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authorJeff Mahoney <jeffm@suse.com>2006-06-26 00:27:19 -0700
committerLinus Torvalds <torvalds@g5.osdl.org>2006-06-26 09:58:34 -0700
commit5806f07cd2c32920d5105e0f9ff3117338f34eec (patch)
tree65242ea629a19308656a3090fee6b513dfa0f723 /lib/idr.c
parentc51c2752491e5e771de6c8861a85ba46752d7888 (diff)
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[PATCH] lib: add idr_replace
This patch adds idr_replace() to replace an existing pointer in a single operation. Device-mapper will use this to update the pointer it stored against a given id. Signed-off-by: Jeff Mahoney <jeffm@suse.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Diffstat (limited to 'lib/idr.c')
-rw-r--r--lib/idr.c43
1 files changed, 43 insertions, 0 deletions
diff --git a/lib/idr.c b/lib/idr.c
index de19030a999..4d096819511 100644
--- a/lib/idr.c
+++ b/lib/idr.c
@@ -29,6 +29,7 @@
#include <linux/init.h>
#include <linux/module.h>
#endif
+#include <linux/err.h>
#include <linux/string.h>
#include <linux/idr.h>
@@ -398,6 +399,48 @@ void *idr_find(struct idr *idp, int id)
}
EXPORT_SYMBOL(idr_find);
+/**
+ * idr_replace - replace pointer for given id
+ * @idp: idr handle
+ * @ptr: pointer you want associated with the id
+ * @id: lookup key
+ *
+ * Replace the pointer registered with an id and return the old value.
+ * A -ENOENT return indicates that @id was not found.
+ * A -EINVAL return indicates that @id was not within valid constraints.
+ *
+ * The caller must serialize vs idr_find(), idr_get_new(), and idr_remove().
+ */
+void *idr_replace(struct idr *idp, void *ptr, int id)
+{
+ int n;
+ struct idr_layer *p, *old_p;
+
+ n = idp->layers * IDR_BITS;
+ p = idp->top;
+
+ id &= MAX_ID_MASK;
+
+ if (id >= (1 << n))
+ return ERR_PTR(-EINVAL);
+
+ n -= IDR_BITS;
+ while ((n > 0) && p) {
+ p = p->ary[(id >> n) & IDR_MASK];
+ n -= IDR_BITS;
+ }
+
+ n = id & IDR_MASK;
+ if (unlikely(p == NULL || !test_bit(n, &p->bitmap)))
+ return ERR_PTR(-ENOENT);
+
+ old_p = p->ary[n];
+ p->ary[n] = ptr;
+
+ return old_p;
+}
+EXPORT_SYMBOL(idr_replace);
+
static void idr_cache_ctor(void * idr_layer, kmem_cache_t *idr_layer_cache,
unsigned long flags)
{