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@@ -35,6 +35,14 @@
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#include "configfs_internal.h"
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DECLARE_RWSEM(configfs_rename_sem);
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+/*
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+ * Protects mutations of configfs_dirent linkage together with proper i_mutex
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+ * Mutators of configfs_dirent linkage must *both* have the proper inode locked
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+ * and configfs_dirent_lock locked, in that order.
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+ * This allows one to safely traverse configfs_dirent trees without having to
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+ * lock inodes.
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+ */
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+DEFINE_SPINLOCK(configfs_dirent_lock);
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static void configfs_d_iput(struct dentry * dentry,
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struct inode * inode)
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@@ -79,8 +87,10 @@ static struct configfs_dirent *configfs_new_dirent(struct configfs_dirent * pare
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atomic_set(&sd->s_count, 1);
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INIT_LIST_HEAD(&sd->s_links);
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INIT_LIST_HEAD(&sd->s_children);
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- list_add(&sd->s_sibling, &parent_sd->s_children);
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sd->s_element = element;
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+ spin_lock(&configfs_dirent_lock);
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+ list_add(&sd->s_sibling, &parent_sd->s_children);
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+ spin_unlock(&configfs_dirent_lock);
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return sd;
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}
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@@ -173,7 +183,9 @@ static int create_dir(struct config_item * k, struct dentry * p,
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} else {
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struct configfs_dirent *sd = d->d_fsdata;
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if (sd) {
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+ spin_lock(&configfs_dirent_lock);
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list_del_init(&sd->s_sibling);
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+ spin_unlock(&configfs_dirent_lock);
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configfs_put(sd);
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}
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}
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@@ -224,7 +236,9 @@ int configfs_create_link(struct configfs_symlink *sl,
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else {
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struct configfs_dirent *sd = dentry->d_fsdata;
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if (sd) {
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+ spin_lock(&configfs_dirent_lock);
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list_del_init(&sd->s_sibling);
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+ spin_unlock(&configfs_dirent_lock);
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configfs_put(sd);
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}
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}
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@@ -238,7 +252,9 @@ static void remove_dir(struct dentry * d)
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struct configfs_dirent * sd;
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sd = d->d_fsdata;
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+ spin_lock(&configfs_dirent_lock);
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list_del_init(&sd->s_sibling);
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+ spin_unlock(&configfs_dirent_lock);
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configfs_put(sd);
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if (d->d_inode)
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simple_rmdir(parent->d_inode,d);
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@@ -410,7 +426,9 @@ static void detach_attrs(struct config_item * item)
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list_for_each_entry_safe(sd, tmp, &parent_sd->s_children, s_sibling) {
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if (!sd->s_element || !(sd->s_type & CONFIGFS_NOT_PINNED))
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continue;
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+ spin_lock(&configfs_dirent_lock);
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list_del_init(&sd->s_sibling);
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+ spin_unlock(&configfs_dirent_lock);
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configfs_drop_dentry(sd, dentry);
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configfs_put(sd);
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}
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@@ -1268,7 +1286,9 @@ static int configfs_dir_close(struct inode *inode, struct file *file)
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struct configfs_dirent * cursor = file->private_data;
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mutex_lock(&dentry->d_inode->i_mutex);
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+ spin_lock(&configfs_dirent_lock);
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list_del_init(&cursor->s_sibling);
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+ spin_unlock(&configfs_dirent_lock);
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mutex_unlock(&dentry->d_inode->i_mutex);
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release_configfs_dirent(cursor);
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@@ -1308,7 +1328,9 @@ static int configfs_readdir(struct file * filp, void * dirent, filldir_t filldir
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/* fallthrough */
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default:
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if (filp->f_pos == 2) {
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+ spin_lock(&configfs_dirent_lock);
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list_move(q, &parent_sd->s_children);
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+ spin_unlock(&configfs_dirent_lock);
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}
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for (p=q->next; p!= &parent_sd->s_children; p=p->next) {
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struct configfs_dirent *next;
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@@ -1331,7 +1353,9 @@ static int configfs_readdir(struct file * filp, void * dirent, filldir_t filldir
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dt_type(next)) < 0)
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return 0;
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+ spin_lock(&configfs_dirent_lock);
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list_move(q, p);
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+ spin_unlock(&configfs_dirent_lock);
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p = q;
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filp->f_pos++;
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}
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@@ -1362,6 +1386,7 @@ static loff_t configfs_dir_lseek(struct file * file, loff_t offset, int origin)
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struct list_head *p;
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loff_t n = file->f_pos - 2;
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+ spin_lock(&configfs_dirent_lock);
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list_del(&cursor->s_sibling);
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p = sd->s_children.next;
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while (n && p != &sd->s_children) {
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@@ -1373,6 +1398,7 @@ static loff_t configfs_dir_lseek(struct file * file, loff_t offset, int origin)
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p = p->next;
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}
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list_add_tail(&cursor->s_sibling, p);
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+ spin_unlock(&configfs_dirent_lock);
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}
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}
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mutex_unlock(&dentry->d_inode->i_mutex);
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