os/bluestore: attach csum for compressed blobs

[ifed01]

Fixes: https://tracker.ceph.com/issues/47475
Signed-off-by: Igor Fedotov ifedotov@suse.com

Checklist

• References tracker ticket
• Updates documentation if necessary
• Includes tests for new functionality or reproducer for bug

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[tchaikov]

• https://pulpito.ceph.com/kchai-2020-09-16_14:28:48-rados-wip-kefu-testing-2020-09-16-1741-distro-basic-smithi/
• https://pulpito.ceph.com/kchai-2020-09-17_08:46:35-rados-wip-kefu-testing-2020-09-17-1122-distro-basic-smithi/

[aclamk]

@ifed01 But hasn't it been an assumption that compressors will sanitize its content?
You think its ability for error detection might not be sufficient?

[ifed01]

@ifed01 But hasn't it been an assumption that compressors will sanitize its content?
You think its ability for error detection might not be sufficient?

The following ticket has inspired me for this fix: https://tracker.ceph.com/issues/46490
While the root cause for disk read failures is still unclear there one of their consequence is an assertion during decoding of improperly read (and hence invalid) compression header.
Generally I think that's a good idea to have csum for this sort of data, I presume the overhead is neglectable.

[aclamk]

Tested, works.
This is good improvement.