alex chen
2017-Oct-31 06:20 UTC
[Ocfs2-devel] [PATCH v2] ocfs2: should wait dio before inode lock in ocfs2_setattr()
we should wait dio requests to finish before inode lock in
ocfs2_setattr(), otherwise the following deadlock will be happened:
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.
Signed-off-by: Alex Chen <alex.chen at huawei.com>
Reviewed-by: Jun Piao <piaojun at huawei.com>
Reviewed-by: Joseph Qi <jiangqi903 at gmail.com>
Acked-by: Changwei Ge <ge.changwei at h3c.com>
---
fs/ocfs2/file.c | 9 +++++++--
1 file changed, 7 insertions(+), 2 deletions(-)
diff --git a/fs/ocfs2/file.c b/fs/ocfs2/file.c
index 6e41fc8..dc455d4 100644
--- a/fs/ocfs2/file.c
+++ b/fs/ocfs2/file.c
@@ -1161,6 +1161,13 @@ int ocfs2_setattr(struct dentry *dentry, struct iattr
*attr)
}
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);
@@ -1200,8 +1207,6 @@ int ocfs2_setattr(struct dentry *dentry, struct iattr
*attr)
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,
--
1.9.5.msysgit.1
Andrew Morton
2017-Nov-01 20:49 UTC
[Ocfs2-devel] [PATCH v2] ocfs2: should wait dio before inode lock in ocfs2_setattr()
On Tue, 31 Oct 2017 14:20:38 +0800 alex chen <alex.chen at huawei.com> wrote:> we should wait dio requests to finish before inode lock in > ocfs2_setattr(), otherwise the following deadlock will be happened: > 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. >This sounds like something which should be backported into -stable kernels. Do you agree?