[Devel] [PATCH RHEL7 COMMIT] ms/dcache: lift the "already marked killed" case into shrink_dentry_list()

[Konstantin Khorenko]

The commit is pushed to "branch-rh7-3.10.0-327.18.2.vz7.14.x-ovz" and will appear at https://src.openvz.org/scm/ovz/vzkernel.git
after rh7-3.10.0-327.18.2.vz7.14.8
------>
commit 11ab2f92d2a7fd42ee57d452b1725e20bd2c4cab
Author: Al Viro <viro at zeniv.linux.org.uk>
Date:   Fri May 27 12:53:11 2016 +0400

    ms/dcache: lift the "already marked killed" case into shrink_dentry_list()
    
    It can happen only when dentry_kill() is called with unlock_on_failure
    equal to 0 - other callers had dentry pinned until the moment they've
    got ->d_lock and DCACHE_DENTRY_KILLED is set only after lockref_mark_dead().
    
    IOW, only one of three call sites of dentry_kill() might end up reaching
    that code.  Just move it there.
    
    Signed-off-by: Al Viro <viro at zeniv.linux.org.uk>
    (cherry picked from commit 64fd72e0a44bdd62c5ca277cb24d0d02b2d8e9dc)
    Signed-off-by: Vladimir Davydov <vdavydov at virtuozzo.com>
    
    Conflicts:
    	fs/dcache.c
---
 fs/dcache.c | 17 +++++++++--------
 1 file changed, 9 insertions(+), 8 deletions(-)

diff --git a/fs/dcache.c b/fs/dcache.c
index c584d23..37420f4 100644
--- a/fs/dcache.c
+++ b/fs/dcache.c
@@ -495,14 +495,6 @@ dentry_kill(struct dentry *dentry, int unlock_on_failure)
 	struct inode *inode;
 	struct dentry *parent;
 
-	if (unlikely(dentry->d_flags & DCACHE_DENTRY_KILLED)) {
-		bool can_free = dentry->d_flags & DCACHE_MAY_FREE;
-		spin_unlock(&dentry->d_lock);
-		if (likely(can_free))
-			dentry_free(dentry);
-		return NULL;
-	}
-
 	inode = dentry->d_inode;
 	if (inode && !spin_trylock(&inode->i_lock)) {
 relock:
@@ -845,6 +837,15 @@ static void shrink_dentry_list(struct list_head *list)
 			continue;
 		}
 
+
+		if (unlikely(dentry->d_flags & DCACHE_DENTRY_KILLED)) {
+			bool can_free = dentry->d_flags & DCACHE_MAY_FREE;
+			spin_unlock(&dentry->d_lock);
+			if (can_free)
+				dentry_free(dentry);
+			continue;
+		}
+
 		parent = dentry_kill(dentry, 0);
 		/*
 		 * If dentry_kill returns NULL, we have nothing more to do.