btrfs: don't return VM_FAULT_SIGBUS on failure to set delalloc for mmap write

If the call to btrfs_set_extent_delalloc() fails we are always returning
VM_FAULT_SIGBUS, which is odd since the error means "bad access" and the
most likely cause for btrfs_set_extent_delalloc() is -ENOMEM, which should
be translated to VM_FAULT_OOM.

Instead of returning VM_FAULT_SIGBUS return vmf_error(ret2), which gives
us a more appropriate return value, and we use that everywhere else too.

Reviewed-by: Qu Wenruo <[email protected]>
Signed-off-by: Filipe Manana <[email protected]>
Reviewed-by: David Sterba <[email protected]>
Signed-off-by: David Sterba <[email protected]>

Author: fdmanana

fs/btrfs/file.c

@@ -1937,7 +1937,7 @@ static vm_fault_t btrfs_page_mkwrite(struct vm_fault *vmf)
 					&cached_state);
 	if (ret2) {
 		btrfs_unlock_extent(io_tree, page_start, page_end, &cached_state);
-		ret = VM_FAULT_SIGBUS;
+		ret = vmf_error(ret2);
 		goto out_unlock;
 	}