Zheng Liu 74cd15cd02 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>		2013-02-18 00:32:55 -05:00
..
events	ext4: reclaim extents from extent status tree	2013-02-18 00:32:55 -05:00
define_trace.h	treewide: fix comment/printk/variable typos	2012-09-01 10:33:05 -07:00
ftrace.h	tracing: Kill unused and puzzled sample code in ftrace.h	2012-11-13 15:51:21 -05:00
syscall.h	tracing: Cleanup unnecessary function declarations	2012-10-31 16:45:34 -04:00