afr: Fix the EIO that can occur in afr_inode_refresh as a result

     of cache invalidation(upcall).

Issue:
------
When a cache invalidation is recieved as a result of changing
pending xattr, the read_subvol is reset. Consider the below chain
of execution:

CHILD_DOWN
...
afr_readv
...
afr_inode_refresh
...
afr_inode_read_subvol_reset <- as a result of pending xattr set by
                               some other client GF_EVENT_UPCALL will
                               be sent
afr_refresh_done -> this results in an EIO, as the read subvol was
                    reset by the end of the afr_inode_refresh

Solution:
---------
When GF_EVENT_UPCALL is recieved, instead of resetting read_subvol,
set a variable need_refresh in inode_ctx, the next time some one
starts a txn, along with event gen, need_rrefresh also needs to
be checked.

Change-Id: Ifda21a7a8039b8874215e1afa4bdf20f7d991b58
BUG: 1396952
Signed-off-by: Poornima G <pgurusid@redhat.com>
Reviewed-on: http://review.gluster.org/15892
Reviewed-by: Ravishankar N <ravishankar@redhat.com>
Smoke: Gluster Build System <jenkins@build.gluster.org>
NetBSD-regression: NetBSD Build System <jenkins@build.gluster.org>
CentOS-regression: Gluster Build System <jenkins@build.gluster.org>
Reviewed-by: Pranith Kumar Karampuri <pkarampu@redhat.com>

1 files changed, 5 insertions, 0 deletions

diff --git a/xlators/cluster/afr/src/afr.h b/xlators/cluster/afr/src/afr.h
index 9bfb5812d8a..dcc162f97c3 100644
--- a/xlators/cluster/afr/src/afr.h
+++ b/xlators/cluster/afr/src/afr.h
@@ -812,6 +812,7 @@ typedef struct _afr_inode_ctx {
         uint64_t        read_subvol;
         int             spb_choice;
         gf_timer_t      *timer;
+        gf_boolean_t    need_refresh;
 } afr_inode_ctx_t;
 
 typedef struct afr_spbc_timeout {
@@ -1235,4 +1236,8 @@ __afr_fd_ctx_get (fd_t *fd, xlator_t *this);
 void
 afr_compound_cleanup (compound_args_t *args, dict_t *xdata,
                       dict_t *newloc_xdata);
+
+gf_boolean_t
+afr_is_inode_refresh_reqd (inode_t *inode, xlator_t *this,
+                           int event_gen1, int event_gen2);
 #endif /* __AFR_H__ */