[PATCH] configfs: Fix failing symlink() making rmdir() fail

[linux-2.6-omap-h63xx.git] / fs / configfs / dir.c

diff --git a/fs/configfs/dir.c b/fs/configfs/dir.c
index 179589be063abe97ba0d10a1982bdea244488d36..4e228c80fe9fa02446ccc2ea4d742d2f7067fcd0 100644 (file)
--- a/fs/configfs/dir.c
+++ b/fs/configfs/dir.c
@@ -370,6 +370,9 @@ static int configfs_detach_prep(struct dentry *dentry, struct mutex **wait_mutex
        struct configfs_dirent *sd;
        int ret;
 
+       /* Mark that we're trying to drop the group */
+       parent_sd->s_type |= CONFIGFS_USET_DROPPING;
+
        ret = -EBUSY;
        if (!list_empty(&parent_sd->s_links))
                goto out;
@@ -385,8 +388,6 @@ static int configfs_detach_prep(struct dentry *dentry, struct mutex **wait_mutex
                                        *wait_mutex = &sd->s_dentry->d_inode->i_mutex;
                                return -EAGAIN;
                        }
-                       /* Mark that we're trying to drop the group */
-                       sd->s_type |= CONFIGFS_USET_DROPPING;
 
                        /*
                         * Yup, recursive.  If there's a problem, blame
@@ -414,12 +415,11 @@ static void configfs_detach_rollback(struct dentry *dentry)
        struct configfs_dirent *parent_sd = dentry->d_fsdata;
        struct configfs_dirent *sd;
 
-       list_for_each_entry(sd, &parent_sd->s_children, s_sibling) {
-               if (sd->s_type & CONFIGFS_USET_DEFAULT) {
+       parent_sd->s_type &= ~CONFIGFS_USET_DROPPING;
+
+       list_for_each_entry(sd, &parent_sd->s_children, s_sibling)
+               if (sd->s_type & CONFIGFS_USET_DEFAULT)
                        configfs_detach_rollback(sd->s_dentry);
-                       sd->s_type &= ~CONFIGFS_USET_DROPPING;
-               }
-       }
 }
 
 static void detach_attrs(struct config_item * item)
@@ -1094,7 +1094,7 @@ static int configfs_mkdir(struct inode *dir, struct dentry *dentry, int mode)
        kfree(name);
        if (ret) {
                /*
-                * If item == NULL, then link_obj() was never called.
+                * If ret != 0, then link_obj() was never called.
                 * There are no extra references to clean up.
                 */
                goto out_put;
@@ -1207,6 +1207,11 @@ static int configfs_rmdir(struct inode *dir, struct dentry *dentry)
                return -EINVAL;
        }
 
+       /*
+        * Ensure that no racing symlink() will make detach_prep() fail while
+        * the new link is temporarily attached
+        */
+       mutex_lock(&configfs_symlink_mutex);
        spin_lock(&configfs_dirent_lock);
        do {
                struct mutex *wait_mutex;
@@ -1215,6 +1220,7 @@ static int configfs_rmdir(struct inode *dir, struct dentry *dentry)
                if (ret) {
                        configfs_detach_rollback(dentry);
                        spin_unlock(&configfs_dirent_lock);
+                       mutex_unlock(&configfs_symlink_mutex);
                        if (ret != -EAGAIN) {
                                config_item_put(parent_item);
                                return ret;
@@ -1224,10 +1230,12 @@ static int configfs_rmdir(struct inode *dir, struct dentry *dentry)
                        mutex_lock(wait_mutex);
                        mutex_unlock(wait_mutex);
 
+                       mutex_lock(&configfs_symlink_mutex);
                        spin_lock(&configfs_dirent_lock);
                }
        } while (ret == -EAGAIN);
        spin_unlock(&configfs_dirent_lock);
+       mutex_unlock(&configfs_symlink_mutex);
 
        /* Get a working ref for the duration of this function */
        item = configfs_get_config_item(dentry);
@@ -1517,11 +1525,13 @@ void configfs_unregister_subsystem(struct configfs_subsystem *subsys)
        mutex_lock_nested(&configfs_sb->s_root->d_inode->i_mutex,
                          I_MUTEX_PARENT);
        mutex_lock_nested(&dentry->d_inode->i_mutex, I_MUTEX_CHILD);
+       mutex_lock(&configfs_symlink_mutex);
        spin_lock(&configfs_dirent_lock);
        if (configfs_detach_prep(dentry, NULL)) {
                printk(KERN_ERR "configfs: Tried to unregister non-empty subsystem!\n");
        }
        spin_unlock(&configfs_dirent_lock);
+       mutex_unlock(&configfs_symlink_mutex);
        configfs_detach_group(&group->cg_item);
        dentry->d_inode->i_flags |= S_DEAD;
        mutex_unlock(&dentry->d_inode->i_mutex);