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Btrfs: Try harder while searching for free space

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The loop searching for free space would exit out too soon when
metadata clustering was trying to allocate a large extent.  This makes
sure a full scan of the free space is done searching for only the
minimum extent size requested by the higher layers.

Signed-off-by: Chris Mason <chris.mason@oracle.com>
This commit is contained in:
Chris Mason 2008-11-10 11:47:09 -05:00
parent e04ca626ba
commit f5a31e1667
1 changed files with 29 additions and 7 deletions
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36
fs/btrfs/extent-tree.c
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@ -2123,6 +2123,7 @@ static int noinline find_free_extent(struct btrfs_trans_handle *trans,
int allowed_chunk_alloc = 0;
struct list_head *head = NULL, *cur = NULL;
int loop = 0;
int extra_loop = 0;
struct btrfs_space_info *space_info;
WARN_ON(num_bytes < root->sectorsize);
@ -2191,6 +2192,9 @@ static int noinline find_free_extent(struct btrfs_trans_handle *trans,
free_space = btrfs_find_free_space(block_group, search_start,
total_needed);
if (empty_size)
extra_loop = 1;
if (free_space) {
u64 start = block_group->key.objectid;
u64 end = block_group->key.objectid +
@ -2254,11 +2258,11 @@ static int noinline find_free_extent(struct btrfs_trans_handle *trans,
new_group:
mutex_unlock(&block_group->alloc_mutex);
new_group_no_lock:
/* don't try to compare new allocations against the
* last allocation any more
*/
last_wanted = 0;
if (!allowed_chunk_alloc) {
total_needed -= empty_size;
empty_size = 0;
}
/*
* Here's how this works.
* loop == 0: we were searching a block group via a hint
@ -2276,9 +2280,21 @@ new_group_no_lock:
cur = head->next;
loop++;
} else if (loop == 1 && cur == head) {
int keep_going;
/* at this point we give up on the empty_size
* allocations and just try to allocate the min
* space.
*
* The extra_loop field was set if an empty_size
* allocation was attempted above, and if this
* is try we need to try the loop again without
* the additional empty_size.
*/
total_needed -= empty_size;
empty_size = 0;
keep_going = extra_loop;
loop++;
if (allowed_chunk_alloc && !chunk_alloc_done) {
up_read(&space_info->groups_sem);
@ -2287,13 +2303,19 @@ new_group_no_lock:
if (ret < 0)
break;
down_read(&space_info->groups_sem);
loop++;
head = &space_info->block_groups;
cur = head->next;
/*
* we've allocated a new chunk, keep
* trying
*/
keep_going = 1;
chunk_alloc_done = 1;
} else if (!allowed_chunk_alloc) {
space_info->force_alloc = 1;
break;
}
if (keep_going) {
cur = head->next;
extra_loop = 0;
} else {
break;
}