Date: Thu, 20 Mar 2014 17:33:34 -0700 From: javocado <javocado@gmail.com> To: FreeBSD Filesystems <freebsd-fs@freebsd.org> Subject: Re: rsync w/ fake-super -> crashes zfs Message-ID: <CAP1HOmRfw0_MkHhu%2BWYu4vac25rx2MGzUAGjdbM8PkPRm5LxtQ@mail.gmail.com> In-Reply-To: <CAP1HOmTiiKp7B1FLQ=Kfq_WUe2=nctMTc0nrtiav5kfAraVHgA@mail.gmail.com>
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Gathering more info here... When re-running the rsync command, stripped down: rsync -av --rsync-path="rsync --fake-super" /src /dst we're not seeing any system crashes, yet, but rsync is choking/quitting quite a bit saying a file here or there has a corrupt extattr. Does this point to a problem with ZFS or more with rsync. Any thoughts on the fake-super impact and how it leads to crashing? On Fri, Mar 14, 2014 at 4:57 PM, javocado <javocado@gmail.com> wrote: > System specifics: > ZFS version 28 > FreeBSD 8.3-RELEASE > > We're seeing a repeatable outcome where a remote rsync command like: > > rsync -axzHAXS --rsync-path="rsync --fake-super" --exclude '*/rsync.%stat' > > backing up to our zfs filesystem (with 15M inodes) will lead to a panic > with output like: > > Fatal trap 12: page fault while in kernel modecpuid = 4; apic id = 04fault virtual address = 0x160fault code = supervisor read data, page not presentinstruction pointer = 0x20:0xffffffff80abb546stack pointer = 0x28:0xffffff976c62b910frame pointer = 0x28:0xffffff976c62b9d0code segment = base 0x0, limit 0xfffff, type 0x1b = DPL 0, pres 1, long 1, def32 0, gran 1processor eflags = interrupt enabled, resume, IOPL = 0current process = 7295 (rsync)[thread pid 7295 tid 101008 ]Stopped at zfs_freebsd_remove+0x426: movq 0x160(%rax),%rsi > > > On the sending side (RHEL, ext3), rsync reports errors like: > > rsync: failed to read xattr rsync.%statrsync: failed to write xattr rsync.%statrsync: get_xattr_names: llistxattr > > which we've seen occasionally with other systems when running rsync with fake-super, but it usually doesn't lead to a crash.* > > On the receiving side, other than the crashes, we are seeing a few new files (that don't exist on the source) named: > > rsync.%stat > > which correspond to and contain the owner and permission attributes that should have been stored in the extattr's for the file or directory. Not sure if they are a red herring, but they're usually not something we see (perhaps that's related to the --exclude '*/rsync.%stat' and rsync not being able to cleanup properly). > > We are still testing to see if any options in the rsync command (above) may be contributing to the crash, since fake-super in and of itself runs fine under basic (rsync -av --rsync-path="rsync --fake-super" /src /dst) circumstances. But we suspect that the problem is related to fake-super and its reliance upon extattr's. > > What we really need is a solution to the crashing - some way to make ZFS stop choking on whatever --fake-super produces and/or how it's interacting with extattr's on ZFS. > > > Thanks! > > * we sometimes also see on the sending side w/ fake-super: > rsync: failed to write xattr rsync.%stat for "xxxxxx/file" : No such file > or directory (2) > > when (1) the file exists, (2) it's a symlink > but that isn't happening in this instance. We only mention it here as > another oddity of fake-super + ZFS + extattr > >home | help
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