From: Ian Kent raven@themaw.net Subject: autofs: revert "autofs: take more care to not update last_used on path walk"

While 092a53452b ("autofs: take more care to not update last_used on path walk") 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.

Link: http://lkml.kernel.org/r/151174729420.6162.1832622523537052460.stgit@pluto.t... Fixes: 092a53452b ("autofs: take more care to not update last_used on path walk") Signed-off-by: Ian Kent raven@themaw.net Reviewed-by: NeilBrown neilb@suse.com Cc: Al Viro viro@ZenIV.linux.org.uk Cc: stable@vger.kernel.org [4.11+] Cc: Colin Walters walters@redhat.com Cc: David Howells dhowells@redhat.com Cc: Ondrej Holy oholy@redhat.com Signed-off-by: Andrew Morton akpm@linux-foundation.org ---

fs/autofs4/root.c | 17 ++++++----------- 1 file changed, 6 insertions(+), 11 deletions(-)

diff -puN fs/autofs4/root.c~autofs-revert-take-more-care-to-not-update-last_used-on-path-walk fs/autofs4/root.c --- a/fs/autofs4/root.c~autofs-revert-take-more-care-to-not-update-last_used-on-path-walk +++ a/fs/autofs4/root.c @@ -281,8 +281,8 @@ static int autofs4_mount_wait(const stru 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 */ 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; } _