qemu/include/block
Kevin Wolf 061ca8a368 block: Convert .bdrv_truncate callback to coroutine_fn
bdrv_truncate() is an operation that can block (even for a quite long
time, depending on the PreallocMode) in I/O paths that shouldn't block.
Convert it to a coroutine_fn so that we have the infrastructure for
drivers to make their .bdrv_co_truncate implementation asynchronous.

This change could potentially introduce new race conditions because
bdrv_truncate() isn't necessarily executed atomically any more. Whether
this is a problem needs to be evaluated for each block driver that
supports truncate:

* file-posix/win32, gluster, iscsi, nfs, rbd, ssh, sheepdog: The
  protocol drivers are trivially safe because they don't actually yield
  yet, so there is no change in behaviour.

* copy-on-read, crypto, raw-format: Essentially just filter drivers that
  pass the request to a child node, no problem.

* qcow2: The implementation modifies metadata, so it needs to hold
  s->lock to be safe with concurrent I/O requests. In order to avoid
  double locking, this requires pulling the locking out into
  preallocate_co() and using qcow2_write_caches() instead of
  bdrv_flush().

* qed: Does a single header update, this is fine without locking.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
2018-06-29 14:20:56 +02:00
..
accounting.h block/accounting: introduce latency histogram 2018-03-19 14:58:37 -05:00
aio-wait.h block: Allow AIO_WAIT_WHILE with NULL ctx 2018-06-18 15:03:25 +02:00
aio.h linux-aio: properly bubble up errors from initialization 2018-06-27 13:06:34 +01:00
block_backup.h backup: Switch block_backup.h to byte-based 2017-07-10 13:18:06 +02:00
block_int.h block: Convert .bdrv_truncate callback to coroutine_fn 2018-06-29 14:20:56 +02:00
block.h block: Convert .bdrv_truncate callback to coroutine_fn 2018-06-29 14:20:56 +02:00
blockjob_int.h block: Really pause block jobs on drain 2018-06-18 15:03:25 +02:00
blockjob.h blockjob: Remove BlockJob.driver 2018-05-23 14:30:51 +02:00
dirty-bitmap.h block/dirty-bitmap: Add bdrv_dirty_iter_next_area 2018-06-18 17:04:57 +02:00
nbd.h nbd/server: introduce NBD_CMD_CACHE 2018-06-21 09:41:39 -05:00
nvme.h block: Move NVMe constants to a separate header 2018-02-08 09:22:03 +08:00
qapi.h Drop superfluous includes of qapi-types.h and test-qapi-types.h 2018-02-09 05:05:11 +01:00
qdict.h block: Factor out qobject_input_visitor_new_flat_confused() 2018-06-15 14:49:44 +02:00
raw-aio.h linux-aio: properly bubble up errors from initialization 2018-06-27 13:06:34 +01:00
snapshot.h Move include qemu/option.h from qemu-common.h to actual users 2018-02-09 13:52:16 +01:00
thread-pool.h Clean up decorations and whitespace around header guards 2016-07-12 16:20:46 +02:00
throttle-groups.h block: add throttle block filter driver 2017-09-06 10:12:02 +02:00
write-threshold.h Use scripts/clean-includes to drop redundant qemu/typedefs.h 2016-03-22 22:20:16 +01:00