From mboxrd@z Thu Jan 1 00:00:00 1970 From: Eric Biggers Subject: Re: [PATCH v4 07/17] fs/dcache.c: add shrink_dcache_inode() Date: Wed, 3 Apr 2019 13:36:51 -0700 Message-ID: <20190403203650.GA216239@gmail.com> References: <20190402154600.32432-1-ebiggers@kernel.org> <20190402154600.32432-8-ebiggers@kernel.org> <20190403183411.GV2217@ZenIV.linux.org.uk> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Content-Disposition: inline In-Reply-To: <20190403183411.GV2217@ZenIV.linux.org.uk> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: linux-f2fs-devel-bounces@lists.sourceforge.net To: Al Viro Cc: Satya Tangirala , linux-api@vger.kernel.org, linux-f2fs-devel@lists.sourceforge.net, linux-fscrypt@vger.kernel.org, keyrings@vger.kernel.org, linux-mtd@lists.infradead.org, linux-crypto@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-ext4@vger.kernel.org, Paul Crowley List-Id: linux-api@vger.kernel.org On Wed, Apr 03, 2019 at 07:34:12PM +0100, Al Viro wrote: > On Tue, Apr 02, 2019 at 08:45:50AM -0700, Eric Biggers wrote: > > From: Eric Biggers > > > > 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). > > Huh? > > > + * 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(); > > This is... odd. What's wrong with > if (S_ISDIR(inode->i_mode)) { > dentry = d_find_any_alias(inode); > if (dentry) { > shrink_dcache_parent(dentry); > dput(dentry); > } > } > d_prune_aliases(inode); > instead of that thing? That works, as far as I can tell, so I'll do that instead. I don't think I noticed that d_prune_aliases() existed when I wrote this. Thanks for the suggestion! - Eric