On 2016-02-09 at 18:53 +0100, Edward Shishkin wrote: > Hi all, > > There is a pending patch for precise discarsd, which I can not merge > because it is incomplete. Just want to know, is there any progress on > this? > > So we found that calculating discard params by mkfs and storing > them in superblock is a dirty option, so I suggest to reserve a > contiguous area (1 MiB?) on disk at "mkfs -d" time (just mark it busy > in the bitmap). And calculate erase unit size and offset at mount > time. > If calculation failed for some reasons, then use non-precise discard. > > So, I think, we'll need one d32 field in disk superblock, which > indicates > number of reserved blocks (0 means no reservation) and a pair of > definitions in disk_format40.h: > > #define FORMAT40_FIRST_RESERVED_FOR_PROBING \ > ((REISER4_MASTER_OFFSET / PAGE_CACHE_SIZE) + 6) > #define FORMAT40_MAX_BLOCKS_RESERVED_FOR_PROBING > > If any questions, or technical stoppers, then let me know. > > Thanks, > Edward. > Hello Edward, yes, finishing this is on top of my to-do list (but it is being dequeued at a very slow rate due to the university...). I was under assumption of that we still want to go by path of probing parameters at mkfs time + having a special utility for rewriting these fields. But if you are now ok with probing at mount time, then that's great. I'll try to do something in nearest week or two. -- Ivan Shapovalov / intelfx /
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