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Diffstat (limited to 'Documentation/block/data-integrity.txt')
| -rw-r--r-- | Documentation/block/data-integrity.txt | 54 |
1 files changed, 5 insertions, 49 deletions
diff --git a/Documentation/block/data-integrity.txt b/Documentation/block/data-integrity.txt index 2d735b0ae383..f56ec97f0d14 100644 --- a/Documentation/block/data-integrity.txt +++ b/Documentation/block/data-integrity.txt @@ -129,11 +129,11 @@ interface for this is being worked on. 4.1 BIO The data integrity patches add a new field to struct bio when -CONFIG_BLK_DEV_INTEGRITY is enabled. bio->bi_integrity is a pointer -to a struct bip which contains the bio integrity payload. Essentially -a bip is a trimmed down struct bio which holds a bio_vec containing -the integrity metadata and the required housekeeping information (bvec -pool, vector count, etc.) +CONFIG_BLK_DEV_INTEGRITY is enabled. bio_integrity(bio) returns a +pointer to a struct bip which contains the bio integrity payload. +Essentially a bip is a trimmed down struct bio which holds a bio_vec +containing the integrity metadata and the required housekeeping +information (bvec pool, vector count, etc.) A kernel subsystem can enable data integrity protection on a bio by calling bio_integrity_alloc(bio). This will allocate and attach the @@ -192,16 +192,6 @@ will require extra work due to the application tag. supported by the block device. - int bdev_integrity_enabled(block_device, int rw); - - bdev_integrity_enabled() will return 1 if the block device - supports integrity metadata transfer for the data direction - specified in 'rw'. - - bdev_integrity_enabled() honors the write_generate and - read_verify flags in sysfs and will respond accordingly. - - int bio_integrity_prep(bio); To generate IMD for WRITE and to set up buffers for READ, the @@ -216,36 +206,6 @@ will require extra work due to the application tag. bio_integrity_enabled() returned 1. - int bio_integrity_tag_size(bio); - - If the filesystem wants to use the application tag space it will - first have to find out how much storage space is available. - Because tag space is generally limited (usually 2 bytes per - sector regardless of sector size), the integrity framework - supports interleaving the information between the sectors in an - I/O. - - Filesystems can call bio_integrity_tag_size(bio) to find out how - many bytes of storage are available for that particular bio. - - Another option is bdev_get_tag_size(block_device) which will - return the number of available bytes per hardware sector. - - - int bio_integrity_set_tag(bio, void *tag_buf, len); - - After a successful return from bio_integrity_prep(), - bio_integrity_set_tag() can be used to attach an opaque tag - buffer to a bio. Obviously this only makes sense if the I/O is - a WRITE. - - - int bio_integrity_get_tag(bio, void *tag_buf, len); - - Similarly, at READ I/O completion time the filesystem can - retrieve the tag buffer using bio_integrity_get_tag(). - - 5.3 PASSING EXISTING INTEGRITY METADATA Filesystems that either generate their own integrity metadata or @@ -298,8 +258,6 @@ will require extra work due to the application tag. .name = "STANDARDSBODY-TYPE-VARIANT-CSUM", .generate_fn = my_generate_fn, .verify_fn = my_verify_fn, - .get_tag_fn = my_get_tag_fn, - .set_tag_fn = my_set_tag_fn, .tuple_size = sizeof(struct my_tuple_size), .tag_size = <tag bytes per hw sector>, }; @@ -321,7 +279,5 @@ will require extra work due to the application tag. are available per hardware sector. For DIF this is either 2 or 0 depending on the value of the Control Mode Page ATO bit. - See 6.2 for a description of get_tag_fn and set_tag_fn. - ---------------------------------------------------------------------- 2007-12-24 Martin K. Petersen <martin.petersen@oracle.com> |