glusterfs.git/xlators/cluster/afr/src/afr-read-txn.c, branch v3.12dev

afr: do not mention split-brain in log message in read_txn

2017-03-20T13:58:50+00:00

I am seeing a lot of messages in qe/customer logs where read_txn
complains that file is possibly in split-brain because of no readable
subvol being found, does inode refresh and then there is no split-brain
message post the inode refresh. This means that a lookup was not issued
on the indoe to populate 'readable' or it can mean one brick is source
for data and the other for metadata, making readable to be zero (because
readable=intersection of (data,metadata readable) since commit
7a1c1e290470149696.

Since we anyway log actual split-brains post inode-refresh, move this
message to DEBUG log level.

Change-Id: Idb88b8ea362515279dc9b246f06b6b646c6d8013
BUG: 1433838
Signed-off-by: Ravishankar N 
Reviewed-on: https://review.gluster.org/16879
Reviewed-by: Pranith Kumar Karampuri 
Tested-by: Pranith Kumar Karampuri 
Smoke: Gluster Build System 
NetBSD-regression: NetBSD Build System 
CentOS-regression: Gluster Build System

cluster/afr: Do not log of split-brain when there isn't one

2017-01-12T06:42:02+00:00

* Even on errors like ENOENT, AFR logs split-brain after
  read-txn refresh, introduced by commit a07ddd8f.
  This can be a cause of much panic and confusion and needs to be fixed.

* Also fixed this issue in write-txns.

* Fixed afr read txns to log about split-brain only after knowing that
  there is no split-brain choice configured.

* Removed code duplication

* Fixed incorrect passing of error code in afr_write_txn_refresh_done()
  (the function was passing -0 as errno to gf_msg().

Change-Id: I354f454ce5bf0e5f00bc27916eb597367cb7d927
BUG: 1411625
Signed-off-by: Krutika Dhananjay 
Reviewed-on: http://review.gluster.org/16362
Smoke: Gluster Build System 
NetBSD-regression: NetBSD Build System 
CentOS-regression: Gluster Build System 
Reviewed-by: Ravishankar N 
Reviewed-by: Pranith Kumar Karampuri

afr: Ignore event_generation checks post inode refresh for write txns

2016-12-22T11:06:31+00:00

Before http://review.gluster.org/#/c/15673/, after inode refresh, we
failed read txns in case of EIO or event_generation being zero. For
write transactions, the check was only for EIO. 15673 re-factored the
code to fail both read and write when event_generation=0. This seems to
have caused a regression as explained in the BZ.

This patch restores that behaviour in afr_txn_refresh_done().

Change-Id: Ib8e116506badce6f58b55827dbe403d95069d744
BUG: 1406224
Signed-off-by: Ravishankar N 
Reviewed-on: http://review.gluster.org/16205
Reviewed-by: Pranith Kumar Karampuri 
Smoke: Gluster Build System 
CentOS-regression: Gluster Build System 
NetBSD-regression: NetBSD Build System

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

2016-11-29T04:10:24+00:00

     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 
Reviewed-on: http://review.gluster.org/15892
Reviewed-by: Ravishankar N 
Smoke: Gluster Build System 
NetBSD-regression: NetBSD Build System 
CentOS-regression: Gluster Build System 
Reviewed-by: Pranith Kumar Karampuri

afr: allow I/O when favorite-child-policy is enabled

2016-11-28T07:51:59+00:00

Problem:
Currently, I/O on a split-brained file fails even when the
favorite-child-policy is set until the self-heal is complete.

Fix:
If a valid 'source' is found using the set favorite-child-policy, inspect
and reset the afr pending xattrs on the 'sinks' (inside appropriate locks),
refresh the inode and then proceed with the read or write transaction.

The resetting itself happens in the self-heal code and hence can also
happen in the client side background-heal or by the shd's index-heal in
addition to the txn code path explained above. When it happens in via
heal, we also add checks in undo-pending to not reset the sink xattrs
again.

Change-Id: Ic8c1317720cb26bd114b6fe6af4e58c73b864626
BUG: 1386188
Signed-off-by: Ravishankar N 
Reported-by: Simon Turcotte-Langevin 
Reviewed-on: http://review.gluster.org/15673
Tested-by: Pranith Kumar Karampuri 
Smoke: Gluster Build System 
Reviewed-by: Pranith Kumar Karampuri 
NetBSD-regression: NetBSD Build System 
CentOS-regression: Gluster Build System

cluster/afr: Give option to do consistent-io

2016-08-22T20:55:42+00:00

Problem:
When tiering/rebalance does migrations and afr with 2-way replica is in
picture, migration can read stale data if the source brick goes down and writes
to the destination. After this deletion of the file leads to permanent loss of
data after migration.

Fix:
Rebalance/tiering should migrate only when the data is definitely not stale. So
introduce an option in afr called consistent-io which will be enabled in
migration daemons.

BUG: 1306398
Change-Id: I750f65091cc70a3ed4bf3c12f83d0949af43920a
Signed-off-by: Pranith Kumar K 
Reviewed-on: http://review.gluster.org/13425
Reviewed-by: Anuradha Talur 
Reviewed-by: Krutika Dhananjay 
Smoke: Gluster Build System 
NetBSD-regression: NetBSD Build System 
CentOS-regression: Gluster Build System

afr:Don't wind reads for files in metadata split-brain

2016-06-24T11:26:01+00:00

Problem: For a read on  a file in metadata split-brain:
1.lookup_done resets event_generation to zero.
2. readv is issued, goes to inode refresh due to mismatching event_gen.
3. After refresh is successful, we update event_generation, data and
metdata readable.
3. We then call afr_read_txn_refresh_done() which in turn calls
afr_inode_get_readable() but doesn't check for EIO. So afr_readv_wind
is called with local->readable (which is populated with data_readable),
thus winding the read to a brick.
4. Also, further parallel reads that come directly go to the wind path
because there is no inode_refresh needed.

Fix:
1.For any afr_read_txn(), readable must be an intersection of data and metadata
readable.
2.Check for EIO in afr_read_txn_refresh_done().

Change-Id: I22dd221fdfaf96d7aced2f474e28ed1337d69f0e
BUG: 1305031
Signed-off-by: Ravishankar N 
Reviewed-on: http://review.gluster.org/13389
Reviewed-by: Ashish Pandey 
Smoke: Gluster Build System 
NetBSD-regression: NetBSD Build System 
CentOS-regression: Gluster Build System 
Reviewed-by: Pranith Kumar Karampuri

cluster/afr: Refresh inode for inode-write fops in need

2016-05-20T04:27:59+00:00

Problem:
If a named fresh-lookup is done on an loc and the fop fails on one of the
bricks or not sent on one of the bricks, but by the time response comes to afr,
if the brick is up, 'can_interpret' will be set to false in afr_lookup_done(),
this will lead to inode-ctx for that inode to be not set, this can lead to EIO
in case of a transaction as it depends on 'readable' array to be available by
that point.

Fix:
Refresh inode for inode-write fops for the ctx to be set if it is not already
done at the time of named fresh-lookup or if the file is in split-brain where
we need to perform one more refresh before failing the fop to check if the file
is still in split-brain or not.

BUG: 1336612
Change-Id: I5c50b62c8de06129b8516039f7c252e5008c47a5
Signed-off-by: Pranith Kumar K 
Reviewed-on: http://review.gluster.org/14368
Smoke: Gluster Build System 
NetBSD-regression: NetBSD Build System 
Reviewed-by: Ravishankar N 
CentOS-regression: Gluster Build System

cluster/afr : Examine data/metadata readable for read-subvol

2015-08-25T17:32:49+00:00

During lookup and discover, currently read_subvol is based
only on data_readable. read_subvol should be decided based
on both data_readable and metadata_readable.

Credits to Ravishankar N for the logic of afr_first_up_child
from http://review.gluster.org/10905/ .

Change-Id: I98580b23c278172ee2902be08eeaafb6722e830c
BUG: 1240244
Signed-off-by: Anuradha Talur 
Reviewed-on: http://review.gluster.org/11551
Reviewed-by: Ravishankar N 
Tested-by: Gluster Build System 
Reviewed-by: Krutika Dhananjay 
Reviewed-by: Pranith Kumar Karampuri

cluster/afr: Fix incorrect logging in read transactions

2015-07-27T06:05:50+00:00

afr_read_txn_refresh_done() at its entry point can fail for
reasons like ENOENT/ESTALE but seldom due to EIO, which is something
_AFR_ would internally generate and not receive in response from
a child translator. AFR is reporting "split-brain" for _any_
kind of failure in read txn, of the following kind:

[2015-07-07 18:04:34.787612] E [MSGID: 108008]
[afr-read-txn.c:76:afr_read_txn_refresh_done] 0-vol3-replicate-3:
Failing STAT on gfid 18a973c4-73d3-48b8-942c-33a6f1a8e6b4:
split-brain observed. [Input/output error]

This patch fixes such misleading errors.

To-Do:
Avoid logging EIO if/when split-brain choice is set.
Will do that as part of a separate commit.

Change-Id: Ib513c75168f7026118ad5b3f0b35e9dd498cfe1e
BUG: 1246052
Signed-off-by: Krutika Dhananjay 
Reviewed-on: http://review.gluster.org/11756
Tested-by: NetBSD Build System 
Reviewed-by: Pranith Kumar Karampuri 
Reviewed-by: Anuradha Talur 
Reviewed-by: Ravishankar N 
Tested-by: Gluster Build System