[PATCH 3.14 38/44] dont remove from shrink list in select_collect()

From: Greg Kroah-Hartman
Date: Fri Aug 14 2015 - 13:55:57 EST


3.14-stable review patch. If anyone has any objections, please let me know.

------------------

From: Al Viro <viro@xxxxxxxxxxxxxxxxxx>

commit fe91522a7ba82ca1a51b07e19954b3825e4aaa22 upstream.

If we find something already on a shrink list, just increment
data->found and do nothing else. Loops in shrink_dcache_parent() and
check_submounts_and_drop() will do the right thing - everything we
did put into our list will be evicted and if there had been nothing,
but data->found got non-zero, well, we have somebody else shrinking
those guys; just try again.

Signed-off-by: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
Cc: "Nicholas A. Bellinger" <nab@xxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
fs/dcache.c | 31 ++++++++++---------------------
1 file changed, 10 insertions(+), 21 deletions(-)

--- a/fs/dcache.c
+++ b/fs/dcache.c
@@ -1231,34 +1231,23 @@ static enum d_walk_ret select_collect(vo
if (data->start == dentry)
goto out;

- /*
- * move only zero ref count dentries to the dispose list.
- *
- * Those which are presently on the shrink list, being processed
- * by shrink_dentry_list(), shouldn't be moved. Otherwise the
- * loop in shrink_dcache_parent() might not make any progress
- * and loop forever.
- */
- if (dentry->d_lockref.count) {
- dentry_lru_del(dentry);
- } else if (!(dentry->d_flags & DCACHE_SHRINK_LIST)) {
- /*
- * We can't use d_lru_shrink_move() because we
- * need to get the global LRU lock and do the
- * LRU accounting.
- */
- d_lru_del(dentry);
- d_shrink_add(dentry, &data->dispose);
+ if (dentry->d_flags & DCACHE_SHRINK_LIST) {
data->found++;
- ret = D_WALK_NORETRY;
+ } else {
+ if (dentry->d_flags & DCACHE_LRU_LIST)
+ d_lru_del(dentry);
+ if (!dentry->d_lockref.count) {
+ d_shrink_add(dentry, &data->dispose);
+ data->found++;
+ }
}
/*
* We can return to the caller if we have found some (this
* ensures forward progress). We'll be coming back to find
* the rest.
*/
- if (data->found && need_resched())
- ret = D_WALK_QUIT;
+ if (!list_empty(&data->dispose))
+ ret = need_resched() ? D_WALK_QUIT : D_WALK_NORETRY;
out:
return ret;
}


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