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Commit ac8c3f3d authored by Joe Thornber's avatar Joe Thornber Committed by Alasdair G Kergon
Browse files

dm thin: generate event when metadata threshold passed 



Generate a dm event when the amount of remaining thin pool metadata
space falls below a certain level.

The threshold is taken to be a quarter of the size of the metadata
device with a minimum threshold of 4MB.

Signed-off-by: default avatarJoe Thornber <ejt@redhat.com>
Signed-off-by: default avatarAlasdair G Kergon <agk@redhat.com>
parent 2fc48021

drivers/md/dm-thin-metadata.c

+14 −0
Original line number Original line Diff line number Diff line
@@ -1696,3 +1696,17 @@ void dm_pool_metadata_read_only(struct dm_pool_metadata *pmd) 
	dm_bm_set_read_only(pmd->bm);

	dm_bm_set_read_only(pmd->bm);

	up_write(&pmd->root_lock);

	up_write(&pmd->root_lock);

}

}



int dm_pool_register_metadata_threshold(struct dm_pool_metadata *pmd,

					dm_block_t threshold,

					dm_sm_threshold_fn fn,

					void *context)

{

	int r;



	down_write(&pmd->root_lock);

	r = dm_sm_register_threshold_callback(pmd->metadata_sm, threshold, fn, context);

	up_write(&pmd->root_lock);



	return r;

}

drivers/md/dm-thin-metadata.h

+6 −0
Original line number Original line Diff line number Diff line
@@ -8,6 +8,7 @@ 
#define DM_THIN_METADATA_H

#define DM_THIN_METADATA_H





#include "persistent-data/dm-block-manager.h"

#include "persistent-data/dm-block-manager.h"

#include "persistent-data/dm-space-map.h"





#define THIN_METADATA_BLOCK_SIZE 4096

#define THIN_METADATA_BLOCK_SIZE 4096
@@ -193,6 +194,11 @@ int dm_pool_resize_metadata_dev(struct dm_pool_metadata *pmd, dm_block_t new_siz 
 */

 */

void dm_pool_metadata_read_only(struct dm_pool_metadata *pmd);

void dm_pool_metadata_read_only(struct dm_pool_metadata *pmd);





int dm_pool_register_metadata_threshold(struct dm_pool_metadata *pmd,

					dm_block_t threshold,

					dm_sm_threshold_fn fn,

					void *context);



/*----------------------------------------------------------------*/

/*----------------------------------------------------------------*/





#endif
 
#endif

drivers/md/dm-thin.c

+38 −0
Original line number Original line Diff line number Diff line
@@ -1281,6 +1281,10 @@ static void process_bio_fail(struct thin_c *tc, struct bio *bio) 
	bio_io_error(bio);

	bio_io_error(bio);

}

}





/*

 * FIXME: should we also commit due to size of transaction, measured in

 * metadata blocks?

 */

static int need_commit_due_to_time(struct pool *pool)

static int need_commit_due_to_time(struct pool *pool)

{

{

	return jiffies < pool->last_commit_jiffies ||

	return jiffies < pool->last_commit_jiffies ||
@@ -1909,6 +1913,16 @@ static int parse_pool_features(struct dm_arg_set *as, struct pool_features *pf, 
	return r;

	return r;

}

}





static void metadata_low_callback(void *context)

{

	struct pool *pool = context;



	DMWARN("%s: reached low water mark for metadata device: sending event.",

	       dm_device_name(pool->pool_md));



	dm_table_event(pool->ti->table);

}



static sector_t get_metadata_dev_size(struct block_device *bdev)

static sector_t get_metadata_dev_size(struct block_device *bdev)

{

{

	sector_t metadata_dev_size = i_size_read(bdev->bd_inode) >> SECTOR_SHIFT;

	sector_t metadata_dev_size = i_size_read(bdev->bd_inode) >> SECTOR_SHIFT;
@@ -1932,6 +1946,23 @@ static dm_block_t get_metadata_dev_size_in_blocks(struct block_device *bdev) 
	return metadata_dev_size;

	return metadata_dev_size;

}

}





/*

 * When a metadata threshold is crossed a dm event is triggered, and

 * userland should respond by growing the metadata device.  We could let

 * userland set the threshold, like we do with the data threshold, but I'm

 * not sure they know enough to do this well.

 */

static dm_block_t calc_metadata_threshold(struct pool_c *pt)

{

	/*

	 * 4M is ample for all ops with the possible exception of thin

	 * device deletion which is harmless if it fails (just retry the

	 * delete after you've grown the device).

	 */

	dm_block_t quarter = get_metadata_dev_size_in_blocks(pt->metadata_dev->bdev) / 4;

	return min((dm_block_t)1024ULL /* 4M */, quarter);

}



/*

/*

 * thin-pool <metadata dev> <data dev>

 * thin-pool <metadata dev> <data dev>

 *	     <data block size (sectors)>

 *	     <data block size (sectors)>
@@ -2065,6 +2096,13 @@ static int pool_ctr(struct dm_target *ti, unsigned argc, char **argv) 
	}

	}

	ti->private = pt;

	ti->private = pt;





	r = dm_pool_register_metadata_threshold(pt->pool->pmd,

						calc_metadata_threshold(pt),

						metadata_low_callback,

						pool);

	if (r)

		goto out_free_pt;



	pt->callbacks.congested_fn = pool_is_congested;

	pt->callbacks.congested_fn = pool_is_congested;

	dm_table_add_target_callbacks(ti->table, &pt->callbacks);

	dm_table_add_target_callbacks(ti->table, &pt->callbacks);