[PATCH 8 of 9] MD: add bitmap support

Patch name: md-add-bitmap-support.patch

Add bitmap support to the device-mapper specific metadata area.

This patch allows the creation of the bitmap metadata area upon initial array
creation via device-mapper.

Signed-off-by: Jonathan Brassow

Index: linux-2.6/drivers/md/md.c
============================================================ =======
--- linux-2.6.orig/drivers/md/md.c
+++ linux-2.6/drivers/md/md.c
@@ -1937,6 +1937,7 @@ static int super_2_init_validation(mddev
if (!rebuilds) {
if (new_devs == mddev->raid_disks) {
printk(KERN_INFO "md: %s: Superblocks created for new array\n", mdname(mddev));
+ set_bit(MD_ARRAY_FIRST_USE, &mddev->flags);
} else if (new_devs) {
printk(KERN_ERR "md: %s: New device injected "
"into existing array without 'rebuild' "
@@ -1997,7 +1998,7 @@ static int super_2_validate(mddev_t *mdd
if (!mddev->events && super_2_init_validation(mddev, rdev))
return -EINVAL;

- rdev->mddev->bitmap_info.offset = 0; /* disable bitmap creation */
+ mddev->bitmap_info.offset = 4096 >> 9; /* enable bitmap creation */
rdev->mddev->bitmap_info.default_offset = 4096 >> 9;
if (!test_bit(FirstUse, &rdev->flags)) {
rdev->recovery_offset = le64_to_cpu(sb->disk_recovery_offset);
Index: linux-2.6/drivers/md/bitmap.c
============================================================ =======
--- linux-2.6.orig/drivers/md/bitmap.c
+++ linux-2.6/drivers/md/bitmap.c
@@ -534,6 +534,84 @@ void bitmap_print_sb(struct bitmap *bitm
kunmap_atomic(sb, KM_USER0);
}

+/*
+ * bitmap_new_disk_sb
+ * @bitmap
+ *
+ * This function is somewhat the reverse of bitmap_read_sb. bitmap_read_sb
+ * reads and verifies the on-disk bitmap superblock and populates bitmap_info.
+ * This function verifies 'bitmap_info' and populates the on-disk bitmap
+ * structure, which is to be written to disk.
+ *
+ * Returns: 0 on success, -Exxx on error
+ */
+static int bitmap_new_disk_sb(struct bitmap *bitmap)
+{
+ bitmap_super_t *sb;
+ unsigned long chunksize, daemon_sleep, write_behind;
+ int err = -EINVAL;
+
+ /* page 0 is the superblock, read it... */
+ bitmap->sb_page = read_sb_page(bitmap->mddev,
+ bitmap->mddev->bitmap_info.offset,
+ NULL, 0, sizeof(bitmap_super_t));
+
+ if (IS_ERR(bitmap->sb_page)) {
+ err = PTR_ERR(bitmap->sb_page);
+ bitmap->sb_page = NULL;
+ return err;
+ }
+
+ sb = kmap_atomic(bitmap->sb_page, KM_USER0);
+
+ sb->magic = cpu_to_le32(BITMAP_MAGIC);
+ sb->version = cpu_to_le32(BITMAP_MAJOR_HI);
+
+ chunksize = bitmap->mddev->bitmap_info.chunksize;
+ BUG_ON(!chunksize);
+ if ((1 << ffz(~chunksize)) != chunksize) {
+ kunmap_atomic(sb, KM_USER0);
+ printk(KERN_ERR "bitmap chunksize not a power of 2\n");
+ return -EINVAL;
+ }
+ sb->chunksize = cpu_to_le32(chunksize);
+
+ daemon_sleep = bitmap->mddev->bitmap_info.daemon_sleep;
+ if (!daemon_sleep ||
+ (daemon_sleep < 1) || (daemon_sleep > MAX_SCHEDULE_TIMEOUT)) {
+ printk(KERN_INFO "Choosing daemon_sleep default (5 sec)\n");
+ daemon_sleep = 5 * HZ;
+ }
+ sb->daemon_sleep = cpu_to_le32(daemon_sleep);
+ bitmap->mddev->bitmap_info.daemon_sleep = daemon_sleep;
+
+ /*
+ * FIXME: write_behind for RAID1. If not specified, what
+ * is a good choice? We choose COUNTER_MAX / 2 arbitrarily.
+ */
+ write_behind = bitmap->mddev->bitmap_info.max_write_behind;
+ if (write_behind > COUNTER_MAX)
+ write_behind = COUNTER_MAX / 2;
+ sb->write_behind = cpu_to_le32(write_behind);
+ bitmap->mddev->bitmap_info.max_write_behind = write_behind;
+
+ /* keep the array size field of the bitmap superblock up to date */
+ sb->sync_size = cpu_to_le64(bitmap->mddev->resync_max_sectors);
+
+ memcpy(sb->uuid, bitmap->mddev->uuid, 16);
+
+ bitmap->flags |= BITMAP_STALE;
+ sb->state |= cpu_to_le32(BITMAP_STALE);
+ bitmap->events_cleared = bitmap->mddev->events;
+ sb->events_cleared = cpu_to_le64(bitmap->mddev->events);
+
+ bitmap->flags |= BITMAP_HOSTENDIAN;
+ sb->version = cpu_to_le32(BITMAP_MAJOR_HOSTENDIAN);
+
+ kunmap_atomic(sb, KM_USER0);
+ return 0;
+}
+
/* read the superblock from the bitmap file and initialize some bitmap fields */
static int bitmap_read_sb(struct bitmap *bitmap)
{
@@ -1076,8 +1154,8 @@ static int bitmap_init_from_disk(struct
}

printk(KERN_INFO "%s: bitmap initialized from disk: "
- "read %lu/%lu pages, set %lu bits\n",
- bmname(bitmap), bitmap->file_pages, num_pages, bit_cnt);
+ "read %lu/%lu pages, set %lu of %lu bits\n",
+ bmname(bitmap), bitmap->file_pages, num_pages, bit_cnt, chunks);

return 0;

@@ -1728,9 +1806,16 @@ int bitmap_create(mddev_t *mddev)
vfs_fsync(file, 1);
}
/* read superblock from bitmap file (this sets mddev->bitmap_info.chunksize) */
- if (!mddev->bitmap_info.external)
- err = bitmap_read_sb(bitmap);
- else {
+ if (!mddev->bitmap_info.external) {
+ /*
+ * If 'MD_ARRAY_FIRST_USE' is set, then device-mapper is
+ * instructing us to create a new on-disk bitmap instance.
+ */
+ if (test_and_clear_bit(MD_ARRAY_FIRST_USE, &mddev->flags))
+ err = bitmap_new_disk_sb(bitmap);
+ else
+ err = bitmap_read_sb(bitmap);
+ } else {
err = 0;
if (mddev->bitmap_info.chunksize == 0 ||
mddev->bitmap_info.daemon_sleep == 0)
Index: linux-2.6/drivers/md/md.h
============================================================ =======
--- linux-2.6.orig/drivers/md/md.h
+++ linux-2.6/drivers/md/md.h
@@ -127,6 +127,7 @@ struct mddev_s
#define MD_CHANGE_CLEAN 1 /* transition to or from 'clean' */
#define MD_CHANGE_PENDING 2 /* switch from 'clean' to 'active' in progress */
#define MD_SYNC_STATE_FORCED 3 /* recovery_cp is set and must be honored */
+#define MD_ARRAY_FIRST_USE 4 /* First use of array, needs initialization */

int suspended;
atomic_t active_io;
--
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