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Commit 31097557 authored by Joe Thornber's avatar Joe Thornber Committed by Alasdair G Kergon
Browse files

dm persistent data: introduce dm_bm_set_read_only 



Introduce dm_bm_set_read_only to switch the block manager into a
read-only mode.  To be used when dm-thin degrades due to io errors on
the metadata device.

Signed-off-by: default avatarJoe Thornber <ejt@redhat.com>
Signed-off-by: default avatarMike Snitzer <snitzer@redhat.com>
Signed-off-by: default avatarAlasdair G Kergon <agk@redhat.com>
parent 4afdd680

drivers/md/persistent-data/dm-block-manager.c

+18 −0
Original line number Diff line number Diff line
@@ -364,6 +364,7 @@ static void dm_block_manager_write_callback(struct dm_buffer *buf) 
 *--------------------------------------------------------------*/

struct dm_block_manager {

	struct dm_bufio_client *bufio;

	bool read_only:1;

};



struct dm_block_manager *dm_block_manager_create(struct block_device *bdev,
@@ -390,6 +391,8 @@ struct dm_block_manager *dm_block_manager_create(struct block_device *bdev, 
		goto bad;

	}



	bm->read_only = false;



	return bm;



bad:
@@ -481,6 +484,9 @@ int dm_bm_write_lock(struct dm_block_manager *bm, 
	void *p;

	int r;



	if (bm->read_only)

		return -EPERM;



	p = dm_bufio_read(bm->bufio, b, (struct dm_buffer **) result);

	if (unlikely(IS_ERR(p)))

		return PTR_ERR(p);
@@ -547,6 +553,9 @@ int dm_bm_write_lock_zero(struct dm_block_manager *bm, 
	struct buffer_aux *aux;

	void *p;



	if (bm->read_only)

		return -EPERM;



	p = dm_bufio_new(bm->bufio, b, (struct dm_buffer **) result);

	if (unlikely(IS_ERR(p)))

		return PTR_ERR(p);
@@ -589,6 +598,9 @@ int dm_bm_flush_and_unlock(struct dm_block_manager *bm, 
{

	int r;



	if (bm->read_only)

		return -EPERM;



	r = dm_bufio_write_dirty_buffers(bm->bufio);

	if (unlikely(r)) {

		dm_bm_unlock(superblock);
@@ -600,6 +612,12 @@ int dm_bm_flush_and_unlock(struct dm_block_manager *bm, 
	return dm_bufio_write_dirty_buffers(bm->bufio);

}



void dm_bm_set_read_only(struct dm_block_manager *bm)

{

	bm->read_only = true;

}

EXPORT_SYMBOL_GPL(dm_bm_set_read_only);



u32 dm_bm_checksum(const void *data, size_t len, u32 init_xor)

{

	return crc32c(~(u32) 0, data, len) ^ init_xor;

drivers/md/persistent-data/dm-block-manager.h

+13 −0
Original line number Diff line number Diff line
@@ -108,6 +108,19 @@ int dm_bm_unlock(struct dm_block *b); 
int dm_bm_flush_and_unlock(struct dm_block_manager *bm,

			   struct dm_block *superblock);



/*

 * Switches the bm to a read only mode.  Once read-only mode

 * has been entered the following functions will return -EPERM.

 *

 *   dm_bm_write_lock

 *   dm_bm_write_lock_zero

 *   dm_bm_flush_and_unlock

 *

 * Additionally you should not use dm_bm_unlock_move, however no error will

 * be returned if you do.

 */

void dm_bm_set_read_only(struct dm_block_manager *bm);



u32 dm_bm_checksum(const void *data, size_t len, u32 init_xor);



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