xref: /qemu/block/stream.c (revision 04120e3b)
14f1043b4SStefan Hajnoczi /*
24f1043b4SStefan Hajnoczi  * Image streaming
34f1043b4SStefan Hajnoczi  *
44f1043b4SStefan Hajnoczi  * Copyright IBM, Corp. 2011
54f1043b4SStefan Hajnoczi  *
64f1043b4SStefan Hajnoczi  * Authors:
74f1043b4SStefan Hajnoczi  *  Stefan Hajnoczi   <stefanha@linux.vnet.ibm.com>
84f1043b4SStefan Hajnoczi  *
94f1043b4SStefan Hajnoczi  * This work is licensed under the terms of the GNU LGPL, version 2 or later.
104f1043b4SStefan Hajnoczi  * See the COPYING.LIB file in the top-level directory.
114f1043b4SStefan Hajnoczi  *
124f1043b4SStefan Hajnoczi  */
134f1043b4SStefan Hajnoczi 
144f1043b4SStefan Hajnoczi #include "trace.h"
154f1043b4SStefan Hajnoczi #include "block_int.h"
164f1043b4SStefan Hajnoczi 
174f1043b4SStefan Hajnoczi enum {
184f1043b4SStefan Hajnoczi     /*
194f1043b4SStefan Hajnoczi      * Size of data buffer for populating the image file.  This should be large
204f1043b4SStefan Hajnoczi      * enough to process multiple clusters in a single call, so that populating
214f1043b4SStefan Hajnoczi      * contiguous regions of the image is efficient.
224f1043b4SStefan Hajnoczi      */
234f1043b4SStefan Hajnoczi     STREAM_BUFFER_SIZE = 512 * 1024, /* in bytes */
244f1043b4SStefan Hajnoczi };
254f1043b4SStefan Hajnoczi 
265094a6c0SStefan Hajnoczi #define SLICE_TIME 100000000ULL /* ns */
275094a6c0SStefan Hajnoczi 
285094a6c0SStefan Hajnoczi typedef struct {
295094a6c0SStefan Hajnoczi     int64_t next_slice_time;
305094a6c0SStefan Hajnoczi     uint64_t slice_quota;
315094a6c0SStefan Hajnoczi     uint64_t dispatched;
325094a6c0SStefan Hajnoczi } RateLimit;
335094a6c0SStefan Hajnoczi 
345094a6c0SStefan Hajnoczi static int64_t ratelimit_calculate_delay(RateLimit *limit, uint64_t n)
355094a6c0SStefan Hajnoczi {
365094a6c0SStefan Hajnoczi     int64_t now = qemu_get_clock_ns(rt_clock);
375094a6c0SStefan Hajnoczi 
385094a6c0SStefan Hajnoczi     if (limit->next_slice_time < now) {
395094a6c0SStefan Hajnoczi         limit->next_slice_time = now + SLICE_TIME;
405094a6c0SStefan Hajnoczi         limit->dispatched = 0;
415094a6c0SStefan Hajnoczi     }
42b21d677eSPaolo Bonzini     if (limit->dispatched == 0 || limit->dispatched + n <= limit->slice_quota) {
435094a6c0SStefan Hajnoczi         limit->dispatched += n;
44b21d677eSPaolo Bonzini         return 0;
45b21d677eSPaolo Bonzini     } else {
46b21d677eSPaolo Bonzini         limit->dispatched = n;
47b21d677eSPaolo Bonzini         return limit->next_slice_time - now;
485094a6c0SStefan Hajnoczi     }
495094a6c0SStefan Hajnoczi }
505094a6c0SStefan Hajnoczi 
515094a6c0SStefan Hajnoczi static void ratelimit_set_speed(RateLimit *limit, uint64_t speed)
525094a6c0SStefan Hajnoczi {
535094a6c0SStefan Hajnoczi     limit->slice_quota = speed / (1000000000ULL / SLICE_TIME);
545094a6c0SStefan Hajnoczi }
555094a6c0SStefan Hajnoczi 
564f1043b4SStefan Hajnoczi typedef struct StreamBlockJob {
574f1043b4SStefan Hajnoczi     BlockJob common;
585094a6c0SStefan Hajnoczi     RateLimit limit;
594f1043b4SStefan Hajnoczi     BlockDriverState *base;
60c8c3080fSMarcelo Tosatti     char backing_file_id[1024];
614f1043b4SStefan Hajnoczi } StreamBlockJob;
624f1043b4SStefan Hajnoczi 
634f1043b4SStefan Hajnoczi static int coroutine_fn stream_populate(BlockDriverState *bs,
644f1043b4SStefan Hajnoczi                                         int64_t sector_num, int nb_sectors,
654f1043b4SStefan Hajnoczi                                         void *buf)
664f1043b4SStefan Hajnoczi {
674f1043b4SStefan Hajnoczi     struct iovec iov = {
684f1043b4SStefan Hajnoczi         .iov_base = buf,
694f1043b4SStefan Hajnoczi         .iov_len  = nb_sectors * BDRV_SECTOR_SIZE,
704f1043b4SStefan Hajnoczi     };
714f1043b4SStefan Hajnoczi     QEMUIOVector qiov;
724f1043b4SStefan Hajnoczi 
734f1043b4SStefan Hajnoczi     qemu_iovec_init_external(&qiov, &iov, 1);
744f1043b4SStefan Hajnoczi 
754f1043b4SStefan Hajnoczi     /* Copy-on-read the unallocated clusters */
764f1043b4SStefan Hajnoczi     return bdrv_co_copy_on_readv(bs, sector_num, nb_sectors, &qiov);
774f1043b4SStefan Hajnoczi }
784f1043b4SStefan Hajnoczi 
795a67a104SMarcelo Tosatti static void close_unused_images(BlockDriverState *top, BlockDriverState *base,
805a67a104SMarcelo Tosatti                                 const char *base_id)
815a67a104SMarcelo Tosatti {
825a67a104SMarcelo Tosatti     BlockDriverState *intermediate;
835a67a104SMarcelo Tosatti     intermediate = top->backing_hd;
845a67a104SMarcelo Tosatti 
855a67a104SMarcelo Tosatti     while (intermediate) {
865a67a104SMarcelo Tosatti         BlockDriverState *unused;
875a67a104SMarcelo Tosatti 
885a67a104SMarcelo Tosatti         /* reached base */
895a67a104SMarcelo Tosatti         if (intermediate == base) {
905a67a104SMarcelo Tosatti             break;
915a67a104SMarcelo Tosatti         }
925a67a104SMarcelo Tosatti 
935a67a104SMarcelo Tosatti         unused = intermediate;
945a67a104SMarcelo Tosatti         intermediate = intermediate->backing_hd;
955a67a104SMarcelo Tosatti         unused->backing_hd = NULL;
965a67a104SMarcelo Tosatti         bdrv_delete(unused);
975a67a104SMarcelo Tosatti     }
985a67a104SMarcelo Tosatti     top->backing_hd = base;
995a67a104SMarcelo Tosatti }
1005a67a104SMarcelo Tosatti 
101c8c3080fSMarcelo Tosatti /*
102c8c3080fSMarcelo Tosatti  * Given an image chain: [BASE] -> [INTER1] -> [INTER2] -> [TOP]
103c8c3080fSMarcelo Tosatti  *
104c8c3080fSMarcelo Tosatti  * Return true if the given sector is allocated in top.
105c8c3080fSMarcelo Tosatti  * Return false if the given sector is allocated in intermediate images.
106c8c3080fSMarcelo Tosatti  * Return true otherwise.
107c8c3080fSMarcelo Tosatti  *
108c8c3080fSMarcelo Tosatti  * 'pnum' is set to the number of sectors (including and immediately following
109c8c3080fSMarcelo Tosatti  *  the specified sector) that are known to be in the same
110c8c3080fSMarcelo Tosatti  *  allocated/unallocated state.
111c8c3080fSMarcelo Tosatti  *
112c8c3080fSMarcelo Tosatti  */
113c8c3080fSMarcelo Tosatti static int coroutine_fn is_allocated_base(BlockDriverState *top,
114c8c3080fSMarcelo Tosatti                                           BlockDriverState *base,
115c8c3080fSMarcelo Tosatti                                           int64_t sector_num,
116c8c3080fSMarcelo Tosatti                                           int nb_sectors, int *pnum)
117c8c3080fSMarcelo Tosatti {
118c8c3080fSMarcelo Tosatti     BlockDriverState *intermediate;
119c8c3080fSMarcelo Tosatti     int ret, n;
120c8c3080fSMarcelo Tosatti 
121c8c3080fSMarcelo Tosatti     ret = bdrv_co_is_allocated(top, sector_num, nb_sectors, &n);
122c8c3080fSMarcelo Tosatti     if (ret) {
123c8c3080fSMarcelo Tosatti         *pnum = n;
124c8c3080fSMarcelo Tosatti         return ret;
125c8c3080fSMarcelo Tosatti     }
126c8c3080fSMarcelo Tosatti 
127c8c3080fSMarcelo Tosatti     /*
128c8c3080fSMarcelo Tosatti      * Is the unallocated chunk [sector_num, n] also
129c8c3080fSMarcelo Tosatti      * unallocated between base and top?
130c8c3080fSMarcelo Tosatti      */
131c8c3080fSMarcelo Tosatti     intermediate = top->backing_hd;
132c8c3080fSMarcelo Tosatti 
133efcc7a23SPaolo Bonzini     while (intermediate != base) {
134c8c3080fSMarcelo Tosatti         int pnum_inter;
135c8c3080fSMarcelo Tosatti 
136c8c3080fSMarcelo Tosatti         ret = bdrv_co_is_allocated(intermediate, sector_num, nb_sectors,
137c8c3080fSMarcelo Tosatti                                    &pnum_inter);
138c8c3080fSMarcelo Tosatti         if (ret < 0) {
139c8c3080fSMarcelo Tosatti             return ret;
140c8c3080fSMarcelo Tosatti         } else if (ret) {
141c8c3080fSMarcelo Tosatti             *pnum = pnum_inter;
142c8c3080fSMarcelo Tosatti             return 0;
143c8c3080fSMarcelo Tosatti         }
144c8c3080fSMarcelo Tosatti 
145c8c3080fSMarcelo Tosatti         /*
146c8c3080fSMarcelo Tosatti          * [sector_num, nb_sectors] is unallocated on top but intermediate
147c8c3080fSMarcelo Tosatti          * might have
148c8c3080fSMarcelo Tosatti          *
149c8c3080fSMarcelo Tosatti          * [sector_num+x, nr_sectors] allocated.
150c8c3080fSMarcelo Tosatti          */
151c8c3080fSMarcelo Tosatti         if (n > pnum_inter) {
152c8c3080fSMarcelo Tosatti             n = pnum_inter;
153c8c3080fSMarcelo Tosatti         }
154c8c3080fSMarcelo Tosatti 
155c8c3080fSMarcelo Tosatti         intermediate = intermediate->backing_hd;
156c8c3080fSMarcelo Tosatti     }
157c8c3080fSMarcelo Tosatti 
158efcc7a23SPaolo Bonzini     *pnum = n;
159c8c3080fSMarcelo Tosatti     return 1;
160c8c3080fSMarcelo Tosatti }
161c8c3080fSMarcelo Tosatti 
1624f1043b4SStefan Hajnoczi static void coroutine_fn stream_run(void *opaque)
1634f1043b4SStefan Hajnoczi {
1644f1043b4SStefan Hajnoczi     StreamBlockJob *s = opaque;
1654f1043b4SStefan Hajnoczi     BlockDriverState *bs = s->common.bs;
166c8c3080fSMarcelo Tosatti     BlockDriverState *base = s->base;
1674f1043b4SStefan Hajnoczi     int64_t sector_num, end;
1684f1043b4SStefan Hajnoczi     int ret = 0;
169*04120e3bSAnthony Liguori     int n = 0;
1704f1043b4SStefan Hajnoczi     void *buf;
1714f1043b4SStefan Hajnoczi 
1724f1043b4SStefan Hajnoczi     s->common.len = bdrv_getlength(bs);
1734f1043b4SStefan Hajnoczi     if (s->common.len < 0) {
1744f1043b4SStefan Hajnoczi         block_job_complete(&s->common, s->common.len);
1754f1043b4SStefan Hajnoczi         return;
1764f1043b4SStefan Hajnoczi     }
1774f1043b4SStefan Hajnoczi 
1784f1043b4SStefan Hajnoczi     end = s->common.len >> BDRV_SECTOR_BITS;
1794f1043b4SStefan Hajnoczi     buf = qemu_blockalign(bs, STREAM_BUFFER_SIZE);
1804f1043b4SStefan Hajnoczi 
1814f1043b4SStefan Hajnoczi     /* Turn on copy-on-read for the whole block device so that guest read
1824f1043b4SStefan Hajnoczi      * requests help us make progress.  Only do this when copying the entire
1834f1043b4SStefan Hajnoczi      * backing chain since the copy-on-read operation does not take base into
1844f1043b4SStefan Hajnoczi      * account.
1854f1043b4SStefan Hajnoczi      */
1864f1043b4SStefan Hajnoczi     if (!base) {
1874f1043b4SStefan Hajnoczi         bdrv_enable_copy_on_read(bs);
1884f1043b4SStefan Hajnoczi     }
1894f1043b4SStefan Hajnoczi 
1904f1043b4SStefan Hajnoczi     for (sector_num = 0; sector_num < end; sector_num += n) {
1914513eafeSPaolo Bonzini         uint64_t delay_ns = 0;
1924513eafeSPaolo Bonzini 
1934513eafeSPaolo Bonzini wait:
1944513eafeSPaolo Bonzini         /* Note that even when no rate limit is applied we need to yield
1954513eafeSPaolo Bonzini          * with no pending I/O here so that qemu_aio_flush() returns.
1964513eafeSPaolo Bonzini          */
1974513eafeSPaolo Bonzini         block_job_sleep_ns(&s->common, rt_clock, delay_ns);
1984f1043b4SStefan Hajnoczi         if (block_job_is_cancelled(&s->common)) {
1994f1043b4SStefan Hajnoczi             break;
2004f1043b4SStefan Hajnoczi         }
2014f1043b4SStefan Hajnoczi 
202c8c3080fSMarcelo Tosatti         ret = is_allocated_base(bs, base, sector_num,
2034f1043b4SStefan Hajnoczi                                 STREAM_BUFFER_SIZE / BDRV_SECTOR_SIZE, &n);
2044f1043b4SStefan Hajnoczi         trace_stream_one_iteration(s, sector_num, n, ret);
2054f1043b4SStefan Hajnoczi         if (ret == 0) {
2065094a6c0SStefan Hajnoczi             if (s->common.speed) {
2074513eafeSPaolo Bonzini                 delay_ns = ratelimit_calculate_delay(&s->limit, n);
2085094a6c0SStefan Hajnoczi                 if (delay_ns > 0) {
2094513eafeSPaolo Bonzini                     goto wait;
2105094a6c0SStefan Hajnoczi                 }
2115094a6c0SStefan Hajnoczi             }
2124f1043b4SStefan Hajnoczi             ret = stream_populate(bs, sector_num, n, buf);
2134f1043b4SStefan Hajnoczi         }
2144f1043b4SStefan Hajnoczi         if (ret < 0) {
2154f1043b4SStefan Hajnoczi             break;
2164f1043b4SStefan Hajnoczi         }
217c8c3080fSMarcelo Tosatti         ret = 0;
2184f1043b4SStefan Hajnoczi 
2194f1043b4SStefan Hajnoczi         /* Publish progress */
2204f1043b4SStefan Hajnoczi         s->common.offset += n * BDRV_SECTOR_SIZE;
2214f1043b4SStefan Hajnoczi     }
2224f1043b4SStefan Hajnoczi 
2234f1043b4SStefan Hajnoczi     if (!base) {
2244f1043b4SStefan Hajnoczi         bdrv_disable_copy_on_read(bs);
2254f1043b4SStefan Hajnoczi     }
2264f1043b4SStefan Hajnoczi 
2273e914655SPaolo Bonzini     if (!block_job_is_cancelled(&s->common) && sector_num == end && ret == 0) {
228f6133defSPaolo Bonzini         const char *base_id = NULL, *base_fmt = NULL;
229c8c3080fSMarcelo Tosatti         if (base) {
230c8c3080fSMarcelo Tosatti             base_id = s->backing_file_id;
231f6133defSPaolo Bonzini             if (base->drv) {
232f6133defSPaolo Bonzini                 base_fmt = base->drv->format_name;
233c8c3080fSMarcelo Tosatti             }
234f6133defSPaolo Bonzini         }
235f6133defSPaolo Bonzini         ret = bdrv_change_backing_file(bs, base_id, base_fmt);
2365a67a104SMarcelo Tosatti         close_unused_images(bs, base, base_id);
2374f1043b4SStefan Hajnoczi     }
2384f1043b4SStefan Hajnoczi 
2394f1043b4SStefan Hajnoczi     qemu_vfree(buf);
2404f1043b4SStefan Hajnoczi     block_job_complete(&s->common, ret);
2414f1043b4SStefan Hajnoczi }
2424f1043b4SStefan Hajnoczi 
243882ec7ceSStefan Hajnoczi static void stream_set_speed(BlockJob *job, int64_t speed, Error **errp)
2445094a6c0SStefan Hajnoczi {
2455094a6c0SStefan Hajnoczi     StreamBlockJob *s = container_of(job, StreamBlockJob, common);
2465094a6c0SStefan Hajnoczi 
247882ec7ceSStefan Hajnoczi     if (speed < 0) {
248882ec7ceSStefan Hajnoczi         error_set(errp, QERR_INVALID_PARAMETER, "speed");
2499e6636c7SStefan Hajnoczi         return;
2505094a6c0SStefan Hajnoczi     }
251882ec7ceSStefan Hajnoczi     ratelimit_set_speed(&s->limit, speed / BDRV_SECTOR_SIZE);
2525094a6c0SStefan Hajnoczi }
2535094a6c0SStefan Hajnoczi 
2544f1043b4SStefan Hajnoczi static BlockJobType stream_job_type = {
2554f1043b4SStefan Hajnoczi     .instance_size = sizeof(StreamBlockJob),
2564f1043b4SStefan Hajnoczi     .job_type      = "stream",
2575094a6c0SStefan Hajnoczi     .set_speed     = stream_set_speed,
2584f1043b4SStefan Hajnoczi };
2594f1043b4SStefan Hajnoczi 
260fd7f8c65SStefan Hajnoczi void stream_start(BlockDriverState *bs, BlockDriverState *base,
261c83c66c3SStefan Hajnoczi                   const char *base_id, int64_t speed,
262c83c66c3SStefan Hajnoczi                   BlockDriverCompletionFunc *cb,
263fd7f8c65SStefan Hajnoczi                   void *opaque, Error **errp)
2644f1043b4SStefan Hajnoczi {
2654f1043b4SStefan Hajnoczi     StreamBlockJob *s;
2664f1043b4SStefan Hajnoczi 
267c83c66c3SStefan Hajnoczi     s = block_job_create(&stream_job_type, bs, speed, cb, opaque, errp);
2684f1043b4SStefan Hajnoczi     if (!s) {
269fd7f8c65SStefan Hajnoczi         return;
2704f1043b4SStefan Hajnoczi     }
2714f1043b4SStefan Hajnoczi 
2724f1043b4SStefan Hajnoczi     s->base = base;
273c8c3080fSMarcelo Tosatti     if (base_id) {
274c8c3080fSMarcelo Tosatti         pstrcpy(s->backing_file_id, sizeof(s->backing_file_id), base_id);
275c8c3080fSMarcelo Tosatti     }
2764f1043b4SStefan Hajnoczi 
277fa4478d5SPaolo Bonzini     s->common.co = qemu_coroutine_create(stream_run);
278fa4478d5SPaolo Bonzini     trace_stream_start(bs, base, s, s->common.co, opaque);
279fa4478d5SPaolo Bonzini     qemu_coroutine_enter(s->common.co, s);
2804f1043b4SStefan Hajnoczi }
281