The sysfs nodes under bitmap are not recorded in md.4, add them based on md.rst and kernel source code. Cc: NeilBrown <neilb@xxxxxxxx> Signed-off-by: Guoqing Jiang <gqjiang@xxxxxxxx> --- Hi, Please feel free to correct the descriptions since my understanding could be wrong. Thanks, Guoqing md.4 | 57 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 57 insertions(+) diff --git a/md.4 b/md.4 index 3a1d6777e5b7..e81f38e40e77 100644 --- a/md.4 +++ b/md.4 @@ -1101,6 +1101,63 @@ stripe that requires some "prereading". For fairness this defaults to maximizes sequential-write throughput at the cost of fairness to threads doing small or random writes. +.TP +.B md/bitmap/backlog +This is only available on RAID1. when write-mostly devices are active, +write requests to those devices proceed in the background. + +This variable sets a limit on the number of concurrent background writes, +the valid values are 0 to 256, 0 means that write-behind is not allowed, +while any other number means it can happen. If there are more write request +than the number, new writes will by synchronous. + +.TP +.B md/bitmap/can_clear +Write 'true' to 'bitmap/can_clear' will allow bits in the bitmap to be +cleared again, write 'false' means bits in the bitmap don't need to be +cleared. + +.TP +.B md/bitmap/chunksize +The bitmap chunksize can only be changed when no bitmap is active, and +the value should be power of 2 and bigger than 512. + +.TP +.B md/bitmap/location +This indicates where the write-intent bitmap for the array is stored. + +Write 'none' to 'bitmap/location' will clear bitmap, and the previous +location value must be write to it to restore bitmap. + +.TP +.B md/bitmap/max_backlog_used +This keeps track of the maximum number of concurrent write-behind requests +for an md array, writing any value to this file will clear it. + +.TP +.B md/bitmap/metadata +This can be either 'internal' or 'external'. 'internal' is set by default, +which means the metadata for bitmap is stored in the first 256 bytes of +the bitmap space. 'external' means that bitmap metadata is managed externally +to the kernel. + +.TP +.B md/bitmap/space +This shows the space (in sectors) which is available at md/bitmap/location, +and allows the kernel to know when it is safe to resize the bitmap to match +a resized array. It should big enough to contain the total bytes in the bitmap. + +For 1.0 metadata, assume we can use up to the superblock if before, else +to 4K beyond superblock. For other metadata versions, assume no change is +possible. + +.TP +.B md/bitmap/time_base +This shows the time (in seconds) between disk flushes, and is used to looking +for bits in the bitmap to be cleared. + +The default value is 5 seconds, and it should be an unsigned long value. + .SS KERNEL PARAMETERS The md driver recognised several different kernel parameters. -- 2.12.3
