[PATCH v2] jbd2: preserve original nofs flag during journal restart

Tahsin Erdogan
2017-05-17T16:16:29Z

When a transaction starts, start_this_handle() saves current
PF_MEMALLOC_NOFS value so that it can be restored at journal stop time.
Journal restart is a special case that calls start_this_handle() without
stopping the transaction. start_this_handle() isn't aware that the
original value is already stored so it overwrites it with current value.

For instance, a call sequence like below leaves PF_MEMALLOC_NOFS flag set
at the end:

jbd2_journal_start()
jbd2__journal_restart()
jbd2_journal_stop()

Make jbd2__journal_restart() restore the original value before calling
start_this_handle().

Fixes: 81378da64de6 ("jbd2: mark the transaction context with the scope GFP_NOFS context")
Signed-off-by: Tahsin Erdogan <tahsin@google.com>
Reviewed-by: Jan Kara <jack@suse.cz>
---
v2: added comment to jbd2__journal_restart()

fs/jbd2/transaction.c | 2 ++
1 file changed, 2 insertions(+)

diff --git a/fs/jbd2/transaction.c b/fs/jbd2/transaction.c
index 9ee4832b6f8b..05c0323493fb 100644
--- a/fs/jbd2/transaction.c
+++ b/fs/jbd2/transaction.c
@@ -680,6 +680,8 @@ int jbd2__journal_restart(handle_t *handle, int nblocks, gfp_t gfp_mask)

rwsem_release(&journal->j_trans_commit_map, 1, _THIS_IP_);
handle->h_buffer_credits = nblocks;
+ /* Restore original nofs flag as jbd2_journal_stop() would do. */
+ memalloc_nofs_restore(handle->saved_alloc_context);
ret = start_this_handle(journal, handle, gfp_mask);
return ret;
}
--
2.13.0.303.g4ebf302169-goog