The patch titled
radixtree: introduce radix_tree_scan_hole[_backward]()
has been removed from the -mm tree. Its filename was
radixtree-introduce-radix_tree_scan_hole.patch
This patch was dropped because an updated version will be merged
------------------------------------------------------
Subject: radixtree: introduce radix_tree_scan_hole[_backward]()
From: Wu Fengguang <wfg@xxxxxxxxxxxxxxxx>
Introduce a pair of functions to scan radix tree for hole/empty item.
- radix_tree_scan_hole(root, index, max_scan)
- radix_tree_scan_hole_backward(root, index, max_scan)
The implementation is dumb and obviously correct.
It will help to debug the smart ones to be introduced in future.
Signed-off-by: Wu Fengguang <wfg@xxxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxx>
---
include/linux/radix-tree.h | 4 +
lib/radix-tree.c | 71 +++++++++++++++++++++++++++++++++++
2 files changed, 75 insertions(+)
diff -puN include/linux/radix-tree.h~radixtree-introduce-radix_tree_scan_hole include/linux/radix-tree.h
--- a/include/linux/radix-tree.h~radixtree-introduce-radix_tree_scan_hole
+++ a/include/linux/radix-tree.h
@@ -156,6 +156,10 @@ void *radix_tree_delete(struct radix_tre
unsigned int
radix_tree_gang_lookup(struct radix_tree_root *root, void **results,
unsigned long first_index, unsigned int max_items);
+unsigned long radix_tree_scan_hole_backward(struct radix_tree_root *root,
+ unsigned long index, unsigned long max_scan);
+unsigned long radix_tree_scan_hole(struct radix_tree_root *root,
+ unsigned long index, unsigned long max_scan);
int radix_tree_preload(gfp_t gfp_mask);
void radix_tree_init(void);
void *radix_tree_tag_set(struct radix_tree_root *root,
diff -puN lib/radix-tree.c~radixtree-introduce-radix_tree_scan_hole lib/radix-tree.c
--- a/lib/radix-tree.c~radixtree-introduce-radix_tree_scan_hole
+++ a/lib/radix-tree.c
@@ -598,6 +598,77 @@ int radix_tree_tag_get(struct radix_tree
EXPORT_SYMBOL(radix_tree_tag_get);
#endif
+static unsigned long radix_tree_scan_hole_dumb(struct radix_tree_root *root,
+ unsigned long index, unsigned long max_scan)
+{
+ unsigned long i;
+
+ for (i = 0; i < max_scan; i++) {
+ if (!radix_tree_lookup(root, index + i))
+ break;
+ if (index + i == ULONG_MAX)
+ break;
+ }
+
+ return index + i;
+}
+
+static unsigned long radix_tree_scan_hole_backward_dumb(
+ struct radix_tree_root *root,
+ unsigned long index, unsigned long max_scan)
+{
+ unsigned long i;
+
+ for (i = 0; i < max_scan; i++) {
+ if (!radix_tree_lookup(root, index - i))
+ break;
+ if (index - i == 0)
+ break;
+ }
+
+ return index - i;
+}
+
+/**
+ * radix_tree_scan_hole - scan for hole
+ * @root: radix tree root
+ * @index: index key
+ * @max_scan: advice on max items to scan (it may scan a little more)
+ *
+ * Scan forward from @index for a hole/empty item, stop when
+ * - hit hole
+ * - hit index ULONG_MAX
+ * - @max_scan or more items scanned
+ *
+ * One can be sure that (@returned_index >= @index).
+ */
+unsigned long radix_tree_scan_hole(struct radix_tree_root *root,
+ unsigned long index, unsigned long max_scan)
+{
+ return radix_tree_scan_hole_dumb(root, index, max_scan);
+}
+EXPORT_SYMBOL(radix_tree_scan_hole);
+
+/**
+ * radix_tree_scan_hole_backward - scan backward for hole
+ * @root: radix tree root
+ * @index: index key
+ * @max_scan: advice on max items to scan (it may scan a little more)
+ *
+ * Scan backward from @index for a hole/empty item, stop when
+ * - hit hole
+ * - hit index 0
+ * - @max_scan or more items scanned
+ *
+ * One can be sure that (@returned_index <= @index).
+ */
+unsigned long radix_tree_scan_hole_backward(struct radix_tree_root *root,
+ unsigned long index, unsigned long max_scan)
+{
+ return radix_tree_scan_hole_backward_dumb(root, index, max_scan);
+}
+EXPORT_SYMBOL(radix_tree_scan_hole_backward);
+
static unsigned int
__lookup(struct radix_tree_node *slot, void **results, unsigned long index,
unsigned int max_items, unsigned long *next_index)
_
Patches currently in -mm which might be from wfg@xxxxxxxxxxxxxxxx are
radixtree-introduce-radix_tree_scan_hole.patch
mm-introduce-probe_page.patch
mm-introduce-pg_readahead.patch
readahead-add-look-ahead-support-to-__do_page_cache_readahead.patch
readahead-delay-page-release-in-do_generic_mapping_read.patch
readahead-insert-cond_resched-calls.patch
readahead-minmax_ra_pages.patch
readahead-events-accounting.patch
readahead-rescue_pages.patch
readahead-sysctl-parameters.patch
readahead-min-max-sizes.patch
readahead-state-based-method-aging-accounting.patch
readahead-state-based-method-routines.patch
readahead-state-based-method.patch
readahead-context-based-method.patch
readahead-initial-method-guiding-sizes.patch
readahead-initial-method-thrashing-guard-size.patch
readahead-initial-method-expected-read-size.patch
readahead-initial-method-user-recommended-size.patch
readahead-initial-method.patch
readahead-backward-prefetching-method.patch
readahead-seeking-reads-method.patch
readahead-thrashing-recovery-method.patch
readahead-call-scheme.patch
readahead-laptop-mode.patch
readahead-loop-case.patch
readahead-nfsd-case.patch
readahead-turn-on-by-default.patch
readahead-debug-radix-tree-new-functions.patch
readahead-debug-traces-showing-accessed-file-names.patch
readahead-debug-traces-showing-read-patterns.patch
readahead-remove-size-limit-on-read_ahead_kb.patch
readahead-backward-prefetching-method-fix.patch
readahead-remove-the-size-limit-of-max_sectors_kb-on-read_ahead_kb.patch
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