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ocfs2: fix race between searching chunks and release journal_head from buffer_head
Encountered a race between ocfs2_test_bg_bit_allocatable() and jbd2_journal_put_journal_head() resulting in the below vmcore. PID: 106879 TASK: ffff880244ba9c00 CPU: 2 COMMAND: "loop3" Call trace: panic oops_end no_context __bad_area_nosemaphore bad_area_nosemaphore __do_page_fault do_page_fault page_fault [exception RIP: ocfs2_block_group_find_clear_bits+316] ocfs2_block_group_find_clear_bits [ocfs2] ocfs2_cluster_group_search [ocfs2] ocfs2_search_chain [ocfs2] ocfs2_claim_suballoc_bits [ocfs2] __ocfs2_claim_clusters [ocfs2] ocfs2_claim_clusters [ocfs2] ocfs2_local_alloc_slide_window [ocfs2] ocfs2_reserve_local_alloc_bits [ocfs2] ocfs2_reserve_clusters_with_limit [ocfs2] ocfs2_reserve_clusters [ocfs2] ocfs2_lock_refcount_allocators [ocfs2] ocfs2_make_clusters_writable [ocfs2] ocfs2_replace_cow [ocfs2] ocfs2_refcount_cow [ocfs2] ocfs2_file_write_iter [ocfs2] lo_rw_aio loop_queue_work kthread_worker_fn kthread ret_from_fork When ocfs2_test_bg_bit_allocatable() called bh2jh(bg_bh), the bg_bh->b_private NULL as jbd2_journal_put_journal_head() raced and released the jounal head from the buffer head. Needed to take bit lock for the bit 'BH_JournalHead' to fix this race. Link: https://lkml.kernel.org/r/1634820718-6043-1-git-send-email-gautham.ananthakrishna@oracle.com Signed-off-by: Gautham Ananthakrishna <gautham.ananthakrishna@oracle.com> Reviewed-by: Joseph Qi <joseph.qi@linux.alibaba.com> Cc: <rajesh.sivaramasubramaniom@oracle.com> Cc: Mark Fasheh <mark@fasheh.com> Cc: Joel Becker <jlbec@evilplan.org> Cc: Junxiao Bi <junxiao.bi@oracle.com> Cc: Changwei Ge <gechangwei@live.cn> Cc: Gang He <ghe@suse.com> Cc: Jun Piao <piaojun@huawei.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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@ -1251,7 +1251,7 @@ static int ocfs2_test_bg_bit_allocatable(struct buffer_head *bg_bh,
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{
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struct ocfs2_group_desc *bg = (struct ocfs2_group_desc *) bg_bh->b_data;
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struct journal_head *jh;
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int ret;
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int ret = 1;
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if (ocfs2_test_bit(nr, (unsigned long *)bg->bg_bitmap))
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return 0;
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@ -1259,14 +1259,18 @@ static int ocfs2_test_bg_bit_allocatable(struct buffer_head *bg_bh,
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if (!buffer_jbd(bg_bh))
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return 1;
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jh = bh2jh(bg_bh);
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spin_lock(&jh->b_state_lock);
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bg = (struct ocfs2_group_desc *) jh->b_committed_data;
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if (bg)
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ret = !ocfs2_test_bit(nr, (unsigned long *)bg->bg_bitmap);
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else
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ret = 1;
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spin_unlock(&jh->b_state_lock);
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jbd_lock_bh_journal_head(bg_bh);
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if (buffer_jbd(bg_bh)) {
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jh = bh2jh(bg_bh);
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spin_lock(&jh->b_state_lock);
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bg = (struct ocfs2_group_desc *) jh->b_committed_data;
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if (bg)
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ret = !ocfs2_test_bit(nr, (unsigned long *)bg->bg_bitmap);
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else
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ret = 1;
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spin_unlock(&jh->b_state_lock);
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}
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jbd_unlock_bh_journal_head(bg_bh);
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return ret;
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}
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