[PATCH] xfs: set xefi_discard when creating a deferred agfl free log intent item

[PATCH] xfs: set xefi_discard when creating a deferred agfl free log intent item

[Darrick J. Wong]

From: Darrick J. Wong <darrick.wong@oracle.com>

Make sure that we actually initialize xefi_discard when we're scheduling
a deferred free of an AGFL block.  This was (eventually) found by the
UBSAN while I was banging on realtime rmap problems, but it exists in
the upstream codebase.  While we're at it, rearrange the structure to
reduce the struct size from 64 to 56 bytes.

Fixes: fcb762f5de2e ("xfs: add bmapi nodiscard flag")
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
---
 fs/xfs/libxfs/xfs_alloc.c |    1 +
 fs/xfs/libxfs/xfs_bmap.h  |    2 +-
 2 files changed, 2 insertions(+), 1 deletion(-)

diff --git a/fs/xfs/libxfs/xfs_alloc.c b/fs/xfs/libxfs/xfs_alloc.c
index 852b536551b5..15640015be9d 100644
--- a/fs/xfs/libxfs/xfs_alloc.c
+++ b/fs/xfs/libxfs/xfs_alloc.c
@@ -2467,6 +2467,7 @@ xfs_defer_agfl_block(
 	new->xefi_startblock = XFS_AGB_TO_FSB(mp, agno, agbno);
 	new->xefi_blockcount = 1;
 	new->xefi_oinfo = *oinfo;
+	new->xefi_skip_discard = false;
 
 	trace_xfs_agfl_free_defer(mp, agno, 0, agbno, 1);
 
diff --git a/fs/xfs/libxfs/xfs_bmap.h b/fs/xfs/libxfs/xfs_bmap.h
index e1bd484e5548..6747e97a7949 100644
--- a/fs/xfs/libxfs/xfs_bmap.h
+++ b/fs/xfs/libxfs/xfs_bmap.h
@@ -52,9 +52,9 @@ struct xfs_extent_free_item
 {
 	xfs_fsblock_t		xefi_startblock;/* starting fs block number */
 	xfs_extlen_t		xefi_blockcount;/* number of blocks in extent */
+	bool			xefi_skip_discard;
 	struct list_head	xefi_list;
 	struct xfs_owner_info	xefi_oinfo;	/* extent owner */
-	bool			xefi_skip_discard;
 };
 
 #define	XFS_BMAP_MAX_NMAP	4

Re: [PATCH] xfs: set xefi_discard when creating a deferred agfl free log intent item

[Brian Foster]

On Thu, Oct 22, 2020 at 11:46:49AM -0700, Darrick J. Wong wrote:
> From: Darrick J. Wong <darrick.wong@oracle.com>
> 
> Make sure that we actually initialize xefi_discard when we're scheduling
> a deferred free of an AGFL block.  This was (eventually) found by the
> UBSAN while I was banging on realtime rmap problems, but it exists in
> the upstream codebase.  While we're at it, rearrange the structure to
> reduce the struct size from 64 to 56 bytes.
> 
> Fixes: fcb762f5de2e ("xfs: add bmapi nodiscard flag")
> Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
> ---

Reviewed-by: Brian Foster <bfoster@redhat.com>

>  fs/xfs/libxfs/xfs_alloc.c |    1 +
>  fs/xfs/libxfs/xfs_bmap.h  |    2 +-
>  2 files changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/fs/xfs/libxfs/xfs_alloc.c b/fs/xfs/libxfs/xfs_alloc.c
> index 852b536551b5..15640015be9d 100644
> --- a/fs/xfs/libxfs/xfs_alloc.c
> +++ b/fs/xfs/libxfs/xfs_alloc.c
> @@ -2467,6 +2467,7 @@ xfs_defer_agfl_block(
>  	new->xefi_startblock = XFS_AGB_TO_FSB(mp, agno, agbno);
>  	new->xefi_blockcount = 1;
>  	new->xefi_oinfo = *oinfo;
> +	new->xefi_skip_discard = false;
>  
>  	trace_xfs_agfl_free_defer(mp, agno, 0, agbno, 1);
>  
> diff --git a/fs/xfs/libxfs/xfs_bmap.h b/fs/xfs/libxfs/xfs_bmap.h
> index e1bd484e5548..6747e97a7949 100644
> --- a/fs/xfs/libxfs/xfs_bmap.h
> +++ b/fs/xfs/libxfs/xfs_bmap.h
> @@ -52,9 +52,9 @@ struct xfs_extent_free_item
>  {
>  	xfs_fsblock_t		xefi_startblock;/* starting fs block number */
>  	xfs_extlen_t		xefi_blockcount;/* number of blocks in extent */
> +	bool			xefi_skip_discard;
>  	struct list_head	xefi_list;
>  	struct xfs_owner_info	xefi_oinfo;	/* extent owner */
> -	bool			xefi_skip_discard;
>  };
>  
>  #define	XFS_BMAP_MAX_NMAP	4
>