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Commit c297eb42 authored by Ilya Dryomov's avatar Ilya Dryomov
Browse files

libceph: always signal completion when done 



r_safe_completion is currently, and has always been, signaled only if
on-disk ack was requested.  It's there for fsync and syncfs, which wait
for in-flight writes to flush - all data write requests set ONDISK.

However, the pool perm check code introduced in 4.2 sends a write
request with only ACK set.  An unfortunately timed syncfs can then hang
forever: r_safe_completion won't be signaled because only an unsafe
reply was requested.

We could patch ceph_osdc_sync() to skip !ONDISK write requests, but
that is somewhat incomplete and yet another special case.  Instead,
rename this completion to r_done_completion and always signal it when
the OSD client is done with the request, whether unsafe, safe, or
error.  This is a bit cleaner and helps with the cancellation code.

Reported-by: default avatarYan, Zheng <zyan@redhat.com>
Signed-off-by: default avatarIlya Dryomov <idryomov@gmail.com>
parent 80e80fbb

fs/ceph/file.c

+1 −1
Original line number Diff line number Diff line
@@ -864,7 +864,7 @@ void ceph_sync_write_wait(struct inode *inode) 


		dout("sync_write_wait on tid %llu (until %llu)\n",

		     req->r_tid, last_tid);

		wait_for_completion(&req->r_safe_completion);

		wait_for_completion(&req->r_done_completion);

		ceph_osdc_put_request(req);



		spin_lock(&ci->i_unsafe_lock);

include/linux/ceph/osd_client.h

+1 −1
Original line number Diff line number Diff line
@@ -176,7 +176,7 @@ struct ceph_osd_request { 
	struct kref       r_kref;

	bool              r_mempool;

	struct completion r_completion;

	struct completion r_safe_completion;  /* fsync waiter */

	struct completion r_done_completion;  /* fsync waiter */

	ceph_osdc_callback_t r_callback;

	ceph_osdc_unsafe_callback_t r_unsafe_callback;

	struct list_head  r_unsafe_item;

net/ceph/osd_client.c

+11 −14
Original line number Diff line number Diff line
@@ -460,7 +460,7 @@ static void request_init(struct ceph_osd_request *req) 


	kref_init(&req->r_kref);

	init_completion(&req->r_completion);

	init_completion(&req->r_safe_completion);

	init_completion(&req->r_done_completion);

	RB_CLEAR_NODE(&req->r_node);

	RB_CLEAR_NODE(&req->r_mc_node);

	INIT_LIST_HEAD(&req->r_unsafe_item);
@@ -1772,7 +1772,7 @@ static void complete_request(struct ceph_osd_request *req, int err) 
	req->r_result = err;

	__finish_request(req);

	__complete_request(req);

	complete_all(&req->r_safe_completion);

	complete_all(&req->r_done_completion);

	ceph_osdc_put_request(req);

}
@@ -1797,7 +1797,9 @@ static void cancel_request(struct ceph_osd_request *req) 
	dout("%s req %p tid %llu\n", __func__, req, req->r_tid);



	cancel_map_check(req);

	finish_request(req);

	__finish_request(req);

	complete_all(&req->r_done_completion);

	ceph_osdc_put_request(req);

}



static void check_pool_dne(struct ceph_osd_request *req)
@@ -2808,12 +2810,12 @@ static bool done_request(const struct ceph_osd_request *req, 
 * ->r_unsafe_callback is set?	yes			no

 *

 * first reply is OK (needed	r_cb/r_completion,	r_cb/r_completion,

 * any or needed/got safe)	r_safe_completion	r_safe_completion

 * any or needed/got safe)	r_done_completion	r_done_completion

 *

 * first reply is unsafe	r_unsafe_cb(true)	(nothing)

 *

 * when we get the safe reply	r_unsafe_cb(false),	r_cb/r_completion,

 *				r_safe_completion	r_safe_completion

 *				r_done_completion	r_done_completion

 */

static void handle_reply(struct ceph_osd *osd, struct ceph_msg *msg)

{
@@ -2934,8 +2936,7 @@ static void handle_reply(struct ceph_osd *osd, struct ceph_msg *msg) 
			dout("req %p tid %llu cb\n", req, req->r_tid);

			__complete_request(req);

		}

		if (m.flags & CEPH_OSD_FLAG_ONDISK)

			complete_all(&req->r_safe_completion);

		complete_all(&req->r_done_completion);

		ceph_osdc_put_request(req);

	} else {

		if (req->r_unsafe_callback) {
@@ -3471,9 +3472,8 @@ int ceph_osdc_start_request(struct ceph_osd_client *osdc, 
EXPORT_SYMBOL(ceph_osdc_start_request);



/*

 * Unregister a registered request.  The request is not completed (i.e.

 * no callbacks or wakeups) - higher layers are supposed to know what

 * they are canceling.

 * Unregister a registered request.  The request is not completed:

 * ->r_result isn't set and __complete_request() isn't called.

 */

void ceph_osdc_cancel_request(struct ceph_osd_request *req)

{
@@ -3500,9 +3500,6 @@ static int wait_request_timeout(struct ceph_osd_request *req, 
	if (left <= 0) {

		left = left ?: -ETIMEDOUT;

		ceph_osdc_cancel_request(req);



		/* kludge - need to to wake ceph_osdc_sync() */

		complete_all(&req->r_safe_completion);

	} else {

		left = req->r_result; /* completed */

	}
@@ -3549,7 +3546,7 @@ void ceph_osdc_sync(struct ceph_osd_client *osdc) 
			up_read(&osdc->lock);

			dout("%s waiting on req %p tid %llu last_tid %llu\n",

			     __func__, req, req->r_tid, last_tid);

			wait_for_completion(&req->r_safe_completion);

			wait_for_completion(&req->r_done_completion);

			ceph_osdc_put_request(req);

			goto again;

		}