1 files changed, 84 insertions, 91 deletions

diff --git a/fs/xfs/scrub/cow_repair.c b/fs/xfs/scrub/cow_repair.c
index 0075b6d5a1b5..8dd9c0266e21 100644
--- a/fs/xfs/scrub/cow_repair.c
+++ b/fs/xfs/scrub/cow_repair.c
@@ -29,6 +29,7 @@
 #include "xfs_rtalloc.h"
 #include "xfs_rtbitmap.h"
 #include "xfs_rtgroup.h"
+#include "xfs_bmap_util.h"
 #include "scrub/xfs_scrub.h"
 #include "scrub/scrub.h"
 #include "scrub/common.h"
@@ -80,12 +81,6 @@ struct xrep_cow {
 	unsigned int		next_bno;
 };
 
-/* CoW staging extent. */
-struct xrep_cow_extent {
-	xfs_fsblock_t		fsbno;
-	xfs_extlen_t		len;
-};
-
 /*
  * Mark the part of the file range that corresponds to the given physical
  * space.  Caller must ensure that the physical range is within xc->irec.
@@ -231,6 +226,29 @@ xrep_cow_mark_missing_staging_rmap(
 }
 
 /*
+ * Trim the start and end of the current mapping by up to 1/4 of the length
+ * and mark that as "bad" to test the cow fork repair mechanism.
+ */
+static inline int
+xrep_cow_debug_replacement(
+	struct xrep_cow		*xc)
+{
+	xfs_fsblock_t		fsbno = xc->irec.br_startblock;
+	xfs_extlen_t		len = xc->irec.br_blockcount;
+	uint32_t		trim;
+
+	/* get_random_u32_below requires a nonzero argument */
+	trim = len > 4 ? get_random_u32_below(len / 4) : 0;
+	len -= trim;
+
+	trim = len > 4 ? get_random_u32_below(len / 4) : 0;
+	fsbno += trim;
+	len -= trim;
+
+	return xrep_cow_mark_file_range(xc, fsbno, len);
+}
+
+/*
  * Find any part of the CoW fork mapping that isn't a single-owner CoW staging
  * extent and mark the corresponding part of the file range in the bitmap.
  */
@@ -299,8 +317,9 @@ xrep_cow_find_bad(
 	 * If userspace is forcing us to rebuild the CoW fork or someone turned
 	 * on the debugging knob, replace everything in the CoW fork.
 	 */
-	if ((sc->sm->sm_flags & XFS_SCRUB_IFLAG_FORCE_REBUILD) ||
-	    XFS_TEST_ERROR(sc->mp, XFS_ERRTAG_FORCE_SCRUB_REPAIR))
+	if (XFS_TEST_ERROR(sc->mp, XFS_ERRTAG_FORCE_SCRUB_REPAIR))
+		error = xrep_cow_debug_replacement(xc);
+	else if (sc->sm->sm_flags & XFS_SCRUB_IFLAG_FORCE_REBUILD)
 		error = xrep_cow_mark_file_range(xc, xc->irec.br_startblock,
 				xc->irec.br_blockcount);
 
@@ -381,8 +400,9 @@ xrep_cow_find_bad_rt(
 	 * turned on the debugging knob, replace everything in the
 	 * CoW fork and then scan for staging extents in the refcountbt.
 	 */
-	if ((sc->sm->sm_flags & XFS_SCRUB_IFLAG_FORCE_REBUILD) ||
-	    XFS_TEST_ERROR(sc->mp, XFS_ERRTAG_FORCE_SCRUB_REPAIR))
+	if (XFS_TEST_ERROR(sc->mp, XFS_ERRTAG_FORCE_SCRUB_REPAIR))
+		error = xrep_cow_debug_replacement(xc);
+	else if (sc->sm->sm_flags & XFS_SCRUB_IFLAG_FORCE_REBUILD)
 		error = xrep_cow_mark_file_range(xc, xc->irec.br_startblock,
 				xc->irec.br_blockcount);
 
@@ -401,22 +421,21 @@ out_rtg:
 STATIC int
 xrep_cow_alloc(
 	struct xfs_scrub	*sc,
-	xfs_extlen_t		maxlen,
-	struct xrep_cow_extent	*repl)
+	struct xfs_bmbt_irec	*del)
 {
 	struct xfs_alloc_arg	args = {
 		.tp		= sc->tp,
 		.mp		= sc->mp,
 		.oinfo		= XFS_RMAP_OINFO_SKIP_UPDATE,
 		.minlen		= 1,
-		.maxlen		= maxlen,
+		.maxlen		= del->br_blockcount,
 		.prod		= 1,
 		.resv		= XFS_AG_RESV_NONE,
 		.datatype	= XFS_ALLOC_USERDATA,
 	};
 	int			error;
 
-	error = xfs_trans_reserve_more(sc->tp, maxlen, 0);
+	error = xfs_trans_reserve_more(sc->tp, del->br_blockcount, 0);
 	if (error)
 		return error;
 
@@ -428,8 +447,8 @@ xrep_cow_alloc(
 
 	xfs_refcount_alloc_cow_extent(sc->tp, false, args.fsbno, args.len);
 
-	repl->fsbno = args.fsbno;
-	repl->len = args.len;
+	del->br_startblock = args.fsbno;
+	del->br_blockcount = args.len;
 	return 0;
 }
 
@@ -440,10 +459,12 @@ xrep_cow_alloc(
 STATIC int
 xrep_cow_alloc_rt(
 	struct xfs_scrub	*sc,
-	xfs_extlen_t		maxlen,
-	struct xrep_cow_extent	*repl)
+	struct xfs_bmbt_irec	*del)
 {
-	xfs_rtxlen_t		maxrtx = xfs_rtb_to_rtx(sc->mp, maxlen);
+	xfs_fsblock_t		fsbno;
+	xfs_rtxlen_t		maxrtx =
+		min(U32_MAX, xfs_blen_to_rtbxlen(sc->mp, del->br_blockcount));
+	xfs_extlen_t		len;
 	int			error;
 
 	error = xfs_trans_reserve_more(sc->tp, 0, maxrtx);
@@ -451,11 +472,14 @@ xrep_cow_alloc_rt(
 		return error;
 
 	error = xfs_rtallocate_rtgs(sc->tp, NULLRTBLOCK, 1, maxrtx, 1, false,
-			false, &repl->fsbno, &repl->len);
+			false, &fsbno, &len);
 	if (error)
 		return error;
 
-	xfs_refcount_alloc_cow_extent(sc->tp, true, repl->fsbno, repl->len);
+	xfs_refcount_alloc_cow_extent(sc->tp, true, fsbno, len);
+
+	del->br_startblock = fsbno;
+	del->br_blockcount = len;
 	return 0;
 }
 
@@ -469,19 +493,19 @@ static inline int
 xrep_cow_find_mapping(
 	struct xrep_cow		*xc,
 	struct xfs_iext_cursor	*icur,
-	xfs_fileoff_t		startoff,
-	struct xfs_bmbt_irec	*got)
+	xfs_fileoff_t		badoff,
+	xfs_extlen_t		badlen,
+	struct xfs_bmbt_irec	*got,
+	struct xfs_bmbt_irec	*rep)
 {
 	struct xfs_inode	*ip = xc->sc->ip;
 	struct xfs_ifork	*ifp = xfs_ifork_ptr(ip, XFS_COW_FORK);
 
-	if (!xfs_iext_lookup_extent(ip, ifp, startoff, icur, got))
+	if (!xfs_iext_lookup_extent(ip, ifp, badoff, icur, got))
 		goto bad;
+	memcpy(rep, got, sizeof(*rep));
 
-	if (got->br_startoff > startoff)
-		goto bad;
-
-	if (got->br_blockcount == 0)
+	if (got->br_startoff > badoff)
 		goto bad;
 
 	if (isnullstartblock(got->br_startblock))
@@ -490,56 +514,28 @@ xrep_cow_find_mapping(
 	if (xfs_bmap_is_written_extent(got))
 		goto bad;
 
-	return 0;
-bad:
-	ASSERT(0);
-	return -EFSCORRUPTED;
-}
-
-#define REPLACE_LEFT_SIDE	(1U << 0)
-#define REPLACE_RIGHT_SIDE	(1U << 1)
+	if (got->br_startoff < badoff) {
+		const int64_t	delta = badoff - got->br_startoff;
 
-/*
- * Given a CoW fork mapping @got and a replacement mapping @repl, remap the
- * beginning of @got with the space described by @rep.
- */
-static inline void
-xrep_cow_replace_mapping(
-	struct xfs_inode		*ip,
-	struct xfs_iext_cursor		*icur,
-	const struct xfs_bmbt_irec	*got,
-	const struct xrep_cow_extent	*repl)
-{
-	struct xfs_bmbt_irec		new = *got; /* struct copy */
-
-	ASSERT(repl->len > 0);
-	ASSERT(!isnullstartblock(got->br_startblock));
+		rep->br_blockcount -= delta;
+		rep->br_startoff += delta;
+		rep->br_startblock += delta;
+	}
 
-	trace_xrep_cow_replace_mapping(ip, got, repl->fsbno, repl->len);
+	if (got->br_startoff + got->br_blockcount > badoff + badlen) {
+		const int64_t	delta = (got->br_startoff + got->br_blockcount) -
+					(badoff + badlen);
 
-	if (got->br_blockcount == repl->len) {
-		/*
-		 * The new extent is a complete replacement for the existing
-		 * extent.  Update the COW fork record.
-		 */
-		new.br_startblock = repl->fsbno;
-		xfs_iext_update_extent(ip, BMAP_COWFORK, icur, &new);
-		return;
+		rep->br_blockcount -= delta;
 	}
 
-	/*
-	 * The new extent can replace the beginning of the COW fork record.
-	 * Move the left side of @got upwards, then insert the new record.
-	 */
-	new.br_startoff += repl->len;
-	new.br_startblock += repl->len;
-	new.br_blockcount -= repl->len;
-	xfs_iext_update_extent(ip, BMAP_COWFORK, icur, &new);
+	if (got->br_blockcount == 0)
+		goto bad;
 
-	new.br_startoff = got->br_startoff;
-	new.br_startblock = repl->fsbno;
-	new.br_blockcount = repl->len;
-	xfs_iext_insert(ip, icur, &new, BMAP_COWFORK);
+	return 0;
+bad:
+	ASSERT(0);
+	return -EFSCORRUPTED;
 }
 
 /*
@@ -553,33 +549,30 @@ xrep_cow_replace_range(
 	xfs_extlen_t		*blockcount)
 {
 	struct xfs_iext_cursor	icur;
-	struct xrep_cow_extent	repl;
-	struct xfs_bmbt_irec	got;
+	struct xfs_bmbt_irec	got, rep;
 	struct xfs_scrub	*sc = xc->sc;
-	xfs_fileoff_t		nextoff;
-	xfs_extlen_t		alloc_len;
+	xfs_fsblock_t		old_fsbno;
 	int			error;
 
 	/*
-	 * Put the existing CoW fork mapping in @got.  If @got ends before
-	 * @rep, truncate @rep so we only replace one extent mapping at a time.
+	 * Put the existing CoW fork mapping in @got, and put in @rep the
+	 * contents of @got trimmed to @startoff/@blockcount.  We only want
+	 * to replace the bad region, and only one mapping at a time.
 	 */
-	error = xrep_cow_find_mapping(xc, &icur, startoff, &got);
+	error = xrep_cow_find_mapping(xc, &icur, startoff, *blockcount, &got,
+			&rep);
 	if (error)
 		return error;
-	nextoff = min(startoff + *blockcount,
-		      got.br_startoff + got.br_blockcount);
+	old_fsbno = rep.br_startblock;
 
 	/*
 	 * Allocate a replacement extent.  If we don't fill all the blocks,
 	 * shorten the quantity that will be deleted in this step.
 	 */
-	alloc_len = min_t(xfs_fileoff_t, XFS_MAX_BMBT_EXTLEN,
-			  nextoff - startoff);
 	if (XFS_IS_REALTIME_INODE(sc->ip))
-		error = xrep_cow_alloc_rt(sc, alloc_len, &repl);
+		error = xrep_cow_alloc_rt(sc, &rep);
 	else
-		error = xrep_cow_alloc(sc, alloc_len, &repl);
+		error = xrep_cow_alloc(sc, &rep);
 	if (error)
 		return error;
 
@@ -587,7 +580,7 @@ xrep_cow_replace_range(
 	 * Replace the old mapping with the new one, and commit the metadata
 	 * changes made so far.
 	 */
-	xrep_cow_replace_mapping(sc->ip, &icur, &got, &repl);
+	xfs_bmap_replace_cow_mapping(sc->ip, &icur, &got, &rep);
 
 	xfs_inode_set_cowblocks_tag(sc->ip);
 	error = xfs_defer_finish(&sc->tp);
@@ -596,15 +589,15 @@ xrep_cow_replace_range(
 
 	/* Note the old CoW staging extents; we'll reap them all later. */
 	if (XFS_IS_REALTIME_INODE(sc->ip))
-		error = xrtb_bitmap_set(&xc->old_cowfork_rtblocks,
-				got.br_startblock, repl.len);
+		error = xrtb_bitmap_set(&xc->old_cowfork_rtblocks, old_fsbno,
+				rep.br_blockcount);
 	else
-		error = xfsb_bitmap_set(&xc->old_cowfork_fsblocks,
-				got.br_startblock, repl.len);
+		error = xfsb_bitmap_set(&xc->old_cowfork_fsblocks, old_fsbno,
+				rep.br_blockcount);
 	if (error)
 		return error;
 
-	*blockcount = repl.len;
+	*blockcount = rep.br_blockcount;
 	return 0;
 }