[LU-11770] preserve kernel API when T10-PI patches are applied

• Type: Bug
• Resolution: Fixed
• Priority: Minor
• Fix Version/s: Lustre 2.13.0, Lustre 2.12.4
• Affects Version/s: Lustre 2.12.0
• Severity: 3
• Assignee: Andreas Dilger
• Reporter: Andreas Dilger

Description

Preserve the existing kernel API when the T10-PI patches are applied, so that any other modules using this interface do not break.

In particular, keep the EXPORT_SYMBOL(bio_integrity_alloc) and EXPORT_SYMBOL(bio_integrity_prep) in place.

In struct bio_integrity_payload put *bip_generate_fn and *bip_verify_fn after *bip_vec since that field is directly accessed by callers. In struct blk_integrity_exchg the bi_idx field only needs to be an unsigned short since the bio->bi_idx and bio->bi_vcnt values used with it are also unsigned short, which saves 8 bytes of padding in the struct and puts the added fields at the end to preserve the structure field alignment.

Issue Links

• is related to: LU-11822 what does this mean nbp16-OST0004: unsupported T10PI type ''
• is related to: LU-11712 Lustre build fails when CONFIG_BLK_DEV_INTEGRITY is unset
• is related to: LU-10472 Data Integrity(T10PI) support for Lustre