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ext4: change LRU to round-robin in extent status tree shrinker

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In this commit we discard the lru algorithm for inodes with extent
status tree because it takes significant effort to maintain a lru list
in extent status tree shrinker and the shrinker can take a long time to
scan this lru list in order to reclaim some objects.

We replace the lru ordering with a simple round-robin.  After that we
never need to keep a lru list.  That means that the list needn't be
sorted if the shrinker can not reclaim any objects in the first round.

Cc: Andreas Dilger <adilger.kernel@dilger.ca>
Signed-off-by: Zheng Liu <wenqing.lz@taobao.com>
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
This commit is contained in:
Zheng Liu 2014-11-25 11:45:37 -05:00 • committed by Theodore Ts'o
parent 2f8e0a7c6c
commit edaa53cac8
8 changed files with 119 additions and 154 deletions
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4
fs/ext4/inode.c
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@ -486,7 +486,7 @@ int ext4_map_blocks(handle_t *handle, struct inode *inode,
/* Lookup extent status tree firstly */
if (ext4_es_lookup_extent(inode, map->m_lblk, &es)) {
ext4_es_lru_add(inode);
ext4_es_list_add(inode);
if (ext4_es_is_written(&es) || ext4_es_is_unwritten(&es)) {
map->m_pblk = ext4_es_pblock(&es) +
map->m_lblk - es.es_lblk;
@ -1388,7 +1388,7 @@ static int ext4_da_map_blocks(struct inode *inode, sector_t iblock,
/* Lookup extent status tree firstly */
if (ext4_es_lookup_extent(inode, iblock, &es)) {
ext4_es_lru_add(inode);
ext4_es_list_add(inode);
if (ext4_es_is_hole(&es)) {
retval = 0;
down_read(&EXT4_I(inode)->i_data_sem);