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libext2fs: optimize find_first_{zero,set}() for red-black tree based bitmaps 

Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
maint-test
Theodore Ts'o 2014-01-12 21:46:46 -05:00
parent 14717832dd
commit 3203cd9332
1 changed files with 89 additions and 0 deletions
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89
lib/ext2fs/blkmap64_rb.c
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@ -809,6 +809,93 @@ static void rb_clear_bmap(ext2fs_generic_bitmap bitmap)
check_tree(&bp->root, __func__);
}
static errcode_t rb_find_first_zero(ext2fs_generic_bitmap bitmap,
__u64 start, __u64 end, __u64 *out)
{
struct rb_node *parent = NULL, **n;
struct rb_node *node, *next;
struct ext2fs_rb_private *bp;
struct bmap_rb_extent *ext;
int retval = 1;
bp = (struct ext2fs_rb_private *) bitmap->private;
n = &bp->root.rb_node;
start -= bitmap->start;
end -= bitmap->start;
if (start > end)
return EINVAL;
if (EXT2FS_RB_EMPTY_ROOT(&bp->root))
return ENOENT;
while (*n) {
parent = *n;
ext = node_to_extent(parent);
if (start < ext->start) {
n = &(*n)->rb_left;
} else if (start >= (ext->start + ext->count)) {
n = &(*n)->rb_right;
} else if (ext->start + ext->count <= end) {
*out = ext->start + ext->count + bitmap->start;
return 0;
} else
return ENOENT;
}
*out = start + bitmap->start;
return 0;
}
static errcode_t rb_find_first_set(ext2fs_generic_bitmap bitmap,
__u64 start, __u64 end, __u64 *out)
{
struct rb_node *parent = NULL, **n;
struct rb_node *node, *next;
struct ext2fs_rb_private *bp;
struct bmap_rb_extent *ext;
int retval = 1;
bp = (struct ext2fs_rb_private *) bitmap->private;
n = &bp->root.rb_node;
start -= bitmap->start;
end -= bitmap->start;
if (start > end)
return EINVAL;
if (EXT2FS_RB_EMPTY_ROOT(&bp->root))
return ENOENT;
while (*n) {
parent = *n;
ext = node_to_extent(parent);
if (start < ext->start) {
n = &(*n)->rb_left;
} else if (start >= (ext->start + ext->count)) {
n = &(*n)->rb_right;
} else {
/* The start bit is set */
*out = start + bitmap->start;
return 0;
}
}
node = parent;
ext = node_to_extent(node);
if (ext->start < start) {
node = ext2fs_rb_next(node);
if (node == NULL)
return ENOENT;
ext = node_to_extent(node);
}
if (ext->start <= end) {
*out = ext->start + bitmap->start;
return 0;
}
return ENOENT;
}
#ifdef BMAP_STATS
static void rb_print_stats(ext2fs_generic_bitmap bitmap)
{
@ -890,4 +977,6 @@ 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,
};