glusterfs.git/xlators/performance, branch v3.5.1beta

write-behind: track filesize when doing extending writes

2014-05-09T14:33:39+00:00

A program that calls mmap() on a newly created sparse file, may receive
a SIGBUS signal. If SIGBUS is not handled, a segmentation fault will
occur and the program will exit.

A bug in the write-behind translator can cause the creation of a sparse
file created with open(), seek(), write() to be cached. The last write()
may not be sent to the server, until write-behind deems this necessary.

* open(.., O_TRUNC, ...)/creat() the file, it is 0 bytes big
* seek() into the file, use offset 31
* write() 1 byte to the file
* the range from byte 0-30 are unwritten so called 'sparse'

The following illustration tries to capture this:

    Legend:
    [ = start of file
    _ = unallocated/unwritten bytes
    # = allocated bytes in the file
    ] = end of file

    [_______________#]
     |              |
     '- byte 0      '- byte 31

Without this change, reading from byte 0-30 will return an error, and
reading the same area through an mmap()'d pointer will trigger a SIGBUS.
Reading from this range did not trigger the outstanding write() to be
flushed. The brick that receives the read() (translated over the network
from mmap()) does not know that the file has been extended, and returns
-EINVAL. This error gets transported back from the brick to the
glusterfs-fuse client, and translated by the Linux kernel/VFS into
SIGBUS triggered by mmap().

In order to solve this, a new attribute to the wb_inode structure is
introduced; the current size of the file. All FOPs that can modify the
size, are expected to update wb_inode->size. This makes it possible for
extending writes with an offset bigger than EOF to mark the unwritten
area as modified/pending.

Cherry picked from commit b0515e2a4a08b657ef7e9715fb8c6222c700e78c:
> Change-Id: If5ba6646732e6be26568541ea9b12852a5d0b988
> BUG: 1058663
> Signed-off-by: Niels de Vos 
> Reviewed-on: http://review.gluster.org/6835
> Tested-by: Gluster Build System 
> Reviewed-by: Raghavendra G 
> Reviewed-by: Anand Avati 

Change-Id: Ic73288202c6cb37d8c066628e9c489c6fade49bd
BUG: 1071191
Signed-off-by: Niels de Vos 
Reviewed-on: http://review.gluster.org/7166
Tested-by: Gluster Build System

build: do not create versioned .so files

2014-05-05T13:35:38+00:00

There has been a misspelled option in the Makefile.am files. The option
is called -avoid-version, and not -avoidversion.

It is not trivial to provide a test-case for this. One way would be to
check generated RPMs with a command like this (output should be empty):

  $ rpm -qlp *.rpm | grep -E '/xlator/.+.so.0'

Change-Id: Ie1519455c9f9366feee0d3cafcc384b9eff57776
Reviewed-on-master: http://review.gluster.org/7299
BUG: 1078365
Signed-off-by: Niels de Vos 
Reviewed-on: http://review.gluster.org/7301
Reviewed-by: Lalatendu Mohanty 
Tested-by: Gluster Build System 
Reviewed-by: Kaleb KEITHLEY

performance/io-cache: reduce the severity of log-message

2014-01-28T16:44:34+00:00

During a genuine error condition like network outage, the log grows
with redundant information.

Change-Id: I5a4f2f62da10ef656f14200c4c84a6917b1f0ddd
Signed-off-by: Raghavendra G 
BUG: 1048084
Reviewed-on: http://review.gluster.org/6635
Reviewed-by: Pranith Kumar Karampuri 
Tested-by: Gluster Build System 
Reviewed-by: Vijay Bellur 
Reviewed-on: http://review.gluster.org/6815

write-behind: handle iobref_merge() error gracefully

2013-11-26T18:32:00+00:00

.. by UNWINDing ENOMEM error, rather than crashing.

Change-Id: Ica2d6399eaf7e381e7ebc41155620559c139c4d3
BUG: 1034398
Signed-off-by: Anand Avati 
Reviewed-on: http://review.gluster.org/6349
Tested-by: Gluster Build System 
Reviewed-by: Amar Tumballi

io-cache: handle iobref_merge() error gracefully

2013-11-26T18:31:48+00:00

.. by UNWINDing ENOMEM, rather than leaving pointer in vector pointing
to stale memory.

Change-Id: I7f3917ac056fae144f845c9d123233e91e278187
BUG: 1034398
Signed-off-by: Anand Avati 
Reviewed-on: http://review.gluster.org/6351
Tested-by: Gluster Build System 
Reviewed-by: Amar Tumballi

read-ahead: handle iobref_merge() error gracefully

2013-11-26T18:31:40+00:00

.. by UNWINDing ENOMEM rather than leaving pointers in vector which
points to unref'ed (or even worse, re-used) iobufs.

Change-Id: I849d8cbe5fc02ee992d4e28b7212c49aad4925c7
BUG: 1034398
Signed-off-by: Anand Avati 
Reviewed-on: http://review.gluster.org/6350
Tested-by: Gluster Build System 
Reviewed-by: Amar Tumballi

zerofill: Change the type of len argument of glfs_zerofill() to off_t

2013-11-15T07:29:48+00:00

glfs_zerofill() can be potentially called to zero-out entire file and
hence allow for bigger value of length parameter.

Change-Id: I75f1d11af298915049a3f3a7cb3890a2d72fca63
BUG: 1028673
Signed-off-by: Bharata B Rao 
Reviewed-on: http://review.gluster.org/6266
Tested-by: Gluster Build System 
Reviewed-by: M. Mohan Kumar 
Tested-by: M. Mohan Kumar 
Reviewed-by: Anand Avati

libglusterfs/inode: introduce new APIs for ctx handling

2013-11-13T19:43:48+00:00

* inode_ctx_reset{0,1,2}() for reseting value1, value2, and both respectively
* inode_ctx_get0() - to get the first value only
* inode_ctx_set0() - to set the first value only
* inode_ctx_get1() - to get the second value only
* inode_ctx_set1() - to set the second value only

Change-Id: I4dfbdac81d6a3f4e5784e060c76edabb1692ce03
Signed-off-by: Amar Tumballi 
Reviewed-on: http://review.gluster.org/5890
Reviewed-by: Anand Avati 
Tested-by: Anand Avati

glusterfs: zerofill support

2013-11-11T05:25:49+00:00

Add support for a new ZEROFILL fop. Zerofill writes zeroes to a file in
the specified range. This fop will be useful when a whole file needs to
be initialized with zero (could be useful for zero filled VM disk image
provisioning or  during scrubbing of VM disk images).

Client/application can issue this FOP for zeroing out. Gluster server
will zero out required range of bytes ie server offloaded zeroing. In
the absence of this fop,  client/application has to repetitively issue
write (zero) fop to the server, which is very inefficient method because
of the overheads involved in RPC calls  and acknowledgements.

WRITESAME is a  SCSI T10 command that takes a block of data as input and
writes the same data to other blocks and this write is handled
completely within the storage and hence is known as offload . Linux ,now
has support for SCSI WRITESAME command which is exposed to the user in
the form of BLKZEROOUT ioctl.  BD Xlator can exploit BLKZEROOUT ioctl to
implement this fop. Thus zeroing out operations can be completely
offloaded to the storage device , making it highly efficient.

The fop takes two arguments offset and size. It zeroes out 'size' number
of bytes in an opened file starting from 'offset' position.

This patch adds zerofill support to the following areas:
	- libglusterfs
	- io-stats
	- performance/md-cache,open-behind
	- quota
	- cluster/afr,dht,stripe
	- rpc/xdr
	- protocol/client,server
	- io-threads
	- marker
	- storage/posix
	- libgfapi

Client applications can exloit this fop by using glfs_zerofill introduced in
libgfapi.FUSE support to this fop has not been added as there is no system call
for this fop.

Changes from previous version 3:
* Removed redundant memory failure log messages

Changes from previous version 2:
* Rebased and fixed build error

Changes from previous version 1:
* Rebased for latest master

TODO :
     * Add zerofill support to trace xlator
     * Expose zerofill capability as part of gluster volume info

Here is a performance comparison of server offloaded zeofill vs zeroing
out using repeated writes.

[root@llmvm02 remote]# time ./offloaded aakash-test log 20

real	3m34.155s
user	0m0.018s
sys	0m0.040s
[root@llmvm02 remote]# time ./manually aakash-test log 20

real	4m23.043s
user	0m2.197s
sys	0m14.457s
[root@llmvm02 remote]# time ./offloaded aakash-test log 25;

real	4m28.363s
user	0m0.021s
sys	0m0.025s
[root@llmvm02 remote]# time ./manually aakash-test log 25

real	5m34.278s
user	0m2.957s
sys	0m18.808s

The argument log is a file which we want to set for logging purpose and
the third argument is size in GB .

As we can see there is a performance improvement of around 20% with this
fop.

Change-Id: I081159f5f7edde0ddb78169fb4c21c776ec91a18
BUG: 1028673
Signed-off-by: Aakash Lal Das 
Signed-off-by: M. Mohan Kumar 
Reviewed-on: http://review.gluster.org/5327
Tested-by: Gluster Build System 
Reviewed-by: Vijay Bellur

gNFS: Incorrect NFS ACL encoding for XFS

2013-09-29T23:54:37+00:00

Problem:
Incorrect NFS ACL encoding causes "system.posix_acl_default"
setxattr failure on bricks on XFS file system. XFS (potentially
others?) doesn't understand when the 0x10 prefix is added to the
ACL type field for default ACLs (which the Linux NFS client adds)
which causes setfacl()->setxattr() to fail silently. NFS client
adds NFS_ACL_DEFAULT(0x1000) for default ACL.

FIX:
Mask the prefix (added by NFS client) OFF, so the setfacl is not
rejected when it hits the FS.

Original patch by: "Richard Wareing"

Change-Id: I17ad27d84f030cdea8396eb667ee031f0d41b396
BUG: 1009210
Signed-off-by: Santosh Kumar Pradhan 
Reviewed-on: http://review.gluster.org/5980
Reviewed-by: Amar Tumballi 
Tested-by: Gluster Build System 
Reviewed-by: Anand Avati