From: Xiubo Li xiubli@redhat.com
commit b2f9fa1f3bd8846f50b355fc2168236975c4d264 upstream.
The ceph_cap_flush structures are usually dynamically allocated, but the ceph_cap_snap has an embedded one.
When force umounting, the client will try to remove all the session caps. During this, it will free them, but that should not be done with the ones embedded in a capsnap.
Fix this by adding a new boolean that indicates that the cap flush is embedded in a capsnap, and skip freeing it if that's set.
At the same time, switch to using list_del_init() when detaching the i_list and g_list heads. It's possible for a forced umount to remove these objects but then handle_cap_flushsnap_ack() races in and does the list_del_init() again, corrupting memory.
Cc: stable@vger.kernel.org URL: https://tracker.ceph.com/issues/52283 Signed-off-by: Xiubo Li xiubli@redhat.com Reviewed-by: Jeff Layton jlayton@kernel.org Signed-off-by: Ilya Dryomov idryomov@gmail.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- fs/ceph/caps.c | 21 +++++++++++++-------- fs/ceph/mds_client.c | 7 ++++--- fs/ceph/snap.c | 3 +++ fs/ceph/super.h | 3 ++- 4 files changed, 22 insertions(+), 12 deletions(-)
--- a/fs/ceph/caps.c +++ b/fs/ceph/caps.c @@ -1752,7 +1752,11 @@ int __ceph_mark_dirty_caps(struct ceph_i
struct ceph_cap_flush *ceph_alloc_cap_flush(void) { - return kmem_cache_alloc(ceph_cap_flush_cachep, GFP_KERNEL); + struct ceph_cap_flush *cf; + + cf = kmem_cache_alloc(ceph_cap_flush_cachep, GFP_KERNEL); + cf->is_capsnap = false; + return cf; }
void ceph_free_cap_flush(struct ceph_cap_flush *cf) @@ -1787,7 +1791,7 @@ static bool __detach_cap_flush_from_mdsc prev->wake = true; wake = false; } - list_del(&cf->g_list); + list_del_init(&cf->g_list); return wake; }
@@ -1802,7 +1806,7 @@ static bool __detach_cap_flush_from_ci(s prev->wake = true; wake = false; } - list_del(&cf->i_list); + list_del_init(&cf->i_list); return wake; }
@@ -2422,7 +2426,7 @@ static void __kick_flushing_caps(struct ci->i_ceph_flags &= ~CEPH_I_KICK_FLUSH;
list_for_each_entry_reverse(cf, &ci->i_cap_flush_list, i_list) { - if (!cf->caps) { + if (cf->is_capsnap) { last_snap_flush = cf->tid; break; } @@ -2441,7 +2445,7 @@ static void __kick_flushing_caps(struct
first_tid = cf->tid + 1;
- if (cf->caps) { + if (!cf->is_capsnap) { struct cap_msg_args arg;
dout("kick_flushing_caps %p cap %p tid %llu %s\n", @@ -3564,7 +3568,7 @@ static void handle_cap_flush_ack(struct cleaned = cf->caps;
/* Is this a capsnap? */ - if (cf->caps == 0) + if (cf->is_capsnap) continue;
if (cf->tid <= flush_tid) { @@ -3637,8 +3641,9 @@ out: while (!list_empty(&to_remove)) { cf = list_first_entry(&to_remove, struct ceph_cap_flush, i_list); - list_del(&cf->i_list); - ceph_free_cap_flush(cf); + list_del_init(&cf->i_list); + if (!cf->is_capsnap) + ceph_free_cap_flush(cf); }
if (wake_ci) --- a/fs/ceph/mds_client.c +++ b/fs/ceph/mds_client.c @@ -1618,7 +1618,7 @@ static int remove_session_caps_cb(struct spin_lock(&mdsc->cap_dirty_lock);
list_for_each_entry(cf, &to_remove, i_list) - list_del(&cf->g_list); + list_del_init(&cf->g_list);
if (!list_empty(&ci->i_dirty_item)) { pr_warn_ratelimited( @@ -1670,8 +1670,9 @@ static int remove_session_caps_cb(struct struct ceph_cap_flush *cf; cf = list_first_entry(&to_remove, struct ceph_cap_flush, i_list); - list_del(&cf->i_list); - ceph_free_cap_flush(cf); + list_del_init(&cf->i_list); + if (!cf->is_capsnap) + ceph_free_cap_flush(cf); }
wake_up_all(&ci->i_cap_wq); --- a/fs/ceph/snap.c +++ b/fs/ceph/snap.c @@ -487,6 +487,9 @@ void ceph_queue_cap_snap(struct ceph_ino pr_err("ENOMEM allocating ceph_cap_snap on %p\n", inode); return; } + capsnap->cap_flush.is_capsnap = true; + INIT_LIST_HEAD(&capsnap->cap_flush.i_list); + INIT_LIST_HEAD(&capsnap->cap_flush.g_list);
spin_lock(&ci->i_ceph_lock); used = __ceph_caps_used(ci); --- a/fs/ceph/super.h +++ b/fs/ceph/super.h @@ -181,8 +181,9 @@ struct ceph_cap {
struct ceph_cap_flush { u64 tid; - int caps; /* 0 means capsnap */ + int caps; bool wake; /* wake up flush waiters when finish ? */ + bool is_capsnap; /* true means capsnap */ struct list_head g_list; // global struct list_head i_list; // per inode };