NeilBrown 688834e6ae md/failfast: add failfast flag for md to be used by some personalities. ... This patch just adds a 'failfast' per-device flag which can be stored in v0.90 or v1.x metadata. The flag is not used yet but the intent is that it can be used for mirrored (raid1/raid10) arrays where low latency is more important than keeping all devices on-line. Setting the flag for a device effectively gives permission for that device to be marked as Faulty and excluded from the array on the first error. The underlying driver will be directed not to retry requests that result in failures. There is a proviso that the device must not be marked faulty if that would cause the array as a whole to fail, it may only be marked Faulty if the array remains functional, but is degraded. Failures on read requests will cause the device to be marked as Faulty immediately so that further reads will avoid that device. No attempt will be made to correct read errors by over-writing with the correct data. It is expected that if transient errors, such as cable unplug, are possible, then something in user-space will revalidate failed devices and re-add them when they appear to be working again. Signed-off-by: NeilBrown <neilb@suse.com> Signed-off-by: Shaohua Li <shli@fb.com>		2016-11-22 08:58:17 -08:00
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Kbuild
md_p.h	md/failfast: add failfast flag for md to be used by some personalities.	2016-11-22 08:58:17 -08:00
md_u.h	drivers: md: use ktime_get_real_seconds()	2016-01-06 11:39:53 +11:00