This is a note to let you know that I've just added the patch titled
lib: radix-tree: add radix_tree_delete_item()
to the 3.14-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
lib-radix-tree-add-radix_tree_delete_item.patch
and it can be found in the queue-3.14 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 53c59f262d747ea82e7414774c59a489501186a0 Mon Sep 17 00:00:00 2001
From: Johannes Weiner <hannes@xxxxxxxxxxx>
Date: Thu, 3 Apr 2014 14:47:39 -0700
Subject: lib: radix-tree: add radix_tree_delete_item()
From: Johannes Weiner <hannes@xxxxxxxxxxx>
commit 53c59f262d747ea82e7414774c59a489501186a0 upstream.
Provide a function that does not just delete an entry at a given index,
but also allows passing in an expected item. Delete only if that item
is still located at the specified index.
This is handy when lockless tree traversals want to delete entries as
well because they don't have to do an second, locked lookup to verify
the slot has not changed under them before deleting the entry.
Signed-off-by: Johannes Weiner <hannes@xxxxxxxxxxx>
Reviewed-by: Minchan Kim <minchan@xxxxxxxxxx>
Reviewed-by: Rik van Riel <riel@xxxxxxxxxx>
Acked-by: Mel Gorman <mgorman@xxxxxxx>
Cc: Andrea Arcangeli <aarcange@xxxxxxxxxx>
Cc: Bob Liu <bob.liu@xxxxxxxxxx>
Cc: Christoph Hellwig <hch@xxxxxxxxxxxxx>
Cc: Dave Chinner <david@xxxxxxxxxxxxx>
Cc: Greg Thelen <gthelen@xxxxxxxxxx>
Cc: Hugh Dickins <hughd@xxxxxxxxxx>
Cc: Jan Kara <jack@xxxxxxx>
Cc: KOSAKI Motohiro <kosaki.motohiro@xxxxxxxxxxxxxx>
Cc: Luigi Semenzato <semenzato@xxxxxxxxxx>
Cc: Metin Doslu <metin@xxxxxxxxxxxxx>
Cc: Michel Lespinasse <walken@xxxxxxxxxx>
Cc: Ozgun Erdogan <ozgun@xxxxxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Roman Gushchin <klamm@xxxxxxxxxxxxxx>
Cc: Ryan Mallon <rmallon@xxxxxxxxx>
Cc: Tejun Heo <tj@xxxxxxxxxx>
Cc: Vlastimil Babka <vbabka@xxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Mel Gorman <mgorman@xxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
include/linux/radix-tree.h | 1 +
lib/radix-tree.c | 31 +++++++++++++++++++++++++++----
2 files changed, 28 insertions(+), 4 deletions(-)
--- a/include/linux/radix-tree.h
+++ b/include/linux/radix-tree.h
@@ -219,6 +219,7 @@ static inline void radix_tree_replace_sl
int radix_tree_insert(struct radix_tree_root *, unsigned long, void *);
void *radix_tree_lookup(struct radix_tree_root *, unsigned long);
void **radix_tree_lookup_slot(struct radix_tree_root *, unsigned long);
+void *radix_tree_delete_item(struct radix_tree_root *, unsigned long, void *);
void *radix_tree_delete(struct radix_tree_root *, unsigned long);
unsigned int
radix_tree_gang_lookup(struct radix_tree_root *root, void **results,
--- a/lib/radix-tree.c
+++ b/lib/radix-tree.c
@@ -1337,15 +1337,18 @@ static inline void radix_tree_shrink(str
}
/**
- * radix_tree_delete - delete an item from a radix tree
+ * radix_tree_delete_item - delete an item from a radix tree
* @root: radix tree root
* @index: index key
+ * @item: expected item
*
- * Remove the item at @index from the radix tree rooted at @root.
+ * Remove @item at @index from the radix tree rooted at @root.
*
- * Returns the address of the deleted item, or NULL if it was not present.
+ * Returns the address of the deleted item, or NULL if it was not present
+ * or the entry at the given @index was not @item.
*/
-void *radix_tree_delete(struct radix_tree_root *root, unsigned long index)
+void *radix_tree_delete_item(struct radix_tree_root *root,
+ unsigned long index, void *item)
{
struct radix_tree_node *node = NULL;
struct radix_tree_node *slot = NULL;
@@ -1380,6 +1383,11 @@ void *radix_tree_delete(struct radix_tre
if (slot == NULL)
goto out;
+ if (item && slot != item) {
+ slot = NULL;
+ goto out;
+ }
+
/*
* Clear all tags associated with the item to be deleted.
* This way of doing it would be inefficient, but seldom is any set.
@@ -1424,6 +1432,21 @@ void *radix_tree_delete(struct radix_tre
out:
return slot;
}
+EXPORT_SYMBOL(radix_tree_delete_item);
+
+/**
+ * radix_tree_delete - delete an item from a radix tree
+ * @root: radix tree root
+ * @index: index key
+ *
+ * Remove the item at @index from the radix tree rooted at @root.
+ *
+ * Returns the address of the deleted item, or NULL if it was not present.
+ */
+void *radix_tree_delete(struct radix_tree_root *root, unsigned long index)
+{
+ return radix_tree_delete_item(root, index, NULL);
+}
EXPORT_SYMBOL(radix_tree_delete);
/**
Patches currently in stable-queue which might be from hannes@xxxxxxxxxxx are
queue-3.14/mm-filemap-move-radix-tree-hole-searching-here.patch
queue-3.14/lib-radix-tree-add-radix_tree_delete_item.patch
queue-3.14/mm-fs-prepare-for-non-page-entries-in-page-cache-radix-trees.patch
queue-3.14/mm-shmem-save-one-radix-tree-lookup-when-truncating-swapped-pages.patch
queue-3.14/mm-madvise-fix-madv_willneed-on-shmem-swapouts.patch
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