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.
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().
Thanks,
Edward.
It seems that nobody cares about it..
It's just ATA interface does not provide necessary data.
OK, so our precise discard extension is waiting for the
best times..
I hope we'll be able to merge it eventually (esp. the final patch which
accounts for non-idempotence of check-and-allocate-blocks).
Thanks,
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