glusterfs.git/xlators/mgmt/glusterd/src/glusterd.h, branch v3.7.0beta1

glusterd: Replace transaction peers lists

2015-04-13T06:30:02+00:00

Transaction peer lists were used in GlusterD to peers belonging to a
transaction. This was needed to prevent newly added peers performing
partial transactions, which could be incorrect.

This was accomplished by creating a seperate transaction peers list at
the beginning of every transaction. A transaction peers list referenced
the peerinfo data structures of the peers which were present at the
beginning of the transaction. RCU protection of peerinfos referenced by
the transaction peers list is a hard problem and difficult to do
correctly.

To have proper RCU protection of peerinfos, the transaction peers lists
have been replaced by an alternative method to identify peers that
belong to a transaction. The alternative method is to the global peers
list along with generation numbers to identify peers that should belong
to a transaction.

This change introduces a global peer list generation number, and a
generation number for each peerinfo object. Whenever a peerinfo object
is created, the global generation number is bumped, and the peerinfos
generation number is set to the bumped global generation.

With the above changes, the algorithm to identify peers belonging to a
transaction with RCU protection is as follows,
- At the beginning of a transaction, the current global generation
  number is saved
- To identify if a peers belonging to the transaction,
  - Start a RCU read critical section
  - For each peer in the global peers list,
    - If the peers generation number is not greater than the saved
      generation number, continue with the action on the peer
  - End the RCU read critical section

The above algorithm guarantees that,
- The peer list is not modified when a transaction is iterating through
  it
- The transaction actions are only done on peers that were present when
  the transaction started

But, as a transaction could iterate over the peers list multiple times,
the algorithm cannot guarantee that same set of peers will be selected
every time. A peer could get deleted between two iterations of the list
within a transaction. This problem existed with transaction peers list
as well, but unlike before now it will not lead to invalid memory access
and potential crashes. This problem will be addressed seprately.

This change was developed on the git branch at [1]. This commit is a
combination of the following commits on the development branch.
  52ded5b Add timespec_cmp
  44aedd8 Add create timestamp to peerinfo
  7bcbea5 Fix some silly mistakes
  13e3241 Add start time to opinfo
  17a6727 Use timestamp comparisions to identify xaction peers instead
          of a xaction peer list
  3be05b6 Correct check for peerinfo age
  70d5b58 Use read-critical sections for peer list iteration
  ba4dbca Use peerinfo timestamp checks in op-sm instead of xaction peer
          list
  d63f811 Add more peer status checks when iterating peers list in
          glusterd-syncop
  1998a2a Timestamp based peer list traversal of mgmtv3 xactions
  f3c1a42 Remove transaction peer lists
  b8b08ee Remove unused labels
  32e5f5b Remove 'npeers' usage
  a075fb7 Remove 'npeers' from mgmt-v3 framework
  12c9df2 Use generation number instead of timestamps.
  9723021 Remove timespec_cmp
  80ae2c6 Remove timespec.h include
  a9479b0 Address review comments on 10147/4

[1]: https://github.com/kshlm/glusterfs/tree/urcu

Change-Id: I9be1033525c0a89276f5b5d83dc2eb061918b97f
BUG: 1205186
Signed-off-by: Kaushal M 
Reviewed-on: http://review.gluster.org/10147
Tested-by: Gluster Build System 
Reviewed-by: Atin Mukherjee 
Reviewed-by: Anand Nekkunti 
Reviewed-by: Krishnan Parthasarathi 
Tested-by: Krishnan Parthasarathi

build: make contrib/uuid dependency optional

2015-04-10T11:39:52+00:00

On Linux systems we should use the libuuid from the distribution and not
bundle and statically link the contrib/uuid/ bits.

libglusterfs/src/compat-uuid.h has been introduced and should become an
abstraction layer for different UUID APIs. Non-Linux operating systems
should implement their compatibility layer there.

Once all operating systems have an implementation in compat-uuid.h, we
can remove contrib/uuid/ from the repository completely.

Change-Id: I345e5357644be2521685e00358bb8c83c4ea0577
BUG: 1206587
Signed-off-by: Niels de Vos 
Reviewed-on: http://review.gluster.org/10129
Tested-by: Gluster Build System 
Reviewed-by: Vijay Bellur

Avoid conflict between contrib/uuid and system uuid

2015-04-04T17:48:35+00:00

glusterfs relies on Linux uuid implementation, which
API is incompatible with most other systems's uuid. As
a result, libglusterfs has to embed contrib/uuid,
which is the Linux implementation, on non Linux systems.
This implementation is incompatible with systtem's
built in, but the symbols have the same names.

Usually this is not a problem because when we link
with -lglusterfs, libc's symbols are trumped. However
there is a problem when a program not linked with
-lglusterfs will dlopen() glusterfs component. In
such a case, libc's uuid implementation is already
loaded in the calling program, and it will be used
instead of libglusterfs's implementation, causing
crashes.

A possible workaround is to use pre-load libglusterfs
in the calling program (using LD_PRELOAD on NetBSD for
instance), but such a mechanism is not portable, nor
is it flexible. A much better approach is to rename
libglusterfs's uuid_* functions to gf_uuid_* to avoid
any possible conflict. This is what this change attempts.

BUG: 1206587
Change-Id: I9ccd3e13afed1c7fc18508e92c7beb0f5d49f31a
Signed-off-by: Emmanuel Dreyfus 
Reviewed-on: http://review.gluster.org/10017
Tested-by: Gluster Build System 
Reviewed-by: Niels de Vos

glusterd: clean up global xaction_peer occurances

2015-03-27T04:00:11+00:00

Remove xaction_peers from glusterd_conf_t which was left out by
http://review.gluster.org/#/c/9980/ patch

Change-Id: I8494ec181ec11922861d7bad12c46d45e036637b
BUG: 1204727
Signed-off-by: anand 
Reviewed-on: http://review.gluster.org/10006
Reviewed-by: Atin Mukherjee 
Tested-by: Gluster Build System 
Reviewed-by: Krishnan Parthasarathi 
Tested-by: Krishnan Parthasarathi

cli/glusterd: CLI interface for BitRot detection

2015-03-24T17:26:15+00:00

* BitRot enable/disable CLI per volume
* Volfile generation for Scrubber
* Relevant glusterd infrastructure

Change-Id: I1212af63f93ecc52b22ee6da920e1664f66a1e39
BUG: 1170075
Original-Author: Raghavendra Bhat 
Original-Author: Venky Shankar 
Original-Author: Gaurav Kumar Garg 
Original-Author: Anand Nekkunti 
Reviewed-on: http://review.gluster.org/9986
Tested-by: Gluster Build System 
Reviewed-by: Vijay Bellur

mgmt/glusterd: generate volfile for BitD

2015-03-24T14:56:32+00:00

* Implement the skeleton of bit-rot xlator.

Original-Author: Raghavendra Bhat 
Signed-off-by: Venky Shankar 
Signed-off-by: Gaurav Kumar Garg 
Signed-off-by: Anand Nekkunti 
Change-Id: If33218bdc694f5f09cb7b8097c4fdb74d7a23b2d
BUG: 1170075
Reviewed-on: http://review.gluster.org/9710
Reviewed-by: Vijay Bellur 
Tested-by: Vijay Bellur

afr: arbiter xlator

2015-03-19T17:45:49+00:00

This patch adds the arbiter translator into the tree. This is a server
side xlator used for replica 3 volumes. It sits above posix and will be
loaded on the 3rd (last) brick of every afr subvolume in a replica 3
configuration. It intercepts inode read/write operations: reads are
unwound with ENOTCONN, inode writes are unwound with success without
actually passing them down to posix. Metadata operations are allowed to
pass through.

The CLI for creating a 3 way replica with arbiter is also added but kept
disabled (A 'normal' 3 way replica is created instead).

This patch is a part of the arbiter logic implementation for 3 way AFR,
details of which can be found at http://review.gluster.org/#/c/9656/

Change-Id: I395b81f49d5da52c466daf5c8518f1bbad9c16fa
BUG: 1199985
Signed-off-by: Ravishankar N 
Reviewed-on: http://review.gluster.org/9840
Tested-by: Gluster Build System 
Reviewed-by: Pranith Kumar Karampuri 
Reviewed-by: Vijay Bellur

glusterd: CLI commands to create and manage tiered volumes.

2015-03-19T13:32:28+00:00

A tiered volume is a normal volume with some number of new bricks
representing "hot" storage. The "hot" bricks can be attached or
detached dynamically to a normal volume. When this happens, a new graph
is constructed. The root of the new graph is an instance of the tier
translator. One subvolume of the tier translator leads to the old volume,
and another leads to the new hot bricks.

attach-tier  [ ]  ... [force]

volume detach-tier  [replica ] 
... 

gluster volume rebalance  tier start

gluster volume rebalance  tier stop

gluster volume rebalance  tier status

The "tier start" CLI command starts a server side daemon. The daemon
initiates file level migration based on caching policies. The daemon's
status can be monitored and stopped.

Note development on the "tier status" command is incomplete. It will be
added in a subsequent patch.

When the "hot" storage is detached, the tier translator is removed
from the graph and the tiered volume reverts to its original state as
described in the volume's info file.

For more background and design see the feature page [1].

[1]
http://www.gluster.org/community/documentation/index.php/Features/data-classification

Change-Id: Ic8042ce37327b850b9e199236e5be3dae95d2472
BUG: 1194753
Signed-off-by: Dan Lambright 
Reviewed-on: http://review.gluster.org/9753
Reviewed-by: Vijay Bellur 
Tested-by: Vijay Bellur

Adding ChangeTimeRecorder(CTR) Xlator to GlusterFS

2015-03-19T08:31:29+00:00

**********************************************************************
                            ChangeTimeRecorder(CTR) Xlator           |
**********************************************************************
ChangeTimeRecorder(CTR) is server side xlator(translator) which sits
just above posix xlator. The main role of this xlator is to record the
access/write patterns on a file residing the brick. It records the
read(only data) and write(data and metadata) times and also count on
how many times a file is read or written. This xlator also captures
the hard links to a file(as its required by data tiering to move
files).

CTR Xlator is the consumer of libgfdb.

To Enable/Disable CTR Xlator:
~~~~~~~~~~~~~~~~~~~~~~~~~~~~

 gluster volume set  features.ctr-enabled {on/off}

To Enable/Disable Frequency Counter Recording in CTR Xlator:
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

 gluster volume set  features.record-counters {on/off}

Change-Id: I5d3cf056af61ac8e3f8250321a27cb240a214ac2
BUG: 1194753
Signed-off-by: Joseph Fernandes 
Reviewed-on: http://review.gluster.org/9935
Tested-by: Gluster Build System 
Reviewed-by: Vijay Bellur

cli/glusterd: cli command implementation for bitrot features

2015-03-19T01:34:07+00:00

CLI command for bitrot features.

volume bitrot  enable|disable

Above command will enable/disable bitrot feature for particular volume.

BUG: 1170075
Change-Id: Ie84002ef7f479a285688fdae99c7afa3e91b8b99
Signed-off-by: Gaurav Kumar Garg     
Signed-off-by: Anand nekkunti        
Signed-off-by: Dominic P Geevarghese 
Reviewed-on: http://review.gluster.org/9866
Tested-by: Gluster Build System 
Reviewed-by: Vijay Bellur