Re: nfs on zfs panic

It looks like nvp is NULL at the point where it crashed. Looking at  
the zfs code, zfs_vget always returns zero, even if it failed to find  
a vnode which matches the given 'inode' number. Try changing the  
return statement in zfs_vget from 'return (0)' to 'return (err)'.

PS. the code is in src/sys/contrib/opensolaris/uts/common/fs/zfs/ 
zfs_vfsops.c - it took me a while to find it.

On 26 Jun 2007, at 17:12, Philippe Pegon wrote:

> Hi,
>
> I'm playing with zfs on vmware on FreeBSD current (world and kernel  
> of today with GENERIC kernel). I have 3 disks (virtuals) in raidz :
>
> # zpool status
>   pool: tank
>  state: ONLINE
>  scrub: none requested
> config:
>
>         NAME        STATE     READ WRITE CKSUM
>         tank        ONLINE       0     0     0
>           raidz1    ONLINE       0     0     0
>             da0     ONLINE       0     0     0
>             da1     ONLINE       0     0     0
>             da2     ONLINE       0     0     0
>
> errors: No known data errors
>
> with this zfs configuration :
>
> # zfs list
> NAME         USED  AVAIL  REFER  MOUNTPOINT
> tank         844M  8.93G  25.3K  none
> tank/nfs    24.0K  8.93G  24.0K  /mnt/nfs
> tank/obj     436M  8.93G   436M  /usr/obj
> tank/ports   244M  8.93G   244M  /usr/ports
> tank/src     162M  8.93G   162M  /usr/src
>
> /mnt/nfs is nfs exported (zfs set sharenfs=on tank/nfs) and when I  
> mount it on a Linux box and try a ls from Linux, FreeBSD panic.
>
> panic and debug informations :
>
> # kgdb kernel.debug /var/crash/vmcore.0
> [GDB will not be able to debug user-mode threads: /usr/lib/ 
> libthread_db.so: Undefined symbol "ps_pglobal_lookup"]
> GNU gdb 6.1.1 [FreeBSD]
> Copyright 2004 Free Software Foundation, Inc.
> GDB is free software, covered by the GNU General Public License,  
> and you are
> welcome to change it and/or distribute copies of it under certain  
> conditions.
> Type "show copying" to see the conditions.
> There is absolutely no warranty for GDB.  Type "show warranty" for  
> details.
> This GDB was configured as "i386-marcel-freebsd".
>
>
> Unread portion of the kernel message buffer:
>
>
> Fatal trap 12: page fault while in kernel mode
> cpuid = 0; apic id = 00
> fault virtual address   = 0x10
> fault code              = supervisor read, page not present
> instruction pointer     = 0x20:0xc08d088d
> stack pointer           = 0x28:0xd61f88f0
> frame pointer           = 0x28:0xd61f8bec
> code segment            = base 0x0, limit 0xfffff, type 0x1b
>                         = DPL 0, pres 1, def32 1, gran 1
> processor eflags        = interrupt enabled, resume, IOPL = 0
> current process         = 722 (nfsd)
> panic: from debugger
> cpuid = 0
> Uptime: 3h46m48s
> Physical memory: 499 MB
> Dumping 52 MB: 37 21 5
>
> #0  doadump () at pcpu.h:195
> 195             __asm __volatile("movl %%fs:0,%0" : "=r" (td));
> (kgdb) backtrace
> #0  doadump () at pcpu.h:195
> #1  0xc074997e in boot (howto=260) at /usr/src/sys/kern/ 
> kern_shutdown.c:409
> #2  0xc0749c3b in panic (fmt=Variable "fmt" is not available.
> ) at /usr/src/sys/kern/kern_shutdown.c:563
> #3  0xc048bf87 in db_panic (addr=Could not find the frame base for  
> "db_panic".
> ) at /usr/src/sys/ddb/db_command.c:433
> #4  0xc048c975 in db_command_loop () at /usr/src/sys/ddb/ 
> db_command.c:401
> #5  0xc048e0e5 in db_trap (type=12, code=0) at /usr/src/sys/ddb/ 
> db_main.c:222
> #6  0xc07703d6 in kdb_trap (type=12, code=0, tf=0xd61f88b0) at /usr/ 
> src/sys/kern/subr_kdb.c:502
> #7  0xc09f31bc in trap_fatal (frame=0xd61f88b0, eva=16) at /usr/src/ 
> sys/i386/i386/trap.c:861
> #8  0xc09f33f3 in trap_pfault (frame=0xd61f88b0, usermode=0,  
> eva=16) at /usr/src/sys/i386/i386/trap.c:784
> #9  0xc09f3d92 in trap (frame=0xd61f88b0) at /usr/src/sys/i386/i386/ 
> trap.c:462
> #10 0xc09d9a0b in calltrap () at /usr/src/sys/i386/i386/exception.s: 
> 139
> #11 0xc08d088d in nfsrv_readdirplus (nfsd=0xc3bb4500,  
> slp=0xc3d31900, td=0xc3b0be00, mrq=0xd61f8c58) at /usr/src/sys/ 
> nfsserver/nfs_serv.c:3640
> #12 0xc08de4b4 in nfssvc (td=0xc3b0be00, uap=0xd61f8cfc) at /usr/ 
> src/sys/nfsserver/nfs_syscalls.c:469
> #13 0xc09f36d3 in syscall (frame=0xd61f8d38) at /usr/src/sys/i386/ 
> i386/trap.c:1006
> #14 0xc09d9a70 in Xint0x80_syscall () at /usr/src/sys/i386/i386/ 
> exception.s:196
> #15 0x00000033 in ?? ()
> Previous frame inner to this frame (corrupt stack?)
> (kgdb) list *0xc08d088d
> 0xc08d088d is in nfsrv_readdirplus (/usr/src/sys/nfsserver/ 
> nfs_serv.c:3640).
> 3635                             */
> 3636                            if (VFS_VGET(vp->v_mount, dp- 
> >d_fileno, LK_EXCLUSIVE,
> 3637                                &nvp))
> 3638                                    goto invalid;
> 3639                            bzero((caddr_t)nfhp, NFSX_V3FH);
> 3640                            nfhp->fh_fsid =
> 3641                                    nvp->v_mount->mnt_stat.f_fsid;
> 3642                            /*
> 3643                             * XXXRW: Assert the mountpoints  
> are the same so that
> 3644                             * we know that acquiring Giant  
> based on the
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