lkml.org 
[lkml]   [2017]   [Aug]   [24]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
SubjectRe: Kernels v4.9+ cause short reads of block devices
From
Date
On 8/23/17 4:13 PM, Linus Torvalds wrote:

> Oh, right you are - I'm much too used to 64-bit, where
> MAX_LFS_FILESIZE is basically infinite, and was jusr assuming that it
> was something like the UFS bug we had not that long ago that was due
> to the 32-bit limit.
>
> But yes, on 32-bit, we are limited by the 32-bit index into the page
> cache, and we limit the index to 31 bits too, so we have (PAGE_SIZE <<
> 31) -1, which is that 7ffffffffff.

Yeah, it's an old organically grown storage server (install images, old
vms, etc.) that
I can't convince myself it's worth upgrading.

> The *right* patch is likely to just this instead:
>
> -#define MAX_LFS_FILESIZE (((loff_t)PAGE_SIZE << (BITS_PER_LONG-1))-1)
> +#define MAX_LFS_FILESIZE (((loff_t)PAGE_SIZE <<
> BITS_PER_LONG)-PAGE_SIZE)
>
> which should make MAX_LFS_FILESIZE be 0xffffffff000 and you disk size
> should be ok.

That solves my issue. I'm curious if that check should also be in the
write path. If the
check had been there too I wouldn't have ended up with any corruption.

I'm not sure if anything over 16TB will create/assemble (or if anybody
else is crazy like me).

Doug

\
 
 \ /
  Last update: 2017-08-24 12:05    [W:0.081 / U:0.748 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site