Subject: Re: linux-next: build failure after merge of the mm tree

From: "Darrick J. Wong" <[email-masked]>
Date: Fri, 8 Jul 2022 08:17:51 -0700

On Fri, Jul 08, 2022 at 07:44:37PM +1000, Stephen Rothwell wrote:
> Hi all,
> 
> After merging the mm tree, today's linux-next build (x86_64 allmodconfig)
> failed like this:
> 
> fs/xfs/xfs_notify_failure.c: In function 'xfs_dax_notify_ddev_failure':
> fs/xfs/xfs_notify_failure.c:126:44: error: passing argument 1 of 'xfs_alloc_read_agf' from incompatible pointer type [-Werror=incompatible-pointer-types]
>   126 |                 error = xfs_alloc_read_agf(mp, tp, agno, 0, &agf_bp);
>       |                                            ^~
>       |                                            |
>       |                                            struct xfs_mount *
> In file included from fs/xfs/xfs_notify_failure.c:12:
> fs/xfs/libxfs/xfs_alloc.h:173:42: note: expected 'struct xfs_perag *' but argument is of type 'struct xfs_mount *'
>   173 | int xfs_alloc_read_agf(struct xfs_perag *pag, struct xfs_trans *tp, int flags,
>       |                        ~~~~~~~~~~~~~~~~~~^~~
> fs/xfs/xfs_notify_failure.c:126:25: error: too many arguments to function 'xfs_alloc_read_agf'
>   126 |                 error = xfs_alloc_read_agf(mp, tp, agno, 0, &agf_bp);
>       |                         ^~~~~~~~~~~~~~~~~~
> In file included from fs/xfs/xfs_notify_failure.c:12:
> fs/xfs/libxfs/xfs_alloc.h:173:5: note: declared here
>   173 | int xfs_alloc_read_agf(struct xfs_perag *pag, struct xfs_trans *tp, int flags,
>       |     ^~~~~~~~~~~~~~~~~~
> cc1: all warnings being treated as errors
> 
> Caused by commit
> 
>   469a9c74c119 ("xfs: implement ->notify_failure() for XFS")
> 
> interacting with commit
> 
>   c4829aba9c8d ("xfs: pass perag to xfs_alloc_read_agf()")
> 
> from the xfs tree.
> 
> I have applied the following merge fix patch.
> 
> From: Stephen Rothwell <[email-masked]>
> Date: Fri, 8 Jul 2022 19:11:56 +1000
> Subject: [PATCH] fix up for "xfs: pass perag to xfs_alloc_read_agf()"
> 
> interacting with "xfs: implement ->notify_failure() for XFS"
> 
> Signed-off-by: Stephen Rothwell <[email-masked]>
> ---
>  fs/xfs/xfs_notify_failure.c | 5 ++++-
>  1 file changed, 4 insertions(+), 1 deletion(-)
> 
> diff --git a/fs/xfs/xfs_notify_failure.c b/fs/xfs/xfs_notify_failure.c
> index aa8dc27c599c..f3c62c19475e 100644
> --- a/fs/xfs/xfs_notify_failure.c
> +++ b/fs/xfs/xfs_notify_failure.c
> @@ -18,6 +18,7 @@
>  #include "xfs_rmap_btree.h"
>  #include "xfs_rtalloc.h"
>  #include "xfs_trans.h"
> +#include "xfs_ag.h"
>  
>  #include <linux/mm.h>
>  #include <linux/dax.h>
> @@ -122,8 +123,10 @@ xfs_dax_notify_ddev_failure(
>  		struct failure_info	notify;
>  		struct xfs_agf		*agf;
>  		xfs_agblock_t		agend;
> +		struct xfs_perag	*pag;
>  
> -		error = xfs_alloc_read_agf(mp, tp, agno, 0, &agf_bp);
> +		pag = xfs_perag_get(mp, agno);
> +		error = xfs_alloc_read_agf(pag, tp, 0, &agf_bp);
>  		if (error)
>  			break;

This isn't quite correct -- references to xfs_perag objects must be
released once they are acquired.  The following patch against today's
tree fixes this problem:

diff --git a/fs/xfs/xfs_notify_failure.c b/fs/xfs/xfs_notify_failure.c
index f3c62c19475e..69d9c83ea4b2 100644
--- a/fs/xfs/xfs_notify_failure.c
+++ b/fs/xfs/xfs_notify_failure.c
@@ -127,10 +127,12 @@ xfs_dax_notify_ddev_failure(
 
 		pag = xfs_perag_get(mp, agno);
 		error = xfs_alloc_read_agf(pag, tp, 0, &agf_bp);
-		if (error)
+		if (error) {
+			xfs_perag_put(pag);
 			break;
+		}
 
-		cur = xfs_rmapbt_init_cursor(mp, tp, agf_bp, agf_bp->b_pag);
+		cur = xfs_rmapbt_init_cursor(mp, tp, agf_bp, pag);
 
 		/*
 		 * Set the rmap range from ri_low to ri_high, which represents
@@ -151,6 +153,7 @@ xfs_dax_notify_ddev_failure(
 				xfs_dax_failure_fn, &notify);
 		xfs_btree_del_cursor(cur, error);
 		xfs_trans_brelse(tp, agf_bp);
+		xfs_perag_put(pag);
 		if (error)
 			break;

--D

> -- 
> 2.35.1
> -- 
> Cheers,
> Stephen Rothwell