configfs_detach_prep(): make sure that wait_mutex won't go away

grab a reference to dentry we'd got the sucker from, and return
that dentry via *wait, rather than just returning the address of
->i_mutex.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
This commit is contained in:
Al Viro 2016-04-12 00:37:59 -04:00
parent 779b839133
commit 48f35b7b73
1 changed files with 9 additions and 8 deletions

View File

@ -494,7 +494,7 @@ out:
* If there is an error, the caller will reset the flags via
* configfs_detach_rollback().
*/
static int configfs_detach_prep(struct dentry *dentry, struct mutex **wait_mutex)
static int configfs_detach_prep(struct dentry *dentry, struct dentry **wait)
{
struct configfs_dirent *parent_sd = dentry->d_fsdata;
struct configfs_dirent *sd;
@ -515,8 +515,8 @@ static int configfs_detach_prep(struct dentry *dentry, struct mutex **wait_mutex
if (sd->s_type & CONFIGFS_USET_DEFAULT) {
/* Abort if racing with mkdir() */
if (sd->s_type & CONFIGFS_USET_IN_MKDIR) {
if (wait_mutex)
*wait_mutex = &d_inode(sd->s_dentry)->i_mutex;
if (wait)
*wait= dget(sd->s_dentry);
return -EAGAIN;
}
@ -524,7 +524,7 @@ static int configfs_detach_prep(struct dentry *dentry, struct mutex **wait_mutex
* Yup, recursive. If there's a problem, blame
* deep nesting of default_groups
*/
ret = configfs_detach_prep(sd->s_dentry, wait_mutex);
ret = configfs_detach_prep(sd->s_dentry, wait);
if (!ret)
continue;
} else
@ -1458,7 +1458,7 @@ static int configfs_rmdir(struct inode *dir, struct dentry *dentry)
* the new link is temporarily attached
*/
do {
struct mutex *wait_mutex;
struct dentry *wait;
mutex_lock(&configfs_symlink_mutex);
spin_lock(&configfs_dirent_lock);
@ -1469,7 +1469,7 @@ static int configfs_rmdir(struct inode *dir, struct dentry *dentry)
*/
ret = sd->s_dependent_count ? -EBUSY : 0;
if (!ret) {
ret = configfs_detach_prep(dentry, &wait_mutex);
ret = configfs_detach_prep(dentry, &wait);
if (ret)
configfs_detach_rollback(dentry);
}
@ -1483,8 +1483,9 @@ static int configfs_rmdir(struct inode *dir, struct dentry *dentry)
}
/* Wait until the racing operation terminates */
mutex_lock(wait_mutex);
mutex_unlock(wait_mutex);
inode_lock(d_inode(wait));
inode_unlock(d_inode(wait));
dput(wait);
}
} while (ret == -EAGAIN);