On Tue, Nov 17, 2020 at 07:14:12PM +0530, 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 35.
>
> With block size of 4k, xattr (with local value) insert operation would
> require in the worst case "XFS_DA_NODE_MAXDEPTH + 1" plus
> "XFS_DA_NODE_MAXDEPTH + (64k / 4k)" (required for guaranteeing removal
> of a maximum sized xattr) number of extents. This evaluates to ~28
> extents. To allow for additions of two or more xattrs during extent
> overflow testing, the pseudo max extent count is set to 35.
>
> 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..989b20977654 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 = 35;
Please add a comment here explaining why 35.
Sorry about the longish review delay, last week was a US holiday and
this week I have eye problems again. :(
--D
> +
> 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,
> };
>
> --
> 2.28.0
>
