Item7: cleanup flow after flush_to_disk doesn't remove all contents properly

Priority:	CurrentState:	AppliesTo:	Component:	WaitingFor:
Urgent	Being Worked On	SMR

-- SaurabhKadekodi - 17 Jan 2015

shingledfs: writeback_buffer.c:277: cleanup_flow: Assertion `flow->total_size = 0 && flow->total_blocks = 0' failed.

Program received signal SIGABRT, Aborted.
[Switching to Thread 0x7ffff69ad700 (LWP 3135)]
0x00007ffff73e9bb9 in GI_raise (sig=sig@entry=6) at ../nptl/sysdeps/unix/sysv/linux/raise.c:56
56 ../nptl/sysdeps/unix/sysv/linux/raise.c: No such file or directory.
(gdb) bt
#0 0x00007ffff73e9bb9 in __GI_raise (sig=sig@entry=6) at ../nptl/sysdeps/unix/sysv/linux/raise.c:56
#1 0x00007ffff73ecfc8 in __GI_abort () at abort.c:89
#2 0x00007ffff73e2a76 in __assert_fail_base (fmt=0x7ffff75342b0 "%s%s%s:%u: %s%sAssertion `%s' failed.\n%n", assertion=assertion@entry=0x425458 "flow->total_size = 0 && flow->total_blocks 0",
file=file@entry=0x425290 "writeback_buffer.c", line=line@entry=277, function=function@entry=0x425bb2 <__PRETTY_FUNCTION.7521> "cleanup_flow") at assert.c:92
#3 0x00007ffff73e2b22 in GI___assert_fail (assertion=0x425458 "flow->total_size 0 && flow->total_blocks = 0", file=0x425290 "writeback_buffer.c", line=277,
function=0x425bb2 <__PRETTY_FUNCTION.7521> "cleanup_flow") at assert.c:101
#4 0x000000000040627a in cleanup_flow (flow=0x7fffe80018f0) at writeback_buffer.c:277
#5 0x000000000040766e in flush_to_disk (wb=0x654ca0 <shingledfs_data+21664>, flow=0x7fffe80018f0) at writeback_buffer.c:421
#6 0x00000000004082b1 in insert_into_wb_extent (wb=0x654ca0 <shingledfs_data+21664>, path=0xcc9b80 "/mnt/btrfs/smr/unshingled/.aged_new_files/1232", buf=0x7fffe8f16000 "", offset=0, size=1048576,
inode_num=1233) at writeback_buffer.c:508
#7 0x0000000000407731 in insert_into_wb (wb=0x654ca0 <shingledfs_data+21664>, path=0xcc9b80 "/mnt/btrfs/smr/unshingled/.aged_new_files/1232", buf=0x7fffe8f16000 "", size=2097152, inode_num=1233)
at writeback_buffer.c:445
#8 0x0000000000413802 in bc_worker () at buffercache.c:1624
#9 0x00007ffff7781182 in start_thread (arg=0x7ffff69ad700) at pthread_create.c:312
#10 0x00007ffff74adefd in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:111