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Add ULTRIX 4.0 kernel patch for nfs_statfs() overflow.

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Boris Gjenero
2020-10-27 14:29:49 -04:00
parent c4ebe27a95
commit 09d1302c4c
1 changed files with 17 additions and 3 deletions
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ultrix/README.md
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@@ -66,9 +66,23 @@ similarly. For ULTRIX 4.00 and maybe other versions, Change
#### ULTRIX only sees 22 bits of disk usage
If you look at `du` output in the NFS mount on ULTRIX, you'll see only the
low order 22 bits of the numbers you see for that file system in Linux. The
ignoring of higher bits can cause ULTRIX to decide the file system is full.
From the server, ULTRIX receives a block size and numbers of total, used and
free blocks. It multiplies those numbers by the block size and then divides
by 1024. It seems VAX multiplication and division only works with 32-bit
values, and not double width ones like x86. So the sizes in bytes must fit
within a signed 32-bit number. This patch divides the block size from the
server by 1024, and then multiplies received sizes by that number. It gives the
wrong answer if the block size isn't a multiple of 1024, but it's practically
always a multiple of 1024. If it is smaller than 1024, block sizes are
multiplied by 1. Even when giving wrong results, this is better than what was
there before.
In ULTRIX 4.0 in nfs_statfs() in nfs_vfsops.o or the kernel, find:
`C5ADF0ADF450C68F0004000050D0AC0851D050A108C5ADF0ADF850C68F0004000050D0AC0851D050A10CC5ADF0ADFC50C68F0004000050D0AC0851D050A110`
and change it to:
`D0EDF0FFFFFF53C68F00040000531203D00153D0AC0855C553EDF4FFFFFFA508C553EDF8FFFFFFA50CC553EDFCFFFFFFA510D08FEFBEADDE53D00053D00053`
Test by running `df` in ULTRIX and comparing output to `df` for that file
system in Linux.
## Other notes