I have a FreeNAS (9.10-STABLE-201605240427 ) server, and several CentOS 6.4 boxes. However, the CentOS boxes seem unable to write to a FreeNAS mount any file that's larger 4KB, regardless of whether they're mounted using CIFS or NFS (3 and 4).For some odd reason, whenever you I try to write a file larger than 4KB (the page size), there appears to be some kind of deadlock. Here's an excerpt of the NFS debug log from a CentOS machine, when I try to copy /bin/ls into the mount. Sep  2 22:13:20 RAX-NERVE kernel: NFS: nfs_update_inode(0:17/4 fh_crc=0x2877d5c3 ct=2 info=0x227e7f)Sep  2 22:13:20 RAX-NERVE kernel: NFS: permission(0:17/4), mask=0x1, res=0Sep  2 22:13:20 RAX-NERVE kernel: NFS: atomic_lookup(0:17/4), lsSep  2 22:13:20 RAX-NERVE kernel: NFS: lookup(/ls)Sep  2 22:13:20 RAX-NERVE kernel: NFS call  lookup lsSep  2 22:13:20 RAX-NERVE kernel: encode_compound: tag=Sep  2 22:13:20 RAX-NERVE kernel: decode_attr_type: type=0100000Sep  2 22:13:20 RAX-NERVE kernel: decode_attr_change: change attribute=8013396Sep  2 22:13:20 RAX-NERVE kernel: decode_attr_size: file size=0Sep  2 22:13:20 RAX-NERVE kernel: decode_attr_fsid: fsid=(0x76431d7a/0x9cf9cdde)Sep  2 22:13:20 RAX-NERVE kernel: decode_attr_fileid: fileid=41Sep  2 22:13:20 RAX-NERVE kernel: decode_attr_fs_locations: fs_locations done, error = 0Sep  2 22:13:20 RAX-NERVE kernel: decode_attr_mode: file mode=0775Sep  2 22:13:20 RAX-NERVE kernel: decode_attr_nlink: nlink=1Sep  2 22:13:20 RAX-NERVE kernel: decode_attr_owner: uid=99Sep  2 22:13:20 RAX-NERVE kernel: decode_attr_group: gid=99Sep  2 22:13:20 RAX-NERVE kernel: decode_attr_rdev: rdev=(0x3:0xc7)Sep  2 22:13:20 RAX-NERVE kernel: decode_attr_space_used: space used=512Sep  2 22:13:20 RAX-NERVE kernel: decode_attr_time_access: atime=502412Sep  2 22:13:20 RAX-NERVE kernel: decode_attr_time_metadata: ctime=1472850295Sep  2 22:13:20 RAX-NERVE kernel: decode_attr_time_modify: mtime=1472850295Sep  2 22:13:20 RAX-NERVE kernel: decode_attr_mounted_on_fileid: fileid=41Sep  2 22:13:20 RAX-NERVE kernel: decode_getfattr_attrs: xdr returned -2097152Sep  2 22:13:20 RAX-NERVE kernel: decode_getfattr_generic: xdr returned 0Sep  2 22:13:20 RAX-NERVE kernel: NFS reply lookup: 0Sep  2 22:13:20 RAX-NERVE kernel: NFS: nfs_fhget(0:17/41 fh_crc=0x2947d423 ct=1)Sep  2 22:13:20 RAX-NERVE kernel: NFS: dentry_delete(/ls, 0)Sep  2 22:13:21 RAX-NERVE kernel: NFS: permission(0:17/4), mask=0x1, res=0Sep  2 22:13:21 RAX-NERVE kernel: --> nfs_put_client({2})Sep  2 22:13:21 RAX-NERVE kernel: encode_compound: tag=Sep  2 22:13:21 RAX-NERVE kernel: encode_compound: tag=Sep  2 22:13:21 RAX-NERVE kernel: nfs4_schedule_state_renewal: requeueing work. Lease period = 48Sep  2 22:13:21 RAX-NERVE kernel: --> nfs_put_client({3})Sep  2 22:13:21 RAX-NERVE kernel: --> nfs_put_client({2})Sep  2 22:13:21 RAX-NERVE kernel: <-- nfs4_setup_sequence status=0Sep  2 22:13:21 RAX-NERVE kernel: encode_compound: tag=Sep  2 22:13:21 RAX-NERVE kernel: decode_attr_type: type=0100000Sep  2 22:13:21 RAX-NERVE kernel: decode_attr_change: change attribute=8013396Sep  2 22:13:21 RAX-NERVE kernel: decode_attr_size: file size=0Sep  2 22:13:21 RAX-NERVE kernel: decode_attr_fsid: fsid=(0x76431d7a/0x9cf9cdde)Sep  2 22:13:21 RAX-NERVE kernel: decode_attr_fileid: fileid=41Sep  2 22:13:21 RAX-NERVE kernel: decode_attr_fs_locations: fs_locations done, error = 0Sep  2 22:13:21 RAX-NERVE kernel: decode_attr_mode: file mode=0775Sep  2 22:13:21 RAX-NERVE kernel: decode_attr_nlink: nlink=1Sep  2 22:13:21 RAX-NERVE kernel: decode_attr_owner: uid=-2Sep  2 22:13:21 RAX-NERVE kernel: decode_attr_group: gid=-2Sep  2 22:13:21 RAX-NERVE kernel: decode_attr_rdev: rdev=(0x3:0xc7)Sep  2 22:13:21 RAX-NERVE kernel: decode_attr_space_used: space used=512Sep  2 22:13:21 RAX-NERVE kernel: decode_attr_time_access: atime=502412Sep  2 22:13:21 RAX-NERVE kernel: decode_attr_time_metadata: ctime=1472850295Sep  2 22:13:21 RAX-NERVE kernel: decode_attr_time_modify: mtime=1472850295Sep  2 22:13:21 RAX-NERVE kernel: decode_attr_mounted_on_fileid: fileid=41Sep  2 22:13:21 RAX-NERVE kernel: decode_getfattr_attrs: xdr returned -2097152Sep  2 22:13:21 RAX-NERVE kernel: decode_getfattr_generic: xdr returned 0Sep  2 22:13:21 RAX-NERVE kernel: encode_compound: tag=Sep  2 22:13:21 RAX-NERVE kernel: NFS: nfs_update_inode(0:17/41 fh_crc=0x2947d423 ct=3 info=0x227e7f)Sep  2 22:13:21 RAX-NERVE kernel: NFS: nfs_fhget(0:17/41 fh_crc=0x2947d423 ct=3)Sep  2 22:13:21 RAX-NERVE kernel: NFS: nfsi 0xffff880117664930 disabling cacheSep  2 22:13:21 RAX-NERVE kernel: NFS: permission(0:17/41), mask=0x22, res=0Sep  2 22:13:21 RAX-NERVE kernel: NFS: write(/ls, 109208@0)Sep  2 22:13:21 RAX-NERVE kernel: NFS: write_begin(/ls(41), 4096@0)Sep  2 22:13:21 RAX-NERVE kernel: NFS: write_end(/ls(41), 4096@0)Sep  2 22:13:21 RAX-NERVE kernel: NFS:       nfs_updatepage(/ls 4096@0)Sep  2 22:13:21 RAX-NERVE kernel: NFS:       nfs_updatepage returns 0 (isize 4096)Sep  2 22:13:21 RAX-NERVE kernel: NFS: write_begin(/ls(41), 4096@4096)Sep  2 22:13:21 RAX-NERVE kernel: NFS: write_end(/ls(41), 4096@4096)Sep  2 22:13:21 RAX-NERVE kernel: NFS:       nfs_updatepage(/ls 4096@4096)Sep  2 22:13:21 RAX-NERVE kernel: NFS:       nfs_updatepage returns 0 (isize 8192)Sep  2 22:13:21 RAX-NERVE kernel: NFS: write_begin(/ls(41), 4096@8192)Sep  2 22:13:21 RAX-NERVE kernel: NFS: write_end(/ls(41), 4096@8192)Sep  2 22:13:21 RAX-NERVE kernel: NFS:       nfs_updatepage(/ls 4096@8192)Sep  2 22:13:21 RAX-NERVE kernel: NFS:       nfs_updatepage returns 0 (isize 12288)Sep  2 22:13:21 RAX-NERVE kernel: NFS: write_begin(/ls(41), 4096@12288)Sep  2 22:13:21 RAX-NERVE kernel: NFS: write_end(/ls(41), 4096@12288)Sep  2 22:13:21 RAX-NERVE kernel: NFS:       nfs_updatepage(/ls 4096@12288)Sep  2 22:13:21 RAX-NERVE kernel: NFS:       nfs_updatepage returns 0 (isize 16384)Sep  2 22:13:21 RAX-NERVE kernel: NFS: write_begin(/ls(41), 4096@16384)Sep  2 22:13:21 RAX-NERVE kernel: NFS: write_end(/ls(41), 4096@16384)Sep  2 22:13:21 RAX-NERVE kernel: NFS:       nfs_updatepage(/ls 4096@16384)Sep  2 22:13:21 RAX-NERVE kernel: NFS:       nfs_updatepage returns 0 (isize 20480)Sep  2 22:13:21 RAX-NERVE kernel: NFS: write_begin(/ls(41), 4096@20480)Sep  2 22:13:21 RAX-NERVE kernel: NFS: write_end(/ls(41), 4096@20480)Sep  2 22:13:21 RAX-NERVE kernel: NFS:       nfs_updatepage(/ls 4096@20480)Sep  2 22:13:21 RAX-NERVE kernel: NFS:       nfs_updatepage returns 0 (isize 24576)Sep  2 22:13:21 RAX-NERVE kernel: NFS: write_begin(/ls(41), 4096@24576)Sep  2 22:13:21 RAX-NERVE kernel: NFS: write_end(/ls(41), 4096@24576)Sep  2 22:13:21 RAX-NERVE kernel: NFS:       nfs_updatepage(/ls 4096@24576)Sep  2 22:13:21 RAX-NERVE kernel: NFS:       nfs_updatepage returns 0 (isize 28672)Sep  2 22:13:21 RAX-NERVE kernel: NFS: write_begin(/ls(41), 4096@28672)Sep  2 22:13:21 RAX-NERVE kernel: NFS: write_end(/ls(41), 4096@28672)Sep  2 22:13:21 RAX-NERVE kernel: NFS:       nfs_updatepage(/ls 4096@28672)Sep  2 22:13:21 RAX-NERVE kernel: NFS:       nfs_updatepage returns 0 (isize 32768)Sep  2 22:13:21 RAX-NERVE kernel: NFS: write_begin(/ls(41), 4096@32768)Sep  2 22:13:21 RAX-NERVE kernel: NFS: write_end(/ls(41), 4096@32768)Sep  2 22:13:21 RAX-NERVE kernel: NFS:       nfs_updatepage(/ls 4096@32768)Sep  2 22:13:21 RAX-NERVE kernel: NFS:       nfs_updatepage returns 0 (isize 36864)Sep  2 22:13:21 RAX-NERVE kernel: NFS: write_begin(/ls(41), 4096@36864)Sep  2 22:13:21 RAX-NERVE kernel: NFS: write_end(/ls(41), 4096@36864)Sep  2 22:13:21 RAX-NERVE kernel: NFS:       nfs_updatepage(/ls 4096@36864)Sep  2 22:13:21 RAX-NERVE kernel: NFS:       nfs_updatepage returns 0 (isize 40960)Sep  2 22:13:21 RAX-NERVE kernel: NFS: write_begin(/ls(41), 4096@40960)Sep  2 22:13:21 RAX-NERVE kernel: NFS: write_end(/ls(41), 4096@40960)Sep  2 22:13:21 RAX-NERVE kernel: NFS:       nfs_updatepage(/ls 4096@40960)Sep  2 22:13:21 RAX-NERVE kernel: NFS:       nfs_updatepage returns 0 (isize 45056)Sep  2 22:13:21 RAX-NERVE kernel: NFS: write_begin(/ls(41), 4096@45056)Sep  2 22:13:21 RAX-NERVE kernel: NFS: write_end(/ls(41), 4096@45056)Sep  2 22:13:21 RAX-NERVE kernel: NFS:       nfs_updatepage(/ls 4096@45056)Sep  2 22:13:21 RAX-NERVE kernel: NFS:       nfs_updatepage returns 0 (isize 49152)Sep  2 22:13:21 RAX-NERVE kernel: NFS: write_begin(/ls(41), 4096@49152)Sep  2 22:13:21 RAX-NERVE kernel: NFS: write_end(/ls(41), 4096@49152)Sep  2 22:13:21 RAX-NERVE kernel: NFS:       nfs_updatepage(/ls 4096@49152)Sep  2 22:13:21 RAX-NERVE kernel: NFS:       nfs_updatepage returns 0 (isize 53248)Sep  2 22:13:21 RAX-NERVE kernel: NFS: write_begin(/ls(41), 4096@53248)Sep  2 22:13:21 RAX-NERVE kernel: NFS: write_end(/ls(41), 4096@53248)Sep  2 22:13:21 RAX-NERVE kernel: NFS:       nfs_updatepage(/ls 4096@53248)Sep  2 22:13:21 RAX-NERVE kernel: NFS:       nfs_updatepage returns 0 (isize 57344)Sep  2 22:13:21 RAX-NERVE kernel: NFS: write_begin(/ls(41), 4096@57344)Sep  2 22:13:21 RAX-NERVE kernel: NFS: write_end(/ls(41), 4096@57344)Sep  2 22:13:21 RAX-NERVE kernel: NFS:       nfs_updatepage(/ls 4096@57344)Sep  2 22:13:21 RAX-NERVE kernel: NFS:       nfs_updatepage returns 0 (isize 61440)Sep  2 22:13:21 RAX-NERVE kernel: NFS: write_begin(/ls(41), 4096@61440)Sep  2 22:13:21 RAX-NERVE kernel: NFS: write_end(/ls(41), 4096@61440)Sep  2 22:13:21 RAX-NERVE kernel: NFS:       nfs_updatepage(/ls 4096@61440)Sep  2 22:13:21 RAX-NERVE kernel: NFS:       nfs_updatepage returns 0 (isize 65536)Sep  2 22:13:21 RAX-NERVE kernel: NFS: write_begin(/ls(41), 4096@65536)Sep  2 22:13:21 RAX-NERVE kernel: NFS: write_end(/ls(41), 4096@65536)Sep  2 22:13:21 RAX-NERVE kernel: NFS:       nfs_updatepage(/ls 4096@65536)Sep  2 22:13:21 RAX-NERVE kernel: NFS:       nfs_updatepage returns 0 (isize 69632)Sep  2 22:13:21 RAX-NERVE kernel: NFS: write_begin(/ls(41), 4096@69632)Sep  2 22:13:21 RAX-NERVE kernel: NFS: write_end(/ls(41), 4096@69632)Sep  2 22:13:21 RAX-NERVE kernel: NFS:       nfs_updatepage(/ls 4096@69632)Sep  2 22:13:21 RAX-NERVE kernel: NFS:       nfs_updatepage returns 0 (isize 73728)Sep  2 22:13:21 RAX-NERVE kernel: NFS: write_begin(/ls(41), 4096@73728)Sep  2 22:13:21 RAX-NERVE kernel: NFS: write_end(/ls(41), 4096@73728)Sep  2 22:13:21 RAX-NERVE kernel: NFS:       nfs_updatepage(/ls 4096@73728)Sep  2 22:13:21 RAX-NERVE kernel: NFS:       nfs_updatepage returns 0 (isize 77824)Sep  2 22:13:21 RAX-NERVE kernel: NFS: write_begin(/ls(41), 4096@77824)Sep  2 22:13:21 RAX-NERVE kernel: NFS: write_end(/ls(41), 4096@77824)Sep  2 22:13:21 RAX-NERVE kernel: NFS:       nfs_updatepage(/ls 4096@77824)Sep  2 22:13:21 RAX-NERVE kernel: NFS:       nfs_updatepage returns 0 (isize 81920)Sep  2 22:13:21 RAX-NERVE kernel: NFS: write_begin(/ls(41), 4096@81920)Sep  2 22:13:21 RAX-NERVE kernel: NFS: write_end(/ls(41), 4096@81920)Sep  2 22:13:21 RAX-NERVE kernel: NFS:       nfs_updatepage(/ls 4096@81920)Sep  2 22:13:21 RAX-NERVE kernel: NFS:       nfs_updatepage returns 0 (isize 86016)Sep  2 22:13:21 RAX-NERVE kernel: NFS: write_begin(/ls(41), 4096@86016)Sep  2 22:13:21 RAX-NERVE kernel: NFS: write_end(/ls(41), 4096@86016)Sep  2 22:13:21 RAX-NERVE kernel: NFS:       nfs_updatepage(/ls 4096@86016)Sep  2 22:13:21 RAX-NERVE kernel: NFS:       nfs_updatepage returns 0 (isize 90112)Sep  2 22:13:21 RAX-NERVE kernel: NFS: write_begin(/ls(41), 4096@90112)Sep  2 22:13:21 RAX-NERVE kernel: NFS: write_end(/ls(41), 4096@90112)Sep  2 22:13:21 RAX-NERVE kernel: NFS:       nfs_updatepage(/ls 4096@90112)Sep  2 22:13:21 RAX-NERVE kernel: NFS:       nfs_updatepage returns 0 (isize 94208)Sep  2 22:13:21 RAX-NERVE kernel: NFS: write_begin(/ls(41), 4096@94208)Sep  2 22:13:21 RAX-NERVE kernel: NFS: write_end(/ls(41), 4096@94208)Sep  2 22:13:21 RAX-NERVE kernel: NFS:       nfs_updatepage(/ls 4096@94208)Sep  2 22:13:21 RAX-NERVE kernel: NFS:       nfs_updatepage returns 0 (isize 98304)Sep  2 22:13:21 RAX-NERVE kernel: NFS: write_begin(/ls(41), 4096@98304)Sep  2 22:13:21 RAX-NERVE kernel: NFS: write_end(/ls(41), 4096@98304)Sep  2 22:13:21 RAX-NERVE kernel: NFS:       nfs_updatepage(/ls 4096@98304)Sep  2 22:13:21 RAX-NERVE kernel: NFS:       nfs_updatepage returns 0 (isize 102400)Sep  2 22:13:21 RAX-NERVE kernel: NFS: write_begin(/ls(41), 4096@102400)Sep  2 22:13:21 RAX-NERVE kernel: NFS: write_end(/ls(41), 4096@102400)Sep  2 22:13:21 RAX-NERVE kernel: NFS:       nfs_updatepage(/ls 4096@102400)Sep  2 22:13:21 RAX-NERVE kernel: NFS:       nfs_updatepage returns 0 (isize 106496)Sep  2 22:13:21 RAX-NERVE kernel: NFS: write_begin(/ls(41), 2712@106496)Sep  2 22:13:21 RAX-NERVE kernel: NFS: write_end(/ls(41), 2712@106496)Sep  2 22:13:21 RAX-NERVE kernel: NFS:       nfs_updatepage(/ls 2712@106496)Sep  2 22:13:21 RAX-NERVE kernel: NFS:       nfs_updatepage returns 0 (isize 109208)Sep  2 22:13:21 RAX-NERVE kernel: NFS: flush(/ls)Sep  2 22:13:21 RAX-NERVE kernel: NFS:     0 initiated write call (req 0:17/41, 109208 bytes @ offset 0)Sep  2 22:13:21 RAX-NERVE kernel: <-- nfs4_setup_sequence status=0Sep  2 22:13:21 RAX-NERVE kernel: encode_compound: tag=Sep  2 22:14:09 RAX-NERVE kernel: nfs4_renew_state: startSep  2 22:14:09 RAX-NERVE kernel: nfs4_renew_state: doneSep  2 22:15:33 RAX-NERVE kernel: INFO: task cp:2850 blocked for more than 120 seconds.Sep  2 22:15:33 RAX-NERVE kernel:      Not tainted 2.6.32-642.4.2.el6.x86_64 #1Sep  2 22:15:33 RAX-NERVE kernel: echo 0 > /proc/sys/kernel/hung_task_timeout_secs disables this message.Sep  2 22:15:33 RAX-NERVE kernel: cp            D 0000000000000003     0  2850   2296 0x00000080Sep  2 22:15:33 RAX-NERVE kernel: ffff88012c3afc78 0000000000000082 ffff88012c3afbc8 ffffffffa051b3eeSep  2 22:15:33 RAX-NERVE kernel: ffff88012c3afbf8 ffffffffa051bc90 ffff88012c3afbe8 ffff88012c3afc28Sep  2 22:15:33 RAX-NERVE kernel: ffff88012c77bc70 ffff880117664af8 ffff88012798fad8 ffff88012c3affd8Sep  2 22:15:33 RAX-NERVE kernel: Call Trace:Sep  2 22:15:33 RAX-NERVE kernel: [<ffffffffa051b3ee>] ? rpc_make_runnable+0x7e/0x80 [sunrpc]Sep  2 22:15:33 RAX-NERVE kernel: [<ffffffffa051bc90>] ? rpc_execute+0x50/0xa0 [sunrpc]Sep  2 22:15:33 RAX-NERVE kernel: [<ffffffff8112e3f0>] ? sync_page+0x0/0x50Sep  2 22:15:33 RAX-NERVE kernel: [<ffffffff81549163>] io_schedule+0x73/0xc0Sep  2 22:15:33 RAX-NERVE kernel: [<ffffffff8112e42d>] sync_page+0x3d/0x50Sep  2 22:15:33 RAX-NERVE kernel: [<ffffffff81549c4f>] __wait_on_bit+0x5f/0x90Sep  2 22:15:33 RAX-NERVE kernel: [<ffffffff8112e663>] wait_on_page_bit+0x73/0x80Sep  2 22:15:33 RAX-NERVE kernel: [<ffffffff810a6920>] ? wake_bit_function+0x0/0x50Sep  2 22:15:33 RAX-NERVE kernel: [<ffffffff811447a5>] ? pagevec_lookup_tag+0x25/0x40Sep  2 22:15:33 RAX-NERVE kernel: [<ffffffff8112ea8b>] wait_on_page_writeback_range+0xfb/0x190Sep  2 22:15:33 RAX-NERVE kernel: [<ffffffff8112ec58>] filemap_write_and_wait_range+0x78/0x90Sep  2 22:15:33 RAX-NERVE kernel: [<ffffffff811cc92e>] vfs_fsync_range+0x7e/0x100Sep  2 22:15:33 RAX-NERVE kernel: [<ffffffff811cca1d>] vfs_fsync+0x1d/0x20Sep  2 22:15:33 RAX-NERVE kernel: [<ffffffffa05bb9e0>] nfs_file_flush+0x70/0xa0 [nfs]Sep  2 22:15:33 RAX-NERVE kernel: [<ffffffff811967fc>] filp_close+0x3c/0x90Sep  2 22:15:33 RAX-NERVE kernel: [<ffffffff811968f5>] sys_close+0xa5/0x100Sep  2 22:15:33 RAX-NERVE kernel: [<ffffffff8100b0d2>] system_call_fastpath+0x16/0x1bI have absolutely no idea what could be causing this. Both Windows and OS X clients are able to mount and read/write from these partitions without issue. The devices are plugged directly into the same switch and, apart from a VLAN tag/virtual interface, there's no reason at all for the network to be at fault. Was able to duplicate the issue on an Ubuntu box, so I'm thinking the fault is with the FreeNAS server itself, but a reinstall didn't do the trick. 
FreeNAS/CentOS - hang on write
linux;networking;nfs;freenas