performance/write-behind: fix data corruption while aggregating the adjacent contiguous iobufs into a single iobuf

- while aggregating, we should make sure that the destination has enough
   memory. __wb_collapse_write_bufs assumed that destination vector's iov_base
   was aligned to the start of an iobuf and hence memory of page_size is
   available for aggregation. This assumption is not always true, like in the
   configuration consisting afr->write->io-cache (afr is on top). Refer to the
   bug url for more details.

Signed-off-by: Raghavendra G <raghavendra@gluster.com>
Signed-off-by: Anand V. Avati <avati@dev.gluster.com>

BUG: 542 (write-behind crashes)
URL: http://bugs.gluster.com/cgi-bin/bugzilla3/show_bug.cgi?id=542

0 files changed, 0 insertions, 0 deletions