libceph: store timeouts in jiffies, verify user input

There are currently three libceph-level timeouts that the user can
specify on mount: mount_timeout, osd_idle_ttl and osdkeepalive.  All of
these are in seconds and no checking is done on user input: negative
values are accepted, we multiply them all by HZ which may or may not
overflow, arbitrarily large jiffies then get added together, etc.

There is also a bug in the way mount_timeout=0 is handled.  It's
supposed to mean "infinite timeout", but that's not how wait.h APIs
treat it and so __ceph_open_session() for example will busy loop
without much chance of being interrupted if none of ceph-mons are
there.

Fix all this by verifying user input, storing timeouts capped by
msecs_to_jiffies() in jiffies and using the new ceph_timeout_jiffies()
helper for all user-specified waits to handle infinite timeouts
correctly.

Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
Reviewed-by: Alex Elder <elder@linaro.org>

4 files changed, 10 insertions, 10 deletions

diff --git a/fs/ceph/dir.c b/fs/ceph/dir.c
index 4248307fea90..173dd4b58c71 100644
--- a/fs/ceph/dir.c
+++ b/fs/ceph/dir.c
@@ -1259,8 +1259,8 @@ static int ceph_dir_fsync(struct file *file, loff_t start, loff_t end,
 		     inode, req->r_tid, last_tid);
 		if (req->r_timeout) {
 			unsigned long time_left = wait_for_completion_timeout(
-							&req->r_safe_completion,
-							req->r_timeout);
+					&req->r_safe_completion,
+					ceph_timeout_jiffies(req->r_timeout));
 			if (time_left > 0)
 				ret = 0;
 			else
diff --git a/fs/ceph/mds_client.c b/fs/ceph/mds_client.c
index 69a36f40517f..0b0e0a9a81c0 100644
--- a/fs/ceph/mds_client.c
+++ b/fs/ceph/mds_client.c
@@ -2268,7 +2268,8 @@ int ceph_mdsc_do_request(struct ceph_mds_client *mdsc,
 	dout("do_request waiting\n");
 	if (req->r_timeout) {
 		err = (long)wait_for_completion_killable_timeout(
-			&req->r_completion, req->r_timeout);
+					&req->r_completion,
+					ceph_timeout_jiffies(req->r_timeout));
 		if (err == 0)
 			err = -EIO;
 	} else if (req->r_wait_for_completion) {
@@ -3424,8 +3425,8 @@ int ceph_mdsc_init(struct ceph_fs_client *fsc)
  */
 static void wait_requests(struct ceph_mds_client *mdsc)
 {
+	struct ceph_options *opts = mdsc->fsc->client->options;
 	struct ceph_mds_request *req;
-	struct ceph_fs_client *fsc = mdsc->fsc;
 
 	mutex_lock(&mdsc->mutex);
 	if (__get_oldest_req(mdsc)) {
@@ -3433,7 +3434,7 @@ static void wait_requests(struct ceph_mds_client *mdsc)
 
 		dout("wait_requests waiting for requests\n");
 		wait_for_completion_timeout(&mdsc->safe_umount_waiters,
-				    fsc->client->options->mount_timeout * HZ);
+				    ceph_timeout_jiffies(opts->mount_timeout));
 
 		/* tear down remaining requests */
 		mutex_lock(&mdsc->mutex);
@@ -3556,10 +3557,9 @@ static bool done_closing_sessions(struct ceph_mds_client *mdsc)
  */
 void ceph_mdsc_close_sessions(struct ceph_mds_client *mdsc)
 {
+	struct ceph_options *opts = mdsc->fsc->client->options;
 	struct ceph_mds_session *session;
 	int i;
-	struct ceph_fs_client *fsc = mdsc->fsc;
-	unsigned long timeout = fsc->client->options->mount_timeout * HZ;
 
 	dout("close_sessions\n");
 
@@ -3580,7 +3580,7 @@ void ceph_mdsc_close_sessions(struct ceph_mds_client *mdsc)
 
 	dout("waiting for sessions to close\n");
 	wait_event_timeout(mdsc->session_close_wq, done_closing_sessions(mdsc),
-			   timeout);
+			   ceph_timeout_jiffies(opts->mount_timeout));
 
 	/* tear down remaining sessions */
 	mutex_lock(&mdsc->mutex);
diff --git a/fs/ceph/mds_client.h b/fs/ceph/mds_client.h
index 2ef799961ebb..509d6822e9b1 100644
--- a/fs/ceph/mds_client.h
+++ b/fs/ceph/mds_client.h
@@ -227,7 +227,7 @@ struct ceph_mds_request {
 	int r_err;
 	bool r_aborted;
 
-	unsigned long r_timeout;  /* optional.  jiffies */
+	unsigned long r_timeout;  /* optional.  jiffies, 0 is "wait forever" */
 	unsigned long r_started;  /* start time to measure timeout against */
 	unsigned long r_request_started; /* start time for mds request only,
 					    used to measure lease durations */
diff --git a/fs/ceph/super.c b/fs/ceph/super.c
index 9a5350030af8..edeb83c43112 100644
--- a/fs/ceph/super.c
+++ b/fs/ceph/super.c
@@ -742,7 +742,7 @@ static struct dentry *open_root_dentry(struct ceph_fs_client *fsc,
 	req->r_ino1.ino = CEPH_INO_ROOT;
 	req->r_ino1.snap = CEPH_NOSNAP;
 	req->r_started = started;
-	req->r_timeout = fsc->client->options->mount_timeout * HZ;
+	req->r_timeout = fsc->client->options->mount_timeout;
 	req->r_args.getattr.mask = cpu_to_le32(CEPH_STAT_CAP_INODE);
 	req->r_num_caps = 2;
 	err = ceph_mdsc_do_request(mdsc, NULL, req);