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From: Eric Biggers <ebiggers@kernel.org>
To: linux-fscrypt@vger.kernel.org
Cc: linux-ext4@vger.kernel.org,
	linux-f2fs-devel@lists.sourceforge.net,
	linux-mtd@lists.infradead.org, linux-fsdevel@vger.kernel.org,
	linux-crypto@vger.kernel.org, linux-api@vger.kernel.org,
	keyrings@vger.kernel.org, Satya Tangirala <satyat@google.com>,
	Paul Crowley <paulcrowley@google.com>
Subject: [RFC PATCH v2 10/20] fs/dcache.c: add shrink_dcache_inode()
Date: Mon, 11 Feb 2019 09:27:28 -0800
Message-ID: <20190211172738.4633-11-ebiggers@kernel.org> (raw)
In-Reply-To: <20190211172738.4633-1-ebiggers@kernel.org>

From: Eric Biggers <ebiggers@google.com>

When a filesystem encryption key is removed, we need all files which had
been "unlocked" (had ->i_crypt_info set up) with it to appear "locked"
again.  This is most easily done by evicting the inodes.  This can
currently be done using 'echo 2 > /proc/sys/vm/drop_caches'; however,
that is overkill and not usable by non-root users.

To evict just the needed inodes we also need the ability to evict those
inodes' dentries, since an inode is pinned by its dentries.  Therefore,
add a function shrink_dcache_inode() which iterates through an inode's
dentries and evicts any unused ones as well as any unused descendants
(since there may be negative dentries pinning the inode's dentries).

Signed-off-by: Eric Biggers <ebiggers@google.com>
---
 fs/dcache.c            | 32 ++++++++++++++++++++++++++++++++
 include/linux/dcache.h |  1 +
 2 files changed, 33 insertions(+)

diff --git a/fs/dcache.c b/fs/dcache.c
index 2593153471cf..6a7db8797b2d 100644
--- a/fs/dcache.c
+++ b/fs/dcache.c
@@ -1484,6 +1484,38 @@ void shrink_dcache_parent(struct dentry *parent)
 }
 EXPORT_SYMBOL(shrink_dcache_parent);
 
+/**
+ * shrink_dcache_inode - prune dcache for inode
+ * @inode: inode to prune
+ *
+ * Evict all unused aliases of the specified inode from the dcache.  This is
+ * intended to be used when trying to evict a specific inode, since inodes are
+ * pinned by their dentries.  We also have to descend to ->d_subdirs for each
+ * alias, since aliases may be pinned by negative child dentries.
+ */
+void shrink_dcache_inode(struct inode *inode)
+{
+	for (;;) {
+		struct select_data data;
+		struct dentry *dentry;
+
+		INIT_LIST_HEAD(&data.dispose);
+		data.start = NULL;
+		data.found = 0;
+
+		spin_lock(&inode->i_lock);
+		hlist_for_each_entry(dentry, &inode->i_dentry, d_u.d_alias)
+			d_walk(dentry, &data, select_collect);
+		spin_unlock(&inode->i_lock);
+
+		if (!data.found)
+			break;
+
+		shrink_dentry_list(&data.dispose);
+		cond_resched();
+	}
+}
+
 static enum d_walk_ret umount_check(void *_data, struct dentry *dentry)
 {
 	/* it has busy descendents; complain about those instead */
diff --git a/include/linux/dcache.h b/include/linux/dcache.h
index ef4b70f64f33..c02dab98bc97 100644
--- a/include/linux/dcache.h
+++ b/include/linux/dcache.h
@@ -245,6 +245,7 @@ extern struct dentry * d_obtain_alias(struct inode *);
 extern struct dentry * d_obtain_root(struct inode *);
 extern void shrink_dcache_sb(struct super_block *);
 extern void shrink_dcache_parent(struct dentry *);
+extern void shrink_dcache_inode(struct inode *);
 extern void shrink_dcache_for_umount(struct super_block *);
 extern void d_invalidate(struct dentry *);
 
-- 
2.20.1


  parent reply index

Thread overview: 24+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-02-11 17:27 [RFC PATCH v2 00/20] fscrypt: key management improvements Eric Biggers
2019-02-11 17:27 ` [RFC PATCH v2 01/20] fs, fscrypt: move uapi definitions to new header <linux/fscrypt.h> Eric Biggers
2019-02-11 17:27 ` [RFC PATCH v2 02/20] fscrypt: use FSCRYPT_ prefix for uapi constants Eric Biggers
2019-02-11 17:27 ` [RFC PATCH v2 03/20] fscrypt: use FSCRYPT_* definitions, not FS_* Eric Biggers
2019-02-11 17:27 ` [RFC PATCH v2 04/20] fs: add ->s_master_keys to struct super_block Eric Biggers
2019-02-11 17:27 ` [RFC PATCH v2 05/20] fscrypt: add ->ci_inode to fscrypt_info Eric Biggers
2019-02-11 17:27 ` [RFC PATCH v2 06/20] fscrypt: refactor v1 policy key setup into keysetup_legacy.c Eric Biggers
2019-02-11 17:27 ` [RFC PATCH v2 07/20] fscrypt: add FS_IOC_ADD_ENCRYPTION_KEY ioctl Eric Biggers
2019-02-11 17:27 ` [RFC PATCH v2 08/20] fs/inode.c: export inode_lru_list_del() Eric Biggers
2019-02-11 17:27 ` [RFC PATCH v2 09/20] fs/inode.c: rename and export dispose_list() Eric Biggers
2019-02-11 17:27 ` Eric Biggers [this message]
2019-02-11 17:27 ` [RFC PATCH v2 11/20] fscrypt: add FS_IOC_REMOVE_ENCRYPTION_KEY ioctl Eric Biggers
2019-02-11 22:12   ` Dave Chinner
2019-02-11 23:31     ` Eric Biggers
2019-02-12  0:03       ` Dave Chinner
2019-02-11 17:27 ` [RFC PATCH v2 12/20] fscrypt: add FS_IOC_GET_ENCRYPTION_KEY_STATUS ioctl Eric Biggers
2019-02-11 17:27 ` [RFC PATCH v2 13/20] fscrypt: add an HKDF-SHA512 implementation Eric Biggers
2019-02-11 17:27 ` [RFC PATCH v2 14/20] fscrypt: v2 encryption policy support Eric Biggers
2019-02-11 17:27 ` [RFC PATCH v2 15/20] fscrypt: allow unprivileged users to add/remove keys for v2 policies Eric Biggers
2019-02-11 17:27 ` [RFC PATCH v2 16/20] fscrypt: require that key be added when setting a v2 encryption policy Eric Biggers
2019-02-11 17:27 ` [RFC PATCH v2 17/20] ext4: wire up new fscrypt ioctls Eric Biggers
2019-02-11 17:27 ` [RFC PATCH v2 18/20] f2fs: " Eric Biggers
2019-02-11 17:27 ` [RFC PATCH v2 19/20] ubifs: " Eric Biggers
2019-02-11 17:27 ` [RFC PATCH v2 20/20] fscrypt: document the new ioctls and policy version Eric Biggers

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