btrfs-progs: convert: Introduce new function to remove reserved ranges

Introduce functions to remove reserved ranges for later btrfs-convert
rework.

The reserved ranges includes:
1. [0,1M)
2. [btrfs_sb_offset(1), +BTRFS_STRIPE_LEN)
3. [btrfs_sb_offset(2), +BTRFS_STRIPE_LEN)

Signed-off-by: Qu Wenruo <quwenruo@cn.fujitsu.com>
Signed-off-by: David Sterba <dsterba@suse.com>
This commit is contained in:
Qu Wenruo 2016-01-29 13:03:12 +08:00 committed by David Sterba
parent 8031517744
commit 9d615049d2

View File

@ -2547,6 +2547,123 @@ static int convert_open_fs(const char *devname,
return -1; return -1;
} }
/*
* Remove one reserve range from given cache tree
* if min_stripe_size is non-zero, it will ensure for split case,
* all its split cache extent is no smaller than @min_strip_size / 2.
*/
static int wipe_one_reserved_range(struct cache_tree *tree,
u64 start, u64 len, u64 min_stripe_size,
int ensure_size)
{
struct cache_extent *cache;
int ret;
BUG_ON(ensure_size && min_stripe_size == 0);
/*
* The logical here is simplified to handle special cases only
* So we don't need to consider merge case for ensure_size
*/
BUG_ON(min_stripe_size && (min_stripe_size < len * 2 ||
min_stripe_size / 2 < BTRFS_STRIPE_LEN));
/* Also, wipe range should already be aligned */
BUG_ON(start != round_down(start, BTRFS_STRIPE_LEN) ||
start + len != round_up(start + len, BTRFS_STRIPE_LEN));
min_stripe_size /= 2;
cache = lookup_cache_extent(tree, start, len);
if (!cache)
return 0;
if (start <= cache->start) {
/*
* |--------cache---------|
* |-wipe-|
*/
BUG_ON(start + len <= cache->start);
/*
* The wipe size is smaller than min_stripe_size / 2,
* so the result length should still meet min_stripe_size
* And no need to do alignment
*/
cache->size -= (start + len - cache->start);
if (cache->size == 0) {
remove_cache_extent(tree, cache);
free(cache);
return 0;
}
BUG_ON(ensure_size && cache->size < min_stripe_size);
cache->start = start + len;
return 0;
} else if (start > cache->start && start + len < cache->start +
cache->size) {
/*
* |-------cache-----|
* |-wipe-|
*/
u64 old_len = cache->size;
u64 insert_start = start + len;
u64 insert_len;
cache->size = start - cache->start;
if (ensure_size)
cache->size = max(cache->size, min_stripe_size);
cache->start = start - cache->size;
/* And insert the new one */
insert_len = old_len - start - len;
if (ensure_size)
insert_len = max(insert_len, min_stripe_size);
ret = add_merge_cache_extent(tree, insert_start, insert_len);
return ret;
}
/*
* |----cache-----|
* |--wipe-|
* Wipe len should be small enough and no need to expand the
* remaining extent
*/
cache->size = start - cache->start;
BUG_ON(ensure_size && cache->size < min_stripe_size);
return 0;
}
/*
* Remove reserved ranges from given cache_tree
*
* It will remove the following ranges
* 1) 0~1M
* 2) 2nd superblock, +64K (make sure chunks are 64K aligned)
* 3) 3rd superblock, +64K
*
* @min_stripe must be given for safety check
* and if @ensure_size is given, it will ensure affected cache_extent will be
* larger than min_stripe_size
*/
static int wipe_reserved_ranges(struct cache_tree *tree, u64 min_stripe_size,
int ensure_size)
{
int ret;
ret = wipe_one_reserved_range(tree, 0, 1024 * 1024, min_stripe_size,
ensure_size);
if (ret < 0)
return ret;
ret = wipe_one_reserved_range(tree, btrfs_sb_offset(1),
BTRFS_STRIPE_LEN, min_stripe_size, ensure_size);
if (ret < 0)
return ret;
ret = wipe_one_reserved_range(tree, btrfs_sb_offset(2),
BTRFS_STRIPE_LEN, min_stripe_size, ensure_size);
return ret;
}
/* /*
* Read used space * Read used space
*/ */