Asynchronous wb switching of inodes takes an additional ref count on an inode to make sure inode remains valid until switchover is completed. However, anyone calling ihold() must already have a ref count on inode, but in this case inode->i_count may already be zero: ------------[ cut here ]------------ WARNING: CPU: 1 PID: 917 at fs/inode.c:397 ihold+0x2b/0x30 CPU: 1 PID: 917 Comm: kworker/u4:5 Not tainted 4.7.0-rc2+ #49 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011 Workqueue: writeback wb_workfn (flush-8:16) 0000000000000000 ffff88007ca0fb58 ffffffff805990af 0000000000000000 0000000000000000 ffff88007ca0fb98 ffffffff80268702 0000018d000004e2 ffff88007cef40e8 ffff88007c9b89a8 ffff880079e3a740 0000000000000003 Call Trace: [<ffffffff805990af>] dump_stack+0x4d/0x6e [<ffffffff80268702>] __warn+0xc2/0xe0 [<ffffffff802687d8>] warn_slowpath_null+0x18/0x20 [<ffffffff8035b4ab>] ihold+0x2b/0x30 [<ffffffff80367ecc>] inode_switch_wbs+0x11c/0x180 [<ffffffff80369110>] wbc_detach_inode+0x170/0x1a0 [<ffffffff80369abc>] writeback_sb_inodes+0x21c/0x530 [<ffffffff80369f7e>] wb_writeback+0xee/0x1e0 [<ffffffff8036a147>] wb_workfn+0xd7/0x280 [<ffffffff80287531>] ? try_to_wake_up+0x1b1/0x2b0 [<ffffffff8027bb09>] process_one_work+0x129/0x300 [<ffffffff8027be06>] worker_thread+0x126/0x480 [<ffffffff8098cde7>] ? __schedule+0x1c7/0x561 [<ffffffff8027bce0>] ? process_one_work+0x300/0x300 [<ffffffff80280ff4>] kthread+0xc4/0xe0 [<ffffffff80335578>] ? kfree+0xc8/0x100 [<ffffffff809903cf>] ret_from_fork+0x1f/0x40 [<ffffffff80280f30>] ? __kthread_parkme+0x70/0x70 ---[ end trace aaefd2fd9f306bc4 ]--- Signed-off-by: Tahsin Erdogan <tahsin@xxxxxxxxxx> Acked-by: Tejun Heo <tj@xxxxxxxxxx> Reviewed-by: Jan Kara <jack@xxxxxxx> --- v3: added Reviewed-by Jan Kara v2: removed inode->i_count == 0 check replaced ihold() with __iget() updated commit description fs/fs-writeback.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/fs/fs-writeback.c b/fs/fs-writeback.c index 989a2cef6b76..fe7e83a45eff 100644 --- a/fs/fs-writeback.c +++ b/fs/fs-writeback.c @@ -483,9 +483,9 @@ static void inode_switch_wbs(struct inode *inode, int new_wb_id) goto out_free; } inode->i_state |= I_WB_SWITCH; + __iget(inode); spin_unlock(&inode->i_lock); - ihold(inode); isw->inode = inode; atomic_inc(&isw_nr_in_flight); -- 2.8.0.rc3.226.g39d4020 -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
