Bug 1470220

Description of problem:

When an error occurs on nodes, it is possible that an error unwinding function is called instead of the fuse_release function. In this case, the current state of the code will leak a 88 bytes ctx structure.

Version-Release number of selected component (if applicable):
3.10.3

How reproducible:
100%

Steps to Reproduce:
1.Setup a 3 nodes replicaset (2 nodes might be enough)
2.Write the same file over and over again on one node
3.Try to read that same file over and over again on a second node.

Actual results:
==19736== Thread 1:
==19736== 88 bytes in 1 blocks are definitely lost in loss record 257 of 591
==19736==    at 0x4C277BB: calloc (vg_replace_malloc.c:593)
==19736==    by 0x4E90C31: __gf_calloc (mem-pool.c:117)
==19736==    by 0xD56373D: __fuse_fd_ctx_check_n_create (fuse-bridge.c:79)
==19736==    by 0xD56381E: fuse_fd_ctx_check_n_create (fuse-bridge.c:108)
==19736==    by 0xD56F473: fuse_open_resume (fuse-bridge.c:2148)
==19736==    by 0xD564CE9: fuse_fop_resume (fuse-bridge.c:556)
==19736==    by 0xD562803: fuse_resolve_done (fuse-resolve.c:663)
==19736==    by 0xD5628D9: fuse_resolve_all (fuse-resolve.c:690)
==19736==    by 0xD5627E4: fuse_resolve (fuse-resolve.c:654)
==19736==    by 0xD5628B0: fuse_resolve_all (fuse-resolve.c:686)
==19736==    by 0xD562937: fuse_resolve_continue (fuse-resolve.c:706)
==19736==    by 0xD561CDE: fuse_resolve_inode (fuse-resolve.c:364)
==19736==    by 0xD5627D6: fuse_resolve (fuse-resolve.c:651)
==19736==    by 0xD56285B: fuse_resolve_all (fuse-resolve.c:679)
==19736==    by 0xD562975: fuse_resolve_and_resume (fuse-resolve.c:718)
==19736==    by 0xD56FAF8: fuse_open (fuse-bridge.c:2185)
==19736==    by 0xD57DA2A: fuse_thread_proc (fuse-bridge.c:5068)
==19736==    by 0x5C32AA0: start_thread (pthread_create.c:301)
==19736==    by 0x1633C6FF: ???

Expected results:
no leaks

Additional info:
on our production environment, this happens often enough that we must restart the gluster process every 2-3 months to avoid OOM