LKML Archive on lore.kernel.org
 help / color / Atom feed
From: Ian Kent <raven@themaw.net>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: Colin Walters <walters@redhat.com>,
	Ondrej Holy <oholy@redhat.com>,
	autofs mailing list <autofs@vger.kernel.org>,
	NeilBrown <neilb@suse.com>,
	Kernel Mailing List <linux-kernel@vger.kernel.org>,
	David Howells <dhowells@redhat.com>,
	Al Viro <viro@ZenIV.linux.org.uk>
Subject: [PATCH 1/2] autofs: revert take more care to not update last_used on path walk
Date: Mon, 27 Nov 2017 09:48:14 +0800
Message-ID: <151174729420.6162.1832622523537052460.stgit@pluto.themaw.net> (raw)

While the patch of commit 092a53452b helped (partially) resolve a
problem where automounts were not expiring due to aggressive accesses
from user space it has a side effect for very large environments.

This change helps with the expire problem by making the expire more
aggressive but, for very large environments, that means more mount
requests from clients. When there are a lot of clients that can mean
fairly significant server load increases.

It turns out I put the last_used in this position to solve this
very problem and failed to update my own thinking of the autofs
expire policy. So the patch being reverted introduces a regression
which should be fixed.

Reverts: 092a53452b

Signed-off-by: Ian Kent <raven@themaw.net>
Cc: Neil Brown <neilb@suse.com>
Cc: Al Viro <viro@ZenIV.linux.org.uk>
---
 fs/autofs4/root.c |   17 ++++++-----------
 1 file changed, 6 insertions(+), 11 deletions(-)

diff --git a/fs/autofs4/root.c b/fs/autofs4/root.c
index d79ced925861..82e8f6edfb48 100644
--- a/fs/autofs4/root.c
+++ b/fs/autofs4/root.c
@@ -281,8 +281,8 @@ static int autofs4_mount_wait(const struct path *path, bool rcu_walk)
 		pr_debug("waiting for mount name=%pd\n", path->dentry);
 		status = autofs4_wait(sbi, path, NFY_MOUNT);
 		pr_debug("mount wait done status=%d\n", status);
-		ino->last_used = jiffies;
 	}
+	ino->last_used = jiffies;
 	return status;
 }
 
@@ -321,21 +321,16 @@ static struct dentry *autofs4_mountpoint_changed(struct path *path)
 	 */
 	if (autofs_type_indirect(sbi->type) && d_unhashed(dentry)) {
 		struct dentry *parent = dentry->d_parent;
+		struct autofs_info *ino;
 		struct dentry *new;
 
 		new = d_lookup(parent, &dentry->d_name);
 		if (!new)
 			return NULL;
-		if (new == dentry)
-			dput(new);
-		else {
-			struct autofs_info *ino;
-
-			ino = autofs4_dentry_ino(new);
-			ino->last_used = jiffies;
-			dput(path->dentry);
-			path->dentry = new;
-		}
+		ino = autofs4_dentry_ino(new);
+		ino->last_used = jiffies;
+		dput(path->dentry);
+		path->dentry = new;
 	}
 	return path->dentry;
 }

             reply index

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-11-27  1:48 Ian Kent [this message]
2017-11-27  1:48 ` [PATCH 2/2] autofs: revert fix AT_NO_AUTOMOUNT not being honored Ian Kent
2017-11-28 22:48 ` [PATCH 1/2] autofs: revert take more care to not update last_used on path walk NeilBrown

Reply instructions:

You may reply publically to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=151174729420.6162.1832622523537052460.stgit@pluto.themaw.net \
    --to=raven@themaw.net \
    --cc=akpm@linux-foundation.org \
    --cc=autofs@vger.kernel.org \
    --cc=dhowells@redhat.com \
    --cc=linux-kernel@vger.kernel.org \
    --cc=neilb@suse.com \
    --cc=oholy@redhat.com \
    --cc=viro@ZenIV.linux.org.uk \
    --cc=walters@redhat.com \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

LKML Archive on lore.kernel.org

Archives are clonable:
	git clone --mirror https://lore.kernel.org/lkml/0 lkml/git/0.git
	git clone --mirror https://lore.kernel.org/lkml/1 lkml/git/1.git
	git clone --mirror https://lore.kernel.org/lkml/2 lkml/git/2.git
	git clone --mirror https://lore.kernel.org/lkml/3 lkml/git/3.git
	git clone --mirror https://lore.kernel.org/lkml/4 lkml/git/4.git
	git clone --mirror https://lore.kernel.org/lkml/5 lkml/git/5.git
	git clone --mirror https://lore.kernel.org/lkml/6 lkml/git/6.git
	git clone --mirror https://lore.kernel.org/lkml/7 lkml/git/7.git

	# If you have public-inbox 1.1+ installed, you may
	# initialize and index your mirror using the following commands:
	public-inbox-init -V2 lkml lkml/ https://lore.kernel.org/lkml \
		linux-kernel@vger.kernel.org linux-kernel@archiver.kernel.org
	public-inbox-index lkml


Newsgroup available over NNTP:
	nntp://nntp.lore.kernel.org/org.kernel.vger.linux-kernel


AGPL code for this site: git clone https://public-inbox.org/ public-inbox