From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755312Ab3HFOa3 (ORCPT ); Tue, 6 Aug 2013 10:30:29 -0400 Received: from mail-bk0-f53.google.com ([209.85.214.53]:41995 "EHLO mail-bk0-f53.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754780Ab3HFOaZ (ORCPT ); Tue, 6 Aug 2013 10:30:25 -0400 From: Miklos Szeredi To: rwheeler@redhat.com, avati@redhat.com, viro@ZenIV.linux.org.uk Cc: bfoster@redhat.com, dhowells@redhat.com, eparis@redhat.com, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, linux-nfs@vger.kernel.org, Trond.Myklebust@netapp.com, swhiteho@redhat.com, mszeredi@suse.cz Subject: [PATCH 3/4] fuse: use d_materialise_unique() Date: Tue, 6 Aug 2013 16:30:02 +0200 Message-Id: <1375799403-28544-4-git-send-email-miklos@szeredi.hu> X-Mailer: git-send-email 1.8.1.4 In-Reply-To: <1375799403-28544-1-git-send-email-miklos@szeredi.hu> References: <1375799403-28544-1-git-send-email-miklos@szeredi.hu> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Miklos Szeredi Use d_materialise_unique() instead of d_splice_alias(). This allows dentry subtrees to be moved to a new place if there moved, even if something is referencing a dentry in the subtree (open fd, cwd, etc..). This will also allow us to drop a subtree if it is found to be replaced by something else. In this case the disconnected subtree can later be reconnected to its new location. d_materialise_unique() ensures that a directory entry only ever has one alias. We keep fc->inst_mutex around the calls for d_materialise_unique() on directories to prevent a race with mkdir "stealing" the inode. Signed-off-by: Miklos Szeredi --- fs/fuse/dir.c | 69 ++++++++++++++++++++++------------------------------------- 1 file changed, 26 insertions(+), 43 deletions(-) diff --git a/fs/fuse/dir.c b/fs/fuse/dir.c index 72a5d5b..131d14b 100644 --- a/fs/fuse/dir.c +++ b/fs/fuse/dir.c @@ -267,26 +267,6 @@ int fuse_valid_type(int m) S_ISBLK(m) || S_ISFIFO(m) || S_ISSOCK(m); } -/* - * Add a directory inode to a dentry, ensuring that no other dentry - * refers to this inode. Called with fc->inst_mutex. - */ -static struct dentry *fuse_d_add_directory(struct dentry *entry, - struct inode *inode) -{ - struct dentry *alias = d_find_alias(inode); - if (alias && !(alias->d_flags & DCACHE_DISCONNECTED)) { - /* This tries to shrink the subtree below alias */ - fuse_invalidate_entry(alias); - dput(alias); - if (!hlist_empty(&inode->i_dentry)) - return ERR_PTR(-EBUSY); - } else { - dput(alias); - } - return d_splice_alias(inode, entry); -} - int fuse_lookup_name(struct super_block *sb, u64 nodeid, struct qstr *name, struct fuse_entry_out *outarg, struct inode **inode) { @@ -345,6 +325,24 @@ int fuse_lookup_name(struct super_block *sb, u64 nodeid, struct qstr *name, return err; } +static struct dentry *fuse_materialise_dentry(struct dentry *dentry, + struct inode *inode) +{ + struct dentry *newent; + + if (inode && S_ISDIR(inode->i_mode)) { + struct fuse_conn *fc = get_fuse_conn(inode); + + mutex_lock(&fc->inst_mutex); + newent = d_materialise_unique(dentry, inode); + mutex_unlock(&fc->inst_mutex); + } else { + newent = d_materialise_unique(dentry, inode); + } + + return newent; +} + static struct dentry *fuse_lookup(struct inode *dir, struct dentry *entry, unsigned int flags) { @@ -352,7 +350,6 @@ static struct dentry *fuse_lookup(struct inode *dir, struct dentry *entry, struct fuse_entry_out outarg; struct inode *inode; struct dentry *newent; - struct fuse_conn *fc = get_fuse_conn(dir); bool outarg_valid = true; err = fuse_lookup_name(dir->i_sb, get_node_id(dir), &entry->d_name, @@ -368,16 +365,10 @@ static struct dentry *fuse_lookup(struct inode *dir, struct dentry *entry, if (inode && get_node_id(inode) == FUSE_ROOT_ID) goto out_iput; - if (inode && S_ISDIR(inode->i_mode)) { - mutex_lock(&fc->inst_mutex); - newent = fuse_d_add_directory(entry, inode); - mutex_unlock(&fc->inst_mutex); - err = PTR_ERR(newent); - if (IS_ERR(newent)) - goto out_iput; - } else { - newent = d_splice_alias(inode, entry); - } + newent = fuse_materialise_dentry(entry, inode); + err = PTR_ERR(newent); + if (IS_ERR(newent)) + goto out_err; entry = newent ? newent : entry; if (outarg_valid) @@ -1275,18 +1266,10 @@ static int fuse_direntplus_link(struct file *file, if (!inode) goto out; - if (S_ISDIR(inode->i_mode)) { - mutex_lock(&fc->inst_mutex); - alias = fuse_d_add_directory(dentry, inode); - mutex_unlock(&fc->inst_mutex); - err = PTR_ERR(alias); - if (IS_ERR(alias)) { - iput(inode); - goto out; - } - } else { - alias = d_splice_alias(inode, dentry); - } + alias = fuse_materialise_dentry(dentry, inode); + err = PTR_ERR(alias); + if (IS_ERR(alias)) + goto out; if (alias) { dput(dentry); -- 1.8.1.4