On 7/18/2011 10:18 AM, Andriy Gapon wrote:
on 18/07/2011 17:53 Brandon Falk said the following:
Hello,
In recent branches (confirmed with 224119) builds compiled with clang happen to
throw 'Unknown error: -512' in a lot of places, making the system unusable.
(Untested on gcc compiled systems). Originally I thought the problem was with
specific programs, then I narrowed it down to file I/O, and now I've narrowed it
down to open() with O_TRUNC. Without O_TRUNC there seems to be no issues
whatsoever. With O_TRUNC on open() it fails with that 'Unknown error: -512'
every
other time you run the program. Common issues, portsnap is affected, making it
impossible to fetch/extract ports. As well as redirecting output in shells eg
`echo 'hi'> test` fails every other try. You have the same issue with text
editors like `edit` where it fails every other save. There are no issues with
`echo 'hi'>> test` as there is no O_TRUNC, it only seems to be an O_TRUNC
error.
Any tips? Otherwise I'll be looking into this today myself.
Just a hint that you could try using DTrace syscall and fbt providers to see
where
in kernel (if in kernel) that -512 return value originates.
Update:
I've traced more and more into the kernel, and currently I have found
the following trace:
>>> ufs_setattr() (in sys/ufs/ufs/ufs_vnops.c:507)
(In truncate a bunch of stuff is done, but it succeeds until VOP_SETATTR)
>>> vn_truncate() (in sys/kern/vfs_vnops.c:636)
>>> kern_openat() (in sys/kern/vfs_syscalls.c:1043)
>>> kern_open() (in sys/kern/vfs_syscalls.c:1035)
>>> open() (in sys/kern/vfs_syscalls.c:1006)
ufs_setattr() returns with -1 (EPERM)
I'll continue to try to find the exact problem. A quick workaround
currently would probably be to use a different filesystem other than
ufs, but then again, I have no clue if other filesystems have the same
issue.
Hopefully that trace will help anyone who wants to help out.
-Brandon Falk
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