[PATCH] btrfs: don't leak extent_map in btrfs_get_io_geometry()

[Johannes Thumshirn]

btrfs_get_io_geometry() calls btrfs_get_chunk_map() to acquire a reference
on a extent_map, but on normal operation it does not drop this reference
anymore.

This leads to excessive kmemleak reports.

Always call free_extent_map(), not just in the error case.

Fixes: 5f1411265e16 ("btrfs: Introduce btrfs_io_geometry infrastructure")
Signed-off-by: Johannes Thumshirn <jthumsh...@suse.de>
---
 fs/btrfs/volumes.c | 10 +++++++---
 1 file changed, 7 insertions(+), 3 deletions(-)

diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index a13ddba1ebc3..d74b74ca07af 100644
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -5941,6 +5941,7 @@ int btrfs_get_io_geometry(struct btrfs_fs_info *fs_info, 
enum btrfs_map_op op,
        u64 stripe_len;
        u64 raid56_full_stripe_start = (u64)-1;
        int data_stripes;
+       int ret = 0;
 
        ASSERT(op != BTRFS_MAP_DISCARD);
 
@@ -5961,8 +5962,8 @@ int btrfs_get_io_geometry(struct btrfs_fs_info *fs_info, 
enum btrfs_map_op op,
                btrfs_crit(fs_info,
 "stripe math has gone wrong, stripe_offset=%llu offset=%llu start=%llu 
logical=%llu stripe_len=%llu",
                        stripe_offset, offset, em->start, logical, stripe_len);
-               free_extent_map(em);
-               return -EINVAL;
+               ret = -EINVAL;
+               goto out;
        }
 
        /* stripe_offset is the offset of this block in its stripe */
@@ -6009,7 +6010,10 @@ int btrfs_get_io_geometry(struct btrfs_fs_info *fs_info, 
enum btrfs_map_op op,
        io_geom->stripe_offset = stripe_offset;
        io_geom->raid56_stripe_offset = raid56_full_stripe_start;
 
-       return 0;
+out:
+       /* once for us */
+       free_extent_map(em);
+       return ret;
 }
 
 static int __btrfs_map_block(struct btrfs_fs_info *fs_info,
-- 
2.16.4