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dm thin: allow metadata space larger than supported to go unused 

It was always intended that a user could provide a thin metadata device
that is larger than the max supported by the on-disk format.  The extra
space would just go unused.

Unfortunately that never worked.  If the user attempted to use a larger
metadata device on creation they would get an error like the following:

 device-mapper: space map common: space map too large
 device-mapper: transaction manager: couldn't create metadata space map
 device-mapper: thin metadata: tm_create_with_sm failed
 device-mapper: table: 252:17: thin-pool: Error creating metadata object
 device-mapper: ioctl: error adding target to table

Fix this by allowing the initial metadata space map creation to cap its
size at the max number of blocks supported (DM_SM_METADATA_MAX_BLOCKS).
get_metadata_dev_size() must also impose DM_SM_METADATA_MAX_BLOCKS (via
THIN_METADATA_MAX_SECTORS), otherwise extending metadata would cap at
THIN_METADATA_MAX_SECTORS_WARNING (which is larger than supported).

Also, the calculation for THIN_METADATA_MAX_SECTORS didn't account for
the sizeof the disk_bitmap_header.  So the supported maximum metadata
size is a bit smaller (reduced from 33423360 to 33292800 sectors).

Lastly, remove the "excess space will not be used" warning message from
get_metadata_dev_size(); it resulted in printing the warning multiple
times.  Factor out warn_if_metadata_device_too_big(), call it from
pool_ctr() and maybe_resize_metadata_dev().

Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Acked-by: Joe Thornber <ejt@redhat.com>
This commit is contained in:
Mike Snitzer 2014-02-12 23:58:15 -05:00
parent a1989b3300
commit 7d48935eff
5 changed files with 37 additions and 19 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

4
drivers/md/dm-thin-metadata.c
View File

@ -483,7 +483,7 @@ static int __write_initial_superblock(struct dm_pool_metadata *pmd)
disk_super->data_mapping_root = cpu_to_le64(pmd->root);
disk_super->device_details_root = cpu_to_le64(pmd->details_root);
disk_super->metadata_block_size = cpu_to_le32(THIN_METADATA_BLOCK_SIZE >> SECTOR_SHIFT);
disk_super->metadata_block_size = cpu_to_le32(THIN_METADATA_BLOCK_SIZE);
disk_super->metadata_nr_blocks = cpu_to_le64(bdev_size >> SECTOR_TO_BLOCK_SHIFT);
disk_super->data_block_size = cpu_to_le32(pmd->data_block_size);
@ -651,7 +651,7 @@ static int __create_persistent_data_objects(struct dm_pool_metadata *pmd, bool f
{
int r;
pmd->bm = dm_block_manager_create(pmd->bdev, THIN_METADATA_BLOCK_SIZE,
pmd->bm = dm_block_manager_create(pmd->bdev, THIN_METADATA_BLOCK_SIZE << SECTOR_SHIFT,
THIN_METADATA_CACHE_SIZE,
THIN_MAX_CONCURRENT_LOCKS);
if (IS_ERR(pmd->bm)) {

8
drivers/md/dm-thin-metadata.h
View File

@ -9,16 +9,14 @@
#include "persistent-data/dm-block-manager.h"
#include "persistent-data/dm-space-map.h"
#include "persistent-data/dm-space-map-metadata.h"
#define THIN_METADATA_BLOCK_SIZE 4096
#define THIN_METADATA_BLOCK_SIZE DM_SM_METADATA_BLOCK_SIZE
/*
* The metadata device is currently limited in size.
*
* We have one block of index, which can hold 255 index entries. Each
* index entry contains allocation info about 16k metadata blocks.
*/
#define THIN_METADATA_MAX_SECTORS (255 * (1 << 14) * (THIN_METADATA_BLOCK_SIZE / (1 << SECTOR_SHIFT)))
#define THIN_METADATA_MAX_SECTORS DM_SM_METADATA_MAX_SECTORS
/*
* A metadata device larger than 16GB triggers a warning.

31
drivers/md/dm-thin.c
View File

@ -2000,16 +2000,27 @@ static void metadata_low_callback(void *context)
dm_table_event(pool->ti->table);
}
static sector_t get_metadata_dev_size(struct block_device *bdev)
static sector_t get_dev_size(struct block_device *bdev)
{
sector_t metadata_dev_size = i_size_read(bdev->bd_inode) >> SECTOR_SHIFT;
return i_size_read(bdev->bd_inode) >> SECTOR_SHIFT;
}
static void warn_if_metadata_device_too_big(struct block_device *bdev)
{
sector_t metadata_dev_size = get_dev_size(bdev);
char buffer[BDEVNAME_SIZE];
if (metadata_dev_size > THIN_METADATA_MAX_SECTORS_WARNING) {
if (metadata_dev_size > THIN_METADATA_MAX_SECTORS_WARNING)
DMWARN("Metadata device %s is larger than %u sectors: excess space will not be used.",
bdevname(bdev, buffer), THIN_METADATA_MAX_SECTORS);
metadata_dev_size = THIN_METADATA_MAX_SECTORS_WARNING;
}
}
static sector_t get_metadata_dev_size(struct block_device *bdev)
{
sector_t metadata_dev_size = get_dev_size(bdev);
if (metadata_dev_size > THIN_METADATA_MAX_SECTORS)
metadata_dev_size = THIN_METADATA_MAX_SECTORS;
return metadata_dev_size;
}
@ -2018,7 +2029,7 @@ static dm_block_t get_metadata_dev_size_in_blocks(struct block_device *bdev)
{
sector_t metadata_dev_size = get_metadata_dev_size(bdev);
sector_div(metadata_dev_size, THIN_METADATA_BLOCK_SIZE >> SECTOR_SHIFT);
sector_div(metadata_dev_size, THIN_METADATA_BLOCK_SIZE);
return metadata_dev_size;
}
@ -2096,12 +2107,7 @@ static int pool_ctr(struct dm_target *ti, unsigned argc, char **argv)
ti->error = "Error opening metadata block device";
goto out_unlock;
}
/*
* Run for the side-effect of possibly issuing a warning if the
* device is too big.
*/
(void) get_metadata_dev_size(metadata_dev->bdev);
warn_if_metadata_device_too_big(metadata_dev->bdev);
r = dm_get_device(ti, argv[1], FMODE_READ | FMODE_WRITE, &data_dev);
if (r) {
@ -2288,6 +2294,7 @@ static int maybe_resize_metadata_dev(struct dm_target *ti, bool *need_commit)
return -EINVAL;
} else if (metadata_dev_size > sb_metadata_dev_size) {
warn_if_metadata_device_too_big(pool->md_dev);
DMINFO("%s: growing the metadata device from %llu to %llu blocks",
dm_device_name(pool->pool_md),
sb_metadata_dev_size, metadata_dev_size);

2
drivers/md/persistent-data/dm-space-map-metadata.c
View File

@ -680,6 +680,8 @@ int dm_sm_metadata_create(struct dm_space_map *sm,
if (r)
return r;
if (nr_blocks > DM_SM_METADATA_MAX_BLOCKS)
nr_blocks = DM_SM_METADATA_MAX_BLOCKS;
r = sm_ll_extend(&smm->ll, nr_blocks);
if (r)
return r;

11
drivers/md/persistent-data/dm-space-map-metadata.h
View File

@ -9,6 +9,17 @@
#include "dm-transaction-manager.h"
#define DM_SM_METADATA_BLOCK_SIZE (4096 >> SECTOR_SHIFT)
/*
* The metadata device is currently limited in size.
*
* We have one block of index, which can hold 255 index entries. Each
* index entry contains allocation info about ~16k metadata blocks.
*/
#define DM_SM_METADATA_MAX_BLOCKS (255 * ((1 << 14) - 64))
#define DM_SM_METADATA_MAX_SECTORS (DM_SM_METADATA_MAX_BLOCKS * DM_SM_METADATA_BLOCK_SIZE)
/*
* Unfortunately we have to use two-phase construction due to the cycle
* between the tm and sm.