Return-Path: Received: from mx1.redhat.com ([209.132.183.28]:49342 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751272AbdH2Vhd (ORCPT ); Tue, 29 Aug 2017 17:37:33 -0400 Date: Tue, 29 Aug 2017 17:37:32 -0400 From: "J. Bruce Fields" To: NeilBrown Cc: linux-nfs@vger.kernel.org, linux-fsdevel@vger.kernel.org, Trond Myklebust Subject: Re: [PATCH 1/3] fs: cleanup to hide some details of delegation logic Message-ID: <20170829213731.GH8822@parsley.fieldses.org> References: <1503697958-6122-1-git-send-email-bfields@redhat.com> <1503697958-6122-2-git-send-email-bfields@redhat.com> <87efrwibyz.fsf@notabene.neil.brown.name> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii In-Reply-To: <87efrwibyz.fsf@notabene.neil.brown.name> Sender: linux-nfs-owner@vger.kernel.org List-ID: On Mon, Aug 28, 2017 at 01:54:12PM +1000, NeilBrown wrote: > On Fri, Aug 25 2017, J. Bruce Fields wrote: > > > From: "J. Bruce Fields" > > > > Pull the checks for delegated_inode into break_deleg_wait() to simplify > > the callers a little. > > > > No change in behavior. > > > > Signed-off-by: J. Bruce Fields > > --- > > fs/namei.c | 26 ++++++++++---------------- > > fs/open.c | 16 ++++++---------- > > fs/utimes.c | 8 +++----- > > include/linux/fs.h | 12 +++++++----- > > 4 files changed, 26 insertions(+), 36 deletions(-) > > > > diff --git a/fs/namei.c b/fs/namei.c > > index ddb6a7c2b3d4..5a93be7b2c9c 100644 > > --- a/fs/namei.c > > +++ b/fs/namei.c > > @@ -4048,11 +4048,9 @@ static long do_unlinkat(int dfd, const char __user *pathname) > > if (inode) > > iput(inode); /* truncate the inode here */ > > inode = NULL; > > - if (delegated_inode) { > > - error = break_deleg_wait(&delegated_inode); > > - if (!error) > > - goto retry_deleg; > > - } > > + error = break_deleg_wait(&delegated_inode, error); > > + if (error == DELEG_RETRY) > > + goto retry_deleg; > > > > I don't like the "DELEG_RETRY". You are comparing it against an > 'error', but it doesn't start with '-E', so I get confused (happens > often). > > If this read: > > if (error > 0) > goto retry_deleg; > > it would be must more obvious to me what was happening. Clearly the > return value isn't an error, and it isn't "success" either. This is a > pattern I've seen elsewhere. > > Alternately you could use "-EAGAIN", but I suspect there is a risk of > unwanted side-effects if you re-use and existing code. Yes. OK, I think I like your suggestion. The change would look like the following (untested). --b. diff --git a/fs/namei.c b/fs/namei.c index 5a93be7b2c9c..e8688498aff7 100644 --- a/fs/namei.c +++ b/fs/namei.c @@ -4049,7 +4049,7 @@ static long do_unlinkat(int dfd, const char __user *pathname) iput(inode); /* truncate the inode here */ inode = NULL; error = break_deleg_wait(&delegated_inode, error); - if (error == DELEG_RETRY) + if (error > 0) goto retry_deleg; mnt_drop_write(path.mnt); exit1: @@ -4282,7 +4282,7 @@ SYSCALL_DEFINE5(linkat, int, olddfd, const char __user *, oldname, out_dput: done_path_create(&new_path, new_dentry); error = break_deleg_wait(&delegated_inode, error); - if (error == DELEG_RETRY) { + if (error > 0) { path_put(&old_path); goto retry; } @@ -4598,7 +4598,7 @@ SYSCALL_DEFINE5(renameat2, int, olddfd, const char __user *, oldname, exit3: unlock_rename(new_path.dentry, old_path.dentry); error = break_deleg_wait(&delegated_inode, error); - if (error == DELEG_RETRY) + if (error > 0) goto retry_deleg; mnt_drop_write(old_path.mnt); exit2: diff --git a/fs/open.c b/fs/open.c index d49e9385e45d..80975c4dd146 100644 --- a/fs/open.c +++ b/fs/open.c @@ -533,7 +533,7 @@ static int chmod_common(const struct path *path, umode_t mode) out_unlock: inode_unlock(inode); error = break_deleg_wait(&delegated_inode, error); - if (error == DELEG_RETRY) + if (error > 0) goto retry_deleg; mnt_drop_write(path->mnt); return error; @@ -610,7 +610,7 @@ static int chown_common(const struct path *path, uid_t user, gid_t group) error = notify_change(path->dentry, &newattrs, &delegated_inode); inode_unlock(inode); error = break_deleg_wait(&delegated_inode, error); - if (error == DELEG_RETRY) + if (error > 0) goto retry_deleg; return error; } diff --git a/fs/utimes.c b/fs/utimes.c index 75467b7ebfce..4dc6717638e6 100644 --- a/fs/utimes.c +++ b/fs/utimes.c @@ -90,7 +90,7 @@ static int utimes_common(const struct path *path, struct timespec *times) error = notify_change(path->dentry, &newattrs, &delegated_inode); inode_unlock(inode); error = break_deleg_wait(&delegated_inode, error); - if (error == DELEG_RETRY) + if (error > 0) goto retry_deleg; mnt_drop_write(path->mnt); diff --git a/include/linux/fs.h b/include/linux/fs.h index 1d0d2fde1766..1c7f7be3f26d 100644 --- a/include/linux/fs.h +++ b/include/linux/fs.h @@ -2288,8 +2288,6 @@ static inline int try_break_deleg(struct inode *inode, struct inode **delegated_ return ret; } -#define DELEG_RETRY 1 - static inline int break_deleg_wait(struct inode **delegated_inode, int error) { if (!*delegated_inode) @@ -2297,7 +2295,13 @@ static inline int break_deleg_wait(struct inode **delegated_inode, int error) error = break_deleg(*delegated_inode, O_WRONLY); iput(*delegated_inode); *delegated_inode = NULL; - return error ? error : DELEG_RETRY; + if (error) + return error; + /* + * Signal to the caller that it can retry the original operation + * now that the delegation is broken: + */ + return 1; } static inline int break_layout(struct inode *inode, bool wait)