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btrfs-progs: mkfs/rootdir: Introduce function to get end position of last device extent 

Useful for later 'mkfs.btrfs --rootdir' shrink support.

Signed-off-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
This commit is contained in:
Qu Wenruo 2017-10-20 09:59:04 +08:00 committed by David Sterba
parent 5d0783ad14
commit 0a7a48e1e8
1 changed files with 44 additions and 0 deletions
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44
mkfs/rootdir.c
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@ -26,6 +26,7 @@
#include <fcntl.h>
#include <ftw.h>
#include "ctree.h"
#include "volumes.h"
#include "internal.h"
#include "disk-io.h"
#include "messages.h"
@ -733,3 +734,46 @@ u64 btrfs_mkfs_size_dir(const char *dir_name, u64 sectorsize,
*size_of_data_ret = num_of_data_chunks * default_chunk_size;
return total_size;
}
/*
* Get the end position of the last device extent for given @devid;
* @size_ret is exclsuive (means it should be aligned to sectorsize)
*/
static int get_device_extent_end(struct btrfs_fs_info *fs_info,
u64 devid, u64 *size_ret)
{
struct btrfs_root *dev_root = fs_info->dev_root;
struct btrfs_key key;
struct btrfs_path path;
struct btrfs_dev_extent *de;
int ret;
key.objectid = devid;
key.type = BTRFS_DEV_EXTENT_KEY;
key.offset = (u64)-1;
btrfs_init_path(&path);
ret = btrfs_search_slot(NULL, dev_root, &key, &path, 0, 0);
/* Not really possible */
BUG_ON(ret == 0);
ret = btrfs_previous_item(dev_root, &path, devid, BTRFS_DEV_EXTENT_KEY);
if (ret < 0)
goto out;
/* No dev_extent at all, not really possible for rootdir case */
if (ret > 0) {
*size_ret = 0;
ret = -EUCLEAN;
goto out;
}
btrfs_item_key_to_cpu(path.nodes[0], &key, path.slots[0]);
de = btrfs_item_ptr(path.nodes[0], path.slots[0],
struct btrfs_dev_extent);
*size_ret = key.offset + btrfs_dev_extent_length(path.nodes[0], de);
out:
btrfs_release_path(&path);
return ret;
}