glusterfs.git/xlators/cluster/afr/src/afr-inode-write.c, branch v3.12.9

cluster/afr: Fixing the flaws in arbiter becoming source patch

2018-04-18T13:23:19+00:00

Backport of https://review.gluster.org/19045

Problem:
Setting the write_subvol value to read_subvol in case of metadata
transaction during pre-op (commit 19f9bcff4aada589d4321356c2670ed283f02c03)
might lead to the original problem of arbiter becoming source.

Scenario:
1) All bricks are up and good
2) 2 writes w1 and w2 are in progress in parallel
3) ctx->read_subvol is good for all the subvolumes
4) w1 succeeds on brick0 and fails on brick1, yet to do post-op on
   the disk
5) read/lookup comes on the same file and refreshes read_subvols back
   to all good
6) metadata transaction happens which makes ctx->write_subvol to be
   assigned with ctx->read_subvol which is all good
7) w2 succeeds on brick1 and fails on brick0 and this will update the
   brick in reverse order leading to arbiter becoming source

Fix:
Instead of setting the ctx->write_subvol to ctx->read_subvol in the
pre-op statge, if there is a metadata transaction, check in the
function __afr_set_in_flight_sb_status() if it is a data/metadata
transaction. Use the value of ctx->write_subvol if it is a data
transactions and ctx->read_subvol value for other transactions.

With this patch we assign the value of ctx->write_subvol in the
afr_transaction_perform_fop() with the on disk value, instead of
assigning it in the afr_changelog_pre_op() with the in memory value.

Change-Id: Id2025a7e965f0578af35b1abaac793b019c43cc4
BUG: 1566131
Signed-off-by: karthik-us 
Signed-off-by: Ravishankar N

cluster/afr: Fail open on split-brain

2018-03-08T06:39:57+00:00

Problem:
Append on a file with split-brain succeeds. Open is intercepted by open-behind,
when write comes on the file, open-behind does open+write. Open succeeds
because afr doesn't fail it. Then write succeeds because write-behind
intercepts it. Flush is also intercepted by write-behind, so the application
never gets to know that the write failed.

Fix:
Fail open on split-brain, so that when open-behind does open+write open fails
which leads to write failure. Application will know about this failure.

Change-Id: I4bff1c747c97bb2925d6987f4ced5f1ce75dbc15
BUG: 1544635
Signed-off-by: Pranith Kumar K 
(cherry picked from commit 786343abca3474ff01aa1017210112d97cbc4843)

afr: propagate correct errno for fop failures in arbiter

2017-05-15T12:18:32+00:00

Problem:
If quorum is not met in fop cbk, arbiter sends an ENOTCONN error to the
upper xlators. In a VM workload with sharding enabled, this was leading
to the VM pausing when replace-brick was performed as described in the BZ.

Fix:
Move the fop cbk arbitration logic to afr_handle_quorum() because in
normal replica volumes, that is the function that has the quorum and
errno checks in the fop cbk path before doing a post-op.

Thanks to Pranith for suggesting this approach.

Change-Id: Ie6315db30c5e36326b71b90a01da824109e86796
BUG: 1449610
Signed-off-by: Ravishankar N 
Reviewed-on: https://review.gluster.org/17235
Smoke: Gluster Build System 
Reviewed-by: Pranith Kumar Karampuri 
NetBSD-regression: NetBSD Build System 
CentOS-regression: Gluster Build System

xlators/afr: fix unused variable warnings/errors

2016-09-13T17:04:44+00:00

http://review.gluster.org/14085 fixes a "pragma leak" where the
generated rpc/xdr headers have a pair of pragmas that disable these
warnings. With the warnings disabled, many unused variables have
crept into the code base.

And 14085 won't pass its own smoke test until all these warnings are
fixed.

BUG: 1369124
Change-Id: I55d4106ac828380f3315f5a21593390905d3ab3a
Signed-off-by: Kaleb S. KEITHLEY 
Reviewed-on: http://review.gluster.org/15476
Reviewed-by: Ravishankar N 
Smoke: Gluster Build System 
NetBSD-regression: NetBSD Build System 
CentOS-regression: Gluster Build System

afr: Consume compound fops in afr transaction

2016-09-01T17:22:39+00:00

Change-Id: Ib06ece3cce1b10d28d6d2953da28444f5c2457ad
BUG: 1290304
Signed-off-by: Anuradha Talur 
Reviewed-on: http://review.gluster.org/15014
Tested-by: Pranith Kumar Karampuri 
Smoke: Gluster Build System 
CentOS-regression: Gluster Build System 
NetBSD-regression: NetBSD Build System 
Reviewed-by: Krutika Dhananjay 
Reviewed-by: Pranith Kumar Karampuri

glusterd : Introduce reset brick

2016-08-30T02:55:53+00:00

The command basically allows replace brick with src and
dst bricks as same.

Usage:
gluster v reset-brick   start
This command kills the brick to be reset. Once this command is run,
admin can do other manual operations that they need to do,
like configuring some options for the brick. Once this is done,
resetting the brick can be continued with the following options.

gluster v reset-brick    commit {force}

Does the job of resetting the brick. 'force' option should be used
when the brick already contains volinfo id.

Problem: On doing a disk-replacement of a brick in a replicate volume
the following 2 scenarios may occur :

a) there is a chance that reads are served from this replaced-disk brick,
which leads to empty reads. b) potential data loss if next writes succeed
only on replaced brick, and heal is done to other bricks from this one.

Solution: After disk-replacement, make sure that reset-brick command is
run for that brick so that pending markers are set for the brick and it
is not chosen as source for reads and heal. But, as of now replace-brick
for the same brick-path is not allowed. In order to fix the above
mentioned problem, same brick-path replace-brick is needed.
With this patch reset-brick commit {force} will be allowed even when
source and destination  are identical as long as
1) destination brick is not alive
2) source and destination brick have the same brick uuid and path.
Also, the destination brick after replace-brick will use the same port
as the source brick.

Change-Id: I440b9e892ffb781ea4b8563688c3f85c7a7c89de
BUG: 1266876
Signed-off-by: Anuradha Talur 
Reviewed-on: http://review.gluster.org/12250
Smoke: Gluster Build System 
NetBSD-regression: NetBSD Build System 
CentOS-regression: Gluster Build System 
Reviewed-by: Ashish Pandey 
Reviewed-by: Pranith Kumar Karampuri

cluster/afr: Prevent split-brain when bricks are brought off and on in cyclic order

2016-08-22T09:38:36+00:00

When the bricks are brought offline and then online in cyclic
order while writes are in progress on a file, thanks to inode
refresh in write txns, AFR will mostly fail the write attempt
when the only good copy is offline. However, there is still a
remote possibility that the file will run into split-brain if
the brick that has the lone good copy goes offline *after* the
inode refresh but *before* the write txn completes (I call it
in-flight split-brain in the patch for ease of reference),
requiring intervention from admin to resolve the split-brain
before the IO can resume normally on the file. To get around this,
the patch does the following things:
i) retains the dirty xattrs on the file
ii) avoids marking the last of the good copies as bad (or accused)
    in case it is the one to go down during the course of a write.
iii) fails that particular write with the appropriate errno.

This way, we still have one good copy left despite the split-brain situation
which when it is back online, will be chosen as source to do the heal.

Change-Id: I9ca634b026ac830b172bac076437cc3bf1ae7d8a
BUG: 1363721
Signed-off-by: Krutika Dhananjay 
Reviewed-on: http://review.gluster.org/15080
Tested-by: Pranith Kumar Karampuri 
Smoke: Gluster Build System 
CentOS-regression: Gluster Build System 
Reviewed-by: Ravishankar N 
Reviewed-by: Oleksandr Natalenko 
NetBSD-regression: NetBSD Build System 
Reviewed-by: Pranith Kumar Karampuri

cluster/afr: copy loc before passing to syncop

2016-08-04T08:47:09+00:00

Problem:
When io-threads is enabled on the client side, io-threads destroys the
call-stub in which the loc is stored as soon as the c-stack unwinds.
Because afr is creating a syncop with the address of loc passed in
setxattr by the time syncop tries to access it, io-threads would have
already freed the call-stub. This will lead to crash.

Fix:
Copy loc to frame->local and use it's address.

BUG: 1361678
Change-Id: I16987e491e24b0b4e3d868a6968e802e47c77f7a
Signed-off-by: Pranith Kumar K 
Reviewed-on: http://review.gluster.org/15070
Reviewed-by: Ravishankar N 
Smoke: Gluster Build System 
NetBSD-regression: NetBSD Build System 
CentOS-regression: Gluster Build System

cluster/afr: Unwind with xdata in inode-write fops

2016-06-01T13:28:14+00:00

When there is a failure afr was not unwinding xdata to xlators above.
xdata need not be NULL on failures. So it is important to send it
to parent xlators.

Change-Id: Ic36aac10a79fa91121961932dd1920cb1c2c3a4c
BUG: 1340623
Signed-off-by: Pranith Kumar K 
Reviewed-on: http://review.gluster.org/14567
Smoke: Gluster Build System 
NetBSD-regression: NetBSD Build System 
CentOS-regression: Gluster Build System 
Reviewed-by: Jeff Darcy

cluster/afr: Unwind xdata_rsp even in case of failures

2016-05-31T04:27:35+00:00

DHT expects GF_PREOP_CHECK_FAILED to be present in xdata_rsp in case of mkdir
failures because of stale layout. But AFR was unwinding null xdata_rsp in case
of failures. This was leading to mkdir failures just after remove-brick. Unwind
the xdata_rsp in case of failures to make sure the response from brick reaches
dht.

BUG: 1340623
Change-Id: Idd3f7b95730e8ea987b608e892011ff190e181d1
Signed-off-by: Pranith Kumar K 
Reviewed-on: http://review.gluster.org/14553
NetBSD-regression: NetBSD Build System 
Reviewed-by: Ravishankar N 
Smoke: Gluster Build System 
CentOS-regression: Gluster Build System 
Reviewed-by: Anuradha Talur 
Reviewed-by: Krutika Dhananjay