[PATCH] ceph: fix memory leak in ceph_cleanup_snapid_map

[Luis Henriques <lhenriques@suse.com>]

kmemleak reports the following memory leak:

unreferenced object 0xffff88821feac8a0 (size 96):
  comm "kworker/1:0", pid 17, jiffies 4294896362 (age 20.512s)
  hex dump (first 32 bytes):
    a0 c8 ea 1f 82 88 ff ff 00 c9 ea 1f 82 88 ff ff  ................
    00 00 00 00 00 00 00 00 00 01 00 00 00 00 ad de  ................
  backtrace:
    [<00000000b3ea77fb>] ceph_get_snapid_map+0x75/0x2a0
    [<00000000d4060942>] fill_inode+0xb26/0x1010
    [<0000000049da6206>] ceph_readdir_prepopulate+0x389/0xc40
    [<00000000e2fe2549>] dispatch+0x11ab/0x1521
    [<000000007700b894>] ceph_con_workfn+0xf3d/0x3240
    [<0000000039138a41>] process_one_work+0x24d/0x590
    [<00000000eb751f34>] worker_thread+0x4a/0x3d0
    [<000000007e8f0d42>] kthread+0xfb/0x130
    [<00000000d49bd1fa>] ret_from_fork+0x3a/0x50

A kfree was missing in commit 75c9627efb72 ("ceph: map snapid to anonymous
bdev ID"), while looping the 'to_free' list of ceph_snapid_map objects.

Fixes: 75c9627efb72 ("ceph: map snapid to anonymous bdev ID")
Signed-off-by: Luis Henriques <lhenriques@suse.com>
---
Hi!

A bit of mailing-list archaeology shows that v1 of this patch actually
included this kfree [1], and was lost on v2 [2].

[1] https://patchwork.kernel.org/patch/10114319/
[2] https://patchwork.kernel.org/patch/10749907/

Cheers,
--
Luis

fs/ceph/snap.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/fs/ceph/snap.c b/fs/ceph/snap.c
index ccfcc66aaf44..923be9399b21 100644
--- a/fs/ceph/snap.c
+++ b/fs/ceph/snap.c
@@ -1155,5 +1155,6 @@ void ceph_cleanup_snapid_map(struct ceph_mds_client *mdsc)
 			pr_err("snapid map %llx -> %x still in use\n",
 			       sm->snap, sm->dev);
 		}
+		kfree(sm);
 	}
 }