Commit 1c1646af authored by Darrick J. Wong's avatar Darrick J. Wong
Browse files

xfs: check for reverse mapping records that could be merged 



Enhance the rmap scrubber to flag adjacent records that could be merged.

Signed-off-by: default avatarDarrick J. Wong <djwong@kernel.org>
Reviewed-by: default avatarDave Chinner <dchinner@redhat.com>
parent 29ab991b

fs/xfs/scrub/rmap.c

+52 −0
Original line number Diff line number Diff line
@@ -39,6 +39,12 @@ struct xchk_rmap { 
	 * allocations that cannot be shared.

	 */

	struct xfs_rmap_irec	overlap_rec;



	/*

	 * The previous rmapbt record, so that we can check for two records

	 * that could be one.

	 */

	struct xfs_rmap_irec	prev_rec;

};



/* Cross-reference a rmap against the refcount btree. */
@@ -198,6 +204,51 @@ xchk_rmapbt_check_overlapping( 
	memcpy(&cr->overlap_rec, irec, sizeof(struct xfs_rmap_irec));

}



/* Decide if two reverse-mapping records can be merged. */

static inline bool

xchk_rmap_mergeable(

	struct xchk_rmap		*cr,

	const struct xfs_rmap_irec	*r2)

{

	const struct xfs_rmap_irec	*r1 = &cr->prev_rec;



	/* Ignore if prev_rec is not yet initialized. */

	if (cr->prev_rec.rm_blockcount == 0)

		return false;



	if (r1->rm_owner != r2->rm_owner)

		return false;

	if (r1->rm_startblock + r1->rm_blockcount != r2->rm_startblock)

		return false;

	if ((unsigned long long)r1->rm_blockcount + r2->rm_blockcount >

	    XFS_RMAP_LEN_MAX)

		return false;

	if (XFS_RMAP_NON_INODE_OWNER(r2->rm_owner))

		return true;

	/* must be an inode owner below here */

	if (r1->rm_flags != r2->rm_flags)

		return false;

	if (r1->rm_flags & XFS_RMAP_BMBT_BLOCK)

		return true;

	return r1->rm_offset + r1->rm_blockcount == r2->rm_offset;

}



/* Flag failures for records that could be merged. */

STATIC void

xchk_rmapbt_check_mergeable(

	struct xchk_btree		*bs,

	struct xchk_rmap		*cr,

	const struct xfs_rmap_irec	*irec)

{

	if (bs->sc->sm->sm_flags & XFS_SCRUB_OFLAG_CORRUPT)

		return;



	if (xchk_rmap_mergeable(cr, irec))

		xchk_btree_set_corrupt(bs->sc, bs->cur, 0);



	memcpy(&cr->prev_rec, irec, sizeof(struct xfs_rmap_irec));

}



/* Scrub an rmapbt record. */

STATIC int

xchk_rmapbt_rec(
@@ -214,6 +265,7 @@ xchk_rmapbt_rec( 
	}



	xchk_rmapbt_check_unwritten_in_keyflags(bs);

	xchk_rmapbt_check_mergeable(bs, cr, &irec);

	xchk_rmapbt_check_overlapping(bs, cr, &irec);

	xchk_rmapbt_xref(bs->sc, &irec);

	return 0;