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author | Marcelo Tosatti <mtosatti@redhat.com> | 2012-01-18 14:40:53 +0000 |
---|---|---|
committer | Kevin Wolf <kwolf@redhat.com> | 2012-01-26 14:49:18 +0100 |
commit | c8c3080f4a6fbbf3c9c5d6efd1b49e7ca6479d1e (patch) | |
tree | b034c08322e2c0f1d7bcbf752ff8c123b7a68213 /block | |
parent | 019b8cbf76fc3126d300c401acca3102c69e7876 (diff) | |
download | qemu-c8c3080f4a6fbbf3c9c5d6efd1b49e7ca6479d1e.zip qemu-c8c3080f4a6fbbf3c9c5d6efd1b49e7ca6479d1e.tar.gz qemu-c8c3080f4a6fbbf3c9c5d6efd1b49e7ca6479d1e.tar.bz2 |
block: add support for partial streaming
Add support for streaming data from an intermediate section of the
image chain (see patch and documentation for details).
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Diffstat (limited to 'block')
-rw-r--r-- | block/stream.c | 91 |
1 files changed, 87 insertions, 4 deletions
diff --git a/block/stream.c b/block/stream.c index b54b0b7..d1b3986 100644 --- a/block/stream.c +++ b/block/stream.c @@ -57,6 +57,7 @@ typedef struct StreamBlockJob { BlockJob common; RateLimit limit; BlockDriverState *base; + char backing_file_id[1024]; } StreamBlockJob; static int coroutine_fn stream_populate(BlockDriverState *bs, @@ -75,10 +76,76 @@ static int coroutine_fn stream_populate(BlockDriverState *bs, return bdrv_co_copy_on_readv(bs, sector_num, nb_sectors, &qiov); } +/* + * Given an image chain: [BASE] -> [INTER1] -> [INTER2] -> [TOP] + * + * Return true if the given sector is allocated in top. + * Return false if the given sector is allocated in intermediate images. + * Return true otherwise. + * + * 'pnum' is set to the number of sectors (including and immediately following + * the specified sector) that are known to be in the same + * allocated/unallocated state. + * + */ +static int coroutine_fn is_allocated_base(BlockDriverState *top, + BlockDriverState *base, + int64_t sector_num, + int nb_sectors, int *pnum) +{ + BlockDriverState *intermediate; + int ret, n; + + ret = bdrv_co_is_allocated(top, sector_num, nb_sectors, &n); + if (ret) { + *pnum = n; + return ret; + } + + /* + * Is the unallocated chunk [sector_num, n] also + * unallocated between base and top? + */ + intermediate = top->backing_hd; + + while (intermediate) { + int pnum_inter; + + /* reached base */ + if (intermediate == base) { + *pnum = n; + return 1; + } + ret = bdrv_co_is_allocated(intermediate, sector_num, nb_sectors, + &pnum_inter); + if (ret < 0) { + return ret; + } else if (ret) { + *pnum = pnum_inter; + return 0; + } + + /* + * [sector_num, nb_sectors] is unallocated on top but intermediate + * might have + * + * [sector_num+x, nr_sectors] allocated. + */ + if (n > pnum_inter) { + n = pnum_inter; + } + + intermediate = intermediate->backing_hd; + } + + return 1; +} + static void coroutine_fn stream_run(void *opaque) { StreamBlockJob *s = opaque; BlockDriverState *bs = s->common.bs; + BlockDriverState *base = s->base; int64_t sector_num, end; int ret = 0; int n; @@ -108,8 +175,15 @@ retry: break; } - ret = bdrv_co_is_allocated(bs, sector_num, - STREAM_BUFFER_SIZE / BDRV_SECTOR_SIZE, &n); + + if (base) { + ret = is_allocated_base(bs, base, sector_num, + STREAM_BUFFER_SIZE / BDRV_SECTOR_SIZE, &n); + } else { + ret = bdrv_co_is_allocated(bs, sector_num, + STREAM_BUFFER_SIZE / BDRV_SECTOR_SIZE, + &n); + } trace_stream_one_iteration(s, sector_num, n, ret); if (ret == 0) { if (s->common.speed) { @@ -126,6 +200,7 @@ retry: if (ret < 0) { break; } + ret = 0; /* Publish progress */ s->common.offset += n * BDRV_SECTOR_SIZE; @@ -141,7 +216,11 @@ retry: } if (sector_num == end && ret == 0) { - ret = bdrv_change_backing_file(bs, NULL, NULL); + const char *base_id = NULL; + if (base) { + base_id = s->backing_file_id; + } + ret = bdrv_change_backing_file(bs, base_id, NULL); } qemu_vfree(buf); @@ -167,7 +246,8 @@ static BlockJobType stream_job_type = { }; int stream_start(BlockDriverState *bs, BlockDriverState *base, - BlockDriverCompletionFunc *cb, void *opaque) + const char *base_id, BlockDriverCompletionFunc *cb, + void *opaque) { StreamBlockJob *s; Coroutine *co; @@ -178,6 +258,9 @@ int stream_start(BlockDriverState *bs, BlockDriverState *base, } s->base = base; + if (base_id) { + pstrcpy(s->backing_file_id, sizeof(s->backing_file_id), base_id); + } co = qemu_coroutine_create(stream_run); trace_stream_start(bs, base, s, co, opaque); |