PANIC at zfs_dir.c:784:zfs_link_create()

[nedbass]

Probably related to #3195. The filesystem has xattr=sa set.

ZFS: Loaded module v0.6.3-246_g8120888 (DEBUG mode), ZFS pool version 5000, ZFS filesystem version 5
 vda: vda1 vda9
SPL: using hostid 0x00000000
VERIFY(error == 0) failed
PANIC at zfs_dir.c:784:zfs_link_create()
Showing stack for process 6836
Pid: 6836, comm: mktemp Not tainted 2.6.32-431.23.3.1chaos.ch5.2.x86_64 #1
Call Trace:
 [<ffffffffa03ce8ad>] ? spl_dumpstack+0x3d/0x40 [spl]
 [<ffffffffa03ceaa2>] ? spl_panic+0xc2/0xe0 [spl]
 [<ffffffff81000a64>] ? _stext+0x8cc/0xe68
 [<ffffffff8100add6>] ? ftrace_call+0x5/0x2b
 [<ffffffff8152c309>] ? _cond_resched+0x9/0x40
 [<ffffffffa04ccebb>] ? dbuf_rele+0x6b/0xb0 [zfs]
 [<ffffffffa04ce40e>] ? dmu_buf_rele+0xe/0x10 [zfs]
 [<ffffffffa057b870>] ? zap_unlockdir+0xf0/0x190 [zfs]
 [<ffffffffa057ccc3>] ? zap_add+0xf3/0x1f0 [zfs]
 [<ffffffffa0589860>] ? zfs_link_create+0x680/0x720 [zfs]
 [<ffffffff8152cc89>] ? mutex_unlock+0x9/0x20
 [<ffffffffa05ac0f0>] ? zfs_create+0x670/0x8d0 [zfs]
 [<ffffffffa05d139c>] ? zpl_create+0x9c/0x1d0 [zfs]
 [<ffffffff810f1516>] ? ftrace_test_stop_func+0x16/0x20
 [<ffffffff8100add6>] ? ftrace_call+0x5/0x2b
 [<ffffffff81199586>] ? vfs_create+0xe6/0x110
 [<ffffffff8119d5ce>] ? do_filp_open+0xa8e/0xd20
 [<ffffffff811a98c1>] ? expand_files+0x21/0x220
 [<ffffffff811a9b52>] ? alloc_fd+0x92/0x160
 [<ffffffff81186c89>] ? do_sys_open+0x69/0x140
 [<ffffffff8100add6>] ? ftrace_call+0x5/0x2b
 [<ffffffff81186da0>] ? sys_open+0x20/0x30
 [<ffffffff8100b0b2>] ? system_call_fastpath+0x16/0x1b

Was using this stress test that writes random xattr to the directory while creating, removing, and writing data to files.

#!/bin/bash

DIR=$1
MAX_WRITE_SIZE=131072
DIR_LEN=`echo -n $DIR | wc -c`
MAX_FILENAME_LEN=$(( 255 - $DIR_LEN ))

if [ -z "$DIR" ] ; then
        echo "Usage: $0 <zfs directory>"
        exit  1
fi

shopt -s nullglob

randsleep()
{
        local MAXSLEEP=${1:-'30'}
        sleep $(( $RANDOM % $MAXSLEEP ))
}

randbase64()
{
        local MAXBYTES=${1:-'4096'}
        dd if=/dev/urandom bs=1 count=$(( $RANDOM % $MAXBYTES )) 2>/dev/null |
                openssl enc -a -A
}

coinflip()
{
        if [ 50 -gt $(( $RANDOM % 100 )) ] ; then
                return 0
        else
                return 1
        fi
}

killjobs()
{
        jobs -p | xargs kill
}

# Create randomly named files.
while :; do
        for ((i=0; i< $(( $RANDOM % 256 )); i++)) ; do
                len=$(( 3 + $(( $RANDOM % $(( MAX_FILENAME_LEN - 3 ))))))
                template=`perl -e 'print "X" x $ARGV[0]' $len`
                mktemp /tank/fish/$template > /dev/null
        done
        randsleep
done &

# Write some data to each file.
while :; do
        randsleep
        for f in $DIR/* ; do
                dd oflag=nofollow if=/dev/urandom of="$f" bs=512 \
                        count=$(( $RANDOM % $(( MAX_WRITE_SIZE / 512)))) \
                        2>/dev/null
        done
done &

# Randomly remove files.
while :; do
        randsleep
        for f in $DIR/* ; do
                if coinflip ; then
                        rm "$f" 2>/dev/null
                fi
        done
done &

# Write random xattr values to the directory or remove them.
while :; do
        sleep .5
        if coinflip ; then
                v=`randbase64`
                setfattr -h -n trusted.foo -v 0s$v $DIR 2>/dev/null
        else
                setfattr -h -x trusted.foo $DIR 2>/dev/null
        fi
done &

trap killjobs SIGINT

if [ -n "$2" ] ; then
        sleep $2
        killjobs
else
        wait
fi

[nedbass]

Code snippet for the ASSERT.

        error = zap_add(ZTOZSB(zp)->z_os, dzp->z_id, dl->dl_name,
            8, 1, &value, tx); 
        ASSERT(error == 0);