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Diffstat (limited to 'Documentation/block/data-integrity.rst')
| -rw-r--r-- | Documentation/block/data-integrity.rst | 49 |
1 files changed, 3 insertions, 46 deletions
diff --git a/Documentation/block/data-integrity.rst b/Documentation/block/data-integrity.rst index 6a760c0eb192..99905e880a0e 100644 --- a/Documentation/block/data-integrity.rst +++ b/Documentation/block/data-integrity.rst @@ -153,18 +153,11 @@ bio_free() will automatically free the bip. 4.2 Block Device ---------------- -Because the format of the protection data is tied to the physical -disk, each block device has been extended with a block integrity -profile (struct blk_integrity). This optional profile is registered -with the block layer using blk_integrity_register(). - -The profile contains callback functions for generating and verifying -the protection data, as well as getting and setting application tags. -The profile also contains a few constants to aid in completing, -merging and splitting the integrity metadata. +Block devices can set up the integrity information in the integrity +sub-struture of the queue_limits structure. Layered block devices will need to pick a profile that's appropriate -for all subdevices. blk_integrity_compare() can help with that. DM +for all subdevices. queue_limits_stack_integrity() can help with that. DM and MD linear, RAID0 and RAID1 are currently supported. RAID4/5/6 will require extra work due to the application tag. @@ -250,42 +243,6 @@ will require extra work due to the application tag. integrity upon completion. -5.4 Registering A Block Device As Capable Of Exchanging Integrity Metadata --------------------------------------------------------------------------- - - To enable integrity exchange on a block device the gendisk must be - registered as capable: - - `int blk_integrity_register(gendisk, blk_integrity);` - - The blk_integrity struct is a template and should contain the - following:: - - static struct blk_integrity my_profile = { - .name = "STANDARDSBODY-TYPE-VARIANT-CSUM", - .generate_fn = my_generate_fn, - .verify_fn = my_verify_fn, - .tuple_size = sizeof(struct my_tuple_size), - .tag_size = <tag bytes per hw sector>, - }; - - 'name' is a text string which will be visible in sysfs. This is - part of the userland API so chose it carefully and never change - it. The format is standards body-type-variant. - E.g. T10-DIF-TYPE1-IP or T13-EPP-0-CRC. - - 'generate_fn' generates appropriate integrity metadata (for WRITE). - - 'verify_fn' verifies that the data buffer matches the integrity - metadata. - - 'tuple_size' must be set to match the size of the integrity - metadata per sector. I.e. 8 for DIF and EPP. - - 'tag_size' must be set to identify how many bytes of tag space - are available per hardware sector. For DIF this is either 2 or - 0 depending on the value of the Control Mode Page ATO bit. - ---------------------------------------------------------------------- 2007-12-24 Martin K. Petersen <martin.petersen@oracle.com> |