[RFC] d_prune

Commit Message

Sage Weil March 4, 2011, 11:18 p.m. UTC

None

Patch

diff --git a/Documentation/filesystems/Locking b/Documentation/filesystems/Locking
index 4471a41..180e14b 100644
--- a/Documentation/filesystems/Locking
+++ b/Documentation/filesystems/Locking
@@ -28,6 +28,7 @@  d_revalidate: no              no              yes (ref-walk)  maybe
 d_hash         no              no              no              maybe
 d_compare:     yes             no              no              maybe
 d_delete:      no              yes             no              no
+d_prune:        no              yes             no              no
 d_release:     no              no              yes             no
 d_iput:                no              no              yes             no
 d_dname:       no              no              no              no
diff --git a/fs/dcache.c b/fs/dcache.c
index 2a6bd9a..cdb5d81 100644
--- a/fs/dcache.c
+++ b/fs/dcache.c
@@ -690,6 +690,8 @@  static void try_prune_one_dentry(struct dentry *dentry)
                        spin_unlock(&dentry->d_lock);
                        return;
                }
+               if (dentry->d_op->d_flags & DCACHE_OP_PRUNE)
+                       dentry->d_op->d_prune(dentry);
                dentry = dentry_kill(dentry, 1);
        }
 }
@@ -896,6 +898,8 @@  static void shrink_dcache_for_umount_subtree(struct dentry *dentry)
 
        /* detach this root from the system */
        spin_lock(&dentry->d_lock);
+       if (dentry->d_op->d_flags & DCACHE_OP_PRUNE)
+               dentry->d_op->d_prune(dentry);
        dentry_lru_del(dentry);
        __d_drop(dentry);
        spin_unlock(&dentry->d_lock);
@@ -912,6 +916,8 @@  static void shrink_dcache_for_umount_subtree(struct dentry *dentry)
                                            d_u.d_child) {
                                spin_lock_nested(&loop->d_lock,
                                                DENTRY_D_LOCK_NESTED);
+                               if (dentry->d_op->d_flags & DCACHE_OP_PRUNE)
+                                       dentry->d_op->d_prune(dentry);
                                dentry_lru_del(loop);
                                __d_drop(loop);
                                spin_unlock(&loop->d_lock);
@@ -1375,6 +1381,8 @@  void d_set_d_op(struct dentry *dentry, const struct dentry_operations *op)
                dentry->d_flags |= DCACHE_OP_REVALIDATE;
        if (op->d_delete)
                dentry->d_flags |= DCACHE_OP_DELETE;
+       if (op->d_prune)
+               dentry->d_flags |= DCACHE_OP_PRUNE;
 
 }
 EXPORT_SYMBOL(d_set_d_op);
diff --git a/include/linux/dcache.h b/include/linux/dcache.h
index f958c19..1e83bd8 100644
--- a/include/linux/dcache.h
+++ b/include/linux/dcache.h
@@ -165,6 +165,7 @@  struct dentry_operations {
                        unsigned int, const char *, const struct qstr *);
        int (*d_delete)(const struct dentry *);
        void (*d_release)(struct dentry *);
+       void (*d_prune)(struct dentry *);
        void (*d_iput)(struct dentry *, struct inode *);
        char *(*d_dname)(struct dentry *, char *, int);
        struct vfsmount *(*d_automount)(struct path *);
@@ -219,6 +220,8 @@  struct dentry_operations {
 #define DCACHE_MANAGED_DENTRY \
        (DCACHE_MOUNTED|DCACHE_NEED_AUTOMOUNT|DCACHE_MANAGE_TRANSIT)
 
+#define DCACHE_OP_PRUNE         0x80000
+
 extern seqlock_t rename_lock;
 
 static inline int dname_external(struct dentry *dentry)