diff options
author | Jeff Mahoney <jeffm@suse.com> | 2006-06-26 00:27:19 -0700 |
---|---|---|
committer | Linus Torvalds <torvalds@g5.osdl.org> | 2006-06-26 09:58:34 -0700 |
commit | 5806f07cd2c32920d5105e0f9ff3117338f34eec (patch) | |
tree | 65242ea629a19308656a3090fee6b513dfa0f723 /lib | |
parent | c51c2752491e5e771de6c8861a85ba46752d7888 (diff) |
[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')
-rw-r--r-- | lib/idr.c | 43 |
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) { |