On 2015-07-05 at 21:46 +0800, Edward Shishkin wrote: > > On 07/05/2015 09:08 PM, Ivan Shapovalov wrote: > > On 2015-07-05 at 02:33 +0800, Edward Shishkin wrote: > > > On 07/05/2015 01:53 AM, Ivan Shapovalov wrote: > > > > On 2015-07-04 at 15:53 +0800, Edward Shishkin wrote: > > > > > [...] > > > > > And how to test directly at mount time? > > > > Something along the lines of > > > > - allocate 1 MiB of contiguous space > > > > - fill it with non-zeros > > > > - for N = 1, 2, 4, ...: > > > > - discard N sectors from the contiguous space > > > > - check if anything in the discarded space became zero > > > > -filled > > > > - if it did, infer alignnment from the first zero-filled > > > > block, > > > > infer granularity from the zero-filled region size. > > > > > > mkfs seems to be more suitable for this funny business > > Yeah, sure. So... new superblock format with two extra fields? > > > The change will be forward and backward compatible, so there is no > need in a new format. Just add two new fields to the superblock40. So there will be zeroes in case we mount a non-aware filesystem, correct? > > Also people will want to "mount -o discard" when discard parameters > are not known. In this case I think to provide them > discard_extents(). > which is currently merged. Otherwise use discard_precise_extents(). Yeah. I'll do something with this after I finish porting ->write() to ->write_iter() (or if I run into heavy problems with that). Thanks, -- Ivan Shapovalov / intelfx /
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