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MDEV-34705: Binlog-in-engine: Fix race between reader and flush

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A reader could latch a page that was currently being flushed to disk, while
the flushing thread is temporarily releasing the mutex. If the page was
complete with data when the flushing started, the flush thread would not
correctly wait for the reader to release the latch, and the page could be
freed while the reader was still using it.

Also adjust a couple assertions to reflect the addition of the file header
page as page 0.

Signed-off-by: Kristian Nielsen <knielsen@knielsen-hq.org>
This commit is contained in:
Kristian Nielsen
2025-04-07 08:47:46 +02:00
parent dfb6fc0dc7
commit da3e9edafb
2 changed files with 20 additions and 6 deletions
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2
mysql-test/suite/binlog_in_engine/my.cnf
View File

@@ -3,6 +3,7 @@
[mysqld.1]
innodb
binlog-storage-engine=innodb
max_binlog_size=8M
innodb-binlog-state-interval=128k
log-basename= master
@@ -10,6 +11,7 @@ log-basename= master
#!use-slave-opt
innodb
binlog-storage-engine=innodb
max_binlog_size=8M
innodb-binlog-state-interval=128k
log-slave-updates
log-basename= slave

20
storage/innobase/fsp/fsp_binlog.cc
View File

@@ -292,8 +292,8 @@ fsp_binlog_page_fifo::flush_one_page(uint64_t file_no, bool force)
size_t res= crc32_pwrite_page(fh, e->page_buf, page_no, MYF(MY_WME));
ut_a(res == ibb_page_size);
mysql_mutex_lock(&m_mutex);
if (!is_complete &&
(UNIV_UNLIKELY(e->latched) || UNIV_UNLIKELY(!e->flushed_clean)))
if (UNIV_UNLIKELY(e->latched) ||
(!is_complete && UNIV_UNLIKELY(!e->flushed_clean)))
{
flushing= false;
pthread_cond_broadcast(&m_cond);
@@ -322,9 +322,21 @@ fsp_binlog_page_fifo::flush_one_page(uint64_t file_no, bool force)
my_cond_wait(&m_cond, &m_mutex.m_mutex);
}
flushing= true;
if (!is_complete)
{
/*
The page was not complete, a writer may have added data. Need to redo
the flush.
*/
is_complete= e->complete;
goto retry;
}
/*
The page was complete, but was latched while we were flushing (by a
reader). No need to flush again, just needed to wait until the latch
was released before we can continue to free the page.
*/
}
}
/*
We marked the FIFO as flushing, page could not have disappeared despite
@@ -1331,7 +1343,7 @@ binlog_chunk_reader::fetch_current_page()
binlog_cur_end_offset[s.file_no&1].load(std::memory_order_acquire);
if (s.file_no > active)
{
ut_ad(s.page_no == 0);
ut_ad(s.page_no == 1);
ut_ad(s.in_page_offset == 0);
/*
Allow a reader that reached the very end of the active binlog file to
@@ -1712,7 +1724,7 @@ bool binlog_chunk_reader::data_available()
uint64_t active= active_binlog_file_no.load(std::memory_order_acquire);
if (active != s.file_no)
{
ut_ad(active > s.file_no || (s.page_no == 0 && s.in_page_offset == 0));
ut_ad(active > s.file_no || (s.page_no == 1 && s.in_page_offset == 0));
return active > s.file_no;
}
uint64_t end_offset=