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btrfs: Add a helper try_merge_free_space()

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When adding a new extent, we'll firstly see if we can merge
this extent to the left or/and right extent. Extract this as
a helper try_merge_free_space().

As a side effect, we fix a small bug that if the new extent
has non-bitmap left entry but is unmergeble, we'll directly
link the extent without trying to drop it into bitmap.

This also prepares for the next patch.

Reviewed-by: Josef Bacik <josef@redhat.com>
Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
This commit is contained in:
Li Zefan 2010-11-09 14:56:50 +08:00
parent 5e71b5d5ec
commit 120d66eec0
1 changed files with 43 additions and 32 deletions
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75
fs/btrfs/free-space-cache.c
View File

@ -1363,22 +1363,14 @@ out:
return ret;
}
int btrfs_add_free_space(struct btrfs_block_group_cache *block_group,
u64 offset, u64 bytes)
bool try_merge_free_space(struct btrfs_block_group_cache *block_group,
struct btrfs_free_space *info)
{
struct btrfs_free_space *right_info = NULL;
struct btrfs_free_space *left_info = NULL;
struct btrfs_free_space *info = NULL;
int ret = 0;
info = kzalloc(sizeof(struct btrfs_free_space), GFP_NOFS);
if (!info)
return -ENOMEM;
info->offset = offset;
info->bytes = bytes;
spin_lock(&block_group->tree_lock);
struct btrfs_free_space *left_info;
struct btrfs_free_space *right_info;
bool merged = false;
u64 offset = info->offset;
u64 bytes = info->bytes;
/*
* first we want to see if there is free space adjacent to the range we
@ -1392,27 +1384,11 @@ int btrfs_add_free_space(struct btrfs_block_group_cache *block_group,
else
left_info = tree_search_offset(block_group, offset - 1, 0, 0);
/*
* If there was no extent directly to the left or right of this new
* extent then we know we're going to have to allocate a new extent, so
* before we do that see if we need to drop this into a bitmap
*/
if ((!left_info || left_info->bitmap) &&
(!right_info || right_info->bitmap)) {
ret = insert_into_bitmap(block_group, info);
if (ret < 0) {
goto out;
} else if (ret) {
ret = 0;
goto out;
}
}
if (right_info && !right_info->bitmap) {
unlink_free_space(block_group, right_info);
info->bytes += right_info->bytes;
kfree(right_info);
merged = true;
}
if (left_info && !left_info->bitmap &&
@ -1421,8 +1397,43 @@ int btrfs_add_free_space(struct btrfs_block_group_cache *block_group,
info->offset = left_info->offset;
info->bytes += left_info->bytes;
kfree(left_info);
merged = true;
}
return merged;
}
int btrfs_add_free_space(struct btrfs_block_group_cache *block_group,
u64 offset, u64 bytes)
{
struct btrfs_free_space *info;
int ret = 0;
info = kzalloc(sizeof(struct btrfs_free_space), GFP_NOFS);
if (!info)
return -ENOMEM;
info->offset = offset;
info->bytes = bytes;
spin_lock(&block_group->tree_lock);
if (try_merge_free_space(block_group, info))
goto link;
/*
* There was no extent directly to the left or right of this new
* extent then we know we're going to have to allocate a new extent, so
* before we do that see if we need to drop this into a bitmap
*/
ret = insert_into_bitmap(block_group, info);
if (ret < 0) {
goto out;
} else if (ret) {
ret = 0;
goto out;
}
link:
ret = link_free_space(block_group, info);
if (ret)
kfree(info);