OK ! So USB Driver is trying to read but physically disk is not enumerated but USB Subsystem did recognize the disk as per Logs.

 usb 2-1.1: new high speed USB device number 6 using fsl-ehci

<6>[  216.990681] scsi1 : usb-storage 2-1.1:1.0

<5>[  217.983182] scsi 1:0:0:0: Direct-Access     USB2.0    Flash Disk      0.00 PQ: 0 ANSI: 2

<5>[  217.986978] sd 1:0:0:0: [sdb] 3904512 512-byte logical blocks: (1.99 GB/1.86 GiB)

<5>[  217.987461] sd 1:0:0:0: [sdb] Write Protect is off

<7>[  217.987473] sd 1:0:0:0: [sdb] Mode Sense: 00 00 00 00

<3>[  217.987958] sd 1:0:0:0: [sdb] Asking for cache data failed

<3>[  217.987968] sd 1:0:0:0: [sdb] Assuming drive cache: write through

<3>[  217.991715] sd 1:0:0:0: [sdb] Asking for cache data failed

<3>[  217.991726] sd 1:0:0:0: [sdb] Assuming drive cache: write through

<6>[  218.215499]  sdb:

<3>[  218.221482] sd 1:0:0:0: [sdb] Asking for cache data failed

<3>[  218.221513] sd 1:0:0:0: [sdb] Assuming drive cache: write through

<5>[  218.221529] sd 1:0:0:0: [sdb] Attached SCSI removable disk

<3>[  218.431346] FAT-fs (sda): Directory bread(block 480) failed

<3>[  218.431362] FAT-fs (sda): Directory bread(block 481) failed

<3>[  218.431374] FAT-fs (sda): Directory bread(block 482) failed

<3>[  218.431386] FAT-fs (sda): Directory bread(block 483) failed

Regards
Sanjeev Sharma



On Wed, Jun 18, 2014 at 12:37 PM, Greg KH <greg@kroah.com> wrote:
On Wed, Jun 18, 2014 at 12:22:33PM +0530, sanjeev sharma wrote:
> Hi Greg,
>
> In one of my imx6 based Board when I connect USB Disk first time everything
> work's ok and I can read/write content from USB Flash Driver but when I do
> eject and connect again I could see below continuous messages from dmesg
> and disk never mounted.
>
>  218.431346] FAT-fs (sda): Directory bread(block 480) failed
>
> <3>[  218.431362] FAT-fs (sda): Directory bread(block 481) failed
>
> <3>[  218.431374] FAT-fs (sda): Directory bread(block 482) failed
>
> <3>[  218.431386] FAT-fs (sda): Directory bread(block 483) failed
>
> <3>[  218.431398] FAT-fs (sda): Directory bread(block 484) failed
>
> <3>[  218.431420] FAT-fs (sda): Directory bread(block 485) failed
>
> <3>[  218.431432] FAT-fs (sda): Directory bread(block 486) failed
>
> <3>[  218.431444] FAT-fs (sda): Directory bread(block 487) failed
>
> <3>[  218.431466] FAT-fs (sda): Directory bread(block 488) failed
>
> <3>[  218.431478] FAT-fs (sda): Directory bread(block 489) failed
>
> <3>[  218.431499] FAT-fs (sda): Directory bread(block 490) failed
>
> <3>[  218.431515] FAT-fs (sda): Directory bread(block 491) failed
>
> <3>[  218.431528] FAT-fs (sda): Directory bread(block 492) failed
>
> <3>[  218.431540] FAT-fs (sda): Directory bread(block 493) failed
>
> <3>[  218.431551] FAT-fs (sda): Directory bread(block 494) failed
>
> <3>[  218.431563] FAT-fs (sda): Directory bread(block 495) failed
>
> <3>[  218.431592] FAT-fs (sda): Directory bread(block 496) failed
>
> <3>[  218.431604] FAT-fs (sda): Directory bread(block 497) failed
>
> <3>[  218.431616] FAT-fs (sda): Directory bread(block 498) failed
>
> <3>[  218.431627] FAT-fs (sda): Directory bread(block 499)
>
> is this probably issue in driver where It is failing to properly re-init
> the USB device 2nd time ?

I have no idea, something is trying to read those blocks and failing,
perhaps a program doesn't realize the disk is no longer there anymore?

greg k-h