On 08/10/2015 05:29 AM, Roman Peniaev wrote:
On Mon, Jul 27, 2015 at 11:13 PM, Jens Axboe <axboe@xxxxxxxxx> wrote:
On 07/24/2015 01:49 PM, Roman Pen wrote:
fio does not provide any possibility to verify checksum of a block with
meta
information inside. You can create configuration for verifincation
checksum
of random data either you can verify meta information with some pattern or
random data, but not both.
Why checksumming and meta together can be useful? Meta helps to figure out
internally
on filesystem or storage what block was written in case of corruption,
i.e. offset
of the block and block number explicitly tell us the virtual address of
the block.
On the other hand checksum of random data helps to detect corruption.
Using meta
and pattern together do not help a lot, since 'verify_interval' can be big
enough
and same sequence of pattern bytes will be undistinguishable internally on
filesystem
or storage.
Also, it seems to me that keeping meta header separately from generic
verify header
does not make a lot of sense, since generic verify header can include all
members
of meta header without any performance or other impact.
In this patch I move all members from vhdr_meta structure to generic
verify_header,
always verifying meta with the possiblity to checksum the following data:
random
or pattern.
You are allowed to specify verify_pattern=str with any of the possible
verification
methods and have also meta verification, i.e.
verify=md5
verify_pattern=0xfe
or
verify=sha1
verify_pattern=0xff
etc.
To keep everything compatible with old configurations it is still possible
to specify
verify=meta
but this option marked and depricated and kept only for compatibility
reasons.
Before that patch the verification layout according to the specified
options looks
as the following, e.g.:
#1
--
verify=meta
verify_pattern=0xff
--
result layout of each block: [hdr|meta|pattern]
#2
--
verify_pattern=0xff
--
result layout of each block: [hdr|pattern]
#3
--
verify=pattern
verify_pattern=0xff
--
result layout of each block: [pattern]
After applying of the patch 'vhdr_meta' is always embedded into
'verify_header' and layout
looks as the following, e.g.:
#1
--
verify=meta
verify_pattern=0xff
--
result layout of each block: [hdr+meta|pattern]
#2
--
verify=md5|sha1|etc
verify_pattern=0xff
--
result layout of each block: [hdr+meta|cksum|pattern]
#3
--
verify_pattern=0xff
--
result layout of each block: [hdr+meta|pattern]
#4
--
verify=pattern
verify_pattern=0xff
--
result layout of each block: [pattern]
Good work! I'll make some time this week to fully review this, so we can get
it committed.
Hi, Jens.
Do you still have plans to review this patch?
I do, vacation came in the way, however. Back now, will get to it this week.
--
Jens Axboe
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