From 2c58d548f5706d085c4b009f6abb945220460632 Mon Sep 17 00:00:00 2001
From: Eric Biggers <ebiggers@google.com>
Date: Wed, 10 Apr 2019 13:21:15 -0700
Subject: fscrypt: cache decrypted symlink target in ->i_link
Path lookups that traverse encrypted symlink(s) are very slow because
each encrypted symlink needs to be decrypted each time it's followed.
This also involves dropping out of rcu-walk mode.
Make encrypted symlinks faster by caching the decrypted symlink target
in ->i_link. The first call to fscrypt_get_symlink() sets it. Then,
the existing VFS path lookup code uses the non-NULL ->i_link to take the
fast path where ->get_link() isn't called, and lookups in rcu-walk mode
remain in rcu-walk mode.
Also set ->i_link immediately when a new encrypted symlink is created.
To safely free the symlink target after an RCU grace period has elapsed,
introduce a new function fscrypt_free_inode(), and make the relevant
filesystems call it just before actually freeing the inode.
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
---
fs/f2fs/super.c | 3 +++
1 file changed, 3 insertions(+)
(limited to 'fs/f2fs/super.c')
diff --git a/fs/f2fs/super.c b/fs/f2fs/super.c
index f2aaa2cc6b3e..11b3a039a188 100644
--- a/fs/f2fs/super.c
+++ b/fs/f2fs/super.c
@@ -1003,6 +1003,9 @@ static void f2fs_dirty_inode(struct inode *inode, int flags)
static void f2fs_i_callback(struct rcu_head *head)
{
struct inode *inode = container_of(head, struct inode, i_rcu);
+
+ fscrypt_free_inode(inode);
+
kmem_cache_free(f2fs_inode_cachep, F2FS_I(inode));
}
--
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