diff options
| -rw-r--r-- | block/rbd.c | 112 |
1 files changed, 112 insertions, 0 deletions
diff --git a/block/rbd.c b/block/rbd.c index 701fbf2b0c..def96292e0 100644 --- a/block/rbd.c +++ b/block/rbd.c @@ -97,6 +97,12 @@ typedef struct RBDTask { int64_t ret; } RBDTask; +typedef struct RBDDiffIterateReq { + uint64_t offs; + uint64_t bytes; + bool exists; +} RBDDiffIterateReq; + static int qemu_rbd_connect(rados_t *cluster, rados_ioctx_t *io_ctx, BlockdevOptionsRbd *opts, bool cache, const char *keypairs, const char *secretid, @@ -1259,6 +1265,111 @@ static ImageInfoSpecific *qemu_rbd_get_specific_info(BlockDriverState *bs, return spec_info; } +/* + * rbd_diff_iterate2 allows to interrupt the exection by returning a negative + * value in the callback routine. Choose a value that does not conflict with + * an existing exitcode and return it if we want to prematurely stop the + * execution because we detected a change in the allocation status. + */ +#define QEMU_RBD_EXIT_DIFF_ITERATE2 -9000 + +static int qemu_rbd_diff_iterate_cb(uint64_t offs, size_t len, + int exists, void *opaque) +{ + RBDDiffIterateReq *req = opaque; + + assert(req->offs + req->bytes <= offs); + /* + * we do not diff against a snapshot so we should never receive a callback + * for a hole. + */ + assert(exists); + + if (!req->exists && offs > req->offs) { + /* + * we started in an unallocated area and hit the first allocated + * block. req->bytes must be set to the length of the unallocated area + * before the allocated area. stop further processing. + */ + req->bytes = offs - req->offs; + return QEMU_RBD_EXIT_DIFF_ITERATE2; + } + + if (req->exists && offs > req->offs + req->bytes) { + /* + * we started in an allocated area and jumped over an unallocated area, + * req->bytes contains the length of the allocated area before the + * unallocated area. stop further processing. + */ + return QEMU_RBD_EXIT_DIFF_ITERATE2; + } + + req->bytes += len; + req->exists = true; + + return 0; +} + +static int coroutine_fn qemu_rbd_co_block_status(BlockDriverState *bs, + bool want_zero, int64_t offset, + int64_t bytes, int64_t *pnum, + int64_t *map, + BlockDriverState **file) +{ + BDRVRBDState *s = bs->opaque; + int status, r; + RBDDiffIterateReq req = { .offs = offset }; + uint64_t features, flags; + + assert(offset + bytes <= s->image_size); + + /* default to all sectors allocated */ + status = BDRV_BLOCK_DATA | BDRV_BLOCK_OFFSET_VALID; + *map = offset; + *file = bs; + *pnum = bytes; + + /* check if RBD image supports fast-diff */ + r = rbd_get_features(s->image, &features); + if (r < 0) { + return status; + } + if (!(features & RBD_FEATURE_FAST_DIFF)) { + return status; + } + + /* check if RBD fast-diff result is valid */ + r = rbd_get_flags(s->image, &flags); + if (r < 0) { + return status; + } + if (flags & RBD_FLAG_FAST_DIFF_INVALID) { + return status; + } + + r = rbd_diff_iterate2(s->image, NULL, offset, bytes, true, true, + qemu_rbd_diff_iterate_cb, &req); + if (r < 0 && r != QEMU_RBD_EXIT_DIFF_ITERATE2) { + return status; + } + assert(req.bytes <= bytes); + if (!req.exists) { + if (r == 0) { + /* + * rbd_diff_iterate2 does not invoke callbacks for unallocated + * areas. This here catches the case where no callback was + * invoked at all (req.bytes == 0). + */ + assert(req.bytes == 0); + req.bytes = bytes; + } + status = BDRV_BLOCK_ZERO | BDRV_BLOCK_OFFSET_VALID; + } + + *pnum = req.bytes; + return status; +} + static int64_t qemu_rbd_getlength(BlockDriverState *bs) { BDRVRBDState *s = bs->opaque; @@ -1494,6 +1605,7 @@ static BlockDriver bdrv_rbd = { #ifdef LIBRBD_SUPPORTS_WRITE_ZEROES .bdrv_co_pwrite_zeroes = qemu_rbd_co_pwrite_zeroes, #endif + .bdrv_co_block_status = qemu_rbd_co_block_status, .bdrv_snapshot_create = qemu_rbd_snap_create, .bdrv_snapshot_delete = qemu_rbd_snap_remove, |