Quoting Jan Kara <jack@xxxxxxx>:
On Thu 21-06-12 17:00:27, Cong Meng wrote:
Go through the LRU list of inode from head.
(I'm not sure whether there is any trick here I doesn't get. If yes,
any one could explain it)
Look at inode_lru_list_add(). It adds at the head of the list. So you
should take from the tail to get the least recently used element...
I still have a quetion about the subsequent code and comment:
inode = list_entry(sb->s_inode_lru.prev, struct inode, i_lru);
/*
* we are inverting the sb->s_inode_lru_lock/inode->i_lock here,
* so use a trylock. If we fail to get the lock, just move the
* inode to the back of the list so we don't spin on it.
*/
if (!spin_trylock(&inode->i_lock)) {
list_move_tail(&inode->i_lru, &sb->s_inode_lru);
continue;
}
Shouldn't the inode be moved to the head to avoid spin on it?
I note that list_move was replaced by list_move_tail purposely in a commit.
and below piece of code (at the bottom of prune_icache_sb()):
if (inode != list_entry(sb->s_inode_lru.next,
struct inode, i_lru))
continue; /* wrong inode or list_empty */
Should the inode be compared against to the tail of the list other
than the head
after re-get the lru lock?
thanks.
cong.
Honza
Signed-off-by: Cong Meng <mc@xxxxxxxxxxxxxxxxxx>
---
fs/inode.c | 2 +-
1 files changed, 1 insertions(+), 1 deletions(-)
diff --git a/fs/inode.c b/fs/inode.c
index 775cbab..aac8449 100644
--- a/fs/inode.c
+++ b/fs/inode.c
@@ -704,7 +704,7 @@ void prune_icache_sb(struct super_block *sb,
int nr_to_scan)
if (list_empty(&sb->s_inode_lru))
break;
- inode = list_entry(sb->s_inode_lru.prev, struct inode, i_lru);
+ inode = list_entry(sb->s_inode_lru.next, struct inode, i_lru);
/*
* we are inverting the sb->s_inode_lru_lock/inode->i_lock here,
--
1.7.5.4
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--
Jan Kara <jack@xxxxxxx>
SUSE Labs, CR
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