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SubjectRe: [PATCH 0/5] RCU-walk support for autofs
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On Wed, 2014-08-20 at 11:42 +0800, Ian Kent wrote:
> >
> > From 201f75bc25906e8f64e28b37f1bb478958bf2987 Mon Sep 17 00:00:00 2001
> > From: NeilBrown <neilb@suse.de>
> > Date: Wed, 20 Aug 2014 12:40:06 +1000
> > Subject: [PATCH] autofs4: make "autofs4_can_expire" idempotent.
> >
> > Have a "test" function change the value it is testing can
> > be confusing, particularly as a future patch will be calling
> > this function twice.
> >
> > So move the update for 'last_used' to avoid repeat expiry
> > to the place where the final determination on what to expire is known.
> >
> > Signed-off-by: NeilBrown <neilb@suse.de>
> >
> > diff --git a/fs/autofs4/expire.c b/fs/autofs4/expire.c
> > index bee939efca2b..af09dada91bc 100644
> > --- a/fs/autofs4/expire.c
> > +++ b/fs/autofs4/expire.c
> > @@ -30,12 +30,6 @@ static inline int autofs4_can_expire(struct dentry *dentry,
> > /* Too young to die */
> > if (!timeout || time_after(ino->last_used + timeout, now))
> > return 0;
> > -
> > - /* update last_used here :-
> > - - obviously makes sense if it is in use now
> > - - less obviously, prevents rapid-fire expire
> > - attempts if expire fails the first time */
> > - ino->last_used = now;
> > }
> > return 1;
> > }
> > @@ -541,6 +535,8 @@ int autofs4_expire_run(struct super_block *sb,
> >
> > spin_lock(&sbi->fs_lock);
> > ino = autofs4_dentry_ino(dentry);
> > + /* avoid rapid-fire expire attempts if expiry fails */
> > + ino->last_used = now;
> > ino->flags &= ~AUTOFS_INF_EXPIRING;
> > complete_all(&ino->expire_complete);
> > spin_unlock(&sbi->fs_lock);
> > @@ -567,6 +563,8 @@ int autofs4_do_expire_multi(struct super_block *sb, struct vfsmount *mnt,
> > ret = autofs4_wait(sbi, dentry, NFY_EXPIRE);
> >
> > spin_lock(&sbi->fs_lock);
> > + /* avoid rapid-fire expire attempts if expiry fails */
> > + ino->last_used = now;
> > ino->flags &= ~AUTOFS_INF_EXPIRING;
> > complete_all(&ino->expire_complete);
> > spin_unlock(&sbi->fs_lock);
>

On looking a little closer I've set last_used at slightly different
locations. It is still does the same thing though.

I'm not fussy where we actually do this, so your call.

autofs - fix last_used usage

From: Ian Kent <ikent@redhat.com>

Signed-off-by: Ian Kent <ikent@redhat.com>
---
fs/autofs4/expire.c | 10 ++++------
1 file changed, 4 insertions(+), 6 deletions(-)

diff --git a/fs/autofs4/expire.c b/fs/autofs4/expire.c
index cca5d1e..d97a761 100644
--- a/fs/autofs4/expire.c
+++ b/fs/autofs4/expire.c
@@ -30,12 +30,6 @@ static inline int autofs4_can_expire(struct dentry *dentry,
/* Too young to die */
if (!timeout || time_after(ino->last_used + timeout, now))
return 0;
-
- /* update last_used here :-
- - obviously makes sense if it is in use now
- - less obviously, prevents rapid-fire expire
- attempts if expire fails the first time */
- ino->last_used = now;
}
return 1;
}
@@ -341,6 +335,8 @@ struct dentry *autofs4_expire_direct(struct super_block *sb,
ino->flags |= AUTOFS_INF_EXPIRING;
smp_mb();
ino->flags &= ~AUTOFS_INF_NO_RCU;
+ /* Prevent rapid fire expire events */
+ ino->last_used = now;
init_completion(&ino->expire_complete);
spin_unlock(&sbi->fs_lock);
return root;
@@ -496,6 +492,8 @@ found:
ino->flags |= AUTOFS_INF_EXPIRING;
smp_mb();
ino->flags &= ~AUTOFS_INF_NO_RCU;
+ /* Prevent rapid fire expire events */
+ ino->last_used = now;
init_completion(&ino->expire_complete);
spin_unlock(&sbi->fs_lock);
spin_lock(&sbi->lookup_lock);





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