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Date: Tue, 19 Mar 2013 20:06:03 +0400
From: Andrey Sidorov <qrxd43@...orola.com>
To: linux-ext4@...r.kernel.org
Subject: [PATCH 4/5] libext2fs: ffz/ffs for rb_tree bitmap
find_first_zero / find_first_set Implementation for
rb_tree bitmap. Use of rcursor / rcursor_next makes
successive ffs/ffz/ffs/... calls to be equivalent of
iterating tree via ext2fs_rb_next.
Signed-off-by: Andrey Sidorov <qrxd43@...orola.com>
---
lib/ext2fs/blkmap64_rb.c | 164 +++++++++++++++++++++++++++++++++++++++++++---
1 file changed, 156 insertions(+), 8 deletions(-)
diff --git a/lib/ext2fs/blkmap64_rb.c b/lib/ext2fs/blkmap64_rb.c
index 702187f..76c525e 100644
--- a/lib/ext2fs/blkmap64_rb.c
+++ b/lib/ext2fs/blkmap64_rb.c
@@ -51,6 +51,21 @@ static int rb_insert_extent(__u64 start, __u64 count,
struct ext2fs_rb_private *);
static void rb_get_new_extent(struct bmap_rb_extent **, __u64, __u64);
+static inline struct bmap_rb_extent *
+rb_load_next_cursor(struct ext2fs_rb_private *bp)
+{
+ if (!bp->rcursor_next && bp->rcursor) {
+ struct rb_node *node;
+ node = ext2fs_rb_next(&bp->rcursor->node);
+ if (!node)
+ return NULL;
+ bp->rcursor_next = ext2fs_rb_entry(node,
+ struct bmap_rb_extent,
+ node);
+ }
+ return bp->rcursor_next;
+}
+
/* #define DEBUG_RB */
#ifdef DEBUG_RB
@@ -324,14 +339,7 @@ rb_test_bit(struct ext2fs_rb_private *bp, __u64 bit)
return 1;
}
- next_ext = bp->rcursor_next;
- if (!next_ext) {
- next = ext2fs_rb_next(&rcursor->node);
- if (next)
- next_ext = ext2fs_rb_entry(next, struct bmap_rb_extent,
- node);
- bp->rcursor_next = next_ext;
- }
+ next_ext = rb_load_next_cursor(bp);
if (next_ext) {
if ((bit >= rcursor->start + rcursor->count) &&
(bit < next_ext->start)) {
@@ -855,6 +863,144 @@ static void rb_print_stats(ext2fs_generic_bitmap bitmap)
static void rb_print_stats(ext2fs_generic_bitmap bitmap){}
#endif
+/* Find the first zero bit between start and end, inclusive. */
+static errcode_t rb_find_first_zero(ext2fs_generic_bitmap bitmap,
+ __u64 start, __u64 end, __u64 *out)
+{
+ struct ext2fs_rb_private *bp = bitmap->private;
+ struct rb_node *parent = NULL;
+ struct rb_node **n = &bp->root.rb_node;
+ struct bmap_rb_extent *ext = bp->rcursor;
+
+ start -= bitmap->start;
+ end -= bitmap->start;
+
+ if (!ext)
+ goto search_tree;
+
+ if (start >= ext->start) {
+ if (start <= ext->start + ext->count) {
+ goto match;
+ }
+ ext = rb_load_next_cursor(bp);
+ if (ext && start <= ext->start + ext->count) {
+ if (start >= ext->start) {
+ bp->rcursor = ext;
+ bp->rcursor_next = NULL;
+ }
+ goto match;
+ }
+ }
+
+search_tree:
+ while (*n) {
+ parent = *n;
+ ext = ext2fs_rb_entry(parent, struct bmap_rb_extent, node);
+
+ if (start < ext->start) {
+ n = &(*n)->rb_left;
+ } else if (start >= (ext->start + ext->count)) {
+ n = &(*n)->rb_right;
+ } else {
+ break;
+ }
+ }
+ bp->rcursor = ext;
+ bp->rcursor_next = NULL;
+
+match:
+ if (ext) {
+ if (start >= ext->start && start <= ext->start + ext->count) {
+ if (ext->start + ext->count <= end) {
+ *out = bitmap->start + ext->start + ext->count;
+ return 0;
+ }
+ else {
+ return ENOENT;
+ }
+ }
+ else {
+ *out = bitmap->start + start;
+ return 0;
+ }
+ }
+
+ *out = bitmap->start;
+ return 0;
+}
+
+/* Find the first set bit between start and end, inclusive. */
+static errcode_t rb_find_first_set(ext2fs_generic_bitmap bitmap,
+ __u64 start, __u64 end, __u64 *out)
+{
+ struct ext2fs_rb_private *bp = bitmap->private;
+ struct rb_node *parent = NULL;
+ struct rb_node **n = &bp->root.rb_node;
+ struct bmap_rb_extent *ext = bp->rcursor;
+
+ start -= bitmap->start;
+ end -= bitmap->start;
+
+ if (!ext)
+ goto search_tree;
+
+ if (start >= ext->start) {
+ if (start < ext->start + ext->count) {
+ *out = bitmap->start + start;
+ return 0;
+ }
+
+ ext = rb_load_next_cursor(bp);
+ if (!ext)
+ return ENOENT;
+ if (start < ext->start + ext->count) {
+ bp->rcursor = ext;
+ bp->rcursor_next = NULL;
+ goto match;
+ }
+ }
+
+search_tree:
+ while (*n) {
+ parent = *n;
+ ext = ext2fs_rb_entry(parent, struct bmap_rb_extent, node);
+
+ if (start < ext->start) {
+ n = &(*n)->rb_left;
+ } else if (start >= (ext->start + ext->count)) {
+ n = &(*n)->rb_right;
+ } else {
+ break;
+ }
+ }
+
+ if (ext && start >= ext->start + ext->count) {
+ struct rb_node *next = ext2fs_rb_next(parent);
+ if (next)
+ ext = ext2fs_rb_entry(next, struct bmap_rb_extent,
+ node);
+ }
+
+ bp->rcursor = ext;
+ bp->rcursor_next = NULL;
+
+match:
+ if (ext) {
+ if (start < ext->start) {
+ if (ext->start <= end) {
+ *out = bitmap->start + ext->start;
+ return 0;
+ }
+ }
+ else if (start < ext->start + ext->count) {
+ *out = bitmap->start + start;
+ return 0;
+ }
+ }
+
+ return ENOENT;
+}
+
struct ext2_bitmap_ops ext2fs_blkmap64_rbtree = {
.type = EXT2FS_BMAP64_RBTREE,
.new_bmap = rb_new_bmap,
@@ -871,4 +1017,6 @@ struct ext2_bitmap_ops ext2fs_blkmap64_rbtree = {
.get_bmap_range = rb_get_bmap_range,
.clear_bmap = rb_clear_bmap,
.print_stats = rb_print_stats,
+ .find_first_zero = rb_find_first_zero,
+ .find_first_set = rb_find_first_set,
};
--
1.7.10.4
--
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