Re: [PATCH V7 10/14] xfs: Introduce error injection to reduce maximum inode fork extent count

[Allison Henderson <allison.henderson@xxxxxxxxxx>]

On 10/18/20 11:40 PM, Chandan Babu R wrote:
> This commit adds XFS_ERRTAG_REDUCE_MAX_IEXTENTS error tag which enables
> userspace programs to test "Inode fork extent count overflow detection"
> by reducing maximum possible inode fork extent count to 10.
Ok, makes sense
Reviewed-by: Allison Henderson <allison.henderson@xxxxxxxxxx>

> Reviewed-by: Darrick J. Wong <darrick.wong@xxxxxxxxxx>
> Reviewed-by: Christoph Hellwig <hch@xxxxxx>
> Signed-off-by: Chandan Babu R <chandanrlinux@xxxxxxxxx>
> ---
>   fs/xfs/libxfs/xfs_errortag.h   | 4 +++-
>   fs/xfs/libxfs/xfs_inode_fork.c | 4 ++++
>   fs/xfs/xfs_error.c             | 3 +++
>   3 files changed, 10 insertions(+), 1 deletion(-)
>
> diff --git a/fs/xfs/libxfs/xfs_errortag.h b/fs/xfs/libxfs/xfs_errortag.h
> index 53b305dea381..1c56fcceeea6 100644
> --- a/fs/xfs/libxfs/xfs_errortag.h
> +++ b/fs/xfs/libxfs/xfs_errortag.h
> @@ -56,7 +56,8 @@
>   #define XFS_ERRTAG_FORCE_SUMMARY_RECALC			33
>   #define XFS_ERRTAG_IUNLINK_FALLBACK			34
>   #define XFS_ERRTAG_BUF_IOERROR				35
> -#define XFS_ERRTAG_MAX					36
> +#define XFS_ERRTAG_REDUCE_MAX_IEXTENTS			36
> +#define XFS_ERRTAG_MAX					37
>   
>   /*
>    * Random factors for above tags, 1 means always, 2 means 1/2 time, etc.
> @@ -97,5 +98,6 @@
>   #define XFS_RANDOM_FORCE_SUMMARY_RECALC			1
>   #define XFS_RANDOM_IUNLINK_FALLBACK			(XFS_RANDOM_DEFAULT/10)
>   #define XFS_RANDOM_BUF_IOERROR				XFS_RANDOM_DEFAULT
> +#define XFS_RANDOM_REDUCE_MAX_IEXTENTS			1
>   
>   #endif /* __XFS_ERRORTAG_H_ */
> diff --git a/fs/xfs/libxfs/xfs_inode_fork.c b/fs/xfs/libxfs/xfs_inode_fork.c
> index 8d48716547e5..e080d7e07643 100644
> --- a/fs/xfs/libxfs/xfs_inode_fork.c
> +++ b/fs/xfs/libxfs/xfs_inode_fork.c
> @@ -24,6 +24,7 @@
>   #include "xfs_dir2_priv.h"
>   #include "xfs_attr_leaf.h"
>   #include "xfs_types.h"
> +#include "xfs_errortag.h"
>   
>   kmem_zone_t *xfs_ifork_zone;
>   
> @@ -745,6 +746,9 @@ xfs_iext_count_may_overflow(
>   
>   	max_exts = (whichfork == XFS_ATTR_FORK) ? MAXAEXTNUM : MAXEXTNUM;
>   
> +	if (XFS_TEST_ERROR(false, ip->i_mount, XFS_ERRTAG_REDUCE_MAX_IEXTENTS))
> +		max_exts = 10;
> +
>   	nr_exts = ifp->if_nextents + nr_to_add;
>   	if (nr_exts < ifp->if_nextents || nr_exts > max_exts)
>   		return -EFBIG;
> diff --git a/fs/xfs/xfs_error.c b/fs/xfs/xfs_error.c
> index 7f6e20899473..3780b118cc47 100644
> --- a/fs/xfs/xfs_error.c
> +++ b/fs/xfs/xfs_error.c
> @@ -54,6 +54,7 @@ static unsigned int xfs_errortag_random_default[] = {
>   	XFS_RANDOM_FORCE_SUMMARY_RECALC,
>   	XFS_RANDOM_IUNLINK_FALLBACK,
>   	XFS_RANDOM_BUF_IOERROR,
> +	XFS_RANDOM_REDUCE_MAX_IEXTENTS,
>   };
>   
>   struct xfs_errortag_attr {
> @@ -164,6 +165,7 @@ XFS_ERRORTAG_ATTR_RW(force_repair,	XFS_ERRTAG_FORCE_SCRUB_REPAIR);
>   XFS_ERRORTAG_ATTR_RW(bad_summary,	XFS_ERRTAG_FORCE_SUMMARY_RECALC);
>   XFS_ERRORTAG_ATTR_RW(iunlink_fallback,	XFS_ERRTAG_IUNLINK_FALLBACK);
>   XFS_ERRORTAG_ATTR_RW(buf_ioerror,	XFS_ERRTAG_BUF_IOERROR);
> +XFS_ERRORTAG_ATTR_RW(reduce_max_iextents,	XFS_ERRTAG_REDUCE_MAX_IEXTENTS);
>   
>   static struct attribute *xfs_errortag_attrs[] = {
>   	XFS_ERRORTAG_ATTR_LIST(noerror),
> @@ -202,6 +204,7 @@ static struct attribute *xfs_errortag_attrs[] = {
>   	XFS_ERRORTAG_ATTR_LIST(bad_summary),
>   	XFS_ERRORTAG_ATTR_LIST(iunlink_fallback),
>   	XFS_ERRORTAG_ATTR_LIST(buf_ioerror),
> +	XFS_ERRORTAG_ATTR_LIST(reduce_max_iextents),
>   	NULL,
>   };
>