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From 8c50eedf03d8e62acd387b9aa9369dadcea9324c Mon Sep 17 00:00:00 2001
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From: Peter Lieven <pl@kamp.de>
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Date: Thu, 13 Jan 2022 15:44:26 +0100
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Subject: [PATCH 6/6] block/rbd: workaround for ceph issue #53784
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RH-Author: Stefano Garzarella <sgarzare@redhat.com>
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RH-MergeRequest: 110: block/rbd: fix handling of holes in .bdrv_co_block_status
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RH-Commit: [2/2] 1384557462e89bb539d0d25a1a471ad738fb9e89
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RH-Bugzilla: 2037135
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RH-Acked-by: Stefan Hajnoczi <stefanha@redhat.com>
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RH-Acked-by: Kevin Wolf <kwolf@redhat.com>
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RH-Acked-by: Hanna Reitz <hreitz@redhat.com>
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librbd had a bug until early 2022 that affected all versions of ceph that
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supported fast-diff. This bug results in reporting of incorrect offsets
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if the offset parameter to rbd_diff_iterate2 is not object aligned.
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This patch works around this bug for pre Quincy versions of librbd.
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Fixes: 0347a8fd4c3faaedf119be04c197804be40a384b
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Cc: qemu-stable@nongnu.org
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Signed-off-by: Peter Lieven <pl@kamp.de>
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Message-Id: <20220113144426.4036493-3-pl@kamp.de>
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Reviewed-by: Ilya Dryomov <idryomov@gmail.com>
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Reviewed-by: Stefano Garzarella <sgarzare@redhat.com>
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Tested-by: Stefano Garzarella <sgarzare@redhat.com>
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Signed-off-by: Kevin Wolf <kwolf@redhat.com>
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(cherry picked from commit fc176116cdea816ceb8dd969080b2b95f58edbc0)
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Signed-off-by: Stefano Garzarella <sgarzare@redhat.com>
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---
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 block/rbd.c | 42 ++++++++++++++++++++++++++++++++++++++++--
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 1 file changed, 40 insertions(+), 2 deletions(-)
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diff --git a/block/rbd.c b/block/rbd.c
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index 20bb896c4a..8f183eba2a 100644
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--- a/block/rbd.c
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+++ b/block/rbd.c
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@@ -1320,6 +1320,7 @@ static int coroutine_fn qemu_rbd_co_block_status(BlockDriverState *bs,
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     int status, r;
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     RBDDiffIterateReq req = { .offs = offset };
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     uint64_t features, flags;
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+    uint64_t head = 0;
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     assert(offset + bytes <= s->image_size);
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@@ -1347,7 +1348,43 @@ static int coroutine_fn qemu_rbd_co_block_status(BlockDriverState *bs,
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         return status;
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     }
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-    r = rbd_diff_iterate2(s->image, NULL, offset, bytes, true, true,
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+#if LIBRBD_VERSION_CODE < LIBRBD_VERSION(1, 17, 0)
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+    /*
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+     * librbd had a bug until early 2022 that affected all versions of ceph that
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+     * supported fast-diff. This bug results in reporting of incorrect offsets
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+     * if the offset parameter to rbd_diff_iterate2 is not object aligned.
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+     * Work around this bug by rounding down the offset to object boundaries.
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+     * This is OK because we call rbd_diff_iterate2 with whole_object = true.
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+     * However, this workaround only works for non cloned images with default
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+     * striping.
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+     *
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+     * See: https://tracker.ceph.com/issues/53784
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+     */
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+
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+    /* check if RBD image has non-default striping enabled */
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+    if (features & RBD_FEATURE_STRIPINGV2) {
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+        return status;
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+    }
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+
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+#pragma GCC diagnostic push
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+#pragma GCC diagnostic ignored "-Wdeprecated-declarations"
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+    /*
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+     * check if RBD image is a clone (= has a parent).
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+     *
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+     * rbd_get_parent_info is deprecated from Nautilus onwards, but the
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+     * replacement rbd_get_parent is not present in Luminous and Mimic.
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+     */
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+    if (rbd_get_parent_info(s->image, NULL, 0, NULL, 0, NULL, 0) != -ENOENT) {
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+        return status;
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+    }
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+#pragma GCC diagnostic pop
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+
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+    head = req.offs & (s->object_size - 1);
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+    req.offs -= head;
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+    bytes += head;
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+#endif
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+
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+    r = rbd_diff_iterate2(s->image, NULL, req.offs, bytes, true, true,
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                           qemu_rbd_diff_iterate_cb, &req;;
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     if (r < 0 && r != QEMU_RBD_EXIT_DIFF_ITERATE2) {
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         return status;
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@@ -1366,7 +1403,8 @@ static int coroutine_fn qemu_rbd_co_block_status(BlockDriverState *bs,
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         status = BDRV_BLOCK_ZERO | BDRV_BLOCK_OFFSET_VALID;
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     }
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-    *pnum = req.bytes;
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+    assert(req.bytes > head);
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+    *pnum = req.bytes - head;
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     return status;
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 }
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-- 
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2.27.0
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