[PATCH 3.2 39/79] ocfs2: should wait dio before inode lock in ocfs2_setattr()

Ben Hutchings
2018-02-11T04:20:06Z

From: alex chen <alex.chen@huawei.com>

commit 28f5a8a7c033cbf3e32277f4cc9c6afd74f05300 upstream.

we should wait dio requests to finish before inode lock in
ocfs2_setattr(), otherwise the following deadlock will happen:

process 1 process 2 process 3
truncate file 'A' end_io of writing file 'A' receiving the bast messages
ocfs2_setattr
ocfs2_inode_lock_tracker
ocfs2_inode_lock_full
inode_dio_wait
__inode_dio_wait
-->waiting for all dio
requests finish
dlm_proxy_ast_handler
dlm_do_local_bast
ocfs2_blocking_ast
ocfs2_generic_handle_bast
set OCFS2_LOCK_BLOCKED flag
dio_end_io
dio_bio_end_aio
dio_complete
ocfs2_dio_end_io
ocfs2_dio_end_io_write
ocfs2_inode_lock
__ocfs2_cluster_lock
ocfs2_wait_for_mask
-->waiting for OCFS2_LOCK_BLOCKED
flag to be cleared, that is waiting
for 'process 1' unlocking the inode lock
inode_dio_end
-->here dec the i_dio_count, but will never
be called, so a deadlock happened.

Link: http://lkml.kernel.org/r/59F81636.70508@huawei.com
Signed-off-by: Alex Chen <alex.chen@huawei.com>
Reviewed-by: Jun Piao <piaojun@huawei.com>
Reviewed-by: Joseph Qi <jiangqi903@gmail.com>
Acked-by: Changwei Ge <ge.changwei@h3c.com>
Cc: Mark Fasheh <mfasheh@versity.com>
Cc: Joel Becker <jlbec@evilplan.org>
Cc: Junxiao Bi <junxiao.bi@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
---
fs/ocfs2/file.c | 9 +++++++--
1 file changed, 7 insertions(+), 2 deletions(-)

--- a/fs/ocfs2/file.c
+++ b/fs/ocfs2/file.c
@@ -1130,6 +1130,13 @@ int ocfs2_setattr(struct dentry *dentry,
dquot_initialize(inode);
size_change = S_ISREG(inode->i_mode) && attr->ia_valid & ATTR_SIZE;
if (size_change) {
+ /*
+ * Here we should wait dio to finish before inode lock
+ * to avoid a deadlock between ocfs2_setattr() and
+ * ocfs2_dio_end_io_write()
+ */
+ inode_dio_wait(inode);
+
status = ocfs2_rw_lock(inode, 1);
if (status < 0) {
mlog_errno(status);
@@ -1149,8 +1156,6 @@ int ocfs2_setattr(struct dentry *dentry,
if (status)
goto bail_unlock;

- inode_dio_wait(inode);
-
if (i_size_read(inode) >= attr->ia_size) {
if (ocfs2_should_order_data(inode)) {
status = ocfs2_begin_ordered_truncate(inode,