From: Ian Kent <raven@xxxxxxxxxx>
Subject: autofs: add strictexpire mount option
092a53452b (("autofs: take more care to not update last_used on path
walk") helped to (partially) resolve a problem where automounts were not
expiring due to aggressive accesses from user space.
This patch was later reverted because, for very large environments, it
meant more mount requests from clients and when there are a lot of clients
this caused a fairly significant increase in server load.
But there is a need for both types of expire check, depending on use case,
so add a mount option to allow for strict update of last use of autofs
dentrys (which just means not updating the last use on path walk access).
Link: http://lkml.kernel.org/r/154296973880.9889.14085372741514507967.stgit@pluto-themaw-net
Signed-off-by: Ian Kent <raven@xxxxxxxxxx>
Cc: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
fs/autofs/autofs_i.h | 1 +
fs/autofs/inode.c | 8 +++++++-
fs/autofs/root.c | 5 ++++-
include/uapi/linux/auto_fs.h | 2 +-
4 files changed, 13 insertions(+), 3 deletions(-)
--- a/fs/autofs/autofs_i.h~autofs-add-strictexpire-mount-option
+++ a/fs/autofs/autofs_i.h
@@ -104,6 +104,7 @@ struct autofs_wait_queue {
#define AUTOFS_SBI_MAGIC 0x6d4a556d
#define AUTOFS_SBI_CATATONIC 0x0001
+#define AUTOFS_SBI_STRICTEXPIRE 0x0002
struct autofs_sb_info {
u32 magic;
--- a/fs/autofs/inode.c~autofs-add-strictexpire-mount-option
+++ a/fs/autofs/inode.c
@@ -87,6 +87,8 @@ static int autofs_show_options(struct se
seq_printf(m, ",direct");
else
seq_printf(m, ",indirect");
+ if (sbi->flags & AUTOFS_SBI_STRICTEXPIRE)
+ seq_printf(m, ",strictexpire");
#ifdef CONFIG_CHECKPOINT_RESTORE
if (sbi->pipe)
seq_printf(m, ",pipe_ino=%ld", file_inode(sbi->pipe)->i_ino);
@@ -109,7 +111,7 @@ static const struct super_operations aut
};
enum {Opt_err, Opt_fd, Opt_uid, Opt_gid, Opt_pgrp, Opt_minproto, Opt_maxproto,
- Opt_indirect, Opt_direct, Opt_offset};
+ Opt_indirect, Opt_direct, Opt_offset, Opt_strictexpire};
static const match_table_t tokens = {
{Opt_fd, "fd=%u"},
@@ -121,6 +123,7 @@ static const match_table_t tokens = {
{Opt_indirect, "indirect"},
{Opt_direct, "direct"},
{Opt_offset, "offset"},
+ {Opt_strictexpire, "strictexpire"},
{Opt_err, NULL}
};
@@ -200,6 +203,9 @@ static int parse_options(char *options,
case Opt_offset:
set_autofs_type_offset(&sbi->type);
break;
+ case Opt_strictexpire:
+ sbi->flags |= AUTOFS_SBI_STRICTEXPIRE;
+ break;
default:
return 1;
}
--- a/fs/autofs/root.c~autofs-add-strictexpire-mount-option
+++ a/fs/autofs/root.c
@@ -275,8 +275,11 @@ static int autofs_mount_wait(const struc
pr_debug("waiting for mount name=%pd\n", path->dentry);
status = autofs_wait(sbi, path, NFY_MOUNT);
pr_debug("mount wait done status=%d\n", status);
+ ino->last_used = jiffies;
+ return status;
}
- ino->last_used = jiffies;
+ if (!(sbi->flags & AUTOFS_SBI_STRICTEXPIRE))
+ ino->last_used = jiffies;
return status;
}
--- a/include/uapi/linux/auto_fs.h~autofs-add-strictexpire-mount-option
+++ a/include/uapi/linux/auto_fs.h
@@ -23,7 +23,7 @@
#define AUTOFS_MIN_PROTO_VERSION 3
#define AUTOFS_MAX_PROTO_VERSION 5
-#define AUTOFS_PROTO_SUBVERSION 3
+#define AUTOFS_PROTO_SUBVERSION 4
/*
* The wait_queue_token (autofs_wqt_t) is part of a structure which is passed
_
