block_int-common.h · samitouri/QOSamiQemu

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1	/*
2	* QEMU System Emulator block driver
3	*
4	* Copyright (c) 2003 Fabrice Bellard
5	*
6	* Permission is hereby granted, free of charge, to any person obtaining a copy
7	* of this software and associated documentation files (the "Software"), to deal
8	* in the Software without restriction, including without limitation the rights
9	* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
10	* copies of the Software, and to permit persons to whom the Software is
11	* furnished to do so, subject to the following conditions:
12	*
13	* The above copyright notice and this permission notice shall be included in
14	* all copies or substantial portions of the Software.
15	*
16	* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
17	* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
18	* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
19	* THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
20	* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
21	* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
22	* THE SOFTWARE.
23	*/
24	#ifndef BLOCK_INT_COMMON_H
25	#define BLOCK_INT_COMMON_H
26
27	#include "block/block-common.h"
28	#include "block/block-global-state.h"
29	#include "block/snapshot.h"
30	#include "qemu/aiocb.h"
31	#include "qemu/iov.h"
32	#include "qemu/rcu.h"
33
34	#define BLOCK_FLAG_LAZY_REFCOUNTS 8
35
36	#define BLOCK_OPT_SIZE "size"
37	#define BLOCK_OPT_ENCRYPT "encryption"
38	#define BLOCK_OPT_ENCRYPT_FORMAT "encrypt.format"
39	#define BLOCK_OPT_COMPAT6 "compat6"
40	#define BLOCK_OPT_HWVERSION "hwversion"
41	#define BLOCK_OPT_BACKING_FILE "backing_file"
42	#define BLOCK_OPT_BACKING_FMT "backing_fmt"
43	#define BLOCK_OPT_CLUSTER_SIZE "cluster_size"
44	#define BLOCK_OPT_TABLE_SIZE "table_size"
45	#define BLOCK_OPT_PREALLOC "preallocation"
46	#define BLOCK_OPT_SUBFMT "subformat"
47	#define BLOCK_OPT_COMPAT_LEVEL "compat"
48	#define BLOCK_OPT_LAZY_REFCOUNTS "lazy_refcounts"
49	#define BLOCK_OPT_ADAPTER_TYPE "adapter_type"
50	#define BLOCK_OPT_REDUNDANCY "redundancy"
51	#define BLOCK_OPT_NOCOW "nocow"
52	#define BLOCK_OPT_EXTENT_SIZE_HINT "extent_size_hint"
53	#define BLOCK_OPT_OBJECT_SIZE "object_size"
54	#define BLOCK_OPT_REFCOUNT_BITS "refcount_bits"
55	#define BLOCK_OPT_DATA_FILE "data_file"
56	#define BLOCK_OPT_DATA_FILE_RAW "data_file_raw"
57	#define BLOCK_OPT_COMPRESSION_TYPE "compression_type"
58	#define BLOCK_OPT_EXTL2 "extended_l2"
59	#define BLOCK_OPT_KEEP_DATA_FILE "keep_data_file"
60
61	#define BLOCK_PROBE_BUF_SIZE 512
62
63	enum BdrvTrackedRequestType {
64	BDRV_TRACKED_READ,
65	BDRV_TRACKED_WRITE,
66	BDRV_TRACKED_DISCARD,
67	BDRV_TRACKED_TRUNCATE,
68	};
69
70	/*
71	* That is not quite good that BdrvTrackedRequest structure is public,
72	* as block/io.c is very careful about incoming offset/bytes being
73	* correct. Be sure to assert bdrv_check_request() succeeded after any
74	* modification of BdrvTrackedRequest object out of block/io.c
75	*/
76	typedef struct BdrvTrackedRequest {
77	BlockDriverState *bs;
78	int64_t offset;
79	int64_t bytes;
80	enum BdrvTrackedRequestType type;
81
82	bool serialising;
83	int64_t overlap_offset;
84	int64_t overlap_bytes;
85
86	QLIST_ENTRY(BdrvTrackedRequest) list;
87	Coroutine co; / owner, used for deadlock detection */
88	CoQueue wait_queue; /* coroutines blocked on this request */
89
90	struct BdrvTrackedRequest *waiting_for;
91	} BdrvTrackedRequest;
92
93
94	struct BlockDriver {
95	/*
96	* These fields are initialized when this object is created,
97	* and are never changed afterwards.
98	*/
99
100	const char *format_name;
101	int instance_size;
102
103	/*
104	* Set to true if the BlockDriver is a block filter. Block filters pass
105	* certain callbacks that refer to data (see block.c) to their bs->file
106	* or bs->backing (whichever one exists) if the driver doesn't implement
107	* them. Drivers that do not wish to forward must implement them and return
108	* -ENOTSUP.
109	* Note that filters are not allowed to modify data.
110	*
111	* Filters generally cannot have more than a single filtered child,
112	* because the data they present must at all times be the same as
113	* that on their filtered child. That would be impossible to
114	* achieve for multiple filtered children.
115	* (And this filtered child must then be bs->file or bs->backing.)
116	*/
117	bool is_filter;
118	/*
119	* Only make sense for filter drivers, for others must be false.
120	* If true, filtered child is bs->backing. Otherwise it's bs->file.
121	* Two internal filters use bs->backing as filtered child and has this
122	* field set to true: mirror_top and commit_top. There also two such test
123	* filters in tests/unit/test-bdrv-graph-mod.c.
124	*
125	* Never create any more such filters!
126	*
127	* TODO: imagine how to deprecate this behavior and make all filters work
128	* similarly using bs->file as filtered child.
129	*/
130	bool filtered_child_is_backing;
131
132	/*
133	* Set to true if the BlockDriver is a format driver. Format nodes
134	* generally do not expect their children to be other format nodes
135	* (except for backing files), and so format probing is disabled
136	* on those children.
137	*/
138	bool is_format;
139
140	/*
141	* Set to true if the BlockDriver supports zoned children.
142	*/
143	bool supports_zoned_children;
144
145	/*
146	* Drivers not implementing bdrv_parse_filename nor bdrv_open should have
147	* this field set to true, except ones that are defined only by their
148	* child's bs.
149	* An example of the last type will be the quorum block driver.
150	*/
151	bool bdrv_needs_filename;
152
153	/*
154	* Set if a driver can support backing files. This also implies the
155	* following semantics:
156	*
157	* - Return status 0 of .bdrv_co_block_status means that corresponding
158	* blocks are not allocated in this layer of backing-chain
159	* - For such (unallocated) blocks, read will:
160	* - fill buffer with zeros if there is no backing file
161	* - read from the backing file otherwise, where the block layer
162	* takes care of reading zeros beyond EOF if backing file is short
163	*/
164	bool supports_backing;
165
166	/*
167	* Drivers setting this field must be able to work with just a plain
168	* filename with '<protocol_name>:' as a prefix, and no other options.
169	* Options may be extracted from the filename by implementing
170	* bdrv_parse_filename.
171	*/
172	const char *protocol_name;
173
174	/* List of options for creating images, terminated by name == NULL */
175	QemuOptsList *create_opts;
176
177	/* List of options for image amend */
178	QemuOptsList *amend_opts;
179
180	/*
181	* If this driver supports reopening images this contains a
182	* NULL-terminated list of the runtime options that can be
183	* modified. If an option in this list is unspecified during
184	* reopen then it _must_ be reset to its default value or return
185	* an error.
186	*/
187	const char const mutable_opts;
188
189	/*
190	* Pointer to a NULL-terminated array of names of strong options
191	* that can be specified for bdrv_open(). A strong option is one
192	* that changes the data of a BDS.
193	* If this pointer is NULL, the array is considered empty.
194	* "filename" and "driver" are always considered strong.
195	*/
196	const char const strong_runtime_opts;
197
198
199	/*
200	* Global state (GS) API. These functions run under the BQL.
201	*
202	* See include/block/block-global-state.h for more information about
203	* the GS API.
204	*/
205
206	/*
207	* This function is invoked under BQL before .bdrv_co_amend()
208	* (which in contrast does not necessarily run under the BQL)
209	* to allow driver-specific initialization code that requires
210	* the BQL, like setting up specific permission flags.
211	*/
212	int GRAPH_RDLOCK_PTR (*bdrv_amend_pre_run)(
213	BlockDriverState bs, Error *errp);
214	/*
215	* This function is invoked under BQL after .bdrv_co_amend()
216	* to allow cleaning up what was done in .bdrv_amend_pre_run().
217	*/
218	void GRAPH_RDLOCK_PTR (bdrv_amend_clean)(BlockDriverState bs);
219
220	/*
221	* Return true if @to_replace can be replaced by a BDS with the
222	* same data as @bs without it affecting @bs's behavior (that is,
223	* without it being visible to @bs's parents).
224	*/
225	bool GRAPH_RDLOCK_PTR (*bdrv_recurse_can_replace)(
226	BlockDriverState bs, BlockDriverState to_replace);
227
228	int (bdrv_probe_device)(const char filename);
229
230	/*
231	* Any driver implementing this callback is expected to be able to handle
232	* NULL file names in its .bdrv_open() implementation.
233	*/
234	void (bdrv_parse_filename)(const char filename, QDict *options,
235	Error **errp);
236
237	/* For handling image reopen for split or non-split files. */
238	int GRAPH_UNLOCKED_PTR (*bdrv_reopen_prepare)(
239	BDRVReopenState reopen_state, BlockReopenQueue queue, Error **errp);
240	void GRAPH_UNLOCKED_PTR (*bdrv_reopen_commit)(
241	BDRVReopenState *reopen_state);
242	void GRAPH_UNLOCKED_PTR (*bdrv_reopen_commit_post)(
243	BDRVReopenState *reopen_state);
244	void GRAPH_UNLOCKED_PTR (*bdrv_reopen_abort)(
245	BDRVReopenState *reopen_state);
246	void (bdrv_join_options)(QDict options, QDict *old_options);
247
248	int GRAPH_UNLOCKED_PTR (*bdrv_open)(
249	BlockDriverState bs, QDict options, int flags, Error **errp);
250
251	void GRAPH_UNLOCKED_PTR (bdrv_close)(BlockDriverState bs);
252
253	int coroutine_fn GRAPH_UNLOCKED_PTR (*bdrv_co_create)(
254	BlockdevCreateOptions opts, Error *errp);
255
256	int coroutine_fn GRAPH_UNLOCKED_PTR (*bdrv_co_create_opts)(
257	BlockDriver drv, const char filename, QemuOpts opts, Error *errp);
258
259	int GRAPH_RDLOCK_PTR (*bdrv_amend_options)(
260	BlockDriverState bs, QemuOpts opts,
261	BlockDriverAmendStatusCB status_cb, void cb_opaque,
262	bool force, Error **errp);
263
264	int GRAPH_RDLOCK_PTR (bdrv_make_empty)(BlockDriverState bs);
265
266	/*
267	* Refreshes the bs->exact_filename field. If that is impossible,
268	* bs->exact_filename has to be left empty.
269	*/
270	void GRAPH_RDLOCK_PTR (bdrv_refresh_filename)(BlockDriverState bs);
271
272	/*
273	* Gathers the open options for all children into @target.
274	* A simple format driver (without backing file support) might
275	* implement this function like this:
276	*
277	* QINCREF(bs->file->bs->full_open_options);
278	* qdict_put(target, "file", bs->file->bs->full_open_options);
279	*
280	* If not specified, the generic implementation will simply put
281	* all children's options under their respective name.
282	*
283	* @backing_overridden is true when bs->backing seems not to be
284	* the child that would result from opening bs->backing_file.
285	* Therefore, if it is true, the backing child's options should be
286	* gathered; otherwise, there is no need since the backing child
287	* is the one implied by the image header.
288	*
289	* Note that ideally this function would not be needed. Every
290	* block driver which implements it is probably doing something
291	* shady regarding its runtime option structure.
292	*/
293	void GRAPH_RDLOCK_PTR (*bdrv_gather_child_options)(
294	BlockDriverState bs, QDict target, bool backing_overridden);
295
296	/*
297	* Returns an allocated string which is the directory name of this BDS: It
298	* will be used to make relative filenames absolute by prepending this
299	* function's return value to them.
300	*/
301	char * GRAPH_RDLOCK_PTR (bdrv_dirname)(BlockDriverState bs, Error **errp);
302
303	/*
304	* This informs the driver that we are no longer interested in the result
305	* of in-flight requests, so don't waste the time if possible.
306	*
307	* One example usage is to avoid waiting for an nbd target node reconnect
308	* timeout during job-cancel with force=true.
309	*/
310	void GRAPH_RDLOCK_PTR (bdrv_cancel_in_flight)(BlockDriverState bs);
311
312	int GRAPH_RDLOCK_PTR (bdrv_inactivate)(BlockDriverState bs);
313
314	int GRAPH_RDLOCK_PTR (*bdrv_snapshot_create)(
315	BlockDriverState bs, QEMUSnapshotInfo sn_info);
316
317	int GRAPH_UNLOCKED_PTR (*bdrv_snapshot_goto)(
318	BlockDriverState bs, const char snapshot_id);
319
320	int GRAPH_RDLOCK_PTR (*bdrv_snapshot_delete)(
321	BlockDriverState bs, const char snapshot_id, const char *name,
322	Error **errp);
323
324	int GRAPH_RDLOCK_PTR (*bdrv_snapshot_list)(
325	BlockDriverState bs, QEMUSnapshotInfo *psn_info);
326
327	int GRAPH_RDLOCK_PTR (*bdrv_snapshot_load_tmp)(
328	BlockDriverState bs, const char snapshot_id, const char *name,
329	Error **errp);
330
331	int coroutine_fn GRAPH_RDLOCK_PTR (*bdrv_co_change_backing_file)(
332	BlockDriverState bs, const char backing_file,
333	const char *backing_fmt);
334
335	/* TODO Better pass a option string/QDict/QemuOpts to add any rule? */
336	int (bdrv_debug_breakpoint)(BlockDriverState bs, const char *event,
337	const char *tag);
338	int (bdrv_debug_remove_breakpoint)(BlockDriverState bs,
339	const char *tag);
340	int (bdrv_debug_resume)(BlockDriverState bs, const char *tag);
341	bool (bdrv_debug_is_suspended)(BlockDriverState bs, const char *tag);
342
343	void GRAPH_RDLOCK_PTR (*bdrv_refresh_limits)(
344	BlockDriverState bs, Error *errp);
345
346	/*
347	* Returns 1 if newly created images are guaranteed to contain only
348	* zeros, 0 otherwise.
349	*/
350	int GRAPH_RDLOCK_PTR (bdrv_has_zero_init)(BlockDriverState bs);
351
352	/*
353	* Remove fd handlers, timers, and other event loop callbacks so the event
354	* loop is no longer in use. Called with no in-flight requests and in
355	* depth-first traversal order with parents before child nodes.
356	*/
357	void (bdrv_detach_aio_context)(BlockDriverState bs);
358
359	/*
360	* Add fd handlers, timers, and other event loop callbacks so I/O requests
361	* can be processed again. Called with no in-flight requests and in
362	* depth-first traversal order with child nodes before parent nodes.
363	*/
364	void (bdrv_attach_aio_context)(BlockDriverState bs,
365	AioContext *new_context);
366
367	/**
368	* bdrv_drain_begin is called if implemented in the beginning of a
369	* drain operation to drain and stop any internal sources of requests in
370	* the driver.
371	* bdrv_drain_end is called if implemented at the end of the drain.
372	*
373	* They should be used by the driver to e.g. manage scheduled I/O
374	* requests, or toggle an internal state. After the end of the drain new
375	* requests will continue normally.
376	*
377	* Implementations of both functions must not call aio_poll().
378	*/
379	void (bdrv_drain_begin)(BlockDriverState bs);
380	void (bdrv_drain_end)(BlockDriverState bs);
381
382	/**
383	* Try to get @bs's logical and physical block size.
384	* On success, store them in @bsz and return zero.
385	* On failure, return negative errno.
386	*/
387	int GRAPH_RDLOCK_PTR (*bdrv_probe_blocksizes)(
388	BlockDriverState bs, BlockSizes bsz);
389	/**
390	* Try to get @bs's geometry (cyls, heads, sectors)
391	* On success, store them in @geo and return 0.
392	* On failure return -errno.
393	* Only drivers that want to override guest geometry implement this
394	* callback; see hd_geometry_guess().
395	*/
396	int GRAPH_RDLOCK_PTR (*bdrv_probe_geometry)(
397	BlockDriverState bs, HDGeometry geo);
398
399	/**
400	* Hot add a BDS's child. Used in combination with bdrv_del_child, so the
401	* user can take a child offline when it is broken and take a new child
402	* online.
403	*
404	* All block nodes must be drained.
405	*/
406	void GRAPH_WRLOCK_PTR (*bdrv_add_child)(
407	BlockDriverState parent, BlockDriverState child, Error **errp);
408
409	/**
410	* Hot remove a BDS's child. Used in combination with bdrv_add_child, so the
411	* user can take a child offline when it is broken and take a new child
412	* online.
413	*
414	* All block nodes must be drained.
415	*/
416	void GRAPH_WRLOCK_PTR (*bdrv_del_child)(
417	BlockDriverState parent, BdrvChild child, Error **errp);
418
419	/**
420	* Informs the block driver that a permission change is intended. The
421	* driver checks whether the change is permissible and may take other
422	* preparations for the change (e.g. get file system locks). This operation
423	* is always followed either by a call to either .bdrv_set_perm or
424	* .bdrv_abort_perm_update.
425	*
426	* Checks whether the requested set of cumulative permissions in @perm
427	* can be granted for accessing @bs and whether no other users are using
428	* permissions other than those given in @shared (both arguments take
429	* BLK_PERM_* bitmasks).
430	*
431	* If both conditions are met, 0 is returned. Otherwise, -errno is returned
432	* and errp is set to an error describing the conflict.
433	*/
434	int GRAPH_RDLOCK_PTR (bdrv_check_perm)(BlockDriverState bs, uint64_t perm,
435	uint64_t shared, Error **errp);
436
437	/**
438	* Called to inform the driver that the set of cumulative set of used
439	* permissions for @bs has changed to @perm, and the set of shareable
440	* permission to @shared. The driver can use this to propagate changes to
441	* its children (i.e. request permissions only if a parent actually needs
442	* them).
443	*
444	* This function is only invoked after bdrv_check_perm(), so block drivers
445	* may rely on preparations made in their .bdrv_check_perm implementation.
446	*/
447	void GRAPH_RDLOCK_PTR (*bdrv_set_perm)(
448	BlockDriverState *bs, uint64_t perm, uint64_t shared);
449
450	/*
451	* Called to inform the driver that after a previous bdrv_check_perm()
452	* call, the permission update is not performed and any preparations made
453	* for it (e.g. taken file locks) need to be undone.
454	*
455	* This function can be called even for nodes that never saw a
456	* bdrv_check_perm() call. It is a no-op then.
457	*/
458	void GRAPH_RDLOCK_PTR (bdrv_abort_perm_update)(BlockDriverState bs);
459
460	/**
461	* Returns in @nperm and @nshared the permissions that the driver for @bs
462	* needs on its child @c, based on the cumulative permissions requested by
463	* the parents in @parent_perm and @parent_shared.
464	*
465	* If @c is NULL, return the permissions for attaching a new child for the
466	* given @child_class and @role.
467	*
468	* If @reopen_queue is non-NULL, don't return the currently needed
469	* permissions, but those that will be needed after applying the
470	* @reopen_queue.
471	*/
472	void GRAPH_RDLOCK_PTR (*bdrv_child_perm)(
473	BlockDriverState bs, BdrvChild c, BdrvChildRole role,
474	BlockReopenQueue *reopen_queue,
475	uint64_t parent_perm, uint64_t parent_shared,
476	uint64_t nperm, uint64_t nshared);
477
478	/**
479	* Register/unregister a buffer for I/O. For example, when the driver is
480	* interested to know the memory areas that will later be used in iovs, so
481	* that it can do IOMMU mapping with VFIO etc., in order to get better
482	* performance. In the case of VFIO drivers, this callback is used to do
483	* DMA mapping for hot buffers.
484	*
485	* Returns: true on success, false on failure
486	*/
487	bool GRAPH_RDLOCK_PTR (*bdrv_register_buf)(
488	BlockDriverState bs, void host, size_t size, Error **errp);
489	void GRAPH_RDLOCK_PTR (*bdrv_unregister_buf)(
490	BlockDriverState bs, void host, size_t size);
491
492	/*
493	* This field is modified only under the BQL, and is part of
494	* the global state.
495	*/
496	QLIST_ENTRY(BlockDriver) list;
497
498	/*
499	* I/O API functions. These functions are thread-safe.
500	*
501	* See include/block/block-io.h for more information about
502	* the I/O API.
503	*/
504
505	int (bdrv_probe)(const uint8_t buf, int buf_size, const char *filename);
506
507	int coroutine_fn GRAPH_RDLOCK_PTR (*bdrv_co_amend)(
508	BlockDriverState bs, BlockdevAmendOptions opts, bool force,
509	Error **errp);
510
511	/*
512	* AIO
513	* The given completion callback will be run in the same AioContext as the
514	* one in which the AIO function was called.
515	*/
516
517	BlockAIOCB * GRAPH_RDLOCK_PTR (bdrv_aio_preadv)(BlockDriverState bs,
518	int64_t offset, int64_t bytes, QEMUIOVector *qiov,
519	BdrvRequestFlags flags, BlockCompletionFunc cb, void opaque);
520
521	BlockAIOCB * GRAPH_RDLOCK_PTR (bdrv_aio_pwritev)(BlockDriverState bs,
522	int64_t offset, int64_t bytes, QEMUIOVector *qiov,
523	BdrvRequestFlags flags, BlockCompletionFunc cb, void opaque);
524
525	BlockAIOCB * GRAPH_RDLOCK_PTR (*bdrv_aio_flush)(
526	BlockDriverState bs, BlockCompletionFunc cb, void *opaque);
527
528	int coroutine_fn GRAPH_RDLOCK_PTR (bdrv_co_readv)(BlockDriverState bs,
529	int64_t sector_num, int nb_sectors, QEMUIOVector *qiov);
530
531	/**
532	* @offset: position in bytes to read at
533	* @bytes: number of bytes to read
534	* @qiov: the buffers to fill with read data
535	* @flags: currently unused, always 0
536	*
537	* @offset and @bytes will be a multiple of 'request_alignment',
538	* but the length of individual @qiov elements does not have to
539	* be a multiple.
540	*
541	* @bytes will always equal the total size of @qiov, and will be
542	* no larger than 'max_transfer'.
543	*
544	* The buffer in @qiov may point directly to guest memory.
545	*/
546	int coroutine_fn GRAPH_RDLOCK_PTR (bdrv_co_preadv)(BlockDriverState bs,
547	int64_t offset, int64_t bytes, QEMUIOVector *qiov,
548	BdrvRequestFlags flags);
549
550	int coroutine_fn GRAPH_RDLOCK_PTR (*bdrv_co_preadv_part)(
551	BlockDriverState *bs, int64_t offset, int64_t bytes,
552	QEMUIOVector *qiov, size_t qiov_offset,
553	BdrvRequestFlags flags);
554
555	int coroutine_fn GRAPH_RDLOCK_PTR (bdrv_co_writev)(BlockDriverState bs,
556	int64_t sector_num, int nb_sectors, QEMUIOVector *qiov,
557	int flags);
558	/**
559	* @offset: position in bytes to write at
560	* @bytes: number of bytes to write
561	* @qiov: the buffers containing data to write
562	* @flags: zero or more bits allowed by 'supported_write_flags'
563	*
564	* @offset and @bytes will be a multiple of 'request_alignment',
565	* but the length of individual @qiov elements does not have to
566	* be a multiple.
567	*
568	* @bytes will always equal the total size of @qiov, and will be
569	* no larger than 'max_transfer'.
570	*
571	* The buffer in @qiov may point directly to guest memory.
572	*/
573	int coroutine_fn GRAPH_RDLOCK_PTR (*bdrv_co_pwritev)(
574	BlockDriverState bs, int64_t offset, int64_t bytes, QEMUIOVector qiov,
575	BdrvRequestFlags flags);
576	int coroutine_fn GRAPH_RDLOCK_PTR (*bdrv_co_pwritev_part)(
577	BlockDriverState bs, int64_t offset, int64_t bytes, QEMUIOVector qiov,
578	size_t qiov_offset, BdrvRequestFlags flags);
579
580	/*
581	* Efficiently zero a region of the disk image. Typically an image format
582	* would use a compact metadata representation to implement this. This
583	* function pointer may be NULL or return -ENOSUP and .bdrv_co_writev()
584	* will be called instead.
585	*/
586	int coroutine_fn GRAPH_RDLOCK_PTR (*bdrv_co_pwrite_zeroes)(
587	BlockDriverState *bs, int64_t offset, int64_t bytes,
588	BdrvRequestFlags flags);
589
590	int coroutine_fn GRAPH_RDLOCK_PTR (*bdrv_co_pdiscard)(
591	BlockDriverState *bs, int64_t offset, int64_t bytes);
592
593	/*
594	* Map [offset, offset + nbytes) range onto a child of @bs to copy from,
595	* and invoke bdrv_co_copy_range_from(child, ...), or invoke
596	* bdrv_co_copy_range_to() if @bs is the leaf child to copy data from.
597	*
598	* See the comment of bdrv_co_copy_range for the parameter and return value
599	* semantics.
600	*/
601	int coroutine_fn GRAPH_RDLOCK_PTR (*bdrv_co_copy_range_from)(
602	BlockDriverState bs, BdrvChild src, int64_t offset,
603	BdrvChild *dst, int64_t dst_offset, int64_t bytes,
604	BdrvRequestFlags read_flags, BdrvRequestFlags write_flags);
605
606	/*
607	* Map [offset, offset + nbytes) range onto a child of bs to copy data to,
608	* and invoke bdrv_co_copy_range_to(child, src, ...), or perform the copy
609	* operation if @bs is the leaf and @src has the same BlockDriver. Return
610	* -ENOTSUP if @bs is the leaf but @src has a different BlockDriver.
611	*
612	* See the comment of bdrv_co_copy_range for the parameter and return value
613	* semantics.
614	*/
615	int coroutine_fn GRAPH_RDLOCK_PTR (*bdrv_co_copy_range_to)(
616	BlockDriverState bs, BdrvChild src, int64_t src_offset,
617	BdrvChild *dst, int64_t dst_offset, int64_t bytes,
618	BdrvRequestFlags read_flags, BdrvRequestFlags write_flags);
619
620	/*
621	* Building block for bdrv_block_status[_above] and
622	* bdrv_is_allocated[_above]. The driver should answer only
623	* according to the current layer, and should only need to set
624	* BDRV_BLOCK_DATA, BDRV_BLOCK_ZERO, BDRV_BLOCK_OFFSET_VALID,
625	* and/or BDRV_BLOCK_RAW; if the current layer defers to a backing
626	* layer, the result should be 0 (and not BDRV_BLOCK_ZERO). The
627	* caller will synthesize BDRV_BLOCK_ALLOCATED based on the
628	* non-zero results. See block.h for the overall meaning of the
629	* bits. As a hint, the flags in @mode may include a bitwise-or
630	* of BDRV_WANT_ALLOCATED, BDRV_WANT_OFFSET_VALID, or
631	* BDRV_WANT_ZERO based on what the caller is looking for in the
632	* results. The block layer guarantees input clamped to
633	* bdrv_getlength() and aligned to request_alignment, as well as
634	* non-NULL pnum, map, and file; in turn, the driver must return
635	* an error or set pnum to an aligned non-zero value.
636	*
637	* Note that @bytes is just a hint on how big of a region the
638	* caller wants to inspect. It is not a limit on *pnum.
639	* Implementations are free to return larger values of *pnum if
640	* doing so does not incur a performance penalty.
641	*
642	* block/io.c's bdrv_co_block_status() will utilize an unclamped
643	* *pnum value for the block-status cache on protocol nodes, prior
644	* to clamping *pnum for return to its caller.
645	*/
646	int coroutine_fn GRAPH_RDLOCK_PTR (*bdrv_co_block_status)(
647	BlockDriverState *bs, unsigned int mode,
648	int64_t offset, int64_t bytes, int64_t *pnum,
649	int64_t map, BlockDriverState *file);
650
651	/*
652	* Snapshot-access API.
653	*
654	* Block-driver may provide snapshot-access API: special functions to access
655	* some internal "snapshot". The functions are similar with normal
656	* read/block_status/discard handler, but don't have any specific handling
657	* in generic block-layer: no serializing, no alignment, no tracked
658	* requests. So, block-driver that realizes these APIs is fully responsible
659	* for synchronization between snapshot-access API and normal IO requests.
660	*
661	* TODO: To be able to support qcow2's internal snapshots, this API will
662	* need to be extended to:
663	* - be able to select a specific snapshot
664	* - receive the snapshot's actual length (which may differ from bs's
665	* length)
666	*/
667	int coroutine_fn GRAPH_RDLOCK_PTR (*bdrv_co_preadv_snapshot)(
668	BlockDriverState *bs, int64_t offset, int64_t bytes,
669	QEMUIOVector *qiov, size_t qiov_offset);
670
671	int coroutine_fn GRAPH_RDLOCK_PTR (*bdrv_co_snapshot_block_status)(
672	BlockDriverState *bs, unsigned int mode, int64_t offset,
673	int64_t bytes, int64_t pnum, int64_t map, BlockDriverState **file);
674
675	int coroutine_fn GRAPH_RDLOCK_PTR (*bdrv_co_pdiscard_snapshot)(
676	BlockDriverState *bs, int64_t offset, int64_t bytes);
677
678	/*
679	* Invalidate any cached meta-data.
680	*/
681	void coroutine_fn GRAPH_RDLOCK_PTR (*bdrv_co_invalidate_cache)(
682	BlockDriverState bs, Error *errp);
683
684	/*
685	* Flushes all data for all layers by calling bdrv_co_flush for underlying
686	* layers, if needed. This function is needed for deterministic
687	* synchronization of the flush finishing callback.
688	*/
689	int coroutine_fn GRAPH_RDLOCK_PTR (bdrv_co_flush)(BlockDriverState bs);
690
691	/* Delete a created file. */
692	int coroutine_fn GRAPH_RDLOCK_PTR (*bdrv_co_delete_file)(
693	BlockDriverState bs, Error *errp);
694
695	/*
696	* Flushes all data that was already written to the OS all the way down to
697	* the disk (for example file-posix.c calls fsync()).
698	*/
699	int coroutine_fn GRAPH_RDLOCK_PTR (*bdrv_co_flush_to_disk)(
700	BlockDriverState *bs);
701
702	/*
703	* Flushes all internal caches to the OS. The data may still sit in a
704	* writeback cache of the host OS, but it will survive a crash of the qemu
705	* process.
706	*/
707	int coroutine_fn GRAPH_RDLOCK_PTR (*bdrv_co_flush_to_os)(
708	BlockDriverState *bs);
709
710	/*
711	* Truncate @bs to @offset bytes using the given @prealloc mode
712	* when growing. Modes other than PREALLOC_MODE_OFF should be
713	* rejected when shrinking @bs.
714	*
715	* If @exact is true, @bs must be resized to exactly @offset.
716	* Otherwise, it is sufficient for @bs (if it is a host block
717	* device and thus there is no way to resize it) to be at least
718	* @offset bytes in length.
719	*
720	* If @exact is true and this function fails but would succeed
721	* with @exact = false, it should return -ENOTSUP.
722	*/
723	int coroutine_fn GRAPH_RDLOCK_PTR (*bdrv_co_truncate)(
724	BlockDriverState *bs, int64_t offset, bool exact,
725	PreallocMode prealloc, BdrvRequestFlags flags, Error **errp);
726
727	int64_t coroutine_fn GRAPH_RDLOCK_PTR (*bdrv_co_getlength)(
728	BlockDriverState *bs);
729
730	int64_t coroutine_fn GRAPH_RDLOCK_PTR (*bdrv_co_get_allocated_file_size)(
731	BlockDriverState *bs);
732
733	BlockMeasureInfo (bdrv_measure)(QemuOpts opts, BlockDriverState in_bs,
734	Error **errp);
735
736	int coroutine_fn GRAPH_RDLOCK_PTR (*bdrv_co_pwritev_compressed)(
737	BlockDriverState *bs, int64_t offset, int64_t bytes,
738	QEMUIOVector *qiov);
739
740	int coroutine_fn GRAPH_RDLOCK_PTR (*bdrv_co_pwritev_compressed_part)(
741	BlockDriverState *bs, int64_t offset, int64_t bytes,
742	QEMUIOVector *qiov, size_t qiov_offset);
743
744	int coroutine_fn GRAPH_RDLOCK_PTR (*bdrv_co_get_info)(
745	BlockDriverState bs, BlockDriverInfo bdi);
746
747	ImageInfoSpecific * GRAPH_RDLOCK_PTR (*bdrv_get_specific_info)(
748	BlockDriverState bs, Error *errp);
749	BlockStatsSpecific (bdrv_get_specific_stats)(BlockDriverState *bs);
750
751	int coroutine_fn GRAPH_RDLOCK_PTR (*bdrv_co_save_vmstate)(
752	BlockDriverState bs, QEMUIOVector qiov, int64_t pos);
753
754	int coroutine_fn GRAPH_RDLOCK_PTR (*bdrv_co_load_vmstate)(
755	BlockDriverState bs, QEMUIOVector qiov, int64_t pos);
756
757	int coroutine_fn (bdrv_co_zone_report)(BlockDriverState bs,
758	int64_t offset, unsigned int *nr_zones,
759	BlockZoneDescriptor *zones);
760	int coroutine_fn (bdrv_co_zone_mgmt)(BlockDriverState bs, BlockZoneOp op,
761	int64_t offset, int64_t len);
762	int coroutine_fn (bdrv_co_zone_append)(BlockDriverState bs,
763	int64_t offset, QEMUIOVector qiov,
764	BdrvRequestFlags flags);
765
766	/* removable device specific */
767	bool coroutine_fn GRAPH_RDLOCK_PTR (*bdrv_co_is_inserted)(
768	BlockDriverState *bs);
769	void coroutine_fn GRAPH_RDLOCK_PTR (*bdrv_co_eject)(
770	BlockDriverState *bs, bool eject_flag);
771	void coroutine_fn GRAPH_RDLOCK_PTR (*bdrv_co_lock_medium)(
772	BlockDriverState *bs, bool locked);
773
774	/* to control generic scsi devices */
775	BlockAIOCB coroutine_fn GRAPH_RDLOCK_PTR (bdrv_aio_ioctl)(
776	BlockDriverState bs, unsigned long int req, void buf,
777	BlockCompletionFunc cb, void opaque);
778
779	int coroutine_fn GRAPH_RDLOCK_PTR (*bdrv_co_ioctl)(
780	BlockDriverState bs, unsigned long int req, void buf);
781
782	/*
783	* Returns 0 for completed check, -errno for internal errors.
784	* The check results are stored in result.
785	*/
786	int coroutine_fn GRAPH_RDLOCK_PTR (*bdrv_co_check)(
787	BlockDriverState bs, BdrvCheckResult result, BdrvCheckMode fix);
788
789	void coroutine_fn GRAPH_RDLOCK_PTR (*bdrv_co_debug_event)(
790	BlockDriverState *bs, BlkdebugEvent event);
791
792	bool (bdrv_supports_persistent_dirty_bitmap)(BlockDriverState bs);
793
794	bool coroutine_fn GRAPH_RDLOCK_PTR (*bdrv_co_can_store_new_dirty_bitmap)(
795	BlockDriverState bs, const char name, uint32_t granularity,
796	Error **errp);
797
798	int coroutine_fn GRAPH_RDLOCK_PTR (*bdrv_co_remove_persistent_dirty_bitmap)(
799	BlockDriverState bs, const char name, Error **errp);
800	};
801
802	static inline bool TSA_NO_TSA block_driver_can_compress(BlockDriver *drv)
803	{
804	return drv->bdrv_co_pwritev_compressed \|\|
805	drv->bdrv_co_pwritev_compressed_part;
806	}
807
808	typedef struct BlockLimits {
809	/*
810	* Alignment requirement, in bytes, for offset/length of I/O
811	* requests. Must be a power of 2 less than INT_MAX; defaults to
812	* 1 for drivers with modern byte interfaces, and to 512
813	* otherwise.
814	*/
815	uint32_t request_alignment;
816
817	/*
818	* Maximum number of bytes that can be discarded at once. Must be multiple
819	* of pdiscard_alignment, but need not be power of 2. May be 0 if no
820	* inherent 64-bit limit.
821	*/
822	int64_t max_pdiscard;
823
824	/*
825	* Optimal alignment for discard requests in bytes. Note that this doesn't
826	* have to be a power of two. Must be a multiple of bl.request_alignment,
827	* and must be less than max_pdiscard if that is set. May be 0 if
828	* bl.request_alignment is good enough.
829	*/
830	uint32_t pdiscard_alignment;
831
832	/*
833	* Maximum number of bytes that can zeroized at once. Must be multiple of
834	* pwrite_zeroes_alignment. 0 means no limit.
835	*/
836	int64_t max_pwrite_zeroes;
837
838	/*
839	* Optimal alignment for write zeroes requests in bytes. Note that this
840	* doesn't have to be a power of two. Must be a multiple of
841	* bl.request_alignment, and must be less than max_pwrite_zeroes if that is
842	* set. May be 0 if bl.request_alignment is good enough.
843	*/
844	uint32_t pwrite_zeroes_alignment;
845
846	/*
847	* Optimal transfer length in bytes. A power of 2 is best but not
848	* mandatory. Must be a multiple of bl.request_alignment, or 0 if
849	* no preferred size
850	*/
851	uint32_t opt_transfer;
852
853	/*
854	* Maximal transfer length in bytes. Need not be power of 2, but
855	* must be multiple of opt_transfer and bl.request_alignment, or 0
856	* for no 32-bit limit. For now, anything larger than INT_MAX is
857	* clamped down.
858	*/
859	uint32_t max_transfer;
860
861	/*
862	* Maximal hardware transfer length in bytes. Applies whenever
863	* transfers to the device bypass the kernel I/O scheduler, for
864	* example with SG_IO. If larger than max_transfer or if zero,
865	* blk_get_max_hw_transfer will fall back to max_transfer.
866	*/
867	uint64_t max_hw_transfer;
868
869	/*
870	* Maximum number of scatter/gather elements allowed by the hardware.
871	* Applies whenever transfers to the device bypass the kernel I/O
872	* scheduler, for example with SG_IO. If larger than max_iov
873	* or if zero, blk_get_max_hw_iov will fall back to max_iov.
874	*/
875	int max_hw_iov;
876
877	/*
878	* Minimal required memory alignment in bytes for zero-copy I/O to succeed.
879	* For unaligned requests, a bounce buffer will be used.
880	*/
881	size_t min_mem_alignment;
882
883	/*
884	* Optimal memory alignment in bytes. This is the alignment used for any
885	* buffer allocations QEMU performs internally.
886	*/
887	size_t opt_mem_alignment;
888
889	/* maximum number of iovec elements */
890	int max_iov;
891
892	/*
893	* true if the length of the underlying file can change, and QEMU
894	* is expected to adjust automatically. Mostly for CD-ROM drives,
895	* whose length is zero when the tray is empty (they don't need
896	* an explicit monitor command to load the disk inside the guest).
897	*/
898	bool has_variable_length;
899
900	/* device zone model */
901	BlockZoneModel zoned;
902
903	/* zone size expressed in bytes */
904	uint32_t zone_size;
905
906	/* total number of zones */
907	uint32_t nr_zones;
908
909	/* maximum sectors of a zone append write operation */
910	uint32_t max_append_sectors;
911
912	/* maximum number of open zones */
913	uint32_t max_open_zones;
914
915	/* maximum number of active zones */
916	uint32_t max_active_zones;
917
918	uint32_t write_granularity;
919	} BlockLimits;
920
921	typedef struct BdrvOpBlocker BdrvOpBlocker;
922
923	typedef struct BdrvAioNotifier {
924	void (attached_aio_context)(AioContext new_context, void *opaque);
925	void (detach_aio_context)(void opaque);
926
927	void *opaque;
928	bool deleted;
929
930	QLIST_ENTRY(BdrvAioNotifier) list;
931	} BdrvAioNotifier;
932
933	struct BdrvChildClass {
934	/*
935	* If true, bdrv_replace_node() doesn't change the node this BdrvChild
936	* points to.
937	*/
938	bool stay_at_node;
939
940	/*
941	* If true, the parent is a BlockDriverState and bdrv_next_all_states()
942	* will return it. This information is used for drain_all, where every node
943	* will be drained separately, so the drain only needs to be propagated to
944	* non-BDS parents.
945	*/
946	bool parent_is_bds;
947
948	/*
949	* Global state (GS) API. These functions run under the BQL.
950	*
951	* See include/block/block-global-state.h for more information about
952	* the GS API.
953	*/
954	void (*inherit_options)(BdrvChildRole role, bool parent_is_format,
955	int child_flags, QDict child_options,
956	int parent_flags, QDict *parent_options);
957	void (change_media)(BdrvChild child, bool load);
958
959	/*
960	* Returns a malloced string that describes the parent of the child for a
961	* human reader. This could be a node-name, BlockBackend name, qdev ID or
962	* QOM path of the device owning the BlockBackend, job type and ID etc. The
963	* caller is responsible for freeing the memory.
964	*/
965	char (get_parent_desc)(BdrvChild *child);
966
967	/*
968	* Notifies the parent that the child has been activated/inactivated (e.g.
969	* when migration is completing) and it can start/stop requesting
970	* permissions and doing I/O on it.
971	*/
972	void GRAPH_RDLOCK_PTR (activate)(BdrvChild child, Error **errp);
973	int GRAPH_RDLOCK_PTR (inactivate)(BdrvChild child);
974
975	void GRAPH_WRLOCK_PTR (attach)(BdrvChild child);
976	void GRAPH_WRLOCK_PTR (detach)(BdrvChild child);
977
978	/*
979	* If this pair of functions is implemented, the parent doesn't issue new
980	* requests after returning from .drained_begin() until .drained_end() is
981	* called.
982	*
983	* These functions must not change the graph (and therefore also must not
984	* call aio_poll(), which could change the graph indirectly).
985	*
986	* Note that this can be nested. If drained_begin() was called twice, new
987	* I/O is allowed only after drained_end() was called twice, too.
988	*/
989	void GRAPH_RDLOCK_PTR (drained_begin)(BdrvChild child);
990	void GRAPH_RDLOCK_PTR (drained_end)(BdrvChild child);
991
992	/*
993	* Returns whether the parent has pending requests for the child. This
994	* callback is polled after .drained_begin() has been called until all
995	* activity on the child has stopped.
996	*/
997	bool GRAPH_RDLOCK_PTR (drained_poll)(BdrvChild child);
998
999	/*
1000	* Notifies the parent that the filename of its child has changed (e.g.
1001	* because the direct child was removed from the backing chain), so that it
1002	* can update its reference.
1003	*/
1004	int (update_filename)(BdrvChild child, BlockDriverState *new_base,
1005	const char *filename,
1006	bool backing_mask_protocol,
1007	Error **errp);
1008
1009	/*
1010	* Notifies the parent that the child is trying to change its AioContext.
1011	* The parent may in turn change the AioContext of other nodes in the same
1012	* transaction. Returns true if the change is possible and the transaction
1013	* can be continued. Returns false and sets @errp if not and the transaction
1014	* must be aborted.
1015	*
1016	* @visited will accumulate all visited BdrvChild objects. The caller is
1017	* responsible for freeing the list afterwards.
1018	*
1019	* Must be called with the affected block nodes drained.
1020	*/
1021	bool GRAPH_RDLOCK_PTR (change_aio_ctx)(BdrvChild child, AioContext *ctx,
1022	GHashTable *visited,
1023	Transaction tran, Error *errp);
1024
1025	/*
1026	* I/O API functions. These functions are thread-safe.
1027	*
1028	* See include/block/block-io.h for more information about
1029	* the I/O API.
1030	*/
1031
1032	/*
1033	* Notifies the parent that the child was resized.
1034	*/
1035	void GRAPH_RDLOCK_PTR (resize)(BdrvChild child);
1036
1037	/*
1038	* Returns a name that is supposedly more useful for human users than the
1039	* node name for identifying the node in question (in particular, a BB
1040	* name), or NULL if the parent can't provide a better name.
1041	*/
1042	const char (get_name)(BdrvChild *child);
1043
1044	AioContext (get_parent_aio_context)(BdrvChild *child);
1045	};
1046
1047	extern const BdrvChildClass child_of_bds;
1048
1049	struct BdrvChild {
1050	BlockDriverState *bs;
1051	char *name;
1052	const BdrvChildClass *klass;
1053	BdrvChildRole role;
1054	void *opaque;
1055
1056	/**
1057	* Granted permissions for operating on this BdrvChild (BLK_PERM_* bitmask)
1058	*/
1059	uint64_t perm;
1060
1061	/**
1062	* Permissions that can still be granted to other users of @bs while this
1063	* BdrvChild is still attached to it. (BLK_PERM_* bitmask)
1064	*/
1065	uint64_t shared_perm;
1066
1067	/*
1068	* This link is frozen: the child can neither be replaced nor
1069	* detached from the parent.
1070	*/
1071	bool frozen;
1072
1073	/*
1074	* True if the parent of this child has been drained by this BdrvChild
1075	* (through klass->drained_*).
1076	*
1077	* It is generally true if bs->quiesce_counter > 0. It may differ while the
1078	* child is entering or leaving a drained section.
1079	*/
1080	bool quiesced_parent;
1081
1082	QLIST_ENTRY(BdrvChild GRAPH_RDLOCK_PTR) next;
1083	QLIST_ENTRY(BdrvChild GRAPH_RDLOCK_PTR) next_parent;
1084	};
1085
1086	/*
1087	* Allows bdrv_co_block_status() to cache one data region for a
1088	* protocol node.
1089	*
1090	* @valid: Whether the cache is valid (should be accessed with atomic
1091	* functions so this can be reset by RCU readers)
1092	* @data_start: Offset where we know (or strongly assume) is data
1093	* @data_end: Offset where the data region ends (which is not necessarily
1094	* the start of a zeroed region)
1095	*/
1096	typedef struct BdrvBlockStatusCache {
1097	struct rcu_head rcu;
1098
1099	bool valid;
1100	int64_t data_start;
1101	int64_t data_end;
1102	} BdrvBlockStatusCache;
1103
1104	struct BlockDriverState {
1105	/*
1106	* Protected by big QEMU lock or read-only after opening. No special
1107	* locking needed during I/O...
1108	*/
1109	int open_flags; /* flags used to open the file, re-used for re-open */
1110	bool encrypted; /* if true, the media is encrypted */
1111	bool sg; /* if true, the device is a /dev/sg* */
1112	bool probed; /* if true, format was probed rather than specified */
1113	bool force_share; /* if true, always allow all shared permissions */
1114	bool implicit; /* if true, this filter node was automatically inserted */
1115
1116	BlockDriver drv; / NULL means no media */
1117	void *opaque;
1118
1119	AioContext aio_context; / event loop used for fd handlers, timers, etc */
1120	/*
1121	* long-running tasks intended to always use the same AioContext as this
1122	* BDS may register themselves in this list to be notified of changes
1123	* regarding this BDS's context
1124	*/
1125	QLIST_HEAD(, BdrvAioNotifier) aio_notifiers;
1126	bool walking_aio_notifiers; /* to make removal during iteration safe */
1127
1128	char filename[PATH_MAX];
1129	/*
1130	* If not empty, this image is a diff in relation to backing_file.
1131	* Note that this is the name given in the image header and
1132	* therefore may or may not be equal to .backing->bs->filename.
1133	* If this field contains a relative path, it is to be resolved
1134	* relatively to the overlay's location.
1135	*/
1136	char backing_file[PATH_MAX];
1137	/*
1138	* The backing filename indicated by the image header. Contrary
1139	* to backing_file, if we ever open this file, auto_backing_file
1140	* is replaced by the resulting BDS's filename (i.e. after a
1141	* bdrv_refresh_filename() run).
1142	*/
1143	char auto_backing_file[PATH_MAX];
1144	char backing_format[16]; /* if non-zero and backing_file exists */
1145
1146	QDict *full_open_options;
1147	char exact_filename[PATH_MAX];
1148
1149	/* I/O Limits */
1150	BlockLimits bl;
1151
1152	/*
1153	* Flags honored during pread
1154	*/
1155	BdrvRequestFlags supported_read_flags;
1156	/*
1157	* Flags honored during pwrite (so far: BDRV_REQ_FUA,
1158	* BDRV_REQ_WRITE_UNCHANGED).
1159	* If a driver does not support BDRV_REQ_WRITE_UNCHANGED, those
1160	* writes will be issued as normal writes without the flag set.
1161	* This is important to note for drivers that do not explicitly
1162	* request a WRITE permission for their children and instead take
1163	* the same permissions as their parent did (this is commonly what
1164	* block filters do). Such drivers have to be aware that the
1165	* parent may have taken a WRITE_UNCHANGED permission only and is
1166	* issuing such requests. Drivers either must make sure that
1167	* these requests do not result in plain WRITE accesses (usually
1168	* by supporting BDRV_REQ_WRITE_UNCHANGED, and then forwarding
1169	* every incoming write request as-is, including potentially that
1170	* flag), or they have to explicitly take the WRITE permission for
1171	* their children.
1172	*/
1173	BdrvRequestFlags supported_write_flags;
1174	/*
1175	* Flags honored during pwrite_zeroes (so far: BDRV_REQ_FUA,
1176	* BDRV_REQ_MAY_UNMAP, BDRV_REQ_WRITE_UNCHANGED)
1177	*/
1178	BdrvRequestFlags supported_zero_flags;
1179	/*
1180	* Flags honoured during truncate (so far: BDRV_REQ_ZERO_WRITE).
1181	*
1182	* If BDRV_REQ_ZERO_WRITE is given, the truncate operation must make sure
1183	* that any added space reads as all zeros. If this can't be guaranteed,
1184	* the operation must fail.
1185	*/
1186	BdrvRequestFlags supported_truncate_flags;
1187
1188	/* the following member gives a name to every node on the bs graph. */
1189	char node_name[32];
1190	/* element of the list of named nodes building the graph */
1191	QTAILQ_ENTRY(BlockDriverState) node_list;
1192	/* element of the list of all BlockDriverStates (all_bdrv_states) */
1193	QTAILQ_ENTRY(BlockDriverState) bs_list;
1194	/* element of the list of monitor-owned BDS */
1195	QTAILQ_ENTRY(BlockDriverState) monitor_list;
1196	int refcnt;
1197
1198	/* operation blockers. Protected by BQL. */
1199	QLIST_HEAD(, BdrvOpBlocker) op_blockers[BLOCK_OP_TYPE_MAX];
1200
1201	/*
1202	* The node that this node inherited default options from (and a reopen on
1203	* which can affect this node by changing these defaults). This is always a
1204	* parent node of this node.
1205	*/
1206	BlockDriverState *inherits_from;
1207
1208	/*
1209	* @backing and @file are some of @children or NULL. All these three fields
1210	* (@file, @backing and @children) are modified only in
1211	* bdrv_child_cb_attach() and bdrv_child_cb_detach().
1212	*
1213	* See also comment in include/block/block.h, to learn how backing and file
1214	* are connected with BdrvChildRole.
1215	*/
1216	QLIST_HEAD(, BdrvChild GRAPH_RDLOCK_PTR) children;
1217	BdrvChild * GRAPH_RDLOCK_PTR backing;
1218	BdrvChild * GRAPH_RDLOCK_PTR file;
1219
1220	QLIST_HEAD(, BdrvChild GRAPH_RDLOCK_PTR) parents;
1221
1222	QDict *options;
1223	QDict *explicit_options;
1224	BlockdevDetectZeroesOptions detect_zeroes;
1225
1226	/* The error object in use for blocking operations on backing_hd */
1227	Error *backing_blocker;
1228
1229	/*
1230	* If we are reading a disk image, give its size in sectors.
1231	* Generally read-only; it is written to by load_snapshot and
1232	* save_snaphost, but the block layer is quiescent during those.
1233	*/
1234	int64_t total_sectors;
1235
1236	/* threshold limit for writes, in bytes. "High water mark". */
1237	uint64_t write_threshold_offset;
1238
1239	/*
1240	* Writing to the list requires the BQL _and_ the dirty_bitmap_mutex.
1241	* Reading from the list can be done with either the BQL or the
1242	* dirty_bitmap_mutex. Modifying a bitmap only requires
1243	* dirty_bitmap_mutex.
1244	*/
1245	QemuMutex dirty_bitmap_mutex;
1246	QLIST_HEAD(, BdrvDirtyBitmap) dirty_bitmaps;
1247
1248	/* Offset after the highest byte written to */
1249	uint64_t wr_highest_offset;
1250
1251	/*
1252	* If true, copy read backing sectors into image. Can be >1 if more
1253	* than one client has requested copy-on-read. Accessed with atomic
1254	* ops.
1255	*/
1256	int copy_on_read;
1257
1258	/*
1259	* number of in-flight requests; overall and serialising.
1260	* Accessed with atomic ops.
1261	*/
1262	unsigned int in_flight;
1263	unsigned int serialising_in_flight;
1264
1265	/* do we need to tell the quest if we have a volatile write cache? */
1266	int enable_write_cache;
1267
1268	/* Accessed only in the main thread. */
1269	int quiesce_counter;
1270
1271	unsigned int write_gen; /* Current data generation */
1272
1273	/* Protected by reqs_lock. */
1274	QemuMutex reqs_lock;
1275	QLIST_HEAD(, BdrvTrackedRequest) tracked_requests;
1276	CoQueue flush_queue; /* Serializing flush queue */
1277	bool active_flush_req; /* Flush request in flight? */
1278
1279	/* Only read/written by whoever has set active_flush_req to true. */
1280	unsigned int flushed_gen; /* Flushed write generation */
1281
1282	/* BdrvChild links to this node may never be frozen */
1283	bool never_freeze;
1284
1285	/* Lock for block-status cache RCU writers */
1286	CoMutex bsc_modify_lock;
1287	/* Always non-NULL, but must only be dereferenced under an RCU read guard */
1288	BdrvBlockStatusCache *block_status_cache;
1289
1290	/* array of write pointers' location of each zone in the zoned device. */
1291	BlockZoneWps *wps;
1292	};
1293
1294	struct BlockBackendRootState {
1295	int open_flags;
1296	BlockdevDetectZeroesOptions detect_zeroes;
1297	};
1298
1299	typedef enum BlockMirrorBackingMode {
1300	/*
1301	* Reuse the existing backing chain from the source for the target.
1302	* - sync=full: Set backing BDS to NULL.
1303	* - sync=top: Use source's backing BDS.
1304	* - sync=none: Use source as the backing BDS.
1305	*/
1306	MIRROR_SOURCE_BACKING_CHAIN,
1307
1308	/* Open the target's backing chain completely anew */
1309	MIRROR_OPEN_BACKING_CHAIN,
1310
1311	/* Do not change the target's backing BDS after job completion */
1312	MIRROR_LEAVE_BACKING_CHAIN,
1313	} BlockMirrorBackingMode;
1314
1315
1316	/*
1317	* Essential block drivers which must always be statically linked into qemu, and
1318	* which therefore can be accessed without using bdrv_find_format()
1319	*/
1320	extern BlockDriver bdrv_file;
1321	extern BlockDriver bdrv_raw;
1322	extern BlockDriver bdrv_qcow2;
1323
1324	extern unsigned int bdrv_drain_all_count;
1325	extern QemuOptsList bdrv_create_opts_simple;
1326
1327	/*
1328	* Common functions that are neither I/O nor Global State.
1329	*
1330	* See include/block/block-common.h for more information about
1331	* the Common API.
1332	*/
1333
1334	static inline BlockDriverState child_bs(BdrvChild child)
1335	{
1336	return child ? child->bs : NULL;
1337	}
1338
1339	int bdrv_check_request(int64_t offset, int64_t bytes, Error **errp);
1340	char create_tmp_file(Error *errp);
1341	void bdrv_parse_filename_strip_prefix(const char filename, const char prefix,
1342	QDict *options);
1343
1344
1345	int bdrv_check_qiov_request(int64_t offset, int64_t bytes,
1346	QEMUIOVector *qiov, size_t qiov_offset,
1347	Error **errp);
1348
1349	#ifdef _WIN32
1350	int is_windows_drive(const char *filename);
1351	#endif
1352
1353	#endif /* BLOCK_INT_COMMON_H */