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Old 01-09-2012, 07:33 PM
Mike Snitzer
 
Default dm thin metadata: clarify __open_device functionality and fix callers

The __open_device() error path of __create_thin() and __create_snap()
will call __close_device() even if td was not initialized by
__open_device().

Clearly define what callers should expect from __open_device()'s
return.

Also, remove redundant 'td->changed = 1' in __create_thin() --
__open_device() with create=1 will have set td->changed on successful
return.

Signed-off-by: Mike Snitzer <snitzer@redhat.com>
---
drivers/md/dm-thin-metadata.c | 22 ++++++++++++++++++----
1 files changed, 18 insertions(+), 4 deletions(-)

diff --git a/drivers/md/dm-thin-metadata.c b/drivers/md/dm-thin-metadata.c
index 59c4f04..28f98cb 100644
--- a/drivers/md/dm-thin-metadata.c
+++ b/drivers/md/dm-thin-metadata.c
@@ -789,6 +789,11 @@ int dm_pool_metadata_close(struct dm_pool_metadata *pmd)
return 0;
}

+/*
+ * __open_device: lookup @td if already open, allocate @td on first open.
+ * on success, return @td with an incremented reference count.
+ * on failure, @td is not initialized.
+ */
static int __open_device(struct dm_pool_metadata *pmd,
dm_thin_id dev, int create,
struct dm_thin_device **td)
@@ -803,6 +808,13 @@ static int __open_device(struct dm_pool_metadata *pmd,
*/
list_for_each_entry(td2, &pmd->thin_devices, list)
if (td2->id == dev) {
+ if (create) {
+ /*
+ * inconsistency if looking to create
+ * an already open device.
+ */
+ return -EINVAL;
+ }
td2->open_count++;
*td = td2;
return 0;
@@ -817,6 +829,9 @@ static int __open_device(struct dm_pool_metadata *pmd,
if (r != -ENODATA || !create)
return r;

+ /*
+ * Open is for device creation.
+ */
changed = 1;
details_le.mapped_blocks = 0;
details_le.transaction_id = cpu_to_le64(pmd->trans_id);
@@ -882,12 +897,10 @@ static int __create_thin(struct dm_pool_metadata *pmd,

r = __open_device(pmd, dev, 1, &td);
if (r) {
- __close_device(td);
dm_btree_remove(&pmd->tl_info, pmd->root, &key, &pmd->root);
dm_btree_del(&pmd->bl_info, dev_root);
return r;
}
- td->changed = 1;
__close_device(td);

return r;
@@ -967,14 +980,15 @@ static int __create_snap(struct dm_pool_metadata *pmd,
goto bad;

r = __set_snapshot_details(pmd, td, origin, pmd->time);
- if (r)
+ if (r) {
+ __close_device(td);
goto bad;
+ }

__close_device(td);
return 0;

bad:
- __close_device(td);
dm_btree_remove(&pmd->tl_info, pmd->root, &key, &pmd->root);
dm_btree_remove(&pmd->details_info, pmd->details_root,
&key, &pmd->details_root);
--
1.7.4.4

--
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