mirror of
https://mirrors.bfsu.edu.cn/git/linux.git
synced 2024-11-11 21:38:32 +08:00
btrfs: restructure find_free_dev_extent()
- make it return the start position and length of the max free space when it can not find a suitable free space. - make it more readability Signed-off-by: Miao Xie <miaox@cn.fujitsu.com> Signed-off-by: Chris Mason <chris.mason@oracle.com>
This commit is contained in:
Miao Xie
Chris Mason
parent
1974a3b42d
commit
7bfc837df9
@ -8099,7 +8099,7 @@ int btrfs_can_relocate(struct btrfs_root *root, u64 bytenr)
|
||||
mutex_lock(&root->fs_info->chunk_mutex);
|
||||
list_for_each_entry(device, &fs_devices->alloc_list, dev_alloc_list) {
|
||||
u64 min_free = btrfs_block_group_used(&block_group->item);
|
||||
u64 dev_offset, max_avail;
|
||||
u64 dev_offset;
|
||||
|
||||
/*
|
||||
* check to make sure we can actually find a chunk with enough
|
||||
@ -8107,7 +8107,7 @@ int btrfs_can_relocate(struct btrfs_root *root, u64 bytenr)
|
||||
*/
|
||||
if (device->total_bytes > device->bytes_used + min_free) {
|
||||
ret = find_free_dev_extent(NULL, device, min_free,
|
||||
&dev_offset, &max_avail);
|
||||
&dev_offset, NULL);
|
||||
if (!ret)
|
||||
break;
|
||||
ret = -1;
|
||||
|
||||
@ -729,58 +729,82 @@ error:
|
||||
}
|
||||
|
||||
/*
|
||||
* find_free_dev_extent - find free space in the specified device
|
||||
* @trans: transaction handler
|
||||
* @device: the device which we search the free space in
|
||||
* @num_bytes: the size of the free space that we need
|
||||
* @start: store the start of the free space.
|
||||
* @len: the size of the free space. that we find, or the size of the max
|
||||
* free space if we don't find suitable free space
|
||||
*
|
||||
* this uses a pretty simple search, the expectation is that it is
|
||||
* called very infrequently and that a given device has a small number
|
||||
* of extents
|
||||
*
|
||||
* @start is used to store the start of the free space if we find. But if we
|
||||
* don't find suitable free space, it will be used to store the start position
|
||||
* of the max free space.
|
||||
*
|
||||
* @len is used to store the size of the free space that we find.
|
||||
* But if we don't find suitable free space, it is used to store the size of
|
||||
* the max free space.
|
||||
*/
|
||||
int find_free_dev_extent(struct btrfs_trans_handle *trans,
|
||||
struct btrfs_device *device, u64 num_bytes,
|
||||
u64 *start, u64 *max_avail)
|
||||
u64 *start, u64 *len)
|
||||
{
|
||||
struct btrfs_key key;
|
||||
struct btrfs_root *root = device->dev_root;
|
||||
struct btrfs_dev_extent *dev_extent = NULL;
|
||||
struct btrfs_dev_extent *dev_extent;
|
||||
struct btrfs_path *path;
|
||||
u64 hole_size = 0;
|
||||
u64 last_byte = 0;
|
||||
u64 search_start = 0;
|
||||
u64 hole_size;
|
||||
u64 max_hole_start;
|
||||
u64 max_hole_size;
|
||||
u64 extent_end;
|
||||
u64 search_start;
|
||||
u64 search_end = device->total_bytes;
|
||||
int ret;
|
||||
int slot = 0;
|
||||
int start_found;
|
||||
int slot;
|
||||
struct extent_buffer *l;
|
||||
|
||||
path = btrfs_alloc_path();
|
||||
if (!path)
|
||||
return -ENOMEM;
|
||||
path->reada = 2;
|
||||
start_found = 0;
|
||||
|
||||
/* FIXME use last free of some kind */
|
||||
|
||||
/* we don't want to overwrite the superblock on the drive,
|
||||
* so we make sure to start at an offset of at least 1MB
|
||||
*/
|
||||
search_start = max((u64)1024 * 1024, search_start);
|
||||
search_start = 1024 * 1024;
|
||||
|
||||
if (root->fs_info->alloc_start + num_bytes <= device->total_bytes)
|
||||
if (root->fs_info->alloc_start + num_bytes <= search_end)
|
||||
search_start = max(root->fs_info->alloc_start, search_start);
|
||||
|
||||
max_hole_start = search_start;
|
||||
max_hole_size = 0;
|
||||
|
||||
if (search_start >= search_end) {
|
||||
ret = -ENOSPC;
|
||||
goto error;
|
||||
}
|
||||
|
||||
path = btrfs_alloc_path();
|
||||
if (!path) {
|
||||
ret = -ENOMEM;
|
||||
goto error;
|
||||
}
|
||||
path->reada = 2;
|
||||
|
||||
key.objectid = device->devid;
|
||||
key.offset = search_start;
|
||||
key.type = BTRFS_DEV_EXTENT_KEY;
|
||||
|
||||
ret = btrfs_search_slot(trans, root, &key, path, 0, 0);
|
||||
if (ret < 0)
|
||||
goto error;
|
||||
goto out;
|
||||
if (ret > 0) {
|
||||
ret = btrfs_previous_item(root, path, key.objectid, key.type);
|
||||
if (ret < 0)
|
||||
goto error;
|
||||
if (ret > 0)
|
||||
start_found = 1;
|
||||
goto out;
|
||||
}
|
||||
l = path->nodes[0];
|
||||
btrfs_item_key_to_cpu(l, &key, path->slots[0]);
|
||||
|
||||
while (1) {
|
||||
l = path->nodes[0];
|
||||
slot = path->slots[0];
|
||||
@ -789,24 +813,9 @@ int find_free_dev_extent(struct btrfs_trans_handle *trans,
|
||||
if (ret == 0)
|
||||
continue;
|
||||
if (ret < 0)
|
||||
goto error;
|
||||
no_more_items:
|
||||
if (!start_found) {
|
||||
if (search_start >= search_end) {
|
||||
ret = -ENOSPC;
|
||||
goto error;
|
||||
}
|
||||
*start = search_start;
|
||||
start_found = 1;
|
||||
goto check_pending;
|
||||
}
|
||||
*start = last_byte > search_start ?
|
||||
last_byte : search_start;
|
||||
if (search_end <= *start) {
|
||||
ret = -ENOSPC;
|
||||
goto error;
|
||||
}
|
||||
goto check_pending;
|
||||
goto out;
|
||||
|
||||
break;
|
||||
}
|
||||
btrfs_item_key_to_cpu(l, &key, slot);
|
||||
|
||||
@ -814,48 +823,62 @@ no_more_items:
|
||||
goto next;
|
||||
|
||||
if (key.objectid > device->devid)
|
||||
goto no_more_items;
|
||||
break;
|
||||
|
||||
if (key.offset >= search_start && key.offset > last_byte &&
|
||||
start_found) {
|
||||
if (last_byte < search_start)
|
||||
last_byte = search_start;
|
||||
hole_size = key.offset - last_byte;
|
||||
|
||||
if (hole_size > *max_avail)
|
||||
*max_avail = hole_size;
|
||||
|
||||
if (key.offset > last_byte &&
|
||||
hole_size >= num_bytes) {
|
||||
*start = last_byte;
|
||||
goto check_pending;
|
||||
}
|
||||
}
|
||||
if (btrfs_key_type(&key) != BTRFS_DEV_EXTENT_KEY)
|
||||
goto next;
|
||||
|
||||
start_found = 1;
|
||||
if (key.offset > search_start) {
|
||||
hole_size = key.offset - search_start;
|
||||
|
||||
if (hole_size > max_hole_size) {
|
||||
max_hole_start = search_start;
|
||||
max_hole_size = hole_size;
|
||||
}
|
||||
|
||||
/*
|
||||
* If this free space is greater than which we need,
|
||||
* it must be the max free space that we have found
|
||||
* until now, so max_hole_start must point to the start
|
||||
* of this free space and the length of this free space
|
||||
* is stored in max_hole_size. Thus, we return
|
||||
* max_hole_start and max_hole_size and go back to the
|
||||
* caller.
|
||||
*/
|
||||
if (hole_size >= num_bytes) {
|
||||
ret = 0;
|
||||
goto out;
|
||||
}
|
||||
}
|
||||
|
||||
dev_extent = btrfs_item_ptr(l, slot, struct btrfs_dev_extent);
|
||||
last_byte = key.offset + btrfs_dev_extent_length(l, dev_extent);
|
||||
extent_end = key.offset + btrfs_dev_extent_length(l,
|
||||
dev_extent);
|
||||
if (extent_end > search_start)
|
||||
search_start = extent_end;
|
||||
next:
|
||||
path->slots[0]++;
|
||||
cond_resched();
|
||||
}
|
||||
check_pending:
|
||||
/* we have to make sure we didn't find an extent that has already
|
||||
* been allocated by the map tree or the original allocation
|
||||
*/
|
||||
BUG_ON(*start < search_start);
|
||||
|
||||
if (*start + num_bytes > search_end) {
|
||||
ret = -ENOSPC;
|
||||
goto error;
|
||||
hole_size = search_end- search_start;
|
||||
if (hole_size > max_hole_size) {
|
||||
max_hole_start = search_start;
|
||||
max_hole_size = hole_size;
|
||||
}
|
||||
/* check for pending inserts here */
|
||||
ret = 0;
|
||||
|
||||
error:
|
||||
/* See above. */
|
||||
if (hole_size < num_bytes)
|
||||
ret = -ENOSPC;
|
||||
else
|
||||
ret = 0;
|
||||
|
||||
out:
|
||||
btrfs_free_path(path);
|
||||
error:
|
||||
*start = max_hole_start;
|
||||
if (len && max_hole_size > *len)
|
||||
*len = max_hole_size;
|
||||
return ret;
|
||||
}
|
||||
|
||||
|
||||
Loading…
Reference in New Issue
Block a user