From 9cd5066226770cf3c06a21757b963d315b8fe32b Mon Sep 17 00:00:00 2001 From: Poornima G Date: Mon, 6 Jun 2016 06:29:40 -0400 Subject: gfapi: Fix IO error caused when there is consecutive graph switches Issue: Consider a simple situation, where glfs_init() is done, i.e. initial graph is up. Now perform 2 volume sets that results in 2 client side graph changes. After this perform some IO, the IO fails with ENOTCON. The only way to recover this client is i guess another graph switch or restart. What actually is happening from code perspective: Initial graph lets say A, followed by 2 consecutive graph switches to B and C without any IO those two switches. - graph_setup (A) as a result of GF_EVENT_CHILD_UP, and fs->next_subvol = A - glfs_init() results in fs->active_subvol = A, fs->next_subvol = NULL - graph_setup (B) as a result of GF_EVENT_CHILD_UP, and fs->next_subvol = B - graph_setup (C) as a result of GF_EVENT_CHILD_UP, and fs->next_subvol = C. It also sees that the previous graph B was never set as fs->active_subvol, i.e. no IO or anything happened on B, so can safely send GF_EVENT_PARENT_DOWN (by calling glfs_subvol_done(B)). This parent down on B, results in child_down(B), which is fine. But child_down also triggers graph_setup(B). - graph_setup(B) as a result of GF_EVENT_CHILD_DOWN, and fs->next_subvol = B, and GF_EVENT_PARENT_DOWN on C as explained above. This again leads to GF_EVENT_CHILD_DOWN on C. - graph_setup(C) as a result of GF_EVENT_CHILD_DOWN, and fs->next_subvol = C, and GF_EVENT_PARENT_DOWN on B as explained above. Thus both the graphs B and C are disconnected, and hence the ENOTCON Solution: Remove the call to graph_setup() when the event is GF_EVENT_CHILD_DOWN. It don't see any reason why graph_setup should be called when there is child_down. Not sure what the original reason was, to have graph_setup in child_down. git hostory shows the first patch itself had this call. > Reviewed-on: http://review.gluster.org/14656 > Smoke: Gluster Build System > CentOS-regression: Gluster Build System > NetBSD-regression: NetBSD Build System > Reviewed-by: Jeff Darcy BUG: 1367294 Change-Id: I9de86555f66cc94a05649ac863b40ed3426ffd4b Signed-off-by: Poornima G Signed-off-by: Oleksandr Natalenko Reviewed-on: http://review.gluster.org/14835 Smoke: Gluster Build System CentOS-regression: Gluster Build System NetBSD-regression: NetBSD Build System Reviewed-by: Kaushal M --- api/src/glfs-master.c | 1 - 1 file changed, 1 deletion(-) (limited to 'api') diff --git a/api/src/glfs-master.c b/api/src/glfs-master.c index 77e2d53abb9..b49ce2c8447 100644 --- a/api/src/glfs-master.c +++ b/api/src/glfs-master.c @@ -110,7 +110,6 @@ notify (xlator_t *this, int event, void *data, ...) pthread_cond_broadcast (&fs->child_down_cond); } pthread_mutex_unlock (&fs->mutex); - graph_setup (fs, graph); glfs_init_done (fs, 1); break; case GF_EVENT_CHILD_CONNECTING: -- cgit