ceph: fix kick_requests()

__do_request() may unregister the request. So we should update
iterator 'p' before calling __do_request()

Signed-off-by: Yan, Zheng <zheng.z.yan@intel.com>
rbd: rework rbd_request_fn()

While it was never a good idea to sleep in request_fn(), commit
34c6bc2c919a ("locking/mutexes: Add extra reschedule point") made it
a *bad* idea.  mutex_lock() since 3.15 may reschedule *before* putting
task on the mutex wait queue, which for tasks in !TASK_RUNNING state
means block forever.  request_fn() may be called with !TASK_RUNNING on
the way to schedule() in io_schedule().

Offload request handling to a workqueue, one per rbd device, to avoid
calling blocking primitives from rbd_request_fn().

Fixes: http://tracker.ceph.com/issues/8818

Cc: stable@vger.kernel.org # 3.16, needs backporting for 3.15
Signed-off-by: Ilya Dryomov <ilya.dryomov@inktank.com>
Tested-by: Eric Eastman <eric0e@aol.com>
Tested-by: Greg Wilson <greg.wilson@keepertech.com>
Reviewed-by: Alex Elder <elder@linaro.org>
rbd: allocate img_request with GFP_NOIO instead GFP_ATOMIC

Now that rbd_img_request_create() is called from work functions, no
need to use GFP_ATOMIC.

Signed-off-by: Ilya Dryomov <ilya.dryomov@inktank.com>
Reviewed-by: Alex Elder <elder@linaro.org>
rbd: remove extra newlines from rbd_warn() messages

rbd_warn() string should be a single line - rbd_warn() appends \n.

Signed-off-by: Ilya Dryomov <ilya.dryomov@inktank.com>
libceph: set last_piece in ceph_msg_data_pages_cursor_init() correctly

Determining ->last_piece based on the value of ->page_offset + length
is incorrect because length here is the length of the entire message.
->last_piece set to false even if page array data item length is <=
PAGE_SIZE, which results in invalid length passed to
ceph_tcp_{send,recv}page() and causes various asserts to fire.

    # cat pages-cursor-init.sh
    #!/bin/bash
    rbd create --size 10 --image-format 2 foo
    FOO_DEV=$(rbd map foo)
    dd if=/dev/urandom of=$FOO_DEV bs=1M &>/dev/null
    rbd snap create foo@snap
    rbd snap protect foo@snap
    rbd clone foo@snap bar
    # rbd_resize calls librbd rbd_resize(), size is in bytes
    ./rbd_resize bar $(((4 << 20) + 512))
    rbd resize --size 10 bar
    BAR_DEV=$(rbd map bar)
    # trigger a 512-byte copyup -- 512-byte page array data item
    dd if=/dev/urandom of=$BAR_DEV bs=1M count=1 seek=5

The problem exists only in ceph_msg_data_pages_cursor_init(),
ceph_msg_data_pages_advance() does the right thing.  The size_t cast is
unnecessary.

Cc: stable@vger.kernel.org # 3.10+
Signed-off-by: Ilya Dryomov <ilya.dryomov@inktank.com>
Reviewed-by: Sage Weil <sage@redhat.com>
Reviewed-by: Alex Elder <elder@linaro.org>