From b644de2ba0c5b590db9195c03358ccd0f061daa6 Mon Sep 17 00:00:00 2001 From: Alex Elder Date: Sat, 27 Apr 2013 09:59:31 -0500 Subject: [PATCH] rbd: set up watch in rbd_dev_image_probe() Move setting up the watch request for an image so it's done in rbd_dev_image_probe() rather than rbd_dev_probe_finish(). Move it all the way up to before doing the initial probe. This avoids a potential race condition, in which we get (and use) the initial snapshot context for an image, and it gets changed between that time and the time we get the watch set up. This resolves: http://tracker.ceph.com/issues/3871 Signed-off-by: Alex Elder Reviewed-by: Josh Durgin --- drivers/block/rbd.c | 21 +++++++++++---------- 1 file changed, 11 insertions(+), 10 deletions(-) diff --git a/drivers/block/rbd.c b/drivers/block/rbd.c index 52c722b471e4..ac94aa4b4d22 100644 --- a/drivers/block/rbd.c +++ b/drivers/block/rbd.c @@ -4721,11 +4721,6 @@ static int rbd_dev_probe_parent(struct rbd_device *rbd_dev) static int rbd_dev_probe_finish(struct rbd_device *rbd_dev) { int ret; - int tmp; - - ret = rbd_dev_header_watch_sync(rbd_dev, 1); - if (ret) - return ret; ret = rbd_dev_mapping_set(rbd_dev); if (ret) @@ -4773,9 +4768,6 @@ static int rbd_dev_probe_finish(struct rbd_device *rbd_dev) unregister_blkdev(rbd_dev->major, rbd_dev->name); err_out_id: rbd_dev_id_put(rbd_dev); - tmp = rbd_dev_header_watch_sync(rbd_dev, 0); - if (tmp) - rbd_warn(rbd_dev, "failed to cancel watch event (%d)\n", ret); rbd_dev_mapping_clear(rbd_dev); return ret; @@ -4816,6 +4808,7 @@ static int rbd_dev_header_name(struct rbd_device *rbd_dev) static int rbd_dev_image_probe(struct rbd_device *rbd_dev) { int ret; + int tmp; /* * Get the id from the image id object. If it's not a @@ -4832,16 +4825,20 @@ static int rbd_dev_image_probe(struct rbd_device *rbd_dev) if (ret) goto err_out_format; + ret = rbd_dev_header_watch_sync(rbd_dev, 1); + if (ret) + goto out_header_name; + if (rbd_dev->image_format == 1) ret = rbd_dev_v1_probe(rbd_dev); else ret = rbd_dev_v2_probe(rbd_dev); if (ret) - goto out_header_name; + goto err_out_watch; ret = rbd_dev_snaps_update(rbd_dev); if (ret) - goto out_header_name; + goto err_out_watch; ret = rbd_dev_spec_update(rbd_dev); if (ret) @@ -4861,6 +4858,10 @@ static int rbd_dev_image_probe(struct rbd_device *rbd_dev) rbd_header_free(&rbd_dev->header); err_out_snaps: rbd_remove_all_snaps(rbd_dev); +err_out_watch: + tmp = rbd_dev_header_watch_sync(rbd_dev, 0); + if (tmp) + rbd_warn(rbd_dev, "unable to tear down watch request\n"); out_header_name: kfree(rbd_dev->header_name); rbd_dev->header_name = NULL; -- GitLab