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Use separate bitmaps for each nodes in the cluster
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On-disk format:

0                    4k                     8k                    12k
-------------------------------------------------------------------
| idle                | md super            | bm super [0] + bits |
| bm bits[0, contd]   | bm super[1] + bits  | bm bits[1, contd]   |
| bm super[2] + bits  | bm bits [2, contd]  | bm super[3] + bits  |
| bm bits [3, contd]  |                     |                     |

Bitmap super has a field nodes, which defines the maximum number
of nodes the device can use. While reading the bitmap super, if
the cluster finds out that the number of nodes is > 0:
1. Requests the md-cluster module.
2. Calls md_cluster_ops->join(), which sets up clustering such as
   joining DLM lockspace.

Since the first time, the first bitmap is read. After the call
to the cluster_setup, the bitmap offset is adjusted and the
superblock is re-read. This also ensures the bitmap is read
the bitmap lock (when bitmap lock is introduced in later patches)

Questions:
1. cluster name is repeated in all bitmap supers. Is that okay?

Signed-off-by: Goldwyn Rodrigues <rgoldwyn@suse.com>
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@goldwynr
goldwynr committed Feb 23, 2015
1 parent cf921cc commit b97e925
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Showing 3 changed files with 64 additions and 10 deletions.
67 changes: 57 additions & 10 deletions drivers/md/bitmap.c
View file
Expand Up @@ -205,6 +205,10 @@ static int write_sb_page(struct bitmap *bitmap, struct page *page, int wait)
struct block_device *bdev;
struct mddev *mddev = bitmap->mddev;
struct bitmap_storage *store = &bitmap->storage;
int node_offset = 0;

if (mddev_is_clustered(bitmap->mddev))
node_offset = bitmap->cluster_slot * store->file_pages;

while ((rdev = next_active_rdev(rdev, mddev)) != NULL) {
int size = PAGE_SIZE;
Expand Down Expand Up @@ -549,6 +553,7 @@ static int bitmap_read_sb(struct bitmap *bitmap)
unsigned long sectors_reserved = 0;
int err = -EINVAL;
struct page *sb_page;
int cluster_setup_done = 0;

if (!bitmap->storage.file && !bitmap->mddev->bitmap_info.offset) {
chunksize = 128 * 1024 * 1024;
Expand All @@ -564,6 +569,7 @@ static int bitmap_read_sb(struct bitmap *bitmap)
return -ENOMEM;
bitmap->storage.sb_page = sb_page;

re_read:
if (bitmap->storage.file) {
loff_t isize = i_size_read(bitmap->storage.file->f_mapping->host);
int bytes = isize > PAGE_SIZE ? PAGE_SIZE : isize;
Expand All @@ -579,13 +585,15 @@ static int bitmap_read_sb(struct bitmap *bitmap)
if (err)
return err;

err = -EINVAL;
sb = kmap_atomic(sb_page);

chunksize = le32_to_cpu(sb->chunksize);
daemon_sleep = le32_to_cpu(sb->daemon_sleep) * HZ;
write_behind = le32_to_cpu(sb->write_behind);
sectors_reserved = le32_to_cpu(sb->sectors_reserved);
nodes = le32_to_cpu(sb->nodes);
strlcpy(bitmap->mddev->bitmap_info.cluster_name, sb->cluster_name, 64);

/* verify that the bitmap-specific fields are valid */
if (sb->magic != cpu_to_le32(BITMAP_MAGIC))
Expand Down Expand Up @@ -622,7 +630,7 @@ static int bitmap_read_sb(struct bitmap *bitmap)
goto out;
}
events = le64_to_cpu(sb->events);
if (events < bitmap->mddev->events) {
if (!nodes && (events < bitmap->mddev->events)) {
printk(KERN_INFO
"%s: bitmap file is out of date (%llu < %llu) "
"-- forcing full recovery\n",
Expand All @@ -639,8 +647,34 @@ static int bitmap_read_sb(struct bitmap *bitmap)
bitmap->events_cleared = le64_to_cpu(sb->events_cleared);
strlcpy(bitmap->mddev->bitmap_info.cluster_name, sb->cluster_name, 64);
err = 0;

out:
kunmap_atomic(sb);
if (nodes && !cluster_setup_done) {
sector_t bm_blocks;

bm_blocks = sector_div(bitmap->mddev->resync_max_sectors, (chunksize >> 9));
bm_blocks = bm_blocks << 3;
/* We have bitmap supers at 4k boundaries, hence this
* is hardcoded */
bm_blocks = DIV_ROUND_UP(bm_blocks, 4096);
err = md_setup_cluster(bitmap->mddev, nodes);
if (err) {
pr_err("%s: Could not setup cluster service (%d)\n",
bmname(bitmap), err);
goto out_no_sb;
}
bitmap->cluster_slot = md_cluster_ops->slot_number(bitmap->mddev);
bitmap->mddev->bitmap_info.offset +=
bitmap->cluster_slot * (bm_blocks << 3);
pr_info("%s:%d bm slot: %d offset: %llu\n", __func__, __LINE__,
bitmap->cluster_slot,
(unsigned long long)bitmap->mddev->bitmap_info.offset);
cluster_setup_done = 1;
goto re_read;
}


out_no_sb:
if (test_bit(BITMAP_STALE, &bitmap->flags))
bitmap->events_cleared = bitmap->mddev->events;
Expand All @@ -651,8 +685,11 @@ static int bitmap_read_sb(struct bitmap *bitmap)
if (bitmap->mddev->bitmap_info.space == 0 ||
bitmap->mddev->bitmap_info.space > sectors_reserved)
bitmap->mddev->bitmap_info.space = sectors_reserved;
if (err)
if (err) {
bitmap_print_sb(bitmap);
if (cluster_setup_done)
md_cluster_stop(bitmap->mddev);
}
return err;
}

Expand Down Expand Up @@ -697,9 +734,10 @@ static inline struct page *filemap_get_page(struct bitmap_storage *store,
}

static int bitmap_storage_alloc(struct bitmap_storage *store,
unsigned long chunks, int with_super)
unsigned long chunks, int with_super,
int slot_number)
{
int pnum;
int pnum, offset = 0;
unsigned long num_pages;
unsigned long bytes;

Expand All @@ -708,6 +746,7 @@ static int bitmap_storage_alloc(struct bitmap_storage *store,
bytes += sizeof(bitmap_super_t);

num_pages = DIV_ROUND_UP(bytes, PAGE_SIZE);
offset = slot_number * (num_pages - 1);

store->filemap = kmalloc(sizeof(struct page *)
* num_pages, GFP_KERNEL);
Expand All @@ -718,20 +757,22 @@ static int bitmap_storage_alloc(struct bitmap_storage *store,
store->sb_page = alloc_page(GFP_KERNEL|__GFP_ZERO);
if (store->sb_page == NULL)
return -ENOMEM;
store->sb_page->index = 0;
}

pnum = 0;
if (store->sb_page) {
store->filemap[0] = store->sb_page;
pnum = 1;
store->sb_page->index = offset;
}

for ( ; pnum < num_pages; pnum++) {
store->filemap[pnum] = alloc_page(GFP_KERNEL|__GFP_ZERO);
if (!store->filemap[pnum]) {
store->file_pages = pnum;
return -ENOMEM;
}
store->filemap[pnum]->index = pnum;
store->filemap[pnum]->index = pnum + offset;
}
store->file_pages = pnum;

Expand Down Expand Up @@ -940,7 +981,7 @@ static void bitmap_set_memory_bits(struct bitmap *bitmap, sector_t offset, int n
*/
static int bitmap_init_from_disk(struct bitmap *bitmap, sector_t start)
{
unsigned long i, chunks, index, oldindex, bit;
unsigned long i, chunks, index, oldindex, bit, node_offset = 0;
struct page *page = NULL;
unsigned long bit_cnt = 0;
struct file *file;
Expand Down Expand Up @@ -986,6 +1027,9 @@ static int bitmap_init_from_disk(struct bitmap *bitmap, sector_t start)
if (!bitmap->mddev->bitmap_info.external)
offset = sizeof(bitmap_super_t);

if (mddev_is_clustered(bitmap->mddev))
node_offset = bitmap->cluster_slot * (DIV_ROUND_UP(store->bytes, PAGE_SIZE));

for (i = 0; i < chunks; i++) {
int b;
index = file_page_index(&bitmap->storage, i);
Expand All @@ -1006,7 +1050,7 @@ static int bitmap_init_from_disk(struct bitmap *bitmap, sector_t start)
bitmap->mddev,
bitmap->mddev->bitmap_info.offset,
page,
index, count);
index + node_offset, count);

if (ret)
goto err;
Expand Down Expand Up @@ -1212,7 +1256,6 @@ void bitmap_daemon_work(struct mddev *mddev)
j < bitmap->storage.file_pages
&& !test_bit(BITMAP_STALE, &bitmap->flags);
j++) {

if (test_page_attr(bitmap, j,
BITMAP_PAGE_DIRTY))
/* bitmap_unplug will handle the rest */
Expand Down Expand Up @@ -1596,6 +1639,9 @@ static void bitmap_free(struct bitmap *bitmap)
if (!bitmap) /* there was no bitmap */
return;

if (mddev_is_clustered(bitmap->mddev) && bitmap->mddev->cluster_info)
md_cluster_stop(bitmap->mddev);

/* Shouldn't be needed - but just in case.... */
wait_event(bitmap->write_wait,
atomic_read(&bitmap->pending_writes) == 0);
Expand Down Expand Up @@ -1854,7 +1900,8 @@ int bitmap_resize(struct bitmap *bitmap, sector_t blocks,
memset(&store, 0, sizeof(store));
if (bitmap->mddev->bitmap_info.offset || bitmap->mddev->bitmap_info.file)
ret = bitmap_storage_alloc(&store, chunks,
!bitmap->mddev->bitmap_info.external);
!bitmap->mddev->bitmap_info.external,
bitmap->cluster_slot);
if (ret)
goto err;

Expand Down
1 change: 1 addition & 0 deletions drivers/md/bitmap.h
View file
Expand Up @@ -227,6 +227,7 @@ struct bitmap {
wait_queue_head_t behind_wait;

struct kernfs_node *sysfs_can_clear;
int cluster_slot; /* Slot offset for clustered env */
};

/* the bitmap API */
Expand Down
6 changes: 6 additions & 0 deletions drivers/md/md-cluster.c
View file
Expand Up @@ -196,6 +196,12 @@ static int join(struct mddev *mddev, int nodes)
if (ret)
goto err;
wait_for_completion(&cinfo->completion);
if (nodes <= cinfo->slot_number) {
pr_err("md-cluster: Slot allotted(%d) greater than available slots(%d)", cinfo->slot_number - 1,
nodes);
ret = -ERANGE;
goto err;
}
cinfo->sb_lock = lockres_init(mddev, "cmd-super",
NULL, 0);
if (!cinfo->sb_lock) {
Expand Down

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