* Btrfs allow compression on NoDataCow files? (AFAIK Not, but it does)
@ 2017-12-20 20:59 Timofey Titovets
2017-12-21 18:51 ` Chris Mason
2018-01-02 18:44 ` Liu Bo
0 siblings, 2 replies; 4+ messages in thread
From: Timofey Titovets @ 2017-12-20 20:59 UTC (permalink / raw)
To: linux-btrfs
How reproduce:
touch test_file
chattr +C test_file
dd if=/dev/zero of=test_file bs=1M count=1
btrfs fi def -vrczlib test_file
filefrag -v test_file
test_file
Filesystem type is: 9123683e
File size of test_file is 1048576 (256 blocks of 4096 bytes)
ext: logical_offset: physical_offset: length: expected: flags:
0: 0.. 31: 72917050.. 72917081: 32: encoded
1: 32.. 63: 72917118.. 72917149: 32: 72917082: encoded
2: 64.. 95: 72919494.. 72919525: 32: 72917150: encoded
3: 96.. 127: 72927576.. 72927607: 32: 72919526: encoded
4: 128.. 159: 72943261.. 72943292: 32: 72927608: encoded
5: 160.. 191: 72944929.. 72944960: 32: 72943293: encoded
6: 192.. 223: 72944952.. 72944983: 32: 72944961: encoded
7: 224.. 255: 72967084.. 72967115: 32: 72944984:
last,encoded,eof
test_file: 8 extents found
I can't found at now, where that error happen in code,
but it's reproducible on Linux 4.14.8
Thanks.
--
Have a nice day,
Timofey.
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: Btrfs allow compression on NoDataCow files? (AFAIK Not, but it does)
2017-12-20 20:59 Btrfs allow compression on NoDataCow files? (AFAIK Not, but it does) Timofey Titovets
@ 2017-12-21 18:51 ` Chris Mason
2017-12-22 23:58 ` Kai Krakow
2018-01-02 18:44 ` Liu Bo
1 sibling, 1 reply; 4+ messages in thread
From: Chris Mason @ 2017-12-21 18:51 UTC (permalink / raw)
To: Timofey Titovets, linux-btrfs
On 12/20/2017 03:59 PM, Timofey Titovets wrote:
> How reproduce:
> touch test_file
> chattr +C test_file
> dd if=/dev/zero of=test_file bs=1M count=1
> btrfs fi def -vrczlib test_file
> filefrag -v test_file
>
> test_file
> Filesystem type is: 9123683e
> File size of test_file is 1048576 (256 blocks of 4096 bytes)
> ext: logical_offset: physical_offset: length: expected: flags:
> 0: 0.. 31: 72917050.. 72917081: 32: encoded
> 1: 32.. 63: 72917118.. 72917149: 32: 72917082: encoded
> 2: 64.. 95: 72919494.. 72919525: 32: 72917150: encoded
> 3: 96.. 127: 72927576.. 72927607: 32: 72919526: encoded
> 4: 128.. 159: 72943261.. 72943292: 32: 72927608: encoded
> 5: 160.. 191: 72944929.. 72944960: 32: 72943293: encoded
> 6: 192.. 223: 72944952.. 72944983: 32: 72944961: encoded
> 7: 224.. 255: 72967084.. 72967115: 32: 72944984:
> last,encoded,eof
> test_file: 8 extents found
>
> I can't found at now, where that error happen in code,
> but it's reproducible on Linux 4.14.8
We'll silently cow in a few cases, this is one.
-chris
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: Btrfs allow compression on NoDataCow files? (AFAIK Not, but it does)
2017-12-21 18:51 ` Chris Mason
@ 2017-12-22 23:58 ` Kai Krakow
0 siblings, 0 replies; 4+ messages in thread
From: Kai Krakow @ 2017-12-22 23:58 UTC (permalink / raw)
To: linux-btrfs
Am Thu, 21 Dec 2017 13:51:40 -0500 schrieb Chris Mason:
> On 12/20/2017 03:59 PM, Timofey Titovets wrote:
>> How reproduce:
>> touch test_file
>> chattr +C test_file
>> dd if=/dev/zero of=test_file bs=1M count=1
>> btrfs fi def -vrczlib test_file
>> filefrag -v test_file
>>
>> test_file
>> Filesystem type is: 9123683e
>> File size of test_file is 1048576 (256 blocks of 4096 bytes)
>> ext: logical_offset: physical_offset: length: expected: flags:
>> 0: 0.. 31: 72917050.. 72917081: 32: encoded
>> 1: 32.. 63: 72917118.. 72917149: 32: 72917082: encoded
>> 2: 64.. 95: 72919494.. 72919525: 32: 72917150: encoded
>> 3: 96.. 127: 72927576.. 72927607: 32: 72919526: encoded
>> 4: 128.. 159: 72943261.. 72943292: 32: 72927608: encoded
>> 5: 160.. 191: 72944929.. 72944960: 32: 72943293: encoded
>> 6: 192.. 223: 72944952.. 72944983: 32: 72944961: encoded
>> 7: 224.. 255: 72967084.. 72967115: 32: 72944984:
>> last,encoded,eof
>> test_file: 8 extents found
>>
>> I can't found at now, where that error happen in code,
>> but it's reproducible on Linux 4.14.8
>
> We'll silently cow in a few cases, this is one.
I think the question was about compression, not cow.
I can reproduce this behavior:
$ touch nocow.dat
$ touch cow.dat
$ chattr +c cow.dat
$ chattr +C nocow.dat
$ dd if=/dev/zero of=cow.dat count=1 bs=1M
$ dd if=/dev/zero of=nocow.dat count=1 bs=1M
$ filefrag -v cow.dat
Filesystem type is: 9123683e
File size of cow.dat is 1048576 (256 blocks of 4096 bytes)
ext: logical_offset: physical_offset: length: expected: flags:
0: 0.. 31: 1044845154..1044845185: 32: encoded,shared
1: 32.. 63: 1044845166..1044845197: 32: 1044845186: encoded,shared
2: 64.. 95: 1044845167..1044845198: 32: 1044845198: encoded,shared
3: 96.. 127: 1044851064..1044851095: 32: 1044845199: encoded,shared
4: 128.. 159: 1044851065..1044851096: 32: 1044851096: encoded,shared
5: 160.. 191: 1044852160..1044852191: 32: 1044851097: encoded,shared
6: 192.. 223: 1044943106..1044943137: 32: 1044852192: encoded,shared
7: 224.. 255: 1045054792..1045054823: 32: 1044943138: last,encoded,shared,eof
cow.dat: 8 extents found
$ filefrag -v nocow.dat
Filesystem type is: 9123683e
File size of nocow.dat is 1048576 (256 blocks of 4096 bytes)
ext: logical_offset: physical_offset: length: expected: flags:
0: 0.. 255: 1196077983..1196078238: 256: last,shared,eof
nocow.dat: 1 extent found
Now it seems to be compressed (8x 128k extents):
$ filefrag -v nocow.dat
Filesystem type is: 9123683e
File size of nocow.dat is 1048576 (256 blocks of 4096 bytes)
ext: logical_offset: physical_offset: length: expected: flags:
0: 0.. 31: 1121866367..1121866398: 32: encoded,shared
1: 32.. 63: 1121866369..1121866400: 32: 1121866399: encoded,shared
2: 64.. 95: 1121866370..1121866401: 32: 1121866401: encoded,shared
3: 96.. 127: 1121866371..1121866402: 32: 1121866402: encoded,shared
4: 128.. 159: 1121866372..1121866403: 32: 1121866403: encoded,shared
5: 160.. 191: 1121866373..1121866404: 32: 1121866404: encoded,shared
6: 192.. 223: 1121866374..1121866405: 32: 1121866405: encoded,shared
7: 224.. 255: 1121866375..1121866406: 32: 1121866406: last,encoded,shared,eof
nocow.dat: 8 extents found
--
Regards,
Kai
Replies to list-only preferred.
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: Btrfs allow compression on NoDataCow files? (AFAIK Not, but it does)
2017-12-20 20:59 Btrfs allow compression on NoDataCow files? (AFAIK Not, but it does) Timofey Titovets
2017-12-21 18:51 ` Chris Mason
@ 2018-01-02 18:44 ` Liu Bo
1 sibling, 0 replies; 4+ messages in thread
From: Liu Bo @ 2018-01-02 18:44 UTC (permalink / raw)
To: Timofey Titovets; +Cc: linux-btrfs
On Wed, Dec 20, 2017 at 11:59:20PM +0300, Timofey Titovets wrote:
> How reproduce:
> touch test_file
> chattr +C test_file
> dd if=/dev/zero of=test_file bs=1M count=1
> btrfs fi def -vrczlib test_file
> filefrag -v test_file
>
> test_file
> Filesystem type is: 9123683e
> File size of test_file is 1048576 (256 blocks of 4096 bytes)
> ext: logical_offset: physical_offset: length: expected: flags:
> 0: 0.. 31: 72917050.. 72917081: 32: encoded
> 1: 32.. 63: 72917118.. 72917149: 32: 72917082: encoded
> 2: 64.. 95: 72919494.. 72919525: 32: 72917150: encoded
> 3: 96.. 127: 72927576.. 72927607: 32: 72919526: encoded
> 4: 128.. 159: 72943261.. 72943292: 32: 72927608: encoded
> 5: 160.. 191: 72944929.. 72944960: 32: 72943293: encoded
> 6: 192.. 223: 72944952.. 72944983: 32: 72944961: encoded
> 7: 224.. 255: 72967084.. 72967115: 32: 72944984:
> last,encoded,eof
> test_file: 8 extents found
>
> I can't found at now, where that error happen in code,
> but it's reproducible on Linux 4.14.8
>
Please check the comments in this function need_force_cow(),
* Force cow if given extent needs to be defragged.
and using zlib makes it compress the data.
Thanks,
-liubo
^ permalink raw reply [flat|nested] 4+ messages in thread
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2017-12-20 20:59 Btrfs allow compression on NoDataCow files? (AFAIK Not, but it does) Timofey Titovets
2017-12-21 18:51 ` Chris Mason
2017-12-22 23:58 ` Kai Krakow
2018-01-02 18:44 ` Liu Bo
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