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dc265df3 FE |
1 | From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001 |
2 | From: Fabian Ebner <f.ebner@proxmox.com> | |
3 | Date: Tue, 17 May 2022 09:46:02 +0200 | |
4 | Subject: [PATCH] Revert "block/rbd: implement bdrv_co_block_status" | |
5 | ||
6 | During backup, bdrv_co_block_status is called for each block copy | |
7 | chunk. When RBD is used, the current implementation with | |
8 | rbd_diff_iterate2() using whole_object=true takes about linearly more | |
9 | time, depending on the image size. Since there are linearly more | |
10 | chunks, the slowdown is quadratic, becoming unacceptable for large | |
11 | images (starting somewhere between 500-1000 GiB in my testing). | |
12 | ||
13 | This reverts commit 0347a8fd4c3faaedf119be04c197804be40a384b as a | |
14 | stop-gap measure, until it's clear how to make the implemenation | |
15 | more efficient. | |
16 | ||
17 | Upstream bug report: | |
18 | https://gitlab.com/qemu-project/qemu/-/issues/1026 | |
19 | ||
20 | Signed-off-by: Fabian Ebner <f.ebner@proxmox.com> | |
21 | --- | |
22 | block/rbd.c | 112 ---------------------------------------------------- | |
23 | 1 file changed, 112 deletions(-) | |
24 | ||
25 | diff --git a/block/rbd.c b/block/rbd.c | |
bf251437 | 26 | index 0913a0af39..1dab254517 100644 |
dc265df3 FE |
27 | --- a/block/rbd.c |
28 | +++ b/block/rbd.c | |
bf251437 | 29 | @@ -108,12 +108,6 @@ typedef struct RBDTask { |
dc265df3 FE |
30 | int64_t ret; |
31 | } RBDTask; | |
32 | ||
33 | -typedef struct RBDDiffIterateReq { | |
34 | - uint64_t offs; | |
35 | - uint64_t bytes; | |
36 | - bool exists; | |
37 | -} RBDDiffIterateReq; | |
38 | - | |
39 | static int qemu_rbd_connect(rados_t *cluster, rados_ioctx_t *io_ctx, | |
40 | BlockdevOptionsRbd *opts, bool cache, | |
41 | const char *keypairs, const char *secretid, | |
bf251437 | 42 | @@ -1456,111 +1450,6 @@ static ImageInfoSpecific *qemu_rbd_get_specific_info(BlockDriverState *bs, |
dc265df3 FE |
43 | return spec_info; |
44 | } | |
45 | ||
46 | -/* | |
47 | - * rbd_diff_iterate2 allows to interrupt the exection by returning a negative | |
48 | - * value in the callback routine. Choose a value that does not conflict with | |
49 | - * an existing exitcode and return it if we want to prematurely stop the | |
50 | - * execution because we detected a change in the allocation status. | |
51 | - */ | |
52 | -#define QEMU_RBD_EXIT_DIFF_ITERATE2 -9000 | |
53 | - | |
54 | -static int qemu_rbd_diff_iterate_cb(uint64_t offs, size_t len, | |
55 | - int exists, void *opaque) | |
56 | -{ | |
57 | - RBDDiffIterateReq *req = opaque; | |
58 | - | |
59 | - assert(req->offs + req->bytes <= offs); | |
60 | - /* | |
61 | - * we do not diff against a snapshot so we should never receive a callback | |
62 | - * for a hole. | |
63 | - */ | |
64 | - assert(exists); | |
65 | - | |
66 | - if (!req->exists && offs > req->offs) { | |
67 | - /* | |
68 | - * we started in an unallocated area and hit the first allocated | |
69 | - * block. req->bytes must be set to the length of the unallocated area | |
70 | - * before the allocated area. stop further processing. | |
71 | - */ | |
72 | - req->bytes = offs - req->offs; | |
73 | - return QEMU_RBD_EXIT_DIFF_ITERATE2; | |
74 | - } | |
75 | - | |
76 | - if (req->exists && offs > req->offs + req->bytes) { | |
77 | - /* | |
78 | - * we started in an allocated area and jumped over an unallocated area, | |
79 | - * req->bytes contains the length of the allocated area before the | |
80 | - * unallocated area. stop further processing. | |
81 | - */ | |
82 | - return QEMU_RBD_EXIT_DIFF_ITERATE2; | |
83 | - } | |
84 | - | |
85 | - req->bytes += len; | |
86 | - req->exists = true; | |
87 | - | |
88 | - return 0; | |
89 | -} | |
90 | - | |
91 | -static int coroutine_fn qemu_rbd_co_block_status(BlockDriverState *bs, | |
92 | - bool want_zero, int64_t offset, | |
93 | - int64_t bytes, int64_t *pnum, | |
94 | - int64_t *map, | |
95 | - BlockDriverState **file) | |
96 | -{ | |
97 | - BDRVRBDState *s = bs->opaque; | |
98 | - int status, r; | |
99 | - RBDDiffIterateReq req = { .offs = offset }; | |
100 | - uint64_t features, flags; | |
101 | - | |
102 | - assert(offset + bytes <= s->image_size); | |
103 | - | |
104 | - /* default to all sectors allocated */ | |
105 | - status = BDRV_BLOCK_DATA | BDRV_BLOCK_OFFSET_VALID; | |
106 | - *map = offset; | |
107 | - *file = bs; | |
108 | - *pnum = bytes; | |
109 | - | |
110 | - /* check if RBD image supports fast-diff */ | |
111 | - r = rbd_get_features(s->image, &features); | |
112 | - if (r < 0) { | |
113 | - return status; | |
114 | - } | |
115 | - if (!(features & RBD_FEATURE_FAST_DIFF)) { | |
116 | - return status; | |
117 | - } | |
118 | - | |
119 | - /* check if RBD fast-diff result is valid */ | |
120 | - r = rbd_get_flags(s->image, &flags); | |
121 | - if (r < 0) { | |
122 | - return status; | |
123 | - } | |
124 | - if (flags & RBD_FLAG_FAST_DIFF_INVALID) { | |
125 | - return status; | |
126 | - } | |
127 | - | |
128 | - r = rbd_diff_iterate2(s->image, NULL, offset, bytes, true, true, | |
129 | - qemu_rbd_diff_iterate_cb, &req); | |
130 | - if (r < 0 && r != QEMU_RBD_EXIT_DIFF_ITERATE2) { | |
131 | - return status; | |
132 | - } | |
133 | - assert(req.bytes <= bytes); | |
134 | - if (!req.exists) { | |
135 | - if (r == 0) { | |
136 | - /* | |
137 | - * rbd_diff_iterate2 does not invoke callbacks for unallocated | |
138 | - * areas. This here catches the case where no callback was | |
139 | - * invoked at all (req.bytes == 0). | |
140 | - */ | |
141 | - assert(req.bytes == 0); | |
142 | - req.bytes = bytes; | |
143 | - } | |
144 | - status = BDRV_BLOCK_ZERO | BDRV_BLOCK_OFFSET_VALID; | |
145 | - } | |
146 | - | |
147 | - *pnum = req.bytes; | |
148 | - return status; | |
149 | -} | |
150 | - | |
bf251437 | 151 | static int64_t coroutine_fn qemu_rbd_co_getlength(BlockDriverState *bs) |
dc265df3 FE |
152 | { |
153 | BDRVRBDState *s = bs->opaque; | |
bf251437 | 154 | @@ -1796,7 +1685,6 @@ static BlockDriver bdrv_rbd = { |
dc265df3 FE |
155 | #ifdef LIBRBD_SUPPORTS_WRITE_ZEROES |
156 | .bdrv_co_pwrite_zeroes = qemu_rbd_co_pwrite_zeroes, | |
157 | #endif | |
158 | - .bdrv_co_block_status = qemu_rbd_co_block_status, | |
159 | ||
160 | .bdrv_snapshot_create = qemu_rbd_snap_create, | |
161 | .bdrv_snapshot_delete = qemu_rbd_snap_remove, |