提交 ebf8aa44 编写于 作者: J Jan Kara 提交者: Linus Torvalds

radix-tree: omplement function radix_tree_range_tag_if_tagged

Implement function for setting one tag if another tag is set for each item
in given range.
Signed-off-by: NJan Kara <jack@suse.cz>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Nick Piggin <nickpiggin@yahoo.com.au>
Cc: Chris Mason <chris.mason@oracle.com>
Cc: Theodore Ts'o <tytso@mit.edu>
Cc: Jens Axboe <axboe@kernel.dk>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
上级 44ab57a0
......@@ -192,6 +192,10 @@ unsigned int
radix_tree_gang_lookup_tag_slot(struct radix_tree_root *root, void ***results,
unsigned long first_index, unsigned int max_items,
unsigned int tag);
unsigned long radix_tree_range_tag_if_tagged(struct radix_tree_root *root,
unsigned long *first_indexp, unsigned long last_index,
unsigned long nr_to_tag,
unsigned int fromtag, unsigned int totag);
int radix_tree_tagged(struct radix_tree_root *root, unsigned int tag);
static inline void radix_tree_preload_end(void)
......
......@@ -608,6 +608,100 @@ int radix_tree_tag_get(struct radix_tree_root *root,
}
EXPORT_SYMBOL(radix_tree_tag_get);
/**
* radix_tree_range_tag_if_tagged - for each item in given range set given
* tag if item has another tag set
* @root: radix tree root
* @first_indexp: pointer to a starting index of a range to scan
* @last_index: last index of a range to scan
* @nr_to_tag: maximum number items to tag
* @iftag: tag index to test
* @settag: tag index to set if tested tag is set
*
* This function scans range of radix tree from first_index to last_index
* (inclusive). For each item in the range if iftag is set, the function sets
* also settag. The function stops either after tagging nr_to_tag items or
* after reaching last_index.
*
* The function returns number of leaves where the tag was set and sets
* *first_indexp to the first unscanned index.
*/
unsigned long radix_tree_range_tag_if_tagged(struct radix_tree_root *root,
unsigned long *first_indexp, unsigned long last_index,
unsigned long nr_to_tag,
unsigned int iftag, unsigned int settag)
{
unsigned int height = root->height, shift;
unsigned long tagged = 0, index = *first_indexp;
struct radix_tree_node *open_slots[height], *slot;
last_index = min(last_index, radix_tree_maxindex(height));
if (index > last_index)
return 0;
if (!nr_to_tag)
return 0;
if (!root_tag_get(root, iftag)) {
*first_indexp = last_index + 1;
return 0;
}
if (height == 0) {
*first_indexp = last_index + 1;
root_tag_set(root, settag);
return 1;
}
shift = (height - 1) * RADIX_TREE_MAP_SHIFT;
slot = radix_tree_indirect_to_ptr(root->rnode);
for (;;) {
int offset;
offset = (index >> shift) & RADIX_TREE_MAP_MASK;
if (!slot->slots[offset])
goto next;
if (!tag_get(slot, iftag, offset))
goto next;
tag_set(slot, settag, offset);
if (height == 1) {
tagged++;
goto next;
}
/* Go down one level */
height--;
shift -= RADIX_TREE_MAP_SHIFT;
open_slots[height] = slot;
slot = slot->slots[offset];
continue;
next:
/* Go to next item at level determined by 'shift' */
index = ((index >> shift) + 1) << shift;
if (index > last_index)
break;
if (tagged >= nr_to_tag)
break;
while (((index >> shift) & RADIX_TREE_MAP_MASK) == 0) {
/*
* We've fully scanned this node. Go up. Because
* last_index is guaranteed to be in the tree, what
* we do below cannot wander astray.
*/
slot = open_slots[height];
height++;
shift += RADIX_TREE_MAP_SHIFT;
}
}
/*
* The iftag must have been set somewhere because otherwise
* we would return immediated at the beginning of the function
*/
root_tag_set(root, settag);
*first_indexp = index;
return tagged;
}
EXPORT_SYMBOL(radix_tree_range_tag_if_tagged);
/**
* radix_tree_next_hole - find the next hole (not-present entry)
* @root: tree root
......
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