+ * For example, lets say that @old has bits 4 through 7 set, and
	616	+ * @new has bits 12 through 15 set. This defines the mapping of bit
	617	+ * position 4 to 12, 5 to 13, 6 to 14 and 7 to 15, and of all other
	618	+ * bit positions to 12 (the first set bit in @new. So if say @src
	619	+ * comes into this routine with bits 1, 5 and 7 set, then @dst should
	620	+ * leave with bits 12, 13 and 15 set.
	621	+ */
	622	+void bitmap_remap(unsigned long dst, const unsigned long src,
	623	+ const unsigned long old, const unsigned long new,
	624	+ int bits)
	625	+{
	626	+ int s;
	627	+
	628	+ if (bitmap_weight(old, bits) == 0)
	629	+ return;
	630	+ if (bitmap_weight(new, bits) == 0)
	631	+ return;
	632	+ if (dst == src) /* following doesn't handle inplace remaps */
	633	+ return;
	634	+
	635	+ bitmap_zero(dst, bits);
	636	+ for (s = find_first_bit(src, bits);
	637	+ s < bits;
	638	+ s = find_next_bit(src, bits, s + 1)) {
	639	+ int x = bitmap_pos_to_ord(old, s, bits);
	640	+ int y = bitmap_ord_to_pos(new, x, bits);
	641	+ set_bit(y, dst);
	642	+ }
	643	+}
	644	+EXPORT_SYMBOL(bitmap_remap);
	645	+
	646	+/**
	647	+ * bitmap_bitremap - Apply map defined by a pair of bitmaps to a single bit
	648	+ * @oldbit - bit position to be mapped
	649	+ * @old: defines domain of map
	650	+ * @new: defines range of map
	651	+ * @bits: number of bits in each of these bitmaps
	652	+ *
	653	+ * Let @old and @new define a mapping of bit positions, such that
	654	+ * whatever position is held by the n-th set bit in @old is mapped
	655	+ * to the n-th set bit in @new. In the more general case, allowing
	656	+ * for the possibility that the weight 'w' of @new is less than the
	657	+ * weight of @old, map the position of the n-th set bit in @old to
	658	+ * the position of the m-th set bit in @new, where m == n % w.
	659	+ *
	660	+ * The positions of unset bits in @old are mapped to the position of
	661	+ * the first set bit in @new.
	662	+ *
	663	+ * Apply the above specified mapping to bit position @oldbit, returning
	664	+ * the new bit position.
	665	+ *
	666	+ * For example, lets say that @old has bits 4 through 7 set, and
	667	+ * @new has bits 12 through 15 set. This defines the mapping of bit
	668	+ * position 4 to 12, 5 to 13, 6 to 14 and 7 to 15, and of all other
	669	+ * bit positions to 12 (the first set bit in @new. So if say @oldbit
	670	+ * is 5, then this routine returns 13.
	671	+ */
	672	+int bitmap_bitremap(int oldbit, const unsigned long *old,
	673	+ const unsigned long *new, int bits)
	674	+{
	675	+ int x = bitmap_pos_to_ord(old, oldbit, bits);
	676	+ return bitmap_ord_to_pos(new, x, bits);
	677	+}
	678	+EXPORT_SYMBOL(bitmap_bitremap);
	679	+
514	680	/**
515	681	* bitmap_find_free_region - find a contiguous aligned mem region
516	682	* @bitmap: an array of unsigned longs corresponding to the bitmap