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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: Joe Thornber <ejt@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
This commit is contained in:
Joe Thornber 2012-07-27 15:08:15 +01:00 committed by Alasdair G Kergon
parent 4afdd680f7
commit 310975573b
2 changed files with 31 additions and 0 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

18
drivers/md/persistent-data/dm-block-manager.c
View File

@ -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;

13
drivers/md/persistent-data/dm-block-manager.h
View File

@ -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);
/*----------------------------------------------------------------*/