cluster/afr: Fix for arbiter becoming source

Problem:
When eager-lock is on, and two writes happen in parallel on a FD
we were observing the following behaviour:
- First write fails on one data brick
- Since the post-op is not yet happened, the inode refresh will get
  both the data bricks as readable and set it in the inode context
- In flight split brain check see both the data bricks as readable
  and allows the second write
- Second write fails on the other data brick
- Now the post-op happens and marks both the data bricks as bad and
  arbiter will become source for healing

Fix:
Adding one more variable called write_suvol in inode context and it
will have the in memory representation of the writable subvols. Inode
refresh will not update this value and its lifetime is pre-op through
unlock in the afr transaction. Initially the pre-op will set this
value same as read_subvol in inode context and then in the in flight
split brain check we will use this value instead of read_subvol.
After all the checks we will update the value of this and set the
read_subvol same as this to avoid having incorrect value in that.

Change-Id: I2ef6904524ab91af861d59690974bbc529ab1af3
BUG: 1482064
Signed-off-by: karthik-us <ksubrahm@redhat.com>

1 files changed, 10 insertions, 0 deletions

diff --git a/xlators/cluster/afr/src/afr.h b/xlators/cluster/afr/src/afr.h
index 8cd687398f0..b05ec8f6b96 100644
--- a/xlators/cluster/afr/src/afr.h
+++ b/xlators/cluster/afr/src/afr.h
@@ -838,6 +838,7 @@ typedef struct _afr_local {
 
 typedef struct _afr_inode_ctx {
         uint64_t        read_subvol;
+        uint64_t        write_subvol;
         int             spb_choice;
         gf_timer_t      *timer;
         gf_boolean_t    need_refresh;
@@ -1265,4 +1266,13 @@ afr_serialize_xattrs_with_delimiter (call_frame_t *frame, xlator_t *this,
                                      int32_t *serz_len, char delimiter);
 gf_boolean_t
 afr_is_symmetric_error (call_frame_t *frame, xlator_t *this);
+
+int
+__afr_inode_ctx_get (xlator_t *this, inode_t *inode, afr_inode_ctx_t **ctx);
+
+int
+afr_write_subvol_set (call_frame_t *frame, xlator_t *this);
+
+int
+afr_write_subvol_reset (call_frame_t *frame, xlator_t *this);
 #endif /* __AFR_H__ */