From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jeff Layton Subject: [PATCH] vfs: document locking requirements for d_move, __d_move and d_materialise_unique (try #2) Date: Tue, 26 Jul 2011 13:33:16 -0400 Message-ID: <1311701596-23252-1-git-send-email-jlayton@redhat.com> References: <1311701107-22971-1-git-send-email-jlayton@redhat.com> Cc: linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org To: viro@ZenIV.linux.org.uk Return-path: Received: from mx1.redhat.com ([209.132.183.28]:51887 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751426Ab1GZRdT (ORCPT ); Tue, 26 Jul 2011 13:33:19 -0400 In-Reply-To: <1311701107-22971-1-git-send-email-jlayton@redhat.com> Sender: linux-fsdevel-owner@vger.kernel.org List-ID: Adding a comment to d_materialise_unique per Al's request... d_move and __d_move have some pretty substantial locking requirements, but they are not clearly documented. Add some comments spelling them out. Also, document the requirement for the i_mutex of the parent in d_materialise_unique. Cc: Al Viro Signed-off-by: Jeff Layton --- fs/dcache.c | 11 +++++++---- 1 files changed, 7 insertions(+), 4 deletions(-) diff --git a/fs/dcache.c b/fs/dcache.c index be18598..b05aac3 100644 --- a/fs/dcache.c +++ b/fs/dcache.c @@ -2138,8 +2138,9 @@ static void dentry_unlock_parents_for_move(struct dentry *dentry, * @target: new dentry * * Update the dcache to reflect the move of a file name. Negative - * dcache entries should not be moved in this way. Caller hold - * rename_lock. + * dcache entries should not be moved in this way. Caller must hold + * rename_lock, the i_mutex of the source and target directories, + * and the sb->s_vfs_rename_mutex if they differ. See lock_rename(). */ static void __d_move(struct dentry * dentry, struct dentry * target) { @@ -2202,7 +2203,8 @@ static void __d_move(struct dentry * dentry, struct dentry * target) * @target: new dentry * * Update the dcache to reflect the move of a file name. Negative - * dcache entries should not be moved in this way. + * dcache entries should not be moved in this way. See the locking + * requirements for __d_move. */ void d_move(struct dentry *dentry, struct dentry *target) { @@ -2320,7 +2322,8 @@ static void __d_materialise_dentry(struct dentry *dentry, struct dentry *anon) * @inode: inode to bind to the dentry, to which aliases may be attached * * Introduces an dentry into the tree, substituting an extant disconnected - * root directory alias in its place if there is one + * root directory alias in its place if there is one. Caller must hold the + * i_mutex of the parent directory. */ struct dentry *d_materialise_unique(struct dentry *dentry, struct inode *inode) { -- 1.7.1