Messages in this thread | | | Subject | Re: Kernels v4.9+ cause short reads of block devices | From | Doug Nazar <> | Date | Thu, 24 Aug 2017 06:03:33 -0400 |
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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
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