1. Create a file in the zfs file system
2. Checksum the file for later comparison
3. Create a snapshot of the dataset
4. Append to the original file
5. Verify the snapshot and file agree

all these are done successfully but after that it goes in deadlock state.

ZFS: Loaded ZFS Filesystem v0.4.7
sda: sda1 sda9
sda: sda1 sda9
checking : this : super_block magic no : 2fc12fc1
checking : this : super_block magic no : 2fc12fc1
INFO: task zfs:1963 blocked for more than 120 seconds.
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
zfs D ffff88000714aa80 0 1963 1945 0x00000080
ffff880000113ca8 0000000000000086 ffff880000113c18 ffff880004107380
0000000000000000 ffff880000113ca0 ffff8800040d0ce8 ffff880011423c40
ffff8800039a83c8 000000000000f8e0 ffff8800039a83c8 0000000000015600
Call Trace:
[] ? mutex_lock+0x27/0x4e
[] __down_write_nested+0x93/0xab
[] __down_write+0xb/0xd
[] down_write+0x2f/0x33
[] dsl_dataset_make_exclusive+0x29/0x35 [zfs]
[] dsl_dataset_destroy+0x43/0x3bd [zfs]
[] ? zil_destroy+0x2d/0x141 [zfs]
[] dmu_objset_destroy+0x4c/0x69 [zfs]
[] ? spa_open+0x10/0x12 [zfs]
[] zfs_ioc_destroy+0x14/0x16 [zfs]
[] zfs_ioctl+0x125/0x177 [zfs]
[] vfs_ioctl+0x22/0x87
[] ? tlb_finish_mmu+0x26/0x42
[] do_vfs_ioctl+0x47b/0x4c1
[] sys_ioctl+0x56/0x79
[] system_call_fastpath+0x16/0x1b