xfs: clean up xchk_bmap_check_rmaps usage of XFS_IFORK_Q

XFS_IFORK_Q is supposed to be a predicate, not a function returning a
value.  Its usage is in xchk_bmap_check_rmaps is incorrect, but that
function only cares about whether or not the "size" of the data is zero
or not.  Convert that logic to use a proper boolean, and teach the
caller to skip the call entirely if the end result would be that we'd do
nothing anyway.  This avoids a crash later in this series.

Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
[hch: generalized the NULL ifor check]
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Brian Foster <bfoster@redhat.com>

diff --git a/fs/xfs/scrub/bmap.c b/fs/xfs/scrub/bmap.c
index add8598..93d5b8a 100644 (file)
--- a/fs/xfs/scrub/bmap.c
+++ b/fs/xfs/scrub/bmap.c
@@ -566,8 +566,8 @@ xchk_bmap_check_rmaps(
        struct xfs_scrub        *sc,
        int                     whichfork)
 {
-       loff_t                  size;
        xfs_agnumber_t          agno;
+       bool                    zero_size;
        int                     error;
 
        if (!xfs_sb_version_hasrmapbt(&sc->mp->m_sb) ||
@@ -579,6 +579,8 @@ xchk_bmap_check_rmaps(
        if (XFS_IS_REALTIME_INODE(sc->ip) && whichfork == XFS_DATA_FORK)
                return 0;
 
+       ASSERT(XFS_IFORK_PTR(sc->ip, whichfork) != NULL);
+
        /*
         * Only do this for complex maps that are in btree format, or for
         * situations where we would seem to have a size but zero extents.
@@ -586,19 +588,13 @@ xchk_bmap_check_rmaps(
         * to flag this bmap as corrupt if there are rmaps that need to be
         * reattached.
         */
-       switch (whichfork) {
-       case XFS_DATA_FORK:
-               size = i_size_read(VFS_I(sc->ip));
-               break;
-       case XFS_ATTR_FORK:
-               size = XFS_IFORK_Q(sc->ip);
-               break;
-       default:
-               size = 0;
-               break;
-       }
+       if (whichfork == XFS_DATA_FORK)
+               zero_size = i_size_read(VFS_I(sc->ip)) == 0;
+       else
+               zero_size = false;
+
        if (XFS_IFORK_FORMAT(sc->ip, whichfork) != XFS_DINODE_FMT_BTREE &&
-           (size == 0 || XFS_IFORK_NEXTENTS(sc->ip, whichfork) > 0))
+           (zero_size || XFS_IFORK_NEXTENTS(sc->ip, whichfork) > 0))
                return 0;
 
        for (agno = 0; agno < sc->mp->m_sb.sb_agcount; agno++) {
@@ -627,12 +623,14 @@ xchk_bmap(
        struct xchk_bmap_info   info = { NULL };
        struct xfs_mount        *mp = sc->mp;
        struct xfs_inode        *ip = sc->ip;
-       struct xfs_ifork        *ifp;
+       struct xfs_ifork        *ifp = XFS_IFORK_PTR(ip, whichfork);
        xfs_fileoff_t           endoff;
        struct xfs_iext_cursor  icur;
        int                     error = 0;
 
-       ifp = XFS_IFORK_PTR(ip, whichfork);
+       /* Non-existent forks can be ignored. */
+       if (!ifp)
+               goto out;
 
        info.is_rt = whichfork == XFS_DATA_FORK && XFS_IS_REALTIME_INODE(ip);
        info.whichfork = whichfork;
@@ -641,9 +639,6 @@ xchk_bmap(
 
        switch (whichfork) {
        case XFS_COW_FORK:
-               /* Non-existent CoW forks are ignorable. */
-               if (!ifp)
-                       goto out;
                /* No CoW forks on non-reflink inodes/filesystems. */
                if (!xfs_is_reflink_inode(ip)) {
                        xchk_ino_set_corrupt(sc, sc->ip->i_ino);
@@ -651,8 +646,6 @@ xchk_bmap(
                }
                break;
        case XFS_ATTR_FORK:
-               if (!ifp)
-                       goto out_check_rmap;
                if (!xfs_sb_version_hasattr(&mp->m_sb) &&
                    !xfs_sb_version_hasattr2(&mp->m_sb))
                        xchk_ino_set_corrupt(sc, sc->ip->i_ino);
@@ -717,7 +710,6 @@ xchk_bmap(
                        goto out;
        }
 
-out_check_rmap:
        error = xchk_bmap_check_rmaps(sc, whichfork);
        if (!xchk_fblock_xref_process_error(sc, whichfork, 0, &error))
                goto out;