linux.git/fs/ceph/caps.c, branch v5.2

ceph: fix error handling in ceph_get_caps()

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

The function return 0 even when interrupted or try_get_cap_refs()
return error.

Fixes: 1199d7da2d ("ceph: simplify arguments and return semantics of try_get_cap_refs")
Signed-off-by: "Yan, Zheng" 
Reviewed-by: Jeff Layton 
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: print inode number in __caps_issued_mask debugging messages

2019-05-07T17:22:38+00:00

To make it easier to correlate with MDS logs.

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

ceph: simplify arguments and return semantics of try_get_cap_refs

2019-05-07T17:22:38+00:00

The return of this function is rather complex. It can return 0 or 1,
and in the case of a 1 return, the "err" pointer will be filled out.
This necessitates a lot of copying of values.

We can achieve the same effect by just returning 0, 1 or a negative
error code, and drop the "err" argument from this function.

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

ceph: fix comment over ceph_drop_caps_for_unlink

2019-05-07T17:22:38+00:00

It's not clear what AUTH_RDCACHE means in this context, and we're
clearly just dropping LINK caps here.

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

ceph: remove superfluous inode_lock in ceph_fsync

2019-05-07T17:22:37+00:00

Originally, filemap_write_and_wait took the i_mutex internally, but
commit 02c24a82187d pushed the mutex acquisition into the individual
fsync routines, leaving it up to the subsystem maintainers to remove
it if it wasn't needed.

For ceph, I see no reason to take the inode_lock here. All of the
operations inside that lock are protected by their own locking.

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

ceph: add mount option to limit caps count

2019-03-05T17:55:17+00:00

If number of caps exceed the limit, ceph_trim_dentires() also trim
dentries with valid leases. Trimming dentry releases references to
associated inode, which may evict inode and release caps.

By default, there is no limit for caps count.

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

ceph: touch existing cap when handling reply

2019-03-05T17:55:17+00:00

Move cap to tail of session->s_caps list. So ceph_trim_caps() will
trim older caps first.

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

ceph: send cap releases more aggressively

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

When pending cap releases fill up one message, start a work to send
cap release message. (old way is sending cap releases every 5 seconds)

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

ceph: split large reconnect into multiple messages

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

Signed-off-by: "Yan, Zheng" 
Signed-off-by: Ilya Dryomov