debian/patches/pve/0042-Revert-block-rbd-implement-bdrv_co_block_status.patch

   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 Signed-off-by: Thomas Lamprecht <t.lamprecht@proxmox.com>
  22 ---
  23  block/rbd.c | 112 ----------------------------------------------------
  24  1 file changed, 112 deletions(-)
  25
  26 diff --git a/block/rbd.c b/block/rbd.c
  27 index 0913a0af39..1dab254517 100644
  28 --- a/block/rbd.c
  29 +++ b/block/rbd.c
  30 @@ -108,12 +108,6 @@ typedef struct RBDTask {
  31      int64_t ret;
  32  } RBDTask;
  33
  34 -typedef struct RBDDiffIterateReq {
  35 -    uint64_t offs;
  36 -    uint64_t bytes;
  37 -    bool exists;
  38 -} RBDDiffIterateReq;
  39 -
  40  static int qemu_rbd_connect(rados_t *cluster, rados_ioctx_t *io_ctx,
  41                              BlockdevOptionsRbd *opts, bool cache,
  42                              const char *keypairs, const char *secretid,
  43 @@ -1456,111 +1450,6 @@ static ImageInfoSpecific *qemu_rbd_get_specific_info(BlockDriverState *bs,
  44      return spec_info;
  45  }
  46
  47 -/*
  48 - * rbd_diff_iterate2 allows to interrupt the exection by returning a negative
  49 - * value in the callback routine. Choose a value that does not conflict with
  50 - * an existing exitcode and return it if we want to prematurely stop the
  51 - * execution because we detected a change in the allocation status.
  52 - */
  53 -#define QEMU_RBD_EXIT_DIFF_ITERATE2 -9000
  54 -
  55 -static int qemu_rbd_diff_iterate_cb(uint64_t offs, size_t len,
  56 -                                    int exists, void *opaque)
  57 -{
  58 -    RBDDiffIterateReq *req = opaque;
  59 -
  60 -    assert(req->offs + req->bytes <= offs);
  61 -    /*
  62 -     * we do not diff against a snapshot so we should never receive a callback
  63 -     * for a hole.
  64 -     */
  65 -    assert(exists);
  66 -
  67 -    if (!req->exists && offs > req->offs) {
  68 -        /*
  69 -         * we started in an unallocated area and hit the first allocated
  70 -         * block. req->bytes must be set to the length of the unallocated area
  71 -         * before the allocated area. stop further processing.
  72 -         */
  73 -        req->bytes = offs - req->offs;
  74 -        return QEMU_RBD_EXIT_DIFF_ITERATE2;
  75 -    }
  76 -
  77 -    if (req->exists && offs > req->offs + req->bytes) {
  78 -        /*
  79 -         * we started in an allocated area and jumped over an unallocated area,
  80 -         * req->bytes contains the length of the allocated area before the
  81 -         * unallocated area. stop further processing.
  82 -         */
  83 -        return QEMU_RBD_EXIT_DIFF_ITERATE2;
  84 -    }
  85 -
  86 -    req->bytes += len;
  87 -    req->exists = true;
  88 -
  89 -    return 0;
  90 -}
  91 -
  92 -static int coroutine_fn qemu_rbd_co_block_status(BlockDriverState *bs,
  93 -                                                 bool want_zero, int64_t offset,
  94 -                                                 int64_t bytes, int64_t *pnum,
  95 -                                                 int64_t *map,
  96 -                                                 BlockDriverState **file)
  97 -{
  98 -    BDRVRBDState *s = bs->opaque;
  99 -    int status, r;
 100 -    RBDDiffIterateReq req = { .offs = offset };
 101 -    uint64_t features, flags;
 102 -
 103 -    assert(offset + bytes <= s->image_size);
 104 -
 105 -    /* default to all sectors allocated */
 106 -    status = BDRV_BLOCK_DATA | BDRV_BLOCK_OFFSET_VALID;
 107 -    *map = offset;
 108 -    *file = bs;
 109 -    *pnum = bytes;
 110 -
 111 -    /* check if RBD image supports fast-diff */
 112 -    r = rbd_get_features(s->image, &features);
 113 -    if (r < 0) {
 114 -        return status;
 115 -    }
 116 -    if (!(features & RBD_FEATURE_FAST_DIFF)) {
 117 -        return status;
 118 -    }
 119 -
 120 -    /* check if RBD fast-diff result is valid */
 121 -    r = rbd_get_flags(s->image, &flags);
 122 -    if (r < 0) {
 123 -        return status;
 124 -    }
 125 -    if (flags & RBD_FLAG_FAST_DIFF_INVALID) {
 126 -        return status;
 127 -    }
 128 -
 129 -    r = rbd_diff_iterate2(s->image, NULL, offset, bytes, true, true,
 130 -                          qemu_rbd_diff_iterate_cb, &req);
 131 -    if (r < 0 && r != QEMU_RBD_EXIT_DIFF_ITERATE2) {
 132 -        return status;
 133 -    }
 134 -    assert(req.bytes <= bytes);
 135 -    if (!req.exists) {
 136 -        if (r == 0) {
 137 -            /*
 138 -             * rbd_diff_iterate2 does not invoke callbacks for unallocated
 139 -             * areas. This here catches the case where no callback was
 140 -             * invoked at all (req.bytes == 0).
 141 -             */
 142 -            assert(req.bytes == 0);
 143 -            req.bytes = bytes;
 144 -        }
 145 -        status = BDRV_BLOCK_ZERO | BDRV_BLOCK_OFFSET_VALID;
 146 -    }
 147 -
 148 -    *pnum = req.bytes;
 149 -    return status;
 150 -}
 151 -
 152  static int64_t coroutine_fn qemu_rbd_co_getlength(BlockDriverState *bs)
 153  {
 154      BDRVRBDState *s = bs->opaque;
 155 @@ -1796,7 +1685,6 @@ static BlockDriver bdrv_rbd = {
 156  #ifdef LIBRBD_SUPPORTS_WRITE_ZEROES
 157      .bdrv_co_pwrite_zeroes  = qemu_rbd_co_pwrite_zeroes,
 158  #endif
 159 -    .bdrv_co_block_status   = qemu_rbd_co_block_status,
 160
 161      .bdrv_snapshot_create   = qemu_rbd_snap_create,
 162      .bdrv_snapshot_delete   = qemu_rbd_snap_remove,