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[PATCH] md: new sysfs interface for setting bits in the write-intent-bitmap

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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 <neilb@suse.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
This commit is contained in:
Paul Clements
2006-10-03 01:15:49 -07:00
committed by Linus Torvalds
parent 76186dd8b7
commit 9b1d1dac18
4 changed files with 56 additions and 0 deletions
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31
drivers/md/md.c
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@@ -2523,6 +2523,36 @@ new_dev_store(mddev_t *mddev, const char *buf, size_t len)
static struct md_sysfs_entry md_new_device =
__ATTR(new_dev, S_IWUSR, null_show, new_dev_store);
static ssize_t
bitmap_store(mddev_t *mddev, const char *buf, size_t len)
{
char *end;
unsigned long chunk, end_chunk;
if (!mddev->bitmap)
goto out;
/* buf should be <chunk> <chunk> ... or <chunk>-<chunk> ... (range) */
while (*buf) {
chunk = end_chunk = simple_strtoul(buf, &end, 0);
if (buf == end) break;
if (*end == '-') { /* range */
buf = end + 1;
end_chunk = simple_strtoul(buf, &end, 0);
if (buf == end) break;
}
if (*end && !isspace(*end)) break;
bitmap_dirty_bits(mddev->bitmap, chunk, end_chunk);
buf = end;
while (isspace(*buf)) buf++;
}
bitmap_unplug(mddev->bitmap); /* flush the bits to disk */
out:
return len;
}
static struct md_sysfs_entry md_bitmap =
__ATTR(bitmap_set_bits, S_IWUSR, null_show, bitmap_store);
static ssize_t
size_show(mddev_t *mddev, char *page)
{
@@ -2843,6 +2873,7 @@ static struct attribute *md_redundancy_attrs[] = {
&md_sync_completed.attr,
&md_suspend_lo.attr,
&md_suspend_hi.attr,
&md_bitmap.attr,
NULL,
};
static struct attribute_group md_redundancy_group = {