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authorZheng Liu <wenqing.lz@taobao.com>2013-02-18 09:32:55 +0400
committerTheodore Ts'o <tytso@mit.edu>2013-02-18 09:32:55 +0400
commit74cd15cd02708c7188581f279f33a98b2ae8d322 (patch)
tree5d5c2380ffc7ddf1cd529127b89bf572c1798ffd /fs/ext4/extents_status.h
parentbdedbb7b8d5b960e1ff0d116f5d4935febe73183 (diff)
downloadlinux-74cd15cd02708c7188581f279f33a98b2ae8d322.tar.xz
ext4: reclaim extents from extent status tree
Although extent status is loaded on-demand, we also need to reclaim extent from the tree when we are under a heavy memory pressure because in some cases fragmented extent tree causes status tree costs too much memory. Here we maintain a lru list in super_block. When the extent status of an inode is accessed and changed, this inode will be move to the tail of the list. The inode will be dropped from this list when it is cleared. In the inode, a counter is added to count the number of cached objects in extent status tree. Here only written/unwritten/hole extent is counted because delayed extent doesn't be reclaimed due to fiemap, bigalloc and seek_data/hole need it. The counter will be increased as a new extent is allocated, and it will be decreased as a extent is freed. In this commit we use normal shrinker framework to reclaim memory from the status tree. ext4_es_reclaim_extents_count() traverses the lru list to count the number of reclaimable extents. ext4_es_shrink() tries to reclaim written/unwritten/hole extents from extent status tree. The inode that has been shrunk is moved to the tail of lru list. Signed-off-by: Zheng Liu <wenqing.lz@taobao.com> Signed-off-by: "Theodore Ts'o" <tytso@mit.edu> Cc: Jan kara <jack@suse.cz>
Diffstat (limited to 'fs/ext4/extents_status.h')
-rw-r--r--fs/ext4/extents_status.h5
1 files changed, 5 insertions, 0 deletions
diff --git a/fs/ext4/extents_status.h b/fs/ext4/extents_status.h
index 8ffc90c784fa..cf83e77b16cb 100644
--- a/fs/ext4/extents_status.h
+++ b/fs/ext4/extents_status.h
@@ -106,4 +106,9 @@ static inline void ext4_es_store_status(struct extent_status *es,
es->es_pblk = block;
}
+extern void ext4_es_register_shrinker(struct super_block *sb);
+extern void ext4_es_unregister_shrinker(struct super_block *sb);
+extern void ext4_es_lru_add(struct inode *inode);
+extern void ext4_es_lru_del(struct inode *inode);
+
#endif /* _EXT4_EXTENTS_STATUS_H */