Calls of retain_dentry() happen immediately after getting false
from fast_dput() and getting true from retain_dentry() is
treated the same way as non-zero refcount would be treated by
fast_dput() - unlock dentry and bugger off.
Doing that in fast_dput() itself is simpler.
Reviewed-by: Christian Brauner <brauner@xxxxxxxxxx>
Signed-off-by: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
---
fs/dcache.c | 13 ++++---------
1 file changed, 4 insertions(+), 9 deletions(-)
diff --git a/fs/dcache.c b/fs/dcache.c
index 8ce0fe70f303..b69ff3a0b30f 100644
--- a/fs/dcache.c
+++ b/fs/dcache.c
@@ -757,6 +757,8 @@ static struct dentry *dentry_kill(struct dentry *dentry)
* Try to do a lockless dput(), and return whether that was successful.
*
* If unsuccessful, we return false, having already taken the dentry lock.
+ * In that case refcount is guaranteed to be zero and we have already
+ * decided that it's not worth keeping around.
*
* The caller needs to hold the RCU read lock, so that the dentry is
* guaranteed to stay around even if the refcount goes down to zero!
@@ -842,7 +844,7 @@ static inline bool fast_dput(struct dentry *dentry)
* don't need to do anything else.
*/
locked:
- if (dentry->d_lockref.count) {
+ if (dentry->d_lockref.count || retain_dentry(dentry)) {
spin_unlock(&dentry->d_lock);
return true;
}
@@ -889,12 +891,6 @@ void dput(struct dentry *dentry)
/* Slow case: now with the dentry lock held */
rcu_read_unlock();
-
- if (likely(retain_dentry(dentry))) {
- spin_unlock(&dentry->d_lock);
- return;
- }
-
dentry->d_lockref.count = 1;
dentry = dentry_kill(dentry);
}
@@ -920,8 +916,7 @@ void dput_to_list(struct dentry *dentry, struct list_head *list)
return;
}
rcu_read_unlock();
- if (!retain_dentry(dentry))
- to_shrink_list(dentry, list);
+ to_shrink_list(dentry, list);
spin_unlock(&dentry->d_lock);
}
--
2.39.2
