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btrfs: delayed-ref: extract find_first_ref_head from find_ref_head 

The find_ref_head shouldn't return the first entry even if no exact match
is found. So move the hidden behavior to higher level.

Besides, remove the useless local variables in the btrfs_select_ref_head.

Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: Lu Fengqi <lufq.fnst@cn.fujitsu.com>
[ reformat comment ]
Signed-off-by: David Sterba <dsterba@suse.com>
This commit is contained in:
Lu Fengqi 2018-10-15 14:25:38 +08:00 committed by David Sterba
parent 5ce555578e
commit 0a9df0df17
1 changed files with 27 additions and 23 deletions
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50
fs/btrfs/delayed-ref.c
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@ -164,14 +164,27 @@ static struct btrfs_delayed_ref_node* tree_insert(struct rb_root_cached *root,
return NULL;
}
static struct btrfs_delayed_ref_head *find_first_ref_head(
struct btrfs_delayed_ref_root *dr)
{
struct rb_node *n;
struct btrfs_delayed_ref_head *entry;
n = rb_first_cached(&dr->href_root);
if (!n)
return NULL;
entry = rb_entry(n, struct btrfs_delayed_ref_head, href_node);
return entry;
}
/*
* find an head entry based on bytenr. This returns the delayed ref
* head if it was able to find one, or NULL if nothing was in that spot.
* If return_bigger is given, the next bigger entry is returned if no exact
* match is found. But if no bigger one is found then the first node of the
* ref head tree will be returned.
* Find a head entry based on bytenr. This returns the delayed ref head if it
* was able to find one, or NULL if nothing was in that spot. If return_bigger
* is given, the next bigger entry is returned if no exact match is found.
*/
static struct btrfs_delayed_ref_head* find_ref_head(
static struct btrfs_delayed_ref_head *find_ref_head(
struct btrfs_delayed_ref_root *dr, u64 bytenr,
bool return_bigger)
{
@ -195,10 +208,9 @@ static struct btrfs_delayed_ref_head* find_ref_head(
if (bytenr > entry->bytenr) {
n = rb_next(&entry->href_node);
if (!n)
n = rb_first_cached(&dr->href_root);
return NULL;
entry = rb_entry(n, struct btrfs_delayed_ref_head,
href_node);
return entry;
}
return entry;
}
@ -355,33 +367,25 @@ struct btrfs_delayed_ref_head *btrfs_select_ref_head(
struct btrfs_delayed_ref_root *delayed_refs)
{
struct btrfs_delayed_ref_head *head;
u64 start;
bool loop = false;
again:
start = delayed_refs->run_delayed_start;
head = find_ref_head(delayed_refs, start, true);
if (!head && !loop) {
head = find_ref_head(delayed_refs, delayed_refs->run_delayed_start,
true);
if (!head && delayed_refs->run_delayed_start != 0) {
delayed_refs->run_delayed_start = 0;
start = 0;
loop = true;
head = find_ref_head(delayed_refs, start, true);
if (!head)
return NULL;
} else if (!head && loop) {
return NULL;
head = find_first_ref_head(delayed_refs);
}
if (!head)
return NULL;
while (head->processing) {
struct rb_node *node;
node = rb_next(&head->href_node);
if (!node) {
if (loop)
if (delayed_refs->run_delayed_start == 0)
return NULL;
delayed_refs->run_delayed_start = 0;
start = 0;
loop = true;
goto again;
}
head = rb_entry(node, struct btrfs_delayed_ref_head,