[PATCH] ->d_parent fixes

Protect d_parent with "dparent_lock", making ready to get rid of
BKL for d_move().

fs/dcache.c

@@ -30,6 +30,7 @@
 /* #define DCACHE_DEBUG 1 */
 
 spinlock_t dcache_lock __cacheline_aligned_in_smp = SPIN_LOCK_UNLOCKED;
+rwlock_t dparent_lock __cacheline_aligned_in_smp = RW_LOCK_UNLOCKED;
 
 /* Right now the dcache depends on the kernel lock */
 #define check_lock()	if (!kernel_locked()) BUG()
@@ -916,7 +917,9 @@ void d_move(struct dentry * dentry, struct dentry * target)
 
 	/* Switch the parents and the names.. */
 	switch_names(dentry, target);
+	write_lock(&dparent_lock);
 	do_switch(dentry->d_parent, target->d_parent);
+	write_unlock(&dparent_lock);
 	do_switch(dentry->d_name.len, target->d_name.len);
 	do_switch(dentry->d_name.hash, target->d_name.hash);
 

fs/fat/inode.c

@@ -516,7 +516,9 @@ int fat_dentry_to_fh(struct dentry *de, __u32 *fh, int *lenp, int needparent)
 	fh[1] = inode->i_generation;
 	fh[2] = MSDOS_I(inode)->i_location;
 	fh[3] = MSDOS_I(inode)->i_logstart;
+	read_lock(&dparent_lock);
 	fh[4] = MSDOS_I(de->d_parent->d_inode)->i_logstart;
+	read_unlock(&dparent_lock);
 	return 3;
 }
 

fs/reiserfs/inode.c

@@ -1325,15 +1325,17 @@ int reiserfs_dentry_to_fh(struct dentry *dentry, __u32 *data, int *lenp, int nee
     if (maxlen < 5 || ! need_parent)
         return 3 ;
 
+    read_lock(&dparent_lock);
     inode = dentry->d_parent->d_inode ;
     data[3] = inode->i_ino ;
     data[4] = le32_to_cpu(INODE_PKEY (inode)->k_dir_id) ;
     *lenp = 5 ;
-    if (maxlen < 6)
-	    return 5 ;
-    data[5] = inode->i_generation ;
-    *lenp = 6 ;
-    return 6 ;
+    if (maxlen >= 6) {
+	    data[5] = inode->i_generation ;
+	    *lenp = 6 ;
+    }
+    read_unlock(&dparent_lock);
+    return *lenp ;
 }
 
 

fs/smbfs/dir.c

@@ -378,12 +378,14 @@ smb_new_dentry(struct dentry *dentry)
 void
 smb_renew_times(struct dentry * dentry)
 {
+	read_lock(&dparent_lock);
 	for (;;) {
 		dentry->d_time = jiffies;
 		if (IS_ROOT(dentry))
 			break;
 		dentry = dentry->d_parent;
 	}
+	read_unlock(&dparent_lock);
 }
 
 static struct dentry *

fs/smbfs/proc.c

@@ -245,15 +245,20 @@ static int smb_build_path(struct smb_sb_info *server, char * buf, int maxlen,
 	 * Build the path string walking the tree backward from end to ROOT
 	 * and store it in reversed order [see reverse_string()]
 	 */
+	read_lock(&dparent_lock);
 	while (!IS_ROOT(entry)) {
-		if (maxlen < 3)
+		if (maxlen < 3) {
+			read_unlock(&dparent_lock);
 			return -ENAMETOOLONG;
+		}
 
 		len = server->convert(path, maxlen-2, 
 				      entry->d_name.name, entry->d_name.len,
 				      server->local_nls, server->remote_nls);
-		if (len < 0)
+		if (len < 0) {
+			read_unlock(&dparent_lock);
 			return len;
+		}
 		reverse_string(path, len);
 		path += len;
 		*path++ = '\\';
@@ -263,6 +268,7 @@ static int smb_build_path(struct smb_sb_info *server, char * buf, int maxlen,
 		if (IS_ROOT(entry))
 			break;
 	}
+	read_unlock(&dparent_lock);
 	reverse_string(buf, path-buf);
 
 	/* maxlen is at least 1 */

include/linux/dcache.h

@@ -126,6 +126,7 @@ d_iput:		no		no		yes
 #define DCACHE_REFERENCED	0x0008  /* Recently used, don't discard. */
 
 extern spinlock_t dcache_lock;
+extern rwlock_t dparent_lock;
 
 /**
  * d_drop - drop a dentry

include/linux/dnotify.h

@@ -33,13 +33,13 @@ static inline void inode_dir_notify(struct inode *inode, unsigned long event)
 static inline void dnotify_parent(struct dentry *dentry, unsigned long event)
 {
 	struct dentry *parent;
-	spin_lock(&dcache_lock);
+	read_lock(&dparent_lock);
 	parent = dentry->d_parent;
 	if (parent->d_inode->i_dnotify_mask & event) {
 		dget(parent);
-		spin_unlock(&dcache_lock);
+		read_unlock(&dparent_lock);
 		__inode_dir_notify(parent->d_inode, event);
 		dput(parent);
 	} else
-		spin_unlock(&dcache_lock);
+		read_unlock(&dparent_lock);
 }

include/linux/fs.h

@@ -1511,9 +1511,9 @@ extern int inode_setattr(struct inode *, struct iattr *);
 static inline ino_t parent_ino(struct dentry *dentry)
 {
 	ino_t res;
-	spin_lock(&dcache_lock);
+	read_lock(&dparent_lock);
 	res = dentry->d_parent->d_inode->i_ino;
-	spin_unlock(&dcache_lock);
+	read_unlock(&dparent_lock);
 	return res;
 }