linux-stable.git/fs/ceph/snap.c, branch v5.4.166

ceph: take snap_empty_lock atomically with snaprealm refcount change

2021-08-18T06:57:04+00:00

commit 8434ffe71c874b9c4e184b88d25de98c2bf5fe3f upstream.

There is a race in ceph_put_snap_realm. The change to the nref and the
spinlock acquisition are not done atomically, so you could decrement
nref, and before you take the spinlock, the nref is incremented again.
At that point, you end up putting it on the empty list when it
shouldn't be there. Eventually __cleanup_empty_realms runs and frees
it when it's still in-use.

Fix this by protecting the 1->0 transition with atomic_dec_and_lock,
and just drop the spinlock if we can get the rwsem.

Because these objects can also undergo a 0->1 refcount transition, we
must protect that change as well with the spinlock. Increment locklessly
unless the value is at 0, in which case we take the spinlock, increment
and then take it off the empty list if it did the 0->1 transition.

With these changes, I'm removing the dout() messages from these
functions, as well as in __put_snap_realm. They've always been racy, and
it's better to not print values that may be misleading.

Cc: stable@vger.kernel.org
URL: https://tracker.ceph.com/issues/46419
Reported-by: Mark Nelson 
Signed-off-by: Jeff Layton 
Reviewed-by: Luis Henriques 
Signed-off-by: Ilya Dryomov 
Signed-off-by: Greg Kroah-Hartman

ceph: clean up locking annotation for ceph_get_snap_realm and __lookup_snap_realm

2021-08-18T06:57:04+00:00

commit df2c0cb7f8e8c83e495260ad86df8c5da947f2a7 upstream.

They both say that the snap_rwsem must be held for write, but I don't
see any real reason for it, and it's not currently always called that
way.

The lookup is just walking the rbtree, so holding it for read should be
fine there. The "get" is bumping the refcount and (possibly) removing
it from the empty list. I see no need to hold the snap_rwsem for write
for that.

Signed-off-by: Jeff Layton 
Reviewed-by: Ilya Dryomov 
Signed-off-by: Ilya Dryomov 
Signed-off-by: Greg Kroah-Hartman

ceph: add some lockdep assertions around snaprealm handling

2021-08-18T06:57:04+00:00

commit a6862e6708c15995bc10614b2ef34ca35b4b9078 upstream.

Turn some comments into lockdep asserts.

Signed-off-by: Jeff Layton 
Reviewed-by: Ilya Dryomov 
Signed-off-by: Ilya Dryomov 
Signed-off-by: Greg Kroah-Hartman

ceph: fix memory leak in ceph_cleanup_snapid_map()

2020-04-01T09:01:59+00:00

commit c8d6ee01449cd0d2f30410681cccb616a88f50b1 upstream.

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 is missing while looping the 'to_free' list of ceph_snapid_map
objects.

Cc: stable@vger.kernel.org
Fixes: 75c9627efb72 ("ceph: map snapid to anonymous bdev ID")
Signed-off-by: Luis Henriques 
Reviewed-by: Jeff Layton 
Signed-off-by: Ilya Dryomov 
Signed-off-by: Greg Kroah-Hartman

ceph: fix buffer free while holding i_ceph_lock in __ceph_build_xattrs_blob()

2019-08-22T08:47:41+00:00

Calling ceph_buffer_put() in __ceph_build_xattrs_blob() may result in
freeing the i_xattrs.blob buffer while holding the i_ceph_lock.  This can
be fixed by having this function returning the old blob buffer and have
the callers of this function freeing it when the lock is released.

The following backtrace was triggered by fstests generic/117.

  BUG: sleeping function called from invalid context at mm/vmalloc.c:2283
  in_atomic(): 1, irqs_disabled(): 0, pid: 649, name: fsstress
  4 locks held by fsstress/649:
   #0: 00000000a7478e7e (&type->s_umount_key#19){++++}, at: iterate_supers+0x77/0xf0
   #1: 00000000f8de1423 (&(&ci->i_ceph_lock)->rlock){+.+.}, at: ceph_check_caps+0x7b/0xc60
   #2: 00000000562f2b27 (&s->s_mutex){+.+.}, at: ceph_check_caps+0x3bd/0xc60
   #3: 00000000f83ce16a (&mdsc->snap_rwsem){++++}, at: ceph_check_caps+0x3ed/0xc60
  CPU: 1 PID: 649 Comm: fsstress Not tainted 5.2.0+ #439
  Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.12.1-0-ga5cab58-prebuilt.qemu.org 04/01/2014
  Call Trace:
   dump_stack+0x67/0x90
   ___might_sleep.cold+0x9f/0xb1
   vfree+0x4b/0x60
   ceph_buffer_release+0x1b/0x60
   __ceph_build_xattrs_blob+0x12b/0x170
   __send_cap+0x302/0x540
   ? __lock_acquire+0x23c/0x1e40
   ? __mark_caps_flushing+0x15c/0x280
   ? _raw_spin_unlock+0x24/0x30
   ceph_check_caps+0x5f0/0xc60
   ceph_flush_dirty_caps+0x7c/0x150
   ? __ia32_sys_fdatasync+0x20/0x20
   ceph_sync_fs+0x5a/0x130
   iterate_supers+0x8f/0xf0
   ksys_sync+0x4f/0xb0
   __ia32_sys_sync+0xa/0x10
   do_syscall_64+0x50/0x1c0
   entry_SYSCALL_64_after_hwframe+0x49/0xbe
  RIP: 0033:0x7fc6409ab617

Signed-off-by: Luis Henriques 
Reviewed-by: Jeff Layton 
Signed-off-by: Ilya Dryomov

ceph: handle change_attr in cap messages

2019-07-08T12:01:43+00:00

Signed-off-by: Jeff Layton 
Reviewed-by: "Yan, Zheng" 
Signed-off-by: Ilya Dryomov

ceph: handle btime in cap messages

2019-07-08T12:01:43+00:00

Signed-off-by: Jeff Layton 
Reviewed-by: "Yan, Zheng" 
Signed-off-by: Ilya Dryomov

ceph: avoid iput_final() while holding mutex or in dispatch thread

2019-06-05T18:34:39+00:00

iput_final() may wait for reahahead pages. The wait can cause deadlock.
For example:

  Workqueue: ceph-msgr ceph_con_workfn [libceph]
    Call Trace:
     schedule+0x36/0x80
     io_schedule+0x16/0x40
     __lock_page+0x101/0x140
     truncate_inode_pages_range+0x556/0x9f0
     truncate_inode_pages_final+0x4d/0x60
     evict+0x182/0x1a0
     iput+0x1d2/0x220
     iterate_session_caps+0x82/0x230 [ceph]
     dispatch+0x678/0xa80 [ceph]
     ceph_con_workfn+0x95b/0x1560 [libceph]
     process_one_work+0x14d/0x410
     worker_thread+0x4b/0x460
     kthread+0x105/0x140
     ret_from_fork+0x22/0x40

  Workqueue: ceph-msgr ceph_con_workfn [libceph]
    Call Trace:
     __schedule+0x3d6/0x8b0
     schedule+0x36/0x80
     schedule_preempt_disabled+0xe/0x10
     mutex_lock+0x2f/0x40
     ceph_check_caps+0x505/0xa80 [ceph]
     ceph_put_wrbuffer_cap_refs+0x1e5/0x2c0 [ceph]
     writepages_finish+0x2d3/0x410 [ceph]
     __complete_request+0x26/0x60 [libceph]
     handle_reply+0x6c8/0xa10 [libceph]
     dispatch+0x29a/0xbb0 [libceph]
     ceph_con_workfn+0x95b/0x1560 [libceph]
     process_one_work+0x14d/0x410
     worker_thread+0x4b/0x460
     kthread+0x105/0x140
     ret_from_fork+0x22/0x40

In above example, truncate_inode_pages_range() waits for readahead pages
while holding s_mutex. ceph_check_caps() waits for s_mutex and blocks
OSD dispatch thread. Later OSD replies (for readahead) can't be handled.

ceph_check_caps() also may lock snap_rwsem for read. So similar deadlock
can happen if iput_final() is called while holding snap_rwsem.

In general, it's not good to call iput_final() inside MDS/OSD dispatch
threads or while holding any mutex.

The fix is introducing ceph_async_iput(), which calls iput_final() in
workqueue.

Signed-off-by: "Yan, Zheng" 
Reviewed-by: Jeff Layton 
Signed-off-by: Ilya Dryomov

ceph: fix ci->i_head_snapc leak

2019-04-23T19:37:54+00:00

We missed two places that i_wrbuffer_ref_head, i_wr_ref, i_dirty_caps
and i_flushing_caps may change. When they are all zeros, we should free
i_head_snapc.

Cc: stable@vger.kernel.org
Link: https://tracker.ceph.com/issues/38224
Reported-and-tested-by: Luis Henriques 
Signed-off-by: "Yan, Zheng" 
Signed-off-by: Ilya Dryomov

ceph: map snapid to anonymous bdev ID

2019-03-05T17:55:16+00:00

ceph_getattr() return zero dev ID for head inodes and set dev ID to
snapid directly for snaphost inodes. This is not good because userspace
utilities may consider device ID of 0 as invalid, snapid may conflict
with other device's ID.

This patch introduces "snapids to anonymous bdev IDs" map. we create a
new mapping when we see a snapid for the first time. we trim unused
mapping after it is ilde for 5 minutes.

Link: http://tracker.ceph.com/issues/22353
Signed-off-by: "Yan, Zheng" 
Acked-by: Jeff Layton 
Signed-off-by: Ilya Dryomov