xref: /openbmc/qemu/include/block/block-io.h (revision 21063bce)
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_IO_H
25 #define BLOCK_IO_H
26 
27 #include "block/aio-wait.h"
28 #include "block/block-common.h"
29 #include "qemu/coroutine.h"
30 #include "qemu/iov.h"
31 
32 /*
33  * I/O API functions. These functions are thread-safe, and therefore
34  * can run in any thread as long as the thread has called
35  * aio_context_acquire/release().
36  *
37  * These functions can only call functions from I/O and Common categories,
38  * but can be invoked by GS, "I/O or GS" and I/O APIs.
39  *
40  * All functions in this category must use the macro
41  * IO_CODE();
42  * to catch when they are accidentally called by the wrong API.
43  */
44 
45 int co_wrapper_mixed_bdrv_rdlock
46 bdrv_pwrite_zeroes(BdrvChild *child, int64_t offset, int64_t bytes,
47                    BdrvRequestFlags flags);
48 
49 int bdrv_make_zero(BdrvChild *child, BdrvRequestFlags flags);
50 
51 int co_wrapper_mixed_bdrv_rdlock
52 bdrv_pread(BdrvChild *child, int64_t offset, int64_t bytes, void *buf,
53            BdrvRequestFlags flags);
54 
55 int co_wrapper_mixed_bdrv_rdlock
56 bdrv_pwrite(BdrvChild *child, int64_t offset,int64_t bytes,
57             const void *buf, BdrvRequestFlags flags);
58 
59 int co_wrapper_mixed_bdrv_rdlock
60 bdrv_pwrite_sync(BdrvChild *child, int64_t offset, int64_t bytes,
61                  const void *buf, BdrvRequestFlags flags);
62 
63 int coroutine_fn GRAPH_RDLOCK
64 bdrv_co_pwrite_sync(BdrvChild *child, int64_t offset, int64_t bytes,
65                     const void *buf, BdrvRequestFlags flags);
66 
67 /*
68  * Efficiently zero a region of the disk image.  Note that this is a regular
69  * I/O request like read or write and should have a reasonable size.  This
70  * function is not suitable for zeroing the entire image in a single request
71  * because it may allocate memory for the entire region.
72  */
73 int coroutine_fn GRAPH_RDLOCK
74 bdrv_co_pwrite_zeroes(BdrvChild *child, int64_t offset, int64_t bytes,
75                       BdrvRequestFlags flags);
76 
77 int coroutine_fn GRAPH_RDLOCK
78 bdrv_co_truncate(BdrvChild *child, int64_t offset, bool exact,
79                  PreallocMode prealloc, BdrvRequestFlags flags, Error **errp);
80 
81 int64_t coroutine_fn GRAPH_RDLOCK bdrv_co_nb_sectors(BlockDriverState *bs);
82 int64_t co_wrapper_mixed_bdrv_rdlock bdrv_nb_sectors(BlockDriverState *bs);
83 
84 int64_t coroutine_fn GRAPH_RDLOCK bdrv_co_getlength(BlockDriverState *bs);
85 int64_t co_wrapper_mixed_bdrv_rdlock bdrv_getlength(BlockDriverState *bs);
86 
87 int64_t coroutine_fn bdrv_co_get_allocated_file_size(BlockDriverState *bs);
88 int64_t co_wrapper bdrv_get_allocated_file_size(BlockDriverState *bs);
89 
90 BlockMeasureInfo *bdrv_measure(BlockDriver *drv, QemuOpts *opts,
91                                BlockDriverState *in_bs, Error **errp);
92 void bdrv_get_geometry(BlockDriverState *bs, uint64_t *nb_sectors_ptr);
93 
94 int coroutine_fn GRAPH_RDLOCK
95 bdrv_co_delete_file(BlockDriverState *bs, Error **errp);
96 
97 void coroutine_fn GRAPH_RDLOCK
98 bdrv_co_delete_file_noerr(BlockDriverState *bs);
99 
100 
101 /* async block I/O */
102 void bdrv_aio_cancel(BlockAIOCB *acb);
103 void bdrv_aio_cancel_async(BlockAIOCB *acb);
104 
105 /* sg packet commands */
106 int coroutine_fn GRAPH_RDLOCK
107 bdrv_co_ioctl(BlockDriverState *bs, int req, void *buf);
108 
109 /* Ensure contents are flushed to disk.  */
110 int coroutine_fn GRAPH_RDLOCK bdrv_co_flush(BlockDriverState *bs);
111 
112 int coroutine_fn GRAPH_RDLOCK bdrv_co_pdiscard(BdrvChild *child, int64_t offset,
113                                                int64_t bytes);
114 
115 bool bdrv_can_write_zeroes_with_unmap(BlockDriverState *bs);
116 int bdrv_block_status(BlockDriverState *bs, int64_t offset,
117                       int64_t bytes, int64_t *pnum, int64_t *map,
118                       BlockDriverState **file);
119 
120 int coroutine_fn GRAPH_RDLOCK
121 bdrv_co_block_status_above(BlockDriverState *bs, BlockDriverState *base,
122                            int64_t offset, int64_t bytes, int64_t *pnum,
123                            int64_t *map, BlockDriverState **file);
124 int bdrv_block_status_above(BlockDriverState *bs, BlockDriverState *base,
125                             int64_t offset, int64_t bytes, int64_t *pnum,
126                             int64_t *map, BlockDriverState **file);
127 
128 int coroutine_fn GRAPH_RDLOCK
129 bdrv_co_is_allocated(BlockDriverState *bs, int64_t offset, int64_t bytes,
130                      int64_t *pnum);
131 int bdrv_is_allocated(BlockDriverState *bs, int64_t offset, int64_t bytes,
132                       int64_t *pnum);
133 
134 int coroutine_fn GRAPH_RDLOCK
135 bdrv_co_is_allocated_above(BlockDriverState *top, BlockDriverState *base,
136                            bool include_base, int64_t offset, int64_t bytes,
137                            int64_t *pnum);
138 int bdrv_is_allocated_above(BlockDriverState *top, BlockDriverState *base,
139                             bool include_base, int64_t offset, int64_t bytes,
140                             int64_t *pnum);
141 
142 int coroutine_fn GRAPH_RDLOCK
143 bdrv_co_is_zero_fast(BlockDriverState *bs, int64_t offset, int64_t bytes);
144 
145 int bdrv_apply_auto_read_only(BlockDriverState *bs, const char *errmsg,
146                               Error **errp);
147 bool bdrv_is_read_only(BlockDriverState *bs);
148 bool bdrv_is_writable(BlockDriverState *bs);
149 bool bdrv_is_sg(BlockDriverState *bs);
150 int bdrv_get_flags(BlockDriverState *bs);
151 
152 bool coroutine_fn GRAPH_RDLOCK bdrv_co_is_inserted(BlockDriverState *bs);
153 bool co_wrapper_bdrv_rdlock bdrv_is_inserted(BlockDriverState *bs);
154 
155 void coroutine_fn GRAPH_RDLOCK
156 bdrv_co_lock_medium(BlockDriverState *bs, bool locked);
157 
158 void coroutine_fn GRAPH_RDLOCK
159 bdrv_co_eject(BlockDriverState *bs, bool eject_flag);
160 
161 const char *bdrv_get_format_name(BlockDriverState *bs);
162 
163 bool bdrv_supports_compressed_writes(BlockDriverState *bs);
164 const char *bdrv_get_node_name(const BlockDriverState *bs);
165 const char *bdrv_get_device_name(const BlockDriverState *bs);
166 const char *bdrv_get_device_or_node_name(const BlockDriverState *bs);
167 
168 int coroutine_fn bdrv_co_get_info(BlockDriverState *bs, BlockDriverInfo *bdi);
169 int co_wrapper_mixed bdrv_get_info(BlockDriverState *bs, BlockDriverInfo *bdi);
170 
171 ImageInfoSpecific *bdrv_get_specific_info(BlockDriverState *bs,
172                                           Error **errp);
173 BlockStatsSpecific *bdrv_get_specific_stats(BlockDriverState *bs);
174 void bdrv_round_to_clusters(BlockDriverState *bs,
175                             int64_t offset, int64_t bytes,
176                             int64_t *cluster_offset,
177                             int64_t *cluster_bytes);
178 
179 void bdrv_get_backing_filename(BlockDriverState *bs,
180                                char *filename, int filename_size);
181 
182 int bdrv_save_vmstate(BlockDriverState *bs, const uint8_t *buf,
183                       int64_t pos, int size);
184 
185 int bdrv_load_vmstate(BlockDriverState *bs, uint8_t *buf,
186                       int64_t pos, int size);
187 
188 /*
189  * Returns the alignment in bytes that is required so that no bounce buffer
190  * is required throughout the stack
191  */
192 size_t bdrv_min_mem_align(BlockDriverState *bs);
193 /* Returns optimal alignment in bytes for bounce buffer */
194 size_t bdrv_opt_mem_align(BlockDriverState *bs);
195 void *qemu_blockalign(BlockDriverState *bs, size_t size);
196 void *qemu_blockalign0(BlockDriverState *bs, size_t size);
197 void *qemu_try_blockalign(BlockDriverState *bs, size_t size);
198 void *qemu_try_blockalign0(BlockDriverState *bs, size_t size);
199 
200 void bdrv_enable_copy_on_read(BlockDriverState *bs);
201 void bdrv_disable_copy_on_read(BlockDriverState *bs);
202 
203 void coroutine_fn bdrv_co_debug_event(BlockDriverState *bs,
204                                       BlkdebugEvent event);
205 void co_wrapper_mixed bdrv_debug_event(BlockDriverState *bs,
206                                        BlkdebugEvent event);
207 
208 #define BLKDBG_EVENT(child, evt) \
209     do { \
210         if (child) { \
211             bdrv_debug_event(child->bs, evt); \
212         } \
213     } while (0)
214 
215 /**
216  * bdrv_get_aio_context:
217  *
218  * Returns: the currently bound #AioContext
219  */
220 AioContext *bdrv_get_aio_context(BlockDriverState *bs);
221 
222 AioContext *bdrv_child_get_parent_aio_context(BdrvChild *c);
223 
224 /**
225  * Move the current coroutine to the AioContext of @bs and return the old
226  * AioContext of the coroutine. Increase bs->in_flight so that draining @bs
227  * will wait for the operation to proceed until the corresponding
228  * bdrv_co_leave().
229  *
230  * Consequently, you can't call drain inside a bdrv_co_enter/leave() section as
231  * this will deadlock.
232  */
233 AioContext *coroutine_fn bdrv_co_enter(BlockDriverState *bs);
234 
235 /**
236  * Ends a section started by bdrv_co_enter(). Move the current coroutine back
237  * to old_ctx and decrease bs->in_flight again.
238  */
239 void coroutine_fn bdrv_co_leave(BlockDriverState *bs, AioContext *old_ctx);
240 
241 AioContext *child_of_bds_get_parent_aio_context(BdrvChild *c);
242 
243 void coroutine_fn GRAPH_RDLOCK bdrv_co_io_plug(BlockDriverState *bs);
244 void coroutine_fn GRAPH_RDLOCK bdrv_co_io_unplug(BlockDriverState *bs);
245 
246 bool coroutine_fn GRAPH_RDLOCK
247 bdrv_co_can_store_new_dirty_bitmap(BlockDriverState *bs, const char *name,
248                                    uint32_t granularity, Error **errp);
249 bool co_wrapper_bdrv_rdlock
250 bdrv_can_store_new_dirty_bitmap(BlockDriverState *bs, const char *name,
251                                 uint32_t granularity, Error **errp);
252 
253 /**
254  *
255  * bdrv_co_copy_range:
256  *
257  * Do offloaded copy between two children. If the operation is not implemented
258  * by the driver, or if the backend storage doesn't support it, a negative
259  * error code will be returned.
260  *
261  * Note: block layer doesn't emulate or fallback to a bounce buffer approach
262  * because usually the caller shouldn't attempt offloaded copy any more (e.g.
263  * calling copy_file_range(2)) after the first error, thus it should fall back
264  * to a read+write path in the caller level.
265  *
266  * @src: Source child to copy data from
267  * @src_offset: offset in @src image to read data
268  * @dst: Destination child to copy data to
269  * @dst_offset: offset in @dst image to write data
270  * @bytes: number of bytes to copy
271  * @flags: request flags. Supported flags:
272  *         BDRV_REQ_ZERO_WRITE - treat the @src range as zero data and do zero
273  *                               write on @dst as if bdrv_co_pwrite_zeroes is
274  *                               called. Used to simplify caller code, or
275  *                               during BlockDriver.bdrv_co_copy_range_from()
276  *                               recursion.
277  *         BDRV_REQ_NO_SERIALISING - do not serialize with other overlapping
278  *                                   requests currently in flight.
279  *
280  * Returns: 0 if succeeded; negative error code if failed.
281  **/
282 int coroutine_fn GRAPH_RDLOCK
283 bdrv_co_copy_range(BdrvChild *src, int64_t src_offset,
284                    BdrvChild *dst, int64_t dst_offset,
285                    int64_t bytes, BdrvRequestFlags read_flags,
286                    BdrvRequestFlags write_flags);
287 
288 /*
289  * "I/O or GS" API functions. These functions can run without
290  * the BQL, but only in one specific iothread/main loop.
291  *
292  * More specifically, these functions use BDRV_POLL_WHILE(bs), which
293  * requires the caller to be either in the main thread and hold
294  * the BlockdriverState (bs) AioContext lock, or directly in the
295  * home thread that runs the bs AioContext. Calling them from
296  * another thread in another AioContext would cause deadlocks.
297  *
298  * Therefore, these functions are not proper I/O, because they
299  * can't run in *any* iothreads, but only in a specific one.
300  *
301  * These functions can call any function from I/O, Common and this
302  * categories, but must be invoked only by other "I/O or GS" and GS APIs.
303  *
304  * All functions in this category must use the macro
305  * IO_OR_GS_CODE();
306  * to catch when they are accidentally called by the wrong API.
307  */
308 
309 #define BDRV_POLL_WHILE(bs, cond) ({                       \
310     BlockDriverState *bs_ = (bs);                          \
311     IO_OR_GS_CODE();                                       \
312     AIO_WAIT_WHILE(bdrv_get_aio_context(bs_),              \
313                    cond); })
314 
315 void bdrv_drain(BlockDriverState *bs);
316 
317 int co_wrapper_mixed_bdrv_rdlock
318 bdrv_truncate(BdrvChild *child, int64_t offset, bool exact,
319               PreallocMode prealloc, BdrvRequestFlags flags, Error **errp);
320 
321 int co_wrapper_mixed_bdrv_rdlock
322 bdrv_check(BlockDriverState *bs, BdrvCheckResult *res, BdrvCheckMode fix);
323 
324 /* Invalidate any cached metadata used by image formats */
325 int co_wrapper_mixed_bdrv_rdlock
326 bdrv_invalidate_cache(BlockDriverState *bs, Error **errp);
327 
328 int co_wrapper_mixed_bdrv_rdlock bdrv_flush(BlockDriverState *bs);
329 
330 int co_wrapper_mixed_bdrv_rdlock
331 bdrv_pdiscard(BdrvChild *child, int64_t offset, int64_t bytes);
332 
333 int co_wrapper_mixed_bdrv_rdlock
334 bdrv_readv_vmstate(BlockDriverState *bs, QEMUIOVector *qiov, int64_t pos);
335 
336 int co_wrapper_mixed_bdrv_rdlock
337 bdrv_writev_vmstate(BlockDriverState *bs, QEMUIOVector *qiov, int64_t pos);
338 
339 /**
340  * bdrv_parent_drained_begin_single:
341  *
342  * Begin a quiesced section for the parent of @c.
343  */
344 void bdrv_parent_drained_begin_single(BdrvChild *c);
345 
346 /**
347  * bdrv_parent_drained_poll_single:
348  *
349  * Returns true if there is any pending activity to cease before @c can be
350  * called quiesced, false otherwise.
351  */
352 bool bdrv_parent_drained_poll_single(BdrvChild *c);
353 
354 /**
355  * bdrv_parent_drained_end_single:
356  *
357  * End a quiesced section for the parent of @c.
358  */
359 void bdrv_parent_drained_end_single(BdrvChild *c);
360 
361 /**
362  * bdrv_drain_poll:
363  *
364  * Poll for pending requests in @bs and its parents (except for @ignore_parent).
365  *
366  * If @ignore_bds_parents is true, parents that are BlockDriverStates must
367  * ignore the drain request because they will be drained separately (used for
368  * drain_all).
369  *
370  * This is part of bdrv_drained_begin.
371  */
372 bool bdrv_drain_poll(BlockDriverState *bs, BdrvChild *ignore_parent,
373                      bool ignore_bds_parents);
374 
375 /**
376  * bdrv_drained_begin:
377  *
378  * Begin a quiesced section for exclusive access to the BDS, by disabling
379  * external request sources including NBD server, block jobs, and device model.
380  *
381  * This function can be recursive.
382  */
383 void bdrv_drained_begin(BlockDriverState *bs);
384 
385 /**
386  * bdrv_do_drained_begin_quiesce:
387  *
388  * Quiesces a BDS like bdrv_drained_begin(), but does not wait for already
389  * running requests to complete.
390  */
391 void bdrv_do_drained_begin_quiesce(BlockDriverState *bs, BdrvChild *parent);
392 
393 /**
394  * bdrv_drained_end:
395  *
396  * End a quiescent section started by bdrv_drained_begin().
397  */
398 void bdrv_drained_end(BlockDriverState *bs);
399 
400 #endif /* BLOCK_IO_H */
401