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>
diff --git a/drivers/md/persistent-data/dm-block-manager.c b/drivers/md/persistent-data/dm-block-manager.c
index ad1712e..5ba2777 100644
--- a/drivers/md/persistent-data/dm-block-manager.c
+++ b/drivers/md/persistent-data/dm-block-manager.c
@@ -364,6 +364,7 @@
*--------------------------------------------------------------*/
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 @@
goto bad;
}
+ bm->read_only = false;
+
return bm;
bad:
@@ -481,6 +484,9 @@
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 @@
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 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 @@
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;