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debugfs: leave freeing a symlink body until inode eviction 

As it is, we have debugfs_remove() racing with symlink traversals.
Supply ->evict_inode() and do freeing there - inode will remain
pinned until we are done with the symlink body.

And rip the idiocy with checking if dentry is positive right after
we'd verified debugfs_positive(), which is a stronger check...

Cc: stable@vger.kernel.org
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
This commit is contained in:
Al Viro 2015-02-21 22:05:11 -05:00
parent dca111782c
commit 0db59e5929
1 changed files with 17 additions and 17 deletions
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22
fs/debugfs/inode.c
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@ -169,10 +169,19 @@ static int debugfs_show_options(struct seq_file *m, struct dentry *root)
return 0;
}
static void debugfs_evict_inode(struct inode *inode)
{
truncate_inode_pages_final(&inode->i_data);
clear_inode(inode);
if (S_ISLNK(inode->i_mode))
kfree(inode->i_private);
}
static const struct super_operations debugfs_super_operations = {
.statfs = simple_statfs,
.remount_fs = debugfs_remount,
.show_options = debugfs_show_options,
.evict_inode = debugfs_evict_inode,
};
static struct vfsmount *debugfs_automount(struct path *path)
@ -511,24 +520,15 @@ static int __debugfs_remove(struct dentry *dentry, struct dentry *parent)
int ret = 0;
if (debugfs_positive(dentry)) {
if (dentry->d_inode) {
dget(dentry);
switch (dentry->d_inode->i_mode & S_IFMT) {
case S_IFDIR:
if (S_ISDIR(dentry->d_inode->i_mode))
ret = simple_rmdir(parent->d_inode, dentry);
break;
case S_IFLNK:
kfree(dentry->d_inode->i_private);
/* fall through */
default:
else
simple_unlink(parent->d_inode, dentry);
break;
}
if (!ret)
d_delete(dentry);
dput(dentry);
}
}
return ret;
}