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[RawwrBag <1366538@xxxxxxxxxxxxxxxxxx>]

Hello! I found the original bug and proposed the original patch to the
kernel SCSI guys. Here's some context:

The SCSI flush command was being treated by a zero-byte write, which
means that if an error was returned, you wouldn't catch it until a
subsequent write (or flush). The way writes work is that all possible
bytes are written, and if something bad happens, an error bubbles out on
the next write attempt. This holds true even for a zero-byte write. This
means that before this bug, to guarantee durability you had to flush
twice (and verify both were error-free). I'm working on a storage
appliance that relies on the fact that a single flush command guarantees
a write made durably to a SCSI device. I'm sure many other storage
products rely on this behavior, too.

I'm not sure why certain USB drives are failing in the flush path on
unmount. Since the flush bug existed for such a long time, I suspect
certain drivers coded around this behavior, and now that it is correct
we are seeing new bugs exposed.

Based on the simplicity and obviousness of our patch for the flush bug,
it would really be ideal to diagnose this further rather than reverting.

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https://bugs.launchpad.net/bugs/1366538

Title:
  Synchronisation/close /dev/sdX: i/o error on target host

Status in linux package in Ubuntu:
  Triaged
Status in linux source package in Trusty:
  Triaged
Status in linux source package in Utopic:
  Triaged
Status in linux source package in Vivid:
  Triaged

Bug description:
  Ubuntu 14.04.1 x86-64
  wanting to unmout a pata drive (usb attached), I get this (title) "Warning from libparted" when gparted launches.
  Same issue with another pc x86-64
  Errors retries then ignore, shred /dev/sdi fails:

  shred: /dev/sdi : pass 1/2 (random)…
  shred: /dev/sdi : pass 1/2 (random)…231MiB/94GiB 0 %
  shred: /dev/sdi : failure of fdatasync: i/o error on target host

  I reached to shred the drive from a 12.04.4 i386 pc with no error.

  Sep  7 15:07:08 nux kernel: [261448.072475] usb 5-1: new high-speed USB device number 10 using xhci_hcd
  Sep  7 15:07:09 nux kernel: [261448.202999] usb 5-1: New USB device found, idVendor=04cf, idProduct=8818
  Sep  7 15:07:09 nux kernel: [261448.203008] usb 5-1: New USB device strings: Mfr=1, Product=2, SerialNumber=0
  Sep  7 15:07:09 nux kernel: [261448.203013] usb 5-1: Product: USB Mass Storage Device
  Sep  7 15:07:09 nux kernel: [261448.203018] usb 5-1: Manufacturer: Myson Century, Inc.
  Sep  7 15:07:09 nux kernel: [261448.205463] usb-storage 5-1:1.0: USB Mass Storage device detected
  Sep  7 15:07:09 nux kernel: [261448.205673] scsi20 : usb-storage 5-1:1.0
  Sep  7 15:07:10 nux kernel: [261449.206849] scsi 20:0:0:0: Direct-Access     HTS72101 0G9AT00          MCZO PQ: 0 ANSI: 0 CCS
  Sep  7 15:07:10 nux kernel: [261449.207763] sd 20:0:0:0: Attached scsi generic sg7 type 0
  Sep  7 15:07:10 nux kernel: [261449.207901] sd 20:0:0:0: [sdi] 195371568 512-byte logical blocks: (100 GB/93.1 GiB)
  Sep  7 15:07:10 nux kernel: [261449.208068] sd 20:0:0:0: [sdi] Write Protect is off
  Sep  7 15:07:10 nux kernel: [261449.208074] sd 20:0:0:0: [sdi] Mode Sense: 00 14 00 00
  Sep  7 15:07:10 nux kernel: [261449.208280] sd 20:0:0:0: [sdi] Write cache: enabled, read cache: enabled, doesn't support DPO or FUA
  Sep  7 15:07:10 nux kernel: [261449.555232]  sdi: unknown partition table
  Sep  7 15:07:10 nux kernel: [261449.555926] sd 20:0:0:0: [sdi] Attached SCSI disk
  Sep  7 15:07:43 nux kernel: [261482.219026] end_request: critical target error, dev sdi, sector 0
  Sep  7 15:07:52 nux kernel: [261492.015180] end_request: critical target error, dev sdi, sector 0
  Sep  7 15:07:55 nux kernel: [261494.261159] end_request: critical target error, dev sdi, sector 0
  Sep  7 15:16:23 nux kernel: [262003.027005] end_request: critical target error, dev sdi, sector 0
  Sep  7 15:16:35 nux kernel: [262014.215352] end_request: critical target error, dev sdi, sector 0
  Sep  7 15:16:35 nux kernel: [262014.859651] end_request: critical target error, dev sdi, sector 0

  [EDIT:
  Once shreded, no error on the i386, but still same error on the 2 x86-64]

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