[v3] ceph: do not print the whole xattr value if it's too long

From: Xiubo Li <xiubli@redhat.com>

If the xattr's value size is long enough the kernel will warn and
then will fail the xfstests test case.

Just print part of the value string if it's too long.

URL: https://tracker.ceph.com/issues/58404
Signed-off-by: Xiubo Li <xiubli@redhat.com>
---

V3:
- s/MAX_XATTR_VAL/MAX_XATTR_VAL_PRINT_LEN/g
- removed the CCing stable mail list


 fs/ceph/xattr.c | 15 +++++++++++----
 1 file changed, 11 insertions(+), 4 deletions(-)

On Thu, Mar 2, 2023 at 4:26 AM <xiubli@redhat.com> wrote:
>
> From: Xiubo Li <xiubli@redhat.com>
>
> If the xattr's value size is long enough the kernel will warn and
> then will fail the xfstests test case.
>
> Just print part of the value string if it's too long.
>
> URL: https://tracker.ceph.com/issues/58404
> Signed-off-by: Xiubo Li <xiubli@redhat.com>
> ---
>
> V3:
> - s/MAX_XATTR_VAL/MAX_XATTR_VAL_PRINT_LEN/g
> - removed the CCing stable mail list
>
>
>  fs/ceph/xattr.c | 15 +++++++++++----
>  1 file changed, 11 insertions(+), 4 deletions(-)
>
> diff --git a/fs/ceph/xattr.c b/fs/ceph/xattr.c
> index b10d459c2326..25a585e63a2d 100644
> --- a/fs/ceph/xattr.c
> +++ b/fs/ceph/xattr.c
> @@ -561,6 +561,8 @@ static struct ceph_vxattr *ceph_match_vxattr(struct inode *inode,
>         return NULL;
>  }
>
> +#define MAX_XATTR_VAL_PRINT_LEN 256
> +
>  static int __set_xattr(struct ceph_inode_info *ci,
>                            const char *name, int name_len,
>                            const char *val, int val_len,
> @@ -654,8 +656,10 @@ static int __set_xattr(struct ceph_inode_info *ci,
>                 dout("__set_xattr_val p=%p\n", p);
>         }
>
> -       dout("__set_xattr_val added %llx.%llx xattr %p %.*s=%.*s\n",
> -            ceph_vinop(&ci->netfs.inode), xattr, name_len, name, val_len, val);
> +       dout("__set_xattr_val added %llx.%llx xattr %p %.*s=%.*s%s\n",

Hi Xiubo,

The function name is incorrect here and above, it should be __set_xattr.

> +            ceph_vinop(&ci->netfs.inode), xattr, name_len, name,
> +            min(val_len, MAX_XATTR_VAL_PRINT_LEN), val,
> +            val_len > MAX_XATTR_VAL_PRINT_LEN ? "..." : "");
>
>         return 0;
>  }
> @@ -681,8 +685,11 @@ static struct ceph_inode_xattr *__get_xattr(struct ceph_inode_info *ci,
>                 else if (c > 0)
>                         p = &(*p)->rb_right;
>                 else {
> -                       dout("__get_xattr %s: found %.*s\n", name,
> -                            xattr->val_len, xattr->val);
> +                       int len = xattr->val_len;
> +
> +                       dout("__get_xattr %s: found %.*s%s\n", name,
> +                            min(len, MAX_XATTR_VAL_PRINT_LEN), xattr->val,
> +                            len > MAX_XATTR_VAL_PRINT_LEN ? "..." : "");

It looks like len variable is introduced just to save a few characters?
If you make it meaningful, dout would actually be more compact:

    int len = min(xattr->val_len, MAX_XATTR_VAL_PRINT_LEN);

    dout("__get_xattr %s: found %.*s%s\n", name, len,
         xattr->val, xattr->val_len > len ? "..." : "");

Thanks,

                Ilya