Date: Fri, 14 Dec 2012 22:43:00 -0600 From: David Noel <david.i.noel@gmail.com> To: freebsd-hackers@freebsd.org Subject: postgres, initdb, FreeBSD bug? Message-ID: <CAHAXwYA6o_hBpAvm=H4bpXNOKr7ec10zH30G3KWQXg7JEj0mDQ@mail.gmail.com>
next in thread | raw e-mail | index | archive | help
I've been fighting with a bug I can't quite seem to figure out and was
told that this might be the place to come. I'm running
postgresql-9.2.2 on FreeBSD 8.3-RELEASE-p5 and am having things break
down when I try to run initdb. I got in contact with the pgsql-general
mailing list and we debugged the issue to the point where it seemed
that this might be a FreeBSD-related error. Relevant excerpts from
several email are below that piece together the error:
I'm running into the following error message when running initdb (FreeBSD host):
ygg# /usr/local/etc/rc.d/postgresql initdb -D /zdb/pgsql/data --debug
The files belonging to this database system will be owned by user "pgsql".
This user must also own the server process.
The database cluster will be initialized with locales
COLLATE: C
CTYPE: en_US.UTF-8
MESSAGES: en_US.UTF-8
MONETARY: en_US.UTF-8
NUMERIC: en_US.UTF-8
TIME: en_US.UTF-8
The default text search configuration will be set to "english".
creating directory /zdb/pgsql/data ... ok
creating subdirectories ... ok
selecting default max_connections ... 100
selecting default shared_buffers ... 32MB
creating configuration files ... ok
creating template1 database in /zdb/pgsql/data/base/1 ... FATAL:
could not open file "pg_xlog/000000010000000000000001" (log file 0,
segment 1): No such file or directory
child process exited with exit code 1
initdb: removing data directory "/zdb/pgsql/data"
...
Interestingly, I have a second--virtually identical--server that I
just tried initdb on. FreeBSD 8.3-RELEASE-p5, postgresql-server-9.2.2.
Exact same "FATAL: could not open file pg_xlog" error. So it is
reproducible.
...
The relevant part of the ktrace output is
71502 postgres CALL unlink(0x7fffffffc130)
71502 postgres NAMI "pg_xlog/xlogtemp.71502"
71502 postgres RET unlink -1 errno 2 No such file or directory
71502 postgres CALL
open(0x7fffffffc130,O_RDWR|O_CREAT|O_EXCL,S_IRUSR|S_IWUSR)
71502 postgres NAMI "pg_xlog/xlogtemp.71502"
71502 postgres RET open 3
71502 postgres CALL write(0x3,0x801a56030,0x2000)
71502 postgres GIO fd 3 wrote 4096 bytes
.... a lot of uninteresting write() calls snipped ...
71502 postgres RET write 8192/0x2000
71502 postgres CALL close(0x3)
71502 postgres RET close 0
71502 postgres CALL unlink(0x7fffffffbc60)
71502 postgres NAMI "pg_xlog/000000010000000000000001"
71502 postgres RET unlink -1 errno 2 No such file or directory
71502 postgres CALL link(0x7fffffffc130,0x7fffffffbc60)
71502 postgres NAMI "pg_xlog/xlogtemp.71502"
71502 postgres NAMI "pg_xlog/000000010000000000000001"
71502 postgres RET link -1 errno 1 Operation not permitted
71502 postgres CALL unlink(0x7fffffffc130)
71502 postgres NAMI "pg_xlog/xlogtemp.71502"
71502 postgres RET unlink 0
71502 postgres CALL open(0x7fffffffc530,O_RDWR,<unused>0x180)
71502 postgres NAMI "pg_xlog/000000010000000000000001"
71502 postgres RET open -1 errno 2 No such file or directory
This corresponds to the execution of XLogFileInit(), and what's
evidently happening is that we successfully create and zero-fill
the first xlog segment file under a temporary name, but then
the attempt to rename it into place with link() fails with EPERM.
This is really a WTF kind of failure, I think. The directory is
certainly writable --- it was made under our own UID, and what's
more we just managed to create the file there under its temp name.
So how can we get an EPERM failure from link()?
I think this is a kernel bug.
regards, tom lane
PS: one odd thing here is that the ereport(LOG) in
InstallXLogFileSegment isn't doing anything; otherwise we'd have gotten
a much more helpful error report about "could not link file". I don't
think we run the bootstrap mode with log_min_messages set high enough to
disable LOG messages, so why isn't it printing? Nonetheless, this error
shouldn't have occurred.
...
Where to from here? The freebsd-database@freebsd.org mailing list? The
postgresql port maintainer? Who should I be in touch with?
...
You need to talk to some FreeBSD kernel hackers about why link()
might be failing here. Since you see it on UFS too, we can probably
exonerate the ZFS filesystem-specific code.
I did some googling and found that EPERM can be issued if the filesystem
doesn't support hard links (which shouldn't apply to ZFS I trust).
Also, Linux has a "protected_hardlinks" option that causes certain
attempts at creating hard links to fail --- but our use-case here
doesn't fall foul of any of those restrictions AFAICS, and of course
FreeBSD isn't Linux. Still, I wonder if you're running into some
misdesigned or misimplemented security restriction. You might want
to look at your kernel parameters and see if any of them look like
they might have to do with restricting hard-link operations.
Also, since Amitabh failed to duplicate the failure on both earlier
and later FreeBSD kernels, and we've not heard reports of this from
anybody else either, it seems more than possible that it's a plain
old bug in the specific kernel version you're using.
As a short-term workaround, I'd suggest rebuilding with
HAVE_WORKING_LINK disabled. (Just remove that #define from
src/include/pg_config_manual.h and rebuild.)
regards, tom lane
...
Does this make any sense to anyone?
-David
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?CAHAXwYA6o_hBpAvm=H4bpXNOKr7ec10zH30G3KWQXg7JEj0mDQ>