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Diffstat (limited to 'Documentation/block/data-integrity.rst')
| -rw-r--r-- | Documentation/block/data-integrity.rst | 51 |
1 files changed, 4 insertions, 47 deletions
diff --git a/Documentation/block/data-integrity.rst b/Documentation/block/data-integrity.rst index 07a97aa26668..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. @@ -209,7 +202,7 @@ will require extra work due to the application tag. sector must be set, and the bio should have all data pages added. It is up to the caller to ensure that the bio does not change while I/O is in progress. - Complete bio with error if prepare failed for some reson. + Complete bio with error if prepare failed for some reason. 5.3 Passing Existing Integrity Metadata @@ -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> |