glusterfs.git/xlators/cluster/afr/src/afr-dir-write.c, branch v3.12.14

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

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

afr: Avoid resetting event_gen when brick is always down

2017-01-13T02:54:02+00:00

Problem:
__afr_set_in_flight_sb_status(), which resets event_gen to zero, is
called if failed_subvols[i] is non-zero for any brick. But failed_subvols[i]
is true even if the brick was down *before* the transaction started.
Hence say if 1 brick is down in  a replica-3, every writev that comes
will trigger an inode refresh because of this resetting, as seen from
the no. of FSTATs in the profile info in the BZ.

Fix:
Reset event gen only if the brick was previously a valid read child and
the FOP failed on it the first time.

Also `s/afr_inode_read_subvol_reset/afr_inode_event_gen_reset` because
the function only resets event gen and not the data/metadata readable.

Change-Id: I603ae646cbde96995c35db77916e2ed80b602a91
BUG: 1409206
Signed-off-by: Ravishankar N 
Reviewed-on: http://review.gluster.org/16309
Smoke: Gluster Build System 
Reviewed-by: Pranith Kumar Karampuri 
Tested-by: Pranith Kumar Karampuri 
NetBSD-regression: NetBSD Build System 
CentOS-regression: Gluster Build System

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: 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

cluster/afr: Don't let NFS cache stat after writes

2016-05-05T01:42:14+00:00

Problem:
Afr does post-ops after write but the stat buffer it unwinds is at the
time of write, so if nfs client caches this, it will see different
ctime when it does stat on it after post-op is done. From NFS client's
perspective it thinks the file is changed. Tar which depends on this
to be correct keeps giving 'file changed as we read it' warning.
If Afr instead has to choose to unwind after post-op, eager-lock,
delayed-post-op will have to be disabled which will lead to bad
performance for all write usecases.

Fix:
Don't let client cache stat after write.

Change-Id: Ic6062acc6e5cdd97a9c83c56bd529ec83cee8a23
BUG: 1302948
Signed-off-by: Pranith Kumar K 
Signed-off-by: Anuradha Talur 
Reviewed-on: http://review.gluster.org/13785
Smoke: Gluster Build System 
NetBSD-regression: NetBSD Build System 
CentOS-regression: Gluster Build System 
Reviewed-by: Niels de Vos

afr/index: changes for granular entry self-heal

2016-04-30T13:44:07+00:00

Implements new indices type ENTRY_CHANGES where other
xlators can add/delete names.

Change-Id: I01c5568997085e11d22ba36a4376c70b78fb3827
BUG: 1269461
Signed-off-by: Ravishankar N 
Reviewed-on: http://review.gluster.org/12482
Tested-by: Krutika Dhananjay 
Tested-by: Pranith Kumar Karampuri 
Smoke: Gluster Build System 
NetBSD-regression: NetBSD Build System 
CentOS-regression: Gluster Build System 
Reviewed-by: Pranith Kumar Karampuri

dht/afr/client/posix: Fail mkdir without gfid-req

2016-04-29T13:57:39+00:00

Do not allow directory creations without gfids as
after the directories are created, operations
on them fail anyway. So it is better to fail mkdir.

BUG: 1317361
Change-Id: I8f8e3b38bbded1960b7215bac0432500f7e78038
Signed-off-by: Pranith Kumar K 
Reviewed-on: http://review.gluster.org/13690
Smoke: Gluster Build System 
Reviewed-by: Krutika Dhananjay 
CentOS-regression: Gluster Build System 
NetBSD-regression: NetBSD Build System

cluster/afr: Fix read-child selection in entry create fop

2016-03-28T12:13:41+00:00

When an entry is being created the inode is yet to be linked
so args must be filled with gfid and ia_type for it to give
consistent iatt.

Also handle Dht sending fops on inode not yet linked.

BUG: 1302948
Change-Id: I6969cacb437cad02f66716f3bf8ec004ffe7c691
Signed-off-by: Pranith Kumar K 
Reviewed-on: http://review.gluster.org/13827
Reviewed-by: Krutika Dhananjay 
Smoke: Gluster Build System 
Reviewed-by: Anuradha Talur 
NetBSD-regression: NetBSD Build System 
CentOS-regression: Gluster Build System

afr: Add throttled background client-side heals

2016-03-01T11:23:20+00:00

If a heal is needed after inode refresh (lookup, read_txn), launch it in
the background instead of blocking the fop (that triggered refresh) until the
heal happens.

afr_replies_interpret() is modified such that the heal is
launched only if atleast one sink brick is up.

Max. no of heals that can happen in parallel is configurable via the
'background-self-heal-count' volume option. Any number greater than that
is put in a wait queue whose length is configurable via
'heal-wait-queue-leng' volume option. If the wait queue is also full,
further heals will be ignored.

Default values:  background-self-heal-count=8, heal-wait-queue-leng=128

Change-Id: I1d4a52814cdfd43d90591b6d2ad7b6219937ce70
BUG: 1297172
Signed-off-by: Ravishankar N 
Reviewed-on: http://review.gluster.org/13207
Smoke: Gluster Build System 
CentOS-regression: Gluster Build System 
Reviewed-by: Pranith Kumar Karampuri 
Tested-by: Pranith Kumar Karampuri 
NetBSD-regression: NetBSD Build System