=============================================
[ INFO: possible recursive locking detected ]
4.8.0-0.rc4.git3.1.fc26.x86_64 #1 Not tainted
---------------------------------------------
vi/2961 is trying to acquire lock:
 (&ei->log_mutex){+.+...}, at: [<ffffffffc066b1d2>] btrfs_log_inode+0x162/0x1190 [btrfs]

                                         but task is already holding lock:
 (&ei->log_mutex){+.+...}, at: [<ffffffffc066b1d2>] btrfs_log_inode+0x162/0x1190 [btrfs]

                                         other info that might help us debug this:
 Possible unsafe locking scenario:
       CPU0
       ----
  lock(&ei->log_mutex);
  lock(&ei->log_mutex);

                                          *** DEADLOCK ***
 May be due to missing lock nesting notation
3 locks held by vi/2961:
 #0:  (&sb->s_type->i_mutex_key#12){+.+.+.}, at: [<ffffffffc0639923>] btrfs_sync_file+0x163/0x4c0 [btrfs]
 #1:  (sb_internal){.+.+.+}, at: [<ffffffffb62a76a4>] __sb_start_write+0xb4/0xf0
 #2:  (&ei->log_mutex){+.+...}, at: [<ffffffffc066b1d2>] btrfs_log_inode+0x162/0x1190 [btrfs]

                                         stack backtrace:
CPU: 2 PID: 2961 Comm: vi Not tainted 4.8.0-0.rc4.git3.1.fc26.x86_64 #1
Hardware name: System manufacturer System Product Name/P8H77-M PRO, BIOS 9002 05/30/2014
 0000000000000086 000000009ba21fe8 ffff8e7d7606b840 ffffffffb6468ba3
 ffffffffb7bdeb30 ffff8e7e72090000 ffff8e7d7606b908 ffffffffb610f65e
 0000000072090d50 ffffffff00000003 000000005cb9cb9e ffffffffb7509b00
Call Trace:
 [<ffffffffb6468ba3>] dump_stack+0x86/0xc3
 [<ffffffffb610f65e>] __lock_acquire+0x78e/0x1290
 [<ffffffffb6037f29>] ? sched_clock+0x9/0x10
 [<ffffffffb60eaa67>] ? sched_clock_cpu+0xa7/0xc0
 [<ffffffffb68f77ce>] ? mutex_unlock+0xe/0x10
 [<ffffffffb61105c6>] lock_acquire+0xf6/0x1f0
 [<ffffffffc066b1d2>] ? btrfs_log_inode+0x162/0x1190 [btrfs]
 [<ffffffffb68f6b56>] mutex_lock_nested+0x86/0x3f0
 [<ffffffffc066b1d2>] ? btrfs_log_inode+0x162/0x1190 [btrfs]
 [<ffffffffb68f77ce>] ? mutex_unlock+0xe/0x10
 [<ffffffffc066b1d2>] ? btrfs_log_inode+0x162/0x1190 [btrfs]
 [<ffffffffc066b1d2>] btrfs_log_inode+0x162/0x1190 [btrfs]
 [<ffffffffb60def29>] ? __might_sleep+0x49/0x80
 [<ffffffffc066bd8b>] btrfs_log_inode+0xd1b/0x1190 [btrfs]
 [<ffffffffb6037f29>] ? sched_clock+0x9/0x10
 [<ffffffffc066c4d0>] btrfs_log_inode_parent+0x240/0x940 [btrfs]
 [<ffffffffb62c0fb9>] ? dget_parent+0x99/0x2a0
 [<ffffffffc066db92>] btrfs_log_dentry_safe+0x62/0x80 [btrfs]
 [<ffffffffc0639ad1>] btrfs_sync_file+0x311/0x4c0 [btrfs]
 [<ffffffffb62e200b>] vfs_fsync_range+0x4b/0xb0
 [<ffffffffb610eab5>] ? trace_hardirqs_on_caller+0xf5/0x1b0
 [<ffffffffb62e20cd>] do_fsync+0x3d/0x70
 [<ffffffffb62e2390>] SyS_fsync+0x10/0x20
 [<ffffffffb68fadfc>] entry_SYSCALL_64_fastpath+0x1f/0xbd