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btrfs-progs: extent-tree: Introduce function to find the first overlapping extent 

Introduce a new function, btrfs_search_overlap_extent() to find the first
overlapping extent.

It's useful for later btrfs-convert rework.

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 13:03:23 +08:00 committed by David Sterba
parent f07c814971
commit f5e77e4c52
3 changed files with 89 additions and 0 deletions
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24
ctree.c
View File

@ -2951,3 +2951,27 @@ int btrfs_previous_extent_item(struct btrfs_root *root,
}
return 1;
}
/*
* Search in extent tree to found next meta/data extent
* Caller needs to check for no-hole or skinny metadata features.
*/
int btrfs_next_extent_item(struct btrfs_root *root,
struct btrfs_path *path, u64 max_objectid)
{
struct btrfs_key found_key;
int ret;
while (1) {
ret = btrfs_next_item(root, path);
if (ret)
return ret;
btrfs_item_key_to_cpu(path->nodes[0], &found_key,
path->slots[0]);
if (found_key.objectid > max_objectid)
return 1;
if (found_key.type == BTRFS_EXTENT_ITEM_KEY ||
found_key.type == BTRFS_METADATA_ITEM_KEY)
return 0;
}
}

2
ctree.h
View File

@ -2388,6 +2388,8 @@ int btrfs_previous_item(struct btrfs_root *root,
int type);
int btrfs_previous_extent_item(struct btrfs_root *root,
struct btrfs_path *path, u64 min_objectid);
int btrfs_next_extent_item(struct btrfs_root *root,
struct btrfs_path *path, u64 max_objectid);
int btrfs_cow_block(struct btrfs_trans_handle *trans,
struct btrfs_root *root, struct extent_buffer *buf,
struct extent_buffer *parent, int parent_slot,

63
extent-tree.c
View File

@ -3909,6 +3909,69 @@ int btrfs_fix_block_accounting(struct btrfs_trans_handle *trans,
return 0;
}
static void __get_extent_size(struct btrfs_root *root, struct btrfs_path *path,
u64 *start, u64 *len)
{
struct btrfs_key key;
btrfs_item_key_to_cpu(path->nodes[0], &key, path->slots[0]);
BUG_ON(!(key.type == BTRFS_EXTENT_ITEM_KEY ||
key.type == BTRFS_METADATA_ITEM_KEY));
*start = key.objectid;
if (key.type == BTRFS_EXTENT_ITEM_KEY)
*len = key.offset;
else
*len = root->nodesize;
}
/*
* Find first overlap extent for range [bytenr, bytenr + len)
* Return 0 for found and point path to it.
* Return >0 for not found.
* Return <0 for err
*/
int btrfs_search_overlap_extent(struct btrfs_root *root,
struct btrfs_path *path, u64 bytenr, u64 len)
{
struct btrfs_key key;
u64 cur_start;
u64 cur_len;
int ret;
key.objectid = bytenr;
key.type = BTRFS_EXTENT_DATA_KEY;
key.offset = (u64)-1;
ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
if (ret < 0)
return ret;
BUG_ON(ret == 0);
ret = btrfs_previous_extent_item(root, path, 0);
if (ret < 0)
return ret;
/* no previous, check next extent */
if (ret > 0)
goto next;
__get_extent_size(root, path, &cur_start, &cur_len);
/* Tail overlap */
if (cur_start + cur_len > bytenr)
return 1;
next:
ret = btrfs_next_extent_item(root, path, bytenr + len);
if (ret < 0)
return ret;
/* No next, prev already checked, no overlap */
if (ret > 0)
return 0;
__get_extent_size(root, path, &cur_start, &cur_len);
/* head overlap*/
if (cur_start < bytenr + len)
return 1;
return 0;
}
/*
* Record a file extent. Do all the required works, such as inserting
* file extent item, inserting extent item and backref item into extent