Description of problem:

A large read of 128MB in a single glfs_preadv_async() call with one iovec count causes segfault when io-cache translator is ON. When io-cache is turned off, the same read succeeds.

(gdb) 
80		ret = glfs_preadv_async(fd, &iovr, 1, 0, 0, read_completion_fn, (void *)&iovr);
(gdb) p iovr
$1 = {iov_base = 0x7fffef6fe010, iov_len = 134217728}
(gdb) c
Continuing.

Program received signal SIGSEGV, Segmentation fault.
[Switching to Thread 0x7fffee23b700 (LWP 18639)]
0x00000032a1b462d6 in __memcpy_ssse3_back () from /lib64/libc.so.6
(gdb) bt
#0  0x00000032a1b462d6 in __memcpy_ssse3_back () from /lib64/libc.so.6
#1  0x00007ffff7df060d in iov_copy (dst=0x62f260, dcnt=1, src=0x7fffe805da70, scnt=1024) at ../../libglusterfs/src/common-utils.h:384
#2  0x00007ffff7df1a14 in glfs_preadv (glfd=0x62f440, iovec=0x62f260, iovcnt=1, offset=0, flags=0) at glfs-fops.c:494
#3  0x00007ffff7df1c92 in glfs_io_async_task (data=0x62f280) at glfs-fops.c:591
#4  0x00007ffff775bebb in synctask_wrap (old_task=0x6301a0) at syncop.c:131
#5  0x00000032a1a46370 in ?? () from /lib64/libc.so.6
#6  0x0000000000000000 in ?? ()

Version-Release number of selected component (if applicable):

3.4