[patch] vfs: fix lookup on deleted directory (d70b67c8) · Commits · 戴 / test

Lookup can install a child dentry for a deleted directory. This keeps the directory dentry alive, and the inode pinned in the cache and on disk, even after all external references have gone away. This isn't a big problem normally, since memory pressure or umount will clear out the directory dentry and its children, releasing the inode. But for UBIFS this causes problems because its orphan area can overflow. Fix this by returning ENOENT for all lookups on a S_DEAD directory before creating a child dentry. Thanks to Zoltan Sogor for noticing this while testing UBIFS, and Artem for the excellent analysis of the problem and testing. Reported-by:

Artem Bityutskiy <Artem.Bityutskiy@nokia.com> Tested-by:

Artem Bityutskiy <Artem.Bityutskiy@nokia.com> Signed-off-by:

Miklos Szeredi <mszeredi@suse.cz> Signed-off-by:

Al Viro <viro@zeniv.linux.org.uk>

fs/namei.c

+17 −2

Original line number	Diff line number	Diff line
		@@ -519,7 +519,14 @@ static struct dentry * real_lookup(struct dentry * parent, struct qstr * name, s
		*/
		result = d_lookup(parent, name);
		if (!result) {
		struct dentry * dentry = d_alloc(parent, name);
		struct dentry *dentry;

		/* Don't create child dentry for a dead directory. */
		result = ERR_PTR(-ENOENT);
		if (IS_DEADDIR(dir))
		goto out_unlock;

		dentry = d_alloc(parent, name);
		result = ERR_PTR(-ENOMEM);
		if (dentry) {
		result = dir->i_op->lookup(dir, dentry, nd);
		@@ -528,6 +535,7 @@ static struct dentry * real_lookup(struct dentry * parent, struct qstr * name, s
		else
		result = dentry;
		}
		out_unlock:
		mutex_unlock(&dir->i_mutex);
		return result;
		}
		@@ -1317,7 +1325,14 @@ static struct dentry __lookup_hash(struct qstr name,

		dentry = cached_lookup(base, name, nd);
		if (!dentry) {
		struct dentry *new = d_alloc(base, name);
		struct dentry *new;

		/* Don't create child dentry for a dead directory. */
		dentry = ERR_PTR(-ENOENT);
		if (IS_DEADDIR(inode))
		goto out;

		new = d_alloc(base, name);
		dentry = ERR_PTR(-ENOMEM);
		if (!new)
		goto out;

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