Date:	Thu, 19 Jul 2012 21:49:58 +0900
From:	Mitsuo Hayasaka <mitsuo.hayasaka.hu@...achi.com>
To:	Miklos Szeredi <miklos@...redi.hu>,
	Alexander Viro <viro@...iv.linux.org.uk>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Muthukumar R <muthur@...il.com>
Cc:	fuse-devel@...ts.sourceforge.net, linux-kernel@...r.kernel.org,
	linux-fsdevel@...r.kernel.org, linux-doc@...r.kernel.org,
	yrl.pp-manager.tt@...achi.com,
	Mitsuo Hayasaka <mitsuo.hayasaka.hu@...achi.com>,
	Miklos Szeredi <miklos@...redi.hu>,
	Nikolaus Rath <Nikolaus@...h.org>,
	Liu Yuan <namei.unix@...il.com>,
	Has-Wen Nienhuys <hanwen@...all.nl>
Subject: [PATCH -v2 5/6] fuse: set default global limit considering tunable
 request size

Set default global limits for backgrounded requests and congestion
threshold considering the tunable maximum request size.

They are calculated using size of fuse_req structure, which is
variable due to it. This patch sets them according to the current
request size unless they are set via mod_param by the system
administrator.

Signed-off-by: Mitsuo Hayasaka <mitsuo.hayasaka.hu@...achi.com>
Cc: Miklos Szeredi <miklos@...redi.hu>
Cc: Nikolaus Rath <Nikolaus@...h.org>
Cc: Liu Yuan <namei.unix@...il.com>
Cc: Has-Wen Nienhuys <hanwen@...all.nl>
---

 fs/fuse/fuse_i.h |    4 +++
 fs/fuse/inode.c  |   62 ++++++++++++++++++++++++++++++++++++++++++++----------
 2 files changed, 55 insertions(+), 11 deletions(-)

diff --git a/fs/fuse/fuse_i.h b/fs/fuse/fuse_i.h
index 46df615..2dda6eb 100644
--- a/fs/fuse/fuse_i.h
+++ b/fs/fuse/fuse_i.h
@@ -27,6 +27,10 @@
 /** Default number of pages that can be used in a single read/write request */
 #define FUSE_DEFAULT_MAX_PAGES_PER_REQ 32
 
+/** Maximum size of struct fuse_req */
+#define FUSE_CURRENT_REQ_SIZE (sizeof(struct fuse_req) +\
+			       sysfs_max_req_pages * sizeof(struct page *))
+
 /** Bias for fi->writectr, meaning new writepages must not be sent */
 #define FUSE_NOWRITE INT_MIN
 
diff --git a/fs/fuse/inode.c b/fs/fuse/inode.c
index 5f84a40..dc0302f 100644
--- a/fs/fuse/inode.c
+++ b/fs/fuse/inode.c
@@ -29,25 +29,36 @@ static struct kmem_cache *fuse_inode_cachep;
 struct list_head fuse_conn_list;
 DEFINE_MUTEX(fuse_mutex);
 
-static int set_global_limit(const char *val, struct kernel_param *kp);
+static int set_global_limit_bgreq(const char *val, struct kernel_param *kp);
+static int set_global_limit_thresh(const char *val, struct kernel_param *kp);
 
 unsigned max_user_bgreq;
-module_param_call(max_user_bgreq, set_global_limit, param_get_uint,
-		  &max_user_bgreq, 0644);
+module_param_call(max_user_bgreq, set_global_limit_bgreq,
+		  param_get_uint, &max_user_bgreq, 0644);
 __MODULE_PARM_TYPE(max_user_bgreq, "uint");
 MODULE_PARM_DESC(max_user_bgreq,
  "Global limit for the maximum number of backgrounded requests an "
  "unprivileged user can set");
 
 unsigned max_user_congthresh;
-module_param_call(max_user_congthresh, set_global_limit, param_get_uint,
-		  &max_user_congthresh, 0644);
+module_param_call(max_user_congthresh, set_global_limit_thresh,
+		  param_get_uint, &max_user_congthresh, 0644);
 __MODULE_PARM_TYPE(max_user_congthresh, "uint");
 MODULE_PARM_DESC(max_user_congthresh,
  "Global limit for the maximum congestion threshold an "
  "unprivileged user can set");
 
 /**
+ * The flags below are used in order to distinguish how to set
+ * max_user_bgreq and max_user_congthresh, respectively. They
+ * should be used if they are set via mod_param. If not, we should
+ * check their current limitation using check_global_limit() any
+ * time due to the tunable read/write request size.
+ */
+static bool mod_param_set_flg_bgreq;
+static bool mod_param_set_flg_thresh;
+
+/**
  * Maximum number of pages allocated for struct fuse_req.
  * It can be changed via sysfs to arbitrary number between
  * FUSE_DEFAULT_MAX_PAGES_PER_REQ and nr_pages equivalent
@@ -766,13 +777,39 @@ static void sanitize_global_limit(unsigned *limit)
 {
 	if (*limit == 0)
 		*limit = ((num_physpages << PAGE_SHIFT) >> 13) /
-			 sizeof(struct fuse_req);
+			 FUSE_CURRENT_REQ_SIZE;
 
 	if (*limit >= 1 << 16)
 		*limit = (1 << 16) - 1;
 }
 
-static int set_global_limit(const char *val, struct kernel_param *kp)
+static void check_global_limit(unsigned *limit, bool mod_param_flg)
+{
+	if (!mod_param_flg) {
+		unsigned cur_global_limit = 0;
+
+		sanitize_global_limit(&cur_global_limit);
+		*limit = cur_global_limit;
+	}
+}
+
+static int set_global_limit_bgreq(const char *val, struct kernel_param *kp)
+{
+	int rv;
+
+	rv = param_set_uint(val, kp);
+	if (rv)
+		return rv;
+
+	sanitize_global_limit((unsigned *)kp->arg);
+
+	/* max_user_bgreq is set via mod_param */
+	mod_param_set_flg_bgreq = true;
+
+	return 0;
+}
+
+static int set_global_limit_thresh(const char *val, struct kernel_param *kp)
 {
 	int rv;
 
@@ -782,6 +819,9 @@ static int set_global_limit(const char *val, struct kernel_param *kp)
 
 	sanitize_global_limit((unsigned *)kp->arg);
 
+	/* max_user_congthresh is set via mod_param */
+	mod_param_set_flg_thresh = true;
+
 	return 0;
 }
 
@@ -801,8 +841,8 @@ static void process_init_limits(struct fuse_conn *fc, struct fuse_init_out *arg)
 	if (arg->minor < 13)
 		return;
 
-	sanitize_global_limit(&max_user_bgreq);
-	sanitize_global_limit(&max_user_congthresh);
+	check_global_limit(&max_user_bgreq, mod_param_set_flg_bgreq);
+	check_global_limit(&max_user_congthresh, mod_param_set_flg_thresh);
 
 	if (arg->max_background) {
 		fc->max_background = arg->max_background;
@@ -1309,8 +1349,8 @@ static int __init fuse_init(void)
 	if (res)
 		goto err_sysfs_cleanup;
 
-	sanitize_global_limit(&max_user_bgreq);
-	sanitize_global_limit(&max_user_congthresh);
+	check_global_limit(&max_user_bgreq, mod_param_set_flg_bgreq);
+	check_global_limit(&max_user_congthresh, mod_param_set_flg_thresh);
 
 	return 0;
 

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