xfs: remove unnecessary dstmap in xattr scrubber

Replace bitmap_and with bitmap_intersects in the xattr leaf block
scrubber, since we only care if there's overlap between the used space
bitmap and the free space bitmap.  This means we don't need dstmap any
more, and can thus reduce the memory requirements.

Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Dave Chinner <dchinner@redhat.com>

Author: Darrick J. Wong

fs/xfs/scrub/attr.c

@@ -36,10 +36,10 @@ xchk_setup_xattr_buf(
 
 	/*
 	 * We need enough space to read an xattr value from the file or enough
-	 * space to hold three copies of the xattr free space bitmap.  We don't
+	 * space to hold two copies of the xattr free space bitmap.  We don't
 	 * need the buffer space for both purposes at the same time.
 	 */
-	sz = 3 * sizeof(long) * BITS_TO_LONGS(sc->mp->m_attr_geo->blksize);
+	sz = 2 * sizeof(long) * BITS_TO_LONGS(sc->mp->m_attr_geo->blksize);
 	sz = max_t(size_t, sz, value_size);
 
 	/*
@@ -223,7 +223,6 @@ xchk_xattr_check_freemap(
 	struct xfs_attr3_icleaf_hdr	*leafhdr)
 {
 	unsigned long			*freemap = xchk_xattr_freemap(sc);
-	unsigned long			*dstmap = xchk_xattr_dstmap(sc);
 	unsigned int			mapsize = sc->mp->m_attr_geo->blksize;
 	int				i;
 
@@ -237,7 +236,7 @@ xchk_xattr_check_freemap(
 	}
 
 	/* Look for bits that are set in freemap and are marked in use. */
-	return bitmap_and(dstmap, freemap, map, mapsize) == 0;
+	return !bitmap_intersects(freemap, map, mapsize);
 }
 
 /*

fs/xfs/scrub/attr.h

@@ -21,8 +21,7 @@ struct xchk_xattr_buf {
 	 * Each bitmap contains enough bits to track every byte in an attr
 	 * block (rounded up to the size of an unsigned long).  The attr block
 	 * used space bitmap starts at the beginning of the buffer; the free
-	 * space bitmap follows immediately after; and we have a third buffer
-	 * for storing intermediate bitmap results.
+	 * space bitmap follows immediately after.
 	 */
 	uint8_t			buf[];
 };
@@ -56,13 +55,4 @@ xchk_xattr_freemap(
 			BITS_TO_LONGS(sc->mp->m_attr_geo->blksize);
 }
 
-/* A bitmap used to hold temporary results. */
-static inline unsigned long *
-xchk_xattr_dstmap(
-	struct xfs_scrub	*sc)
-{
-	return xchk_xattr_freemap(sc) +
-			BITS_TO_LONGS(sc->mp->m_attr_geo->blksize);
-}
-
 #endif	/* __XFS_SCRUB_ATTR_H__ */