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authorJoe Thornber <ejt@redhat.com>2012-07-27 15:08:15 +0100
committerAlasdair G Kergon <agk@redhat.com>2012-07-27 15:08:15 +0100
commit310975573ba40ab526b0d76d28225d8d0999d72b (patch)
tree3ad362bb4fc0c70662c7337723222df16611f2eb /drivers/md
parent4afdd680f7c106e1c87b6dd7af9751c282ecb4b0 (diff)
downloadlinux-310975573ba40ab526b0d76d28225d8d0999d72b.tar.bz2
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>
Diffstat (limited to 'drivers/md')
-rw-r--r--drivers/md/persistent-data/dm-block-manager.c18
-rw-r--r--drivers/md/persistent-data/dm-block-manager.h13
2 files changed, 31 insertions, 0 deletions
diff --git a/drivers/md/persistent-data/dm-block-manager.c b/drivers/md/persistent-data/dm-block-manager.c
index ad1712e802f6..5ba277768d99 100644
--- a/drivers/md/persistent-data/dm-block-manager.c
+++ b/drivers/md/persistent-data/dm-block-manager.c
@@ -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;
diff --git a/drivers/md/persistent-data/dm-block-manager.h b/drivers/md/persistent-data/dm-block-manager.h
index 327885566631..be5bff61be28 100644
--- a/drivers/md/persistent-data/dm-block-manager.h
+++ b/drivers/md/persistent-data/dm-block-manager.h
@@ -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);
/*----------------------------------------------------------------*/