[Gluster-devel] GlusterFS FUSE client hangs on rsyncing lots of file

[Oleksandr Natalenko]

While doing rsync over millions of files from ordinary partition to 
GlusterFS volume, just after approx. first 2 million rsync hang happens, 
and the following info appears in dmesg:

===
[17075038.924481] INFO: task rsync:10310 blocked for more than 120 
seconds.
[17075038.931948] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" 
disables this message.
[17075038.940748] rsync           D ffff88207fc13680     0 10310  10309 
0x00000080
[17075038.940752]  ffff8809c578be18 0000000000000086 ffff8809c578bfd8 
0000000000013680
[17075038.940756]  ffff8809c578bfd8 0000000000013680 ffff880310cbe660 
ffff881159d16a30
[17075038.940759]  ffff881e3aa25800 ffff8809c578be48 ffff881159d16b10 
ffff88087d553980
[17075038.940762] Call Trace:
[17075038.940770]  [<ffffffff8160a1d9>] schedule+0x29/0x70
[17075038.940797]  [<ffffffffa023a53d>] __fuse_request_send+0x13d/0x2c0 
[fuse]
[17075038.940801]  [<ffffffffa023db30>] ? 
fuse_get_req_nofail_nopages+0xc0/0x1e0 [fuse]
[17075038.940805]  [<ffffffff81098350>] ? wake_up_bit+0x30/0x30
[17075038.940809]  [<ffffffffa023a6d2>] fuse_request_send+0x12/0x20 
[fuse]
[17075038.940813]  [<ffffffffa024382f>] fuse_flush+0xff/0x150 [fuse]
[17075038.940817]  [<ffffffff811c45c4>] filp_close+0x34/0x80
[17075038.940821]  [<ffffffff811e4ed8>] __close_fd+0x78/0xa0
[17075038.940824]  [<ffffffff811c6103>] SyS_close+0x23/0x50
[17075038.940828]  [<ffffffff81614de9>] system_call_fastpath+0x16/0x1b
===

rsync blocks in D state, and to kill it, I have to do umount --lazy on 
GlusterFS mountpoint, and then kill corresponding client glusterfs 
process. Then rsync exits.

Here is GlusterFS volume info:

===
Volume Name: asterisk_records
Type: Distributed-Replicate
Volume ID: dc1fe561-fa3a-4f2e-8330-ec7e52c75ba4
Status: Started
Number of Bricks: 3 x 2 = 6
Transport-type: tcp
Bricks:
Brick1: 
server1:/bricks/10_megaraid_0_3_9_x_0_4_3_hdd_r1_nolvm_hdd_storage_01/asterisk/records
Brick2: 
server2:/bricks/10_megaraid_8_5_14_x_8_6_16_hdd_r1_nolvm_hdd_storage_01/asterisk/records
Brick3: 
server1:/bricks/11_megaraid_0_5_4_x_0_6_5_hdd_r1_nolvm_hdd_storage_02/asterisk/records
Brick4: 
server2:/bricks/11_megaraid_8_7_15_x_8_8_20_hdd_r1_nolvm_hdd_storage_02/asterisk/records
Brick5: 
server1:/bricks/12_megaraid_0_7_6_x_0_13_14_hdd_r1_nolvm_hdd_storage_03/asterisk/records
Brick6: 
server2:/bricks/12_megaraid_8_9_19_x_8_13_24_hdd_r1_nolvm_hdd_storage_03/asterisk/records
Options Reconfigured:
cluster.lookup-optimize: on
cluster.readdir-optimize: on
client.event-threads: 2
network.inode-lru-limit: 4096
server.event-threads: 4
performance.client-io-threads: on
storage.linux-aio: on
performance.write-behind-window-size: 4194304
performance.stat-prefetch: on
performance.quick-read: on
performance.read-ahead: on
performance.flush-behind: on
performance.write-behind: on
performance.io-thread-count: 2
performance.cache-max-file-size: 1048576
performance.cache-size: 33554432
features.cache-invalidation: on
performance.readdir-ahead: on
===

The issue reproduces each time I rsync such an amount of files.

How could I debug this issue better?