From: Paul Clements 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 --- 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 -puN Documentation/md.txt~md-new-sysfs-interface-for-setting-bits-in-the-write-intent-bitmap Documentation/md.txt --- a/Documentation/md.txt~md-new-sysfs-interface-for-setting-bits-in-the-write-intent-bitmap +++ a/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 -puN drivers/md/bitmap.c~md-new-sysfs-interface-for-setting-bits-in-the-write-intent-bitmap drivers/md/bitmap.c --- a/drivers/md/bitmap.c~md-new-sysfs-interface-for-setting-bits-in-the-write-intent-bitmap +++ a/drivers/md/bitmap.c @@ -613,6 +613,7 @@ static inline unsigned long file_page_of 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 b } 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(struc } +/* 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 -puN drivers/md/md.c~md-new-sysfs-interface-for-setting-bits-in-the-write-intent-bitmap drivers/md/md.c --- a/drivers/md/md.c~md-new-sysfs-interface-for-setting-bits-in-the-write-intent-bitmap +++ a/drivers/md/md.c @@ -2524,6 +2524,36 @@ static struct md_sysfs_entry md_new_devi __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 ... or - ... (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) { return sprintf(page, "%llu\n", (unsigned long long)mddev->size); @@ -2843,6 +2873,7 @@ static struct attribute *md_redundancy_a &md_sync_completed.attr, &md_suspend_lo.attr, &md_suspend_hi.attr, + &md_bitmap.attr, NULL, }; static struct attribute_group md_redundancy_group = { diff -puN include/linux/raid/bitmap.h~md-new-sysfs-interface-for-setting-bits-in-the-write-intent-bitmap include/linux/raid/bitmap.h --- a/include/linux/raid/bitmap.h~md-new-sysfs-interface-for-setting-bits-in-the-write-intent-bitmap +++ a/include/linux/raid/bitmap.h @@ -265,6 +265,8 @@ int bitmap_update_sb(struct bitmap *bitm 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); _