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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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14
drivers/md/bitmap.c
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@ -613,6 +613,7 @@ static inline unsigned long file_page_offset(unsigned long chunk)
static inline struct page *filemap_get_page(struct bitmap *bitmap,
unsigned long chunk)
{
if (file_page_index(chunk) >= bitmap->file_pages) return NULL;
return bitmap->filemap[file_page_index(chunk) - file_page_index(0)];
}
@ -739,6 +740,7 @@ static void bitmap_file_set_bit(struct bitmap *bitmap, sector_t block)
}
page = filemap_get_page(bitmap, chunk);
if (!page) return;
bit = file_page_offset(chunk);
/* set the bit */
@ -1322,6 +1324,18 @@ static void bitmap_set_memory_bits(struct bitmap *bitmap, sector_t offset, int n
}
/* dirty the memory and file bits for bitmap chunks "s" to "e" */
void bitmap_dirty_bits(struct bitmap *bitmap, unsigned long s, unsigned long e)
{
unsigned long chunk;
for (chunk = s; chunk <= e; chunk++) {
sector_t sec = chunk << CHUNK_BLOCK_SHIFT(bitmap);
bitmap_set_memory_bits(bitmap, sec, 1);
bitmap_file_set_bit(bitmap, sec);
}
}
/*
* flush out any pending updates
*/