Hi Ben,
ocfs2_dio_end_io_write() was introduced in 4.6 and the problem this patch fixes is only exist in the kernel 4.6 and above 4.6.
Thanks, Alex
On 2018/2/11 12:20, Ben Hutchings wrote:
3.2.99-rc1 review patch. If anyone has any objections, please let me know.
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,
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