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shift percpu_counter_destroy() into destroy_super_work() 

Of course, this patch is ugly as hell. It will be (partially)
reverted later. We add it to ensure that other WIP changes in
percpu_rw_semaphore won't break fs/super.c.

We do not even need this change right now, percpu_free_rwsem()
is fine in atomic context. But we are going to change this, it
will be might_sleep() after we merge the rcu_sync() patches.

And even after that we do not really need destroy_super_work(),
we will kill it in any case. Instead, destroy_super_rcu() should
just check that rss->cb_state == CB_IDLE and do call_rcu() again
in the (very unlikely) case this is not true.

So this is just the temporary kludge which helps us to avoid the
conflicts with the changes which will be (hopefully) routed via
rcu tree.

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Reviewed-by: Jan Kara <jack@suse.com>
This commit is contained in:
Oleg Nesterov 2015-07-22 20:21:13 +02:00
parent bf3eac84c4
commit 853b39a7c8
2 changed files with 21 additions and 5 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

23
fs/super.c
View File

@ -135,6 +135,24 @@ static unsigned long super_cache_count(struct shrinker *shrink,
return total_objects;
}
static void destroy_super_work(struct work_struct *work)
{
struct super_block *s = container_of(work, struct super_block,
destroy_work);
int i;
for (i = 0; i < SB_FREEZE_LEVELS; i++)
percpu_counter_destroy(&s->s_writers.counter[i]);
kfree(s);
}
static void destroy_super_rcu(struct rcu_head *head)
{
struct super_block *s = container_of(head, struct super_block, rcu);
INIT_WORK(&s->destroy_work, destroy_super_work);
schedule_work(&s->destroy_work);
}
/**
* destroy_super - frees a superblock
* @s: superblock to free
@ -143,16 +161,13 @@ static unsigned long super_cache_count(struct shrinker *shrink,
*/
static void destroy_super(struct super_block *s)
{
int i;
list_lru_destroy(&s->s_dentry_lru);
list_lru_destroy(&s->s_inode_lru);
for (i = 0; i < SB_FREEZE_LEVELS; i++)
percpu_counter_destroy(&s->s_writers.counter[i]);
security_sb_free(s);
WARN_ON(!list_empty(&s->s_mounts));
kfree(s->s_subtype);
kfree(s->s_options);
kfree_rcu(s, rcu);
call_rcu(&s->rcu, destroy_super_rcu);
}
/**

3
include/linux/fs.h
View File

@ -30,6 +30,7 @@
#include <linux/lockdep.h>
#include <linux/percpu-rwsem.h>
#include <linux/blk_types.h>
#include <linux/workqueue.h>
#include <asm/byteorder.h>
#include <uapi/linux/fs.h>
@ -1375,7 +1376,7 @@ struct super_block {
struct list_lru s_dentry_lru ____cacheline_aligned_in_smp;
struct list_lru s_inode_lru ____cacheline_aligned_in_smp;
struct rcu_head rcu;
struct work_struct destroy_work;
/*
* Indicates how deep in a filesystem stack this SB is
*/