From 8a8ad1c2f6ef6fbee7487ec293218f42e72ad6a3 Mon Sep 17 00:00:00 2001 From: Wengang Wang Date: Mon, 23 Jun 2014 13:22:08 -0700 Subject: [PATCH] ocfs2: refcount: take rw_lock in ocfs2_reflink This patch tries to fix this crash: #5 [ffff88003c1cd690] do_invalid_op at ffffffff810166d5 #6 [ffff88003c1cd730] invalid_op at ffffffff8159b2de [exception RIP: ocfs2_direct_IO_get_blocks+359] RIP: ffffffffa05dfa27 RSP: ffff88003c1cd7e8 RFLAGS: 00010202 RAX: 0000000000000000 RBX: ffff88003c1cdaa8 RCX: 0000000000000000 RDX: 000000000000000c RSI: ffff880027a95000 RDI: ffff88003c79b540 RBP: ffff88003c1cd858 R8: 0000000000000000 R9: ffffffff815f6ba0 R10: 00000000000001c9 R11: 00000000000001c9 R12: ffff88002d271500 R13: 0000000000000001 R14: 0000000000000000 R15: 0000000000001000 ORIG_RAX: ffffffffffffffff CS: 0010 SS: 0018 #7 [ffff88003c1cd860] do_direct_IO at ffffffff811cd31b #8 [ffff88003c1cd950] direct_IO_iovec at ffffffff811cde9c #9 [ffff88003c1cd9b0] do_blockdev_direct_IO at ffffffff811ce764 #10 [ffff88003c1cdb80] __blockdev_direct_IO at ffffffff811ce7cc #11 [ffff88003c1cdbb0] ocfs2_direct_IO at ffffffffa05df756 [ocfs2] #12 [ffff88003c1cdbe0] generic_file_direct_write_iter at ffffffff8112f935 #13 [ffff88003c1cdc40] ocfs2_file_write_iter at ffffffffa0600ccc [ocfs2] #14 [ffff88003c1cdd50] do_aio_write at ffffffff8119126c #15 [ffff88003c1cddc0] aio_rw_vect_retry at ffffffff811d9bb4 #16 [ffff88003c1cddf0] aio_run_iocb at ffffffff811db880 #17 [ffff88003c1cde30] io_submit_one at ffffffff811dc238 #18 [ffff88003c1cde80] do_io_submit at ffffffff811dc437 #19 [ffff88003c1cdf70] sys_io_submit at ffffffff811dc530 #20 [ffff88003c1cdf80] system_call_fastpath at ffffffff8159a159 It crashes at BUG_ON(create && (ext_flags & OCFS2_EXT_REFCOUNTED)); in ocfs2_direct_IO_get_blocks. ocfs2_direct_IO_get_blocks is expecting the OCFS2_EXT_REFCOUNTED be removed in ocfs2_prepare_inode_for_write() if it was there. But no cluster lock is taken during the time before (or inside) ocfs2_prepare_inode_for_write() and after ocfs2_direct_IO_get_blocks(). It can happen in this case: Node A(which crashes) Node B ------------------------ --------------------------- ocfs2_file_aio_write ocfs2_prepare_inode_for_write ocfs2_inode_lock ... ocfs2_inode_unlock #no refcount found .... ocfs2_reflink ocfs2_inode_lock ... ocfs2_inode_unlock #now, refcount flag set on extent ... flush change to disk ocfs2_direct_IO_get_blocks ocfs2_get_clusters #extent map miss #buffer_head miss read extents from disk found refcount flag on extent crash.. Fix: Take rw_lock in ocfs2_reflink path Signed-off-by: Wengang Wang Reviewed-by: Mark Fasheh Cc: Joel Becker Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- fs/ocfs2/refcounttree.c | 8 ++++++++ 1 file changed, 8 insertions(+) diff --git a/fs/ocfs2/refcounttree.c b/fs/ocfs2/refcounttree.c index 714e53b9cc660..636aab69ead55 100644 --- a/fs/ocfs2/refcounttree.c +++ b/fs/ocfs2/refcounttree.c @@ -4288,9 +4288,16 @@ static int ocfs2_reflink(struct dentry *old_dentry, struct inode *dir, goto out; } + error = ocfs2_rw_lock(inode, 1); + if (error) { + mlog_errno(error); + goto out; + } + error = ocfs2_inode_lock(inode, &old_bh, 1); if (error) { mlog_errno(error); + ocfs2_rw_unlock(inode, 1); goto out; } @@ -4302,6 +4309,7 @@ static int ocfs2_reflink(struct dentry *old_dentry, struct inode *dir, up_write(&OCFS2_I(inode)->ip_xattr_sem); ocfs2_inode_unlock(inode, 1); + ocfs2_rw_unlock(inode, 1); brelse(old_bh); if (error) {