xfs: cancel tx on xfs_defer_finish() error during xattr set/remove

Chris Dunlop reports a problem where an xattr operation fails, reports the following error to syslog and hangs during unmount:

================================================
[ BUG: lock held when returning to user space! ]
...
------------------------------------------------
<PID> is leaving the kernel with locks still held!
1 lock held by <PID>:
#0: (sb_internal){......}, at: [<ffffffffa07692a3>] xfs_trans_alloc+0xe3/0x130 [xfs]

The failure/shutdown occurs during deferred ops processing which leads to an error return from xfs_defer_finish() via xfs_attr_leaf_addname(). While the root cause of the failure is unknown corruption, the cause of the subsequent BUG above and unmount hang is failure to cancel the transaction before returning to userspace.

The transaction is not cancelled because the out_defer_cancel error handling paths in the xfs_attr_[leaf|node]_[add|remove]name() functions clear args.trans without releasing the transaction. The callers therefore lose the reference to the transaction and fail to cancel it.

Since xfs_attr_[set|remove]() always cancel args.trans when != NULL and xfs_defer_finish()->...->xfs_trans_roll() should always return with a valid transaction, update the leaf/node xattr functions to not reset args.trans in the error path responsible for cancelling deferred ops.

Reported-by Chris Dunlop <[email protected]>

Signed-off-by Brian Foster <[email protected]>

---
 fs/xfs/libxfs/xfs_attr.c | 4 ----
 1 file changed, 4 deletions(-)

fs/xfs/libxfs/xfs_attr.c +0 -4

index a76914db72ef..ce4a34a2751d 100644
@@ -717,7 +717,6 @@ xfs_attr_leaf_addname(xfs_da_args_t *args)
 	return error;
 out_defer_cancel:
 	xfs_defer_cancel(args->dfops);
-	args->trans = NULL;
 	return error;
 }
 

@@ -770,7 +769,6 @@ xfs_attr_leaf_removename(xfs_da_args_t *args)
 	return 0;
 out_defer_cancel:
 	xfs_defer_cancel(args->dfops);
-	args->trans = NULL;
 	return error;
 }
 

@@ -1045,7 +1043,6 @@ xfs_attr_node_addname(xfs_da_args_t *args)
 	return retval;
 out_defer_cancel:
 	xfs_defer_cancel(args->dfops);
-	args->trans = NULL;
 	goto out;
 }
 

@@ -1186,7 +1183,6 @@ xfs_attr_node_removename(xfs_da_args_t *args)
 	return error;
 out_defer_cancel:
 	xfs_defer_cancel(args->dfops);
-	args->trans = NULL;
 	goto out;
 }
 

Signature · 6 lines

2.13.6

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