From 9b1d1dac181d8c1b9492e05cee660a985d035a06 Mon Sep 17 00:00:00 2001
From: Paul Clements <paul.clements@steeleye.com>
Date: Tue, 3 Oct 2006 01:15:49 -0700
Subject: [PATCH] [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 <neilb@suse.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
---
Documentation/md.txt | 9 +++++++++
drivers/md/bitmap.c | 14 ++++++++++++++
drivers/md/md.c | 31 +++++++++++++++++++++++++++++++
include/linux/raid/bitmap.h | 2 ++
4 files changed, 56 insertions(+)
diff --git a/Documentation/md.txt b/Documentation/md.txt
index 0668f9dc9d296..084ecf4eb2f87 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
diff --git a/drivers/md/bitmap.c b/drivers/md/bitmap.c
index ecc56765d949e..0a44298fb3535 100644
--- a/drivers/md/bitmap.c
+++ b/drivers/md/bitmap.c
@@ -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
*/
diff --git a/drivers/md/md.c b/drivers/md/md.c
index 8b08043f07ef0..b95dd8a183ec9 100644
--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -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 = {
diff --git a/include/linux/raid/bitmap.h b/include/linux/raid/bitmap.h
index 63df898fe2e95..84d8877518555 100644
--- a/include/linux/raid/bitmap.h
+++ b/include/linux/raid/bitmap.h
@@ -265,6 +265,8 @@ int bitmap_update_sb(struct bitmap *bitmap);
int bitmap_setallbits(struct bitmap *bitmap);
void bitmap_write_all(struct bitmap *bitmap);
+void bitmap_dirty_bits(struct bitmap *bitmap, unsigned long s, unsigned long e);
+
/* these are exported */
int bitmap_startwrite(struct bitmap *bitmap, sector_t offset,
unsigned long sectors, int behind);
--
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