From patchwork Tue Jan 30 19:03:55 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Linus Torvalds X-Patchwork-Id: 13537870 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 2D3977995D; Tue, 30 Jan 2024 19:04:23 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1706641464; cv=none; b=o0B7DM++OveallHu48BMF14JVDcFOYVD4rYR+55EMSDg4qZSCBrzp+5WqCXxV8z3ZSIn4PMKtc80fIgd4RIg5JRcbme86sITk8pkUp/YIt9KJB2pY6thmu8AxYbQxgnjrl4lJ/8xww29JUVlH/Fp3uoUUF1vOVXXlS2KU7f2n9k= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1706641464; c=relaxed/simple; bh=uW+OU0rYpytIA1AFMT3QHS+mJXzgQjvRvaoJkHkudIo=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=KjfluNwvKJDeD+m5VhlIkZIEqsV8mNomNZQlOqihH2wEG2Kp5663Id0pk/IxGyApLEQXzK/aKJ928l4645gHN0ur7dDJ9YmgemH0E5u0kjQHl+dQT/lRZKfcxQIBXUtGIwDYRq1iY4dhYpUONa2+zCaojXNKmzwVRQIxNUz/itw= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux-foundation.org header.i=@linux-foundation.org header.b=wGjmvTEi; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux-foundation.org header.i=@linux-foundation.org header.b="wGjmvTEi" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 91369C43399; Tue, 30 Jan 2024 19:04:23 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1706641463; bh=uW+OU0rYpytIA1AFMT3QHS+mJXzgQjvRvaoJkHkudIo=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=wGjmvTEiT7sEcOAeBTVz3vAxOPiWnLBmpzpTnw7l8nUEO5LLLIbDIWjK6IaFdeOU4 Fkw4pWkwCYXU+aJqTOdxCzGuWtI+ab9/xRDcPLzv9FA7ZJzGJUlVoTC/GLbo2EXcGM S6VRjgiALRhRcIhP+0JXRRnUDEZkBplONVjBTeA0= From: Linus Torvalds To: Steven Rostedt Cc: Masami Hiramatsu , linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org, Linus Torvalds Subject: [PATCH 6/6] eventfs: clean up dentry ops and add revalidate function Date: Tue, 30 Jan 2024 11:03:55 -0800 Message-ID: <20240130190355.11486-6-torvalds@linux-foundation.org> X-Mailer: git-send-email 2.43.0.5.g38fb137bdb In-Reply-To: <20240130190355.11486-1-torvalds@linux-foundation.org> References: <20240130190355.11486-1-torvalds@linux-foundation.org> Precedence: bulk X-Mailing-List: linux-trace-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 In order for the dentries to stay up-to-date with the eventfs changes, just add a 'd_revalidate' function that checks the 'is_freed' bit. Also, clean up the dentry release to actually use d_release() rather than the slightly odd d_iput() function. We don't care about the inode, all we want to do is to get rid of the refcount to the eventfs data added by dentry->d_fsdata. It would probably be cleaner to make eventfs its own filesystem, or at least set its own dentry ops when looking up eventfs files. But as it is, only eventfs dentries use d_fsdata, so we don't really need to split these things up by use. Another thing that might be worth doing is to make all eventfs lookups mark their dentries as not worth caching. We could do that with d_delete(), but the DCACHE_DONTCACHE flag would likely be even better. As it is, the dentries are all freeable, but they only tend to get freed at memory pressure rather than more proactively. But that's a separate issue. Signed-off-by: Linus Torvalds --- fs/tracefs/event_inode.c | 21 +++++---------------- fs/tracefs/inode.c | 27 ++++++++++++++++++--------- fs/tracefs/internal.h | 3 ++- 3 files changed, 25 insertions(+), 26 deletions(-) diff --git a/fs/tracefs/event_inode.c b/fs/tracefs/event_inode.c index a37db0dac302..acdc797bd9c0 100644 --- a/fs/tracefs/event_inode.c +++ b/fs/tracefs/event_inode.c @@ -414,23 +414,14 @@ static inline struct eventfs_inode *alloc_ei(const char *name) /** - * eventfs_set_ei_status_free - remove the dentry reference from an eventfs_inode - * @ti: the tracefs_inode of the dentry + * eventfs_d_release - dentry is going away * @dentry: dentry which has the reference to remove. * * Remove the association between a dentry from an eventfs_inode. */ -void eventfs_set_ei_status_free(struct tracefs_inode *ti, struct dentry *dentry) +void eventfs_d_release(struct dentry *dentry) { - struct eventfs_inode *ei; - - mutex_lock(&eventfs_mutex); - ei = dentry->d_fsdata; - if (ei) { - dentry->d_fsdata = NULL; - put_ei(ei); - } - mutex_unlock(&eventfs_mutex); + put_ei(dentry->d_fsdata); } /** @@ -517,9 +508,8 @@ static struct dentry *eventfs_root_lookup(struct inode *dir, } enoent: - /* Nothing found? */ - d_add(dentry, NULL); - result = NULL; + /* Don't cache negative lookups, just return an error */ + result = ERR_PTR(-ENOENT); out: mutex_unlock(&eventfs_mutex); @@ -857,6 +847,5 @@ void eventfs_remove_events_dir(struct eventfs_inode *ei) * sticks around while the other ei->dentry are created * and destroyed dynamically. */ - simple_recursive_removal(dentry, NULL); dput(dentry); } diff --git a/fs/tracefs/inode.c b/fs/tracefs/inode.c index e1b172c0e091..64122787e5d0 100644 --- a/fs/tracefs/inode.c +++ b/fs/tracefs/inode.c @@ -379,21 +379,30 @@ static const struct super_operations tracefs_super_operations = { .show_options = tracefs_show_options, }; -static void tracefs_dentry_iput(struct dentry *dentry, struct inode *inode) +/* + * It would be cleaner if eventfs had its own dentry ops. + * + * Note that d_revalidate is called potentially under RCU, + * so it can't take the eventfs mutex etc. It's fine - if + * we open a file just as it's marked dead, things will + * still work just fine, and just see the old stale case. + */ +static void tracefs_d_release(struct dentry *dentry) { - struct tracefs_inode *ti; + if (dentry->d_fsdata) + eventfs_d_release(dentry); +} - if (!dentry || !inode) - return; +static int tracefs_d_revalidate(struct dentry *dentry, unsigned int flags) +{ + struct eventfs_inode *ei = dentry->d_fsdata; - ti = get_tracefs(inode); - if (ti && ti->flags & TRACEFS_EVENT_INODE) - eventfs_set_ei_status_free(ti, dentry); - iput(inode); + return !(ei && ei->is_freed); } static const struct dentry_operations tracefs_dentry_operations = { - .d_iput = tracefs_dentry_iput, + .d_revalidate = tracefs_d_revalidate, + .d_release = tracefs_d_release, }; static int trace_fill_super(struct super_block *sb, void *data, int silent) diff --git a/fs/tracefs/internal.h b/fs/tracefs/internal.h index 72db3bdc4dfb..d4194466b643 100644 --- a/fs/tracefs/internal.h +++ b/fs/tracefs/internal.h @@ -79,6 +79,7 @@ struct inode *tracefs_get_inode(struct super_block *sb); struct dentry *eventfs_start_creating(const char *name, struct dentry *parent); struct dentry *eventfs_failed_creating(struct dentry *dentry); struct dentry *eventfs_end_creating(struct dentry *dentry); -void eventfs_set_ei_status_free(struct tracefs_inode *ti, struct dentry *dentry); + +void eventfs_d_release(struct dentry *dentry); #endif /* _TRACEFS_INTERNAL_H */