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| author |   Zhang Yi <yi.zhang@huawei.com> | 2022-06-11 21:04:26 +0800 |
|---|---|---|
| committer |   Theodore Ts'o <tytso@mit.edu> | 2022-08-02 23:52:19 -0400 |
| commit | a89573ce4ad32f19f43ec669771726817e185be0 (patch) | |
| tree | 760c13d5b326e021d7fec97778566f7231876d16 | |
| parent | jbd2: unexport jbd2_log_start_commit() (diff) | |
| download | linux-dev-a89573ce4ad32f19f43ec669771726817e185be0.tar.xz linux-dev-a89573ce4ad32f19f43ec669771726817e185be0.zip | |
jbd2: fix outstanding credits assert in jbd2_journal_commit_transaction()
We catch an assert problem in jbd2_journal_commit_transaction() when
doing fsstress and request falut injection tests. The problem is
happened in a race condition between jbd2_journal_commit_transaction()
and ext4_end_io_end(). Firstly, ext4_writepages() writeback dirty pages
and start reserved handle, and then the journal was aborted due to some
previous metadata IO error, jbd2_journal_abort() start to commit current
running transaction, the committing procedure could be raced by
ext4_end_io_end() and lead to subtract j_reserved_credits twice from
commit_transaction->t_outstanding_credits, finally the
t_outstanding_credits is mistakenly smaller than t_nr_buffers and
trigger assert.
kjournald2 kworker
jbd2_journal_commit_transaction()
write_unlock(&journal->j_state_lock);
atomic_sub(j_reserved_credits, t_outstanding_credits); //sub once
jbd2_journal_start_reserved()
start_this_handle() //detect aborted journal
jbd2_journal_free_reserved() //get running transaction
read_lock(&journal->j_state_lock)
__jbd2_journal_unreserve_handle()
atomic_sub(j_reserved_credits, t_outstanding_credits);
//sub again
read_unlock(&journal->j_state_lock);
journal->j_running_transaction = NULL;
J_ASSERT(t_nr_buffers <= t_outstanding_credits) //bomb!!!
Fix this issue by using journal->j_state_lock to protect the subtraction
in jbd2_journal_commit_transaction().
Fixes: 96f1e0974575 ("jbd2: avoid long hold times of j_state_lock while committing a transaction")
Signed-off-by: Zhang Yi <yi.zhang@huawei.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Link: https://lore.kernel.org/r/20220611130426.2013258-1-yi.zhang@huawei.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
| -rw-r--r-- | fs/jbd2/commit.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/fs/jbd2/commit.c b/fs/jbd2/commit.c index aa14f20241d7..7cb4f5de8155 100644 --- a/fs/jbd2/commit.c +++ b/fs/jbd2/commit.c @@ -553,13 +553,13 @@ void jbd2_journal_commit_transaction(journal_t *journal) */ jbd2_journal_switch_revoke_table(journal); + write_lock(&journal->j_state_lock); /* * Reserved credits cannot be claimed anymore, free them */ atomic_sub(atomic_read(&journal->j_reserved_credits), &commit_transaction->t_outstanding_credits); - write_lock(&journal->j_state_lock); trace_jbd2_commit_flushing(journal, commit_transaction); stats.run.rs_flushing = jiffies; stats.run.rs_locked = jbd2_time_diff(stats.run.rs_locked, |