glfs_io_async_cbk is called with a NULL iovec from several places but this patch tests iovec for validity:

  GF_VALIDATE_OR_GOTO ("gfapi", iovec, inval);

This causes the glfs_io_async_cbk calls from glfs_pwritev_async_cbk, glfs_fsync_async_cbk, glfs_ftruncate_async_cbk, glfs_discard_async_cbk, and glfs_zerofill_async_cbk to fail with invalid iovec.

Further, the return code from glfs_io_async_cbk is never checked so the memory that would normally have been freed in that function is not, resulting in a memory leak.

+++ This bug was initially created as a clone of Bug #1333266 +++

REVIEW: http://review.gluster.org/14221 (gfapi: Fix a deadlock caused by graph switch while aio in progress) posted (#1) for review on release-3.8 by Poornima G (pgurusid)

--- Additional comment from Vijay Bellur on 2016-05-06 10:23:54 EDT ---

COMMIT: http://review.gluster.org/14221 committed in release-3.8 by Niels de Vos (ndevos) 
------
commit 938dfb9d021db20dc3b511b78ec8c137b8ff3e7c
Author: Poornima G <pgurusid>
Date:   Fri Apr 29 12:24:24 2016 -0400

    gfapi: Fix a deadlock caused by graph switch while aio in progress
    
    RCA:
    Currently async nature is achieved by submitting a syncop operation to
    synctask threads. Consider a scenario where the graph switch is triggered,
    the next write fop checks for the next available graph and sets
    fs->migration_in_progess and triggers the migration of fds and other
    things, which can cause some syncop_lookup operation. While this fop (on
    synctask thread) is waiting for syncop_lookup to return, lets say there
    are another 17 write async calls submitted, all these writes are blocked
    waiting for fs->migration_in_progress to be unset, hence all the 16
    synctask threads are blocked waiting for fs->migration_in_progress to be
    unset. Now the syncop_lookup returns, but there are no synctask threads to
    process the lookup_cbk. If this syncop_lookup doesn't return,
    then fs->migration_in_progress can not be unset by the first fop.
    Thus causing a deadlock.
    
    To fix this deadlock, changing all the async APIs to use STACK_WIND,
    instead of syntask to achieve async nature. glfs_preadv_async is already
    implemented using STACK_WIND, now changing all the other async APIs
    also to do the same.
    
    This patch as such will not reduce the performance of async IO, the only
    thing that can affect is that, in case of write, the buf passed by
    application is copied onto iobuf in the same thread wheras before it
    was being copied in synctask thread.
    
    Since, the syncop + graph switch logic (lock across fops) is not a good
    candidate for synctask, changing the async APIs to use STACK_WIND
    
    Backport of http://review.gluster.org/#/c/14148/
    
    Change-Id: Idf665cae0a8e27697fbfc5ec8d93a6d6bae3a4f1
    BUG: 1333266
    Signed-off-by: Poornima G <pgurusid>
    Reviewed-on: http://review.gluster.org/14221
    Smoke: Gluster Build System <jenkins.com>
    NetBSD-regression: NetBSD Build System <jenkins.org>
    CentOS-regression: Gluster Build System <jenkins.com>
    Reviewed-by: Raghavendra Talur <rtalur>
    Reviewed-by: Rajesh Joseph <rjoseph>
    Reviewed-by: Niels de Vos <ndevos>

--- Additional comment from Niels de Vos on 2016-06-16 10:05:31 EDT ---

This bug is getting closed because a release has been made available that should address the reported issue. In case the problem is still not fixed with glusterfs-3.8.0, please open a new bug report.

glusterfs-3.8.0 has been announced on the Gluster mailinglists [1], packages for several distributions should become available in the near future. Keep an eye on the Gluster Users mailinglist [2] and the update infrastructure for your distribution.

[1] http://blog.gluster.org/2016/06/glusterfs-3-8-released/
[2] http://thread.gmane.org/gmane.comp.file-systems.gluster.user