On 11/9/18 12:21 PM, Andy Grover wrote:
As mentioned elsewhere in dm-integrity.txt, creating a new integrity
device requires creating a small integrity device on top of the base
device that formats the base device, reading the provided data sectors
out of the superblock, and then recreating the integrity device with the
correct size. For this, userspace must know the offset, length, and
endianness of the provided_data_sectors field in the superblock.
Document all fields mentioned in the txt to include this, based on struct
superblock in dm-integrity.c. Extra fields in struct superblock not
already mentioned in the txt remain undocumented.
In 4.19 I just noticed provided_data_sectors is now included in dm
status. I'm assuming that is now the preferred way for userspace to
discover this value? Thus making reading it from the on-disk superblock
unnecessary, and thus *documenting* the superblock format unnecessary.
Sounds good.
So please disregard this patch, although some different documentation
changes are probably now needed.
Thanks -- Regards -- Andy
p.s. I'd just run across an issue where creating an integrity device on
a loopback device would result in the superblock still reading as all
zeroes. Another reason to do it the new way :)
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