From: Miklos Szeredi <mszer...@redhat.com>

Don't hold onto dentry in lru list if need to re-lookup it anyway at next
access.

More advanced version of this patch would periodically flush out dentries
from the lru which have gone stale.

Signed-off-by: Miklos Szeredi <mszer...@redhat.com>
---
 fs/fuse/dir.c | 26 +++++++++++++++++++++++---
 1 file changed, 23 insertions(+), 3 deletions(-)

diff --git a/fs/fuse/dir.c b/fs/fuse/dir.c
index dd0f64f7bc06..fd8636e67ae9 100644
--- a/fs/fuse/dir.c
+++ b/fs/fuse/dir.c
@@ -29,12 +29,26 @@ union fuse_dentry {
        struct rcu_head rcu;
 };
 
-static inline void fuse_dentry_settime(struct dentry *entry, u64 time)
+static void fuse_dentry_settime(struct dentry *dentry, u64 time)
 {
-       ((union fuse_dentry *) entry->d_fsdata)->time = time;
+       /*
+        * Mess with DCACHE_OP_DELETE because dput() will be faster without it.
+        *  Don't care about races, either way it's just an optimization
+        */
+       if ((time && (dentry->d_flags & DCACHE_OP_DELETE)) ||
+           (!time && !(dentry->d_flags & DCACHE_OP_DELETE))) {
+               spin_lock(&dentry->d_lock);
+               if (time)
+                       dentry->d_flags &= ~DCACHE_OP_DELETE;
+               else
+                       dentry->d_flags |= DCACHE_OP_DELETE;
+               spin_unlock(&dentry->d_lock);
+       }
+
+       ((union fuse_dentry *) dentry->d_fsdata)->time = time;
 }
 
-static inline u64 fuse_dentry_time(struct dentry *entry)
+static inline u64 fuse_dentry_time(const struct dentry *entry)
 {
        return ((union fuse_dentry *) entry->d_fsdata)->time;
 }
@@ -255,8 +269,14 @@ static void fuse_dentry_release(struct dentry *dentry)
        kfree_rcu(fd, rcu);
 }
 
+static int fuse_dentry_delete(const struct dentry *dentry)
+{
+       return time_before64(fuse_dentry_time(dentry), get_jiffies_64());
+}
+
 const struct dentry_operations fuse_dentry_operations = {
        .d_revalidate   = fuse_dentry_revalidate,
+       .d_delete       = fuse_dentry_delete,
        .d_init         = fuse_dentry_init,
        .d_release      = fuse_dentry_release,
 };
-- 
2.20.1

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