Re: [PATCH v3 7/9] xfs: use verifier magic field in dir2 leaf verifiers

Darrick J. Wong
2019-02-06T17:45:32Z

On Mon, Feb 04, 2019 at 09:52:29AM -0500, Brian Foster wrote:
> The dir2 leaf verifiers share the same underlying structure
> verification code, but implement six accessor functions to multiplex
> the code across the two verifiers. Further, the magic value isn't
> sufficiently abstracted such that the common helper has to manually
> fix up the magic from the caller on v5 filesystems.
>
> Use the magic field in the verifier structure to eliminate the
> duplicate code and clean this all up. No functional change.
>
> Signed-off-by: Brian Foster <bfoster@redhat.com>
> ---
> fs/xfs/libxfs/xfs_dir2_leaf.c | 88 ++++++++---------------------------
> 1 file changed, 20 insertions(+), 68 deletions(-)
>
> diff --git a/fs/xfs/libxfs/xfs_dir2_leaf.c b/fs/xfs/libxfs/xfs_dir2_leaf.c
> index 1728a3e6f5cf..a99ae2cd292e 100644
> --- a/fs/xfs/libxfs/xfs_dir2_leaf.c
> +++ b/fs/xfs/libxfs/xfs_dir2_leaf.c
> @@ -142,41 +142,32 @@ xfs_dir3_leaf_check_int(
> */
> static xfs_failaddr_t
> xfs_dir3_leaf_verify(
> - struct xfs_buf *bp,
> - uint16_t magic)
> + struct xfs_buf *bp)
> {
> struct xfs_mount *mp = bp->b_target->bt_mount;
> struct xfs_dir2_leaf *leaf = bp->b_addr;
>
> - ASSERT(magic == XFS_DIR2_LEAF1_MAGIC || magic == XFS_DIR2_LEAFN_MAGIC);
> + if (!xfs_verify_magic(bp, leaf->hdr.info.magic))
> + return __this_address;
>
> if (xfs_sb_version_hascrc(&mp->m_sb)) {
> struct xfs_dir3_leaf_hdr *leaf3 = bp->b_addr;
> - uint16_t magic3;
>
> - magic3 = (magic == XFS_DIR2_LEAF1_MAGIC) ? XFS_DIR3_LEAF1_MAGIC
> - : XFS_DIR3_LEAFN_MAGIC;
> -
> - if (leaf3->info.hdr.magic != cpu_to_be16(magic3))
> - return __this_address;
> + ASSERT(leaf3->info.hdr.magic == leaf->hdr.info.magic);

leaf2 and leaf3 directory block headers are supposed to have the magic
at the same offset in the buffer, right? When would this assert fail?

Could we replace this with a BUILD_BUG_ON check of the leaf2/leaf3 magic
number buffer offset in xfs_ondisk.h?

--D

> if (!uuid_equal(&leaf3->info.uuid, &mp->m_sb.sb_meta_uuid))
> return __this_address;
> if (be64_to_cpu(leaf3->info.blkno) != bp->b_bn)
> return __this_address;
> if (!xfs_log_check_lsn(mp, be64_to_cpu(leaf3->info.lsn)))
> return __this_address;
> - } else {
> - if (leaf->hdr.info.magic != cpu_to_be16(magic))
> - return __this_address;
> }
>
> return xfs_dir3_leaf_check_int(mp, NULL, NULL, leaf);
> }
>
> static void
> -__read_verify(
> - struct xfs_buf *bp,
> - uint16_t magic)
> +xfs_dir3_leaf_read_verify(
> + struct xfs_buf *bp)
> {
> struct xfs_mount *mp = bp->b_target->bt_mount;
> xfs_failaddr_t fa;
> @@ -185,23 +176,22 @@ __read_verify(
> !xfs_buf_verify_cksum(bp, XFS_DIR3_LEAF_CRC_OFF))
> xfs_verifier_error(bp, -EFSBADCRC, __this_address);
> else {
> - fa = xfs_dir3_leaf_verify(bp, magic);
> + fa = xfs_dir3_leaf_verify(bp);
> if (fa)
> xfs_verifier_error(bp, -EFSCORRUPTED, fa);
> }
> }
>
> static void
> -__write_verify(
> - struct xfs_buf *bp,
> - uint16_t magic)
> +xfs_dir3_leaf_write_verify(
> + struct xfs_buf *bp)
> {
> struct xfs_mount *mp = bp->b_target->bt_mount;
> struct xfs_buf_log_item *bip = bp->b_log_item;
> struct xfs_dir3_leaf_hdr *hdr3 = bp->b_addr;
> xfs_failaddr_t fa;
>
> - fa = xfs_dir3_leaf_verify(bp, magic);
> + fa = xfs_dir3_leaf_verify(bp);
> if (fa) {
> xfs_verifier_error(bp, -EFSCORRUPTED, fa);
> return;
> @@ -216,60 +206,22 @@ __write_verify(
> xfs_buf_update_cksum(bp, XFS_DIR3_LEAF_CRC_OFF);
> }
>
> -static xfs_failaddr_t
> -xfs_dir3_leaf1_verify(
> - struct xfs_buf *bp)
> -{
> - return xfs_dir3_leaf_verify(bp, XFS_DIR2_LEAF1_MAGIC);
> -}
> -
> -static void
> -xfs_dir3_leaf1_read_verify(
> - struct xfs_buf *bp)
> -{
> - __read_verify(bp, XFS_DIR2_LEAF1_MAGIC);
> -}
> -
> -static void
> -xfs_dir3_leaf1_write_verify(
> - struct xfs_buf *bp)
> -{
> - __write_verify(bp, XFS_DIR2_LEAF1_MAGIC);
> -}
> -
> -static xfs_failaddr_t
> -xfs_dir3_leafn_verify(
> - struct xfs_buf *bp)
> -{
> - return xfs_dir3_leaf_verify(bp, XFS_DIR2_LEAFN_MAGIC);
> -}
> -
> -static void
> -xfs_dir3_leafn_read_verify(
> - struct xfs_buf *bp)
> -{
> - __read_verify(bp, XFS_DIR2_LEAFN_MAGIC);
> -}
> -
> -static void
> -xfs_dir3_leafn_write_verify(
> - struct xfs_buf *bp)
> -{
> - __write_verify(bp, XFS_DIR2_LEAFN_MAGIC);
> -}
> -
> const struct xfs_buf_ops xfs_dir3_leaf1_buf_ops = {
> .name = "xfs_dir3_leaf1",
> - .verify_read = xfs_dir3_leaf1_read_verify,
> - .verify_write = xfs_dir3_leaf1_write_verify,
> - .verify_struct = xfs_dir3_leaf1_verify,
> + .magic = { cpu_to_be16(XFS_DIR2_LEAF1_MAGIC),
> + cpu_to_be16(XFS_DIR3_LEAF1_MAGIC) },
> + .verify_read = xfs_dir3_leaf_read_verify,
> + .verify_write = xfs_dir3_leaf_write_verify,
> + .verify_struct = xfs_dir3_leaf_verify,
> };
>
> const struct xfs_buf_ops xfs_dir3_leafn_buf_ops = {
> .name = "xfs_dir3_leafn",
> - .verify_read = xfs_dir3_leafn_read_verify,
> - .verify_write = xfs_dir3_leafn_write_verify,
> - .verify_struct = xfs_dir3_leafn_verify,
> + .magic = { cpu_to_be16(XFS_DIR2_LEAFN_MAGIC),
> + cpu_to_be16(XFS_DIR3_LEAFN_MAGIC) },
> + .verify_read = xfs_dir3_leaf_read_verify,
> + .verify_write = xfs_dir3_leaf_write_verify,
> + .verify_struct = xfs_dir3_leaf_verify,
> };
>
> int
> --
> 2.17.2
>