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Btrfs: extent_map: use rb_first_cached

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rb_first_cached() trades an extra pointer "leftmost" for doing the
same job as rb_first() but in O(1).

As evict_inode_truncate_pages() removes all extent mapping by always
looking for the first rb entry, it's helpful to use rb_first_cached
instead.

For more details about the optimization see patch "Btrfs: delayed-refs:
use rb_first_cached for href_root".

Tested-by: Holger Hoffstätte <holger@applied-asynchrony.com>
Signed-off-by: Liu Bo <bo.liu@linux.alibaba.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
This commit is contained in:
Liu Bo
2018-08-23 03:51:52 +08:00
committed by David Sterba
parent 03a1d4c891
commit 07e1ce096d
5 changed files with 22 additions and 19 deletions
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2
fs/btrfs/extent_map.h
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@@ -49,7 +49,7 @@ struct extent_map {
};
struct extent_map_tree {
struct rb_root map;
struct rb_root_cached map;
struct list_head modified_extents;
rwlock_t lock;
};