Details
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Bug
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Status: Closed (View Workflow)
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Blocker
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Resolution: Fixed
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10.3(EOL), 10.4(EOL), 10.5, 10.6, 10.7(EOL), 10.8(EOL), 10.9(EOL), 10.10(EOL), 10.11
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None
Description
The function ibuf_init_at_db_start() fails to validate the contents of the root page of the change buffer tree, beyond checking that the page checksum is valid.
Should the page exist but be in a different format (such as a dummy page created after MDEV-29694 removed the change buffer), InnoDB would crash on some DDL operations or on slow shutdown when trying to access the change buffer tree.
Here is how the change buffer creation can be disabled on startup:
diff --git a/storage/innobase/srv/srv0start.cc b/storage/innobase/srv/srv0start.cc
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index 8e291352d55..3f81f33cee1 100644
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--- a/storage/innobase/srv/srv0start.cc
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+++ b/storage/innobase/srv/srv0start.cc
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@@ -1401,17 +1401,48 @@ dberr_t srv_start(bool create_new_db)
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uint32_t(sum_of_new_sizes), &mtr)
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== DB_SUCCESS);
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+#if 1
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ulint ibuf_root = btr_create(
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DICT_CLUSTERED | DICT_IBUF, fil_system.sys_space,
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DICT_IBUF_ID_MIN, nullptr, &mtr, &err);
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+#else
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+ /* Allocate dummy change buffer pages for backward
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+ compatibility and to prevent a downgrade. */
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+ if (err != DB_SUCCESS) {
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+ } else if (buf_block_t *b =
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+ fseg_create(fil_system.sys_space, PAGE_DATA, &mtr,
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+ &err)) {
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+ ut_ad(b->page.id()
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+ == page_id_t(0, FSP_IBUF_HEADER_PAGE_NO));
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+ b = fseg_alloc_free_page_general(
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+ b->page.frame + PAGE_DATA,
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+ FSP_IBUF_TREE_ROOT_PAGE_NO, FSP_UP, false,
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+ &mtr, &mtr, &err);
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+ if (b) {
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+ ut_ad(b->page.id() == page_id_t
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+ (0, FSP_IBUF_TREE_ROOT_PAGE_NO));
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+ mtr.set_modified(*b);
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+ fsp_init_file_page(fil_system.sys_space, b,
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+ &mtr);
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+ } else {
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+ ut_ad(err != DB_SUCCESS);
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+ }
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+ }
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+#endif
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mtr_commit(&mtr);
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+#if 1
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if (ibuf_root == FIL_NULL) {
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return srv_init_abort(err);
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}
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ut_ad(ibuf_root == IBUF_TREE_ROOT_PAGE_NO);
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+#else
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+ if (err != DB_SUCCESS) {
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+ return srv_init_abort(err);
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+ }
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+#endif
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/* To maintain backward compatibility we create only
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the first rollback segment before the double write buffer. |
A proper validation of the change buffer on startup is necessary so that attempts to downgrade from newer major releases that include MDEV-29694 can be prevented.
Attachments
Issue Links
- blocks
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MDEV-29694 Remove the InnoDB change buffer
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- Closed
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- causes
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- Closed
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