From 9b1d1dac181d8c1b9492e05cee660a985d035a06 Mon Sep 17 00:00:00 2001 From: Paul Clements Date: Tue, 3 Oct 2006 01:15:49 -0700 Subject: [PATCH] md: new sysfs interface for setting bits in the write-intent-bitmap Add a new sysfs interface that allows the bitmap of an array to be dirtied. The interface is write-only, and is used as follows: echo "1000" > /sys/block/md2/md/bitmap (dirty the bit for chunk 1000 [offset 0] in the in-memory and on-disk bitmaps of array md2) echo "1000-2000" > /sys/block/md1/md/bitmap (dirty the bits for chunks 1000-2000 in md1's bitmap) This is useful, for example, in cluster environments where you may need to combine two disjoint bitmaps into one (following a server failure, after a secondary server has taken over the array). By combining the bitmaps on the two servers, a full resync can be avoided (This was discussed on the list back on March 18, 2005, "[PATCH 1/2] md bitmap bug fixes" thread). Signed-off-by: Neil Brown Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- Documentation/md.txt | 9 +++++++++ 1 file changed, 9 insertions(+) (limited to 'Documentation/md.txt') diff --git a/Documentation/md.txt b/Documentation/md.txt index 0668f9dc9d2..084ecf4eb2f 100644 --- a/Documentation/md.txt +++ b/Documentation/md.txt @@ -410,6 +410,15 @@ also have than sectors, this my be larger than the number of actual errors by a factor of the number of sectors in a page. + bitmap_set_bits + If the array has a write-intent bitmap, then writing to this + attribute can set bits in the bitmap, indicating that a resync + would need to check the corresponding blocks. Either individual + numbers or start-end pairs can be written. Multiple numbers + can be separated by a space. + Note that the numbers are 'bit' numbers, not 'block' numbers. + They should be scaled by the bitmap_chunksize. + Each active md device may also have attributes specific to the personality module that manages it. These are specific to the implementation of the module and could -- cgit v1.2.3