Find that zio->io_offset is the absolute offset of device, not in sector
unit. And If we need use zdb -R to dump the block, we should use the offset
(zio->io_offset-0x400000).
2009/6/25 zhihui Chen <zhch...@gmail.com>
> I use following dtrace script to trace the postion of one file on zfs:
>
> #!/usr/sbin/dtrace -qs
> zio_done:entry
> /((zio_t *)(arg0))->io_vd/
> {
> zio=(zio_t *)arg0;
> printf("Offset:%x and Size:%x\n",zio->io_offset,zio->io_size);
> printf("vd:%x\n",(unsigned long)(zio->io_vd));
> printf("process name:%s\n",execname);
> tracemem(zio->io_data,40);
> stack();
> }
>
> and I run dd command: "dd if=/export/dsk1/test1 bs=512 count=1", the
> dtrace script will generate following it output:
>
> Offset:657800 and Size:200
> vd:ffffff02d6a1a700
> process name:sched
> aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa
> zfs`zio_execute+0xa0
> genunix`taskq_thread+0x193
> unix`thread_start+0x8
> ^C
>
> The tracemem output is the right context of file test1, which is a 512-byte
> text file. "zpool status" has following output:
>
> pool: tpool
> state: ONLINE
> scrub: none requested
> config:
> NAME STATE READ WRITE CKSUM
> tpool ONLINE 0 0 0
> c2t0d0 ONLINE 0 0 0
> errors: No known data errors
>
> My question is how to translate zio->io_offset (0x657800, equal to decimal
> number 6649856) outputed by dtace to block number on disk c2t0d0?
> I tried to use "dd if=/dev/dsk/c2t0d0 of=text iseek=6650112 bs=512 count=1"
> for a check,but the result is not right.
>
> Thanks
> Zhihui
>
>
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