fs: dcache scale d_unhashed

Protect d_unhashed(dentry) condition with d_lock. This means keeping
DCACHE_UNHASHED bit in synch with hash manipulations.

Signed-off-by: Nick Piggin <npiggin@kernel.dk>

2 files changed, 16 insertions, 18 deletions

diff --git a/fs/autofs4/autofs_i.h b/fs/autofs4/autofs_i.h
index 3d283abf67d7..3912dcf047e5 100644
--- a/fs/autofs4/autofs_i.h
+++ b/fs/autofs4/autofs_i.h
@@ -254,19 +254,6 @@ static inline int simple_positive(struct dentry *dentry)
         return dentry->d_inode && !d_unhashed(dentry);
 }
 
-static inline int __simple_empty(struct dentry *dentry)
-{
-        struct dentry *child;
-        int ret = 0;
-
-        list_for_each_entry(child, &dentry->d_subdirs, d_u.d_child)
-                if (simple_positive(child))
-                        goto out;
-        ret = 1;
-out:
-        return ret;
-}
-
 static inline void autofs4_add_expiring(struct dentry *dentry)
 {
         struct autofs_sb_info *sbi = autofs4_sbi(dentry->d_sb);
diff --git a/fs/autofs4/expire.c b/fs/autofs4/expire.c
index 413b5642e6cf..ee6402050f13 100644
--- a/fs/autofs4/expire.c
+++ b/fs/autofs4/expire.c
@@ -160,14 +160,18 @@ static int autofs4_tree_busy(struct vfsmount *mnt,
 
         spin_lock(&dcache_lock);
         for (p = top; p; p = next_dentry(p, top)) {
+                spin_lock(&p->d_lock);
                 /* Negative dentry - give up */
-                if (!simple_positive(p))
+                if (!simple_positive(p)) {
+                        spin_unlock(&p->d_lock);
                         continue;
+                }
 
                 DPRINTK("dentry %p %.*s",
                         p, (int) p->d_name.len, p->d_name.name);
 
-                p = dget(p);
+                p = dget_dlock(p);
+                spin_unlock(&p->d_lock);
                 spin_unlock(&dcache_lock);
 
                 /*
@@ -228,14 +232,18 @@ static struct dentry *autofs4_check_leaves(struct vfsmount *mnt,
 
         spin_lock(&dcache_lock);
         for (p = parent; p; p = next_dentry(p, parent)) {
+                spin_lock(&p->d_lock);
                 /* Negative dentry - give up */
-                if (!simple_positive(p))
+                if (!simple_positive(p)) {
+                        spin_unlock(&p->d_lock);
                         continue;
+                }
 
                 DPRINTK("dentry %p %.*s",
                         p, (int) p->d_name.len, p->d_name.name);
 
-                p = dget(p);
+                p = dget_dlock(p);
+                spin_unlock(&p->d_lock);
                 spin_unlock(&dcache_lock);
 
                 if (d_mountpoint(p)) {
@@ -324,12 +332,15 @@ struct dentry *autofs4_expire_indirect(struct super_block *sb,
                 struct dentry *dentry = list_entry(next, struct dentry, d_u.d_child);
 
                 /* Negative dentry - give up */
+                spin_lock(&dentry->d_lock);
                 if (!simple_positive(dentry)) {
                         next = next->next;
+                        spin_unlock(&dentry->d_lock);
                         continue;
                 }
 
-                dentry = dget(dentry);
+                dentry = dget_dlock(dentry);
+                spin_unlock(&dentry->d_lock);
                 spin_unlock(&dcache_lock);
 
                 spin_lock(&sbi->fs_lock);