xfs: use xfs_iext_*_extent helpers in xfs_bmap_shift_extents

This abstracts the function away from details of the low-level extent
list implementation.

Note that it seems like the previous implementation of rmap for
the merge case was completely broken, but it no seems appear to
trigger that.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>

fs/xfs/libxfs/xfs_bmap.c

@@ -5881,32 +5881,26 @@ xfs_bmse_merge(
 	int				whichfork,
 	xfs_fileoff_t			shift,		/* shift fsb */
 	int				current_ext,	/* idx of gotp */
-	struct xfs_bmbt_rec_host	*gotp,		/* extent to shift */
-	struct xfs_bmbt_rec_host	*leftp,		/* preceding extent */
+	struct xfs_bmbt_irec		*got,		/* extent to shift */
+	struct xfs_bmbt_irec		*left,		/* preceding extent */
 	struct xfs_btree_cur		*cur,
-	int				*logflags)	/* output */
+	int				*logflags,	/* output */
+	struct xfs_defer_ops		*dfops)
 {
-	struct xfs_bmbt_irec		got;
-	struct xfs_bmbt_irec		left;
+	struct xfs_ifork		*ifp = XFS_IFORK_PTR(ip, whichfork);
+	struct xfs_bmbt_irec		new;
 	xfs_filblks_t			blockcount;
 	int				error, i;
 	struct xfs_mount		*mp = ip->i_mount;
 
-	xfs_bmbt_get_all(gotp, &got);
-	xfs_bmbt_get_all(leftp, &left);
-	blockcount = left.br_blockcount + got.br_blockcount;
+	blockcount = left->br_blockcount + got->br_blockcount;
 
 	ASSERT(xfs_isilocked(ip, XFS_IOLOCK_EXCL));
 	ASSERT(xfs_isilocked(ip, XFS_ILOCK_EXCL));
-	ASSERT(xfs_bmse_can_merge(&left, &got, shift));
+	ASSERT(xfs_bmse_can_merge(left, got, shift));
 
-	/*
-	 * Merge the in-core extents. Note that the host record pointers and
-	 * current_ext index are invalid once the extent has been removed via
-	 * xfs_iext_remove().
-	 */
-	xfs_bmbt_set_blockcount(leftp, blockcount);
-	xfs_iext_remove(ip, current_ext, 1, 0);
+	new = *left;
+	new.br_blockcount = blockcount;
 
 	/*
 	 * Update the on-disk extent count, the btree if necessary and log the
@@ -5917,12 +5911,12 @@ xfs_bmse_merge(
 	*logflags |= XFS_ILOG_CORE;
 	if (!cur) {
 		*logflags |= XFS_ILOG_DEXT;
-		return 0;
+		goto done;
 	}
 
 	/* lookup and remove the extent to merge */
-	error = xfs_bmbt_lookup_eq(cur, got.br_startoff, got.br_startblock,
-				   got.br_blockcount, &i);
+	error = xfs_bmbt_lookup_eq(cur, got->br_startoff, got->br_startblock,
+				   got->br_blockcount, &i);
 	if (error)
 		return error;
 	XFS_WANT_CORRUPTED_RETURN(mp, i == 1);
@@ -5933,16 +5927,29 @@ xfs_bmse_merge(
 	XFS_WANT_CORRUPTED_RETURN(mp, i == 1);
 
 	/* lookup and update size of the previous extent */
-	error = xfs_bmbt_lookup_eq(cur, left.br_startoff, left.br_startblock,
-				   left.br_blockcount, &i);
+	error = xfs_bmbt_lookup_eq(cur, left->br_startoff, left->br_startblock,
+				   left->br_blockcount, &i);
 	if (error)
 		return error;
 	XFS_WANT_CORRUPTED_RETURN(mp, i == 1);
 
-	left.br_blockcount = blockcount;
+	error = xfs_bmbt_update(cur, new.br_startoff, new.br_startblock,
+			        new.br_blockcount, new.br_state);
+	if (error)
+		return error;
 
-	return xfs_bmbt_update(cur, left.br_startoff, left.br_startblock,
-			       left.br_blockcount, left.br_state);
+done:
+	xfs_iext_update_extent(ifp, current_ext - 1, &new);
+	xfs_iext_remove(ip, current_ext, 1, 0);
+
+	/* update reverse mapping */
+	error = xfs_rmap_unmap_extent(mp, dfops, ip, whichfork, got);
+	if (error)
+		return error;
+	error = xfs_rmap_unmap_extent(mp, dfops, ip, whichfork, left);
+	if (error)
+		return error;
+	return xfs_rmap_map_extent(mp, dfops, ip, whichfork, &new);
 }
 
 /*
@@ -5954,7 +5961,7 @@ xfs_bmse_shift_one(
 	int				whichfork,
 	xfs_fileoff_t			offset_shift_fsb,
 	int				*current_ext,
-	struct xfs_bmbt_rec_host	*gotp,
+	struct xfs_bmbt_irec		*got,
 	struct xfs_btree_cur		*cur,
 	int				*logflags,
 	enum shift_direction		direction,
@@ -5963,9 +5970,7 @@ xfs_bmse_shift_one(
 	struct xfs_ifork		*ifp;
 	struct xfs_mount		*mp;
 	xfs_fileoff_t			startoff;
-	struct xfs_bmbt_rec_host	*adj_irecp;
-	struct xfs_bmbt_irec		got;
-	struct xfs_bmbt_irec		adj_irec;
+	struct xfs_bmbt_irec		adj_irec, new;
 	int				error;
 	int				i;
 	int				total_extents;
@@ -5974,106 +5979,100 @@ xfs_bmse_shift_one(
 	ifp = XFS_IFORK_PTR(ip, whichfork);
 	total_extents = xfs_iext_count(ifp);
 
-	xfs_bmbt_get_all(gotp, &got);
-
 	/* delalloc extents should be prevented by caller */
-	XFS_WANT_CORRUPTED_RETURN(mp, !isnullstartblock(got.br_startblock));
+	XFS_WANT_CORRUPTED_RETURN(mp, !isnullstartblock(got->br_startblock));
 
 	if (direction == SHIFT_LEFT) {
-		startoff = got.br_startoff - offset_shift_fsb;
+		startoff = got->br_startoff - offset_shift_fsb;
 
 		/*
 		 * Check for merge if we've got an extent to the left,
 		 * otherwise make sure there's enough room at the start
 		 * of the file for the shift.
 		 */
 		if (!*current_ext) {
-			if (got.br_startoff < offset_shift_fsb)
+			if (got->br_startoff < offset_shift_fsb)
 				return -EINVAL;
 			goto update_current_ext;
 		}
+
 		/*
-		 * grab the left extent and check for a large
-		 * enough hole.
+		 * grab the left extent and check for a large enough hole.
 		 */
-		adj_irecp = xfs_iext_get_ext(ifp, *current_ext - 1);
-		xfs_bmbt_get_all(adj_irecp, &adj_irec);
-
-		if (startoff <
-		    adj_irec.br_startoff + adj_irec.br_blockcount)
+		xfs_iext_get_extent(ifp, *current_ext - 1, &adj_irec);
+		if (startoff < adj_irec.br_startoff + adj_irec.br_blockcount)
 			return -EINVAL;
 
 		/* check whether to merge the extent or shift it down */
-		if (xfs_bmse_can_merge(&adj_irec, &got,
-				       offset_shift_fsb)) {
-			error = xfs_bmse_merge(ip, whichfork, offset_shift_fsb,
-					       *current_ext, gotp, adj_irecp,
-					       cur, logflags);
-			if (error)
-				return error;
-			adj_irec = got;
-			goto update_rmap;
+		if (xfs_bmse_can_merge(&adj_irec, got, offset_shift_fsb)) {
+			return xfs_bmse_merge(ip, whichfork, offset_shift_fsb,
+					      *current_ext, got, &adj_irec,
+					      cur, logflags, dfops);
 		}
 	} else {
-		startoff = got.br_startoff + offset_shift_fsb;
+		startoff = got->br_startoff + offset_shift_fsb;
 		/* nothing to move if this is the last extent */
 		if (*current_ext >= (total_extents - 1))
 			goto update_current_ext;
+
 		/*
 		 * If this is not the last extent in the file, make sure there
 		 * is enough room between current extent and next extent for
 		 * accommodating the shift.
 		 */
-		adj_irecp = xfs_iext_get_ext(ifp, *current_ext + 1);
-		xfs_bmbt_get_all(adj_irecp, &adj_irec);
-		if (startoff + got.br_blockcount > adj_irec.br_startoff)
+		xfs_iext_get_extent(ifp, *current_ext + 1, &adj_irec);
+		if (startoff + got->br_blockcount > adj_irec.br_startoff)
 			return -EINVAL;
+
 		/*
 		 * Unlike a left shift (which involves a hole punch),
 		 * a right shift does not modify extent neighbors
 		 * in any way. We should never find mergeable extents
 		 * in this scenario. Check anyways and warn if we
 		 * encounter two extents that could be one.
 		 */
-		if (xfs_bmse_can_merge(&got, &adj_irec, offset_shift_fsb))
+		if (xfs_bmse_can_merge(got, &adj_irec, offset_shift_fsb))
 			WARN_ON_ONCE(1);
 	}
+
 	/*
 	 * Increment the extent index for the next iteration, update the start
 	 * offset of the in-core extent and update the btree if applicable.
 	 */
 update_current_ext:
-	if (direction == SHIFT_LEFT)
-		(*current_ext)++;
-	else
-		(*current_ext)--;
-	xfs_bmbt_set_startoff(gotp, startoff);
 	*logflags |= XFS_ILOG_CORE;
-	adj_irec = got;
-	if (!cur) {
+
+	new = *got;
+	new.br_startoff = startoff;
+
+	if (cur) {
+		error = xfs_bmbt_lookup_eq(cur, got->br_startoff,
+				got->br_startblock, got->br_blockcount, &i);
+		if (error)
+			return error;
+		XFS_WANT_CORRUPTED_RETURN(mp, i == 1);
+
+		error = xfs_bmbt_update(cur, new.br_startoff,
+				new.br_startblock, new.br_blockcount,
+				new.br_state);
+		if (error)
+			return error;
+	} else {
 		*logflags |= XFS_ILOG_DEXT;
-		goto update_rmap;
 	}
 
-	error = xfs_bmbt_lookup_eq(cur, got.br_startoff, got.br_startblock,
-				   got.br_blockcount, &i);
-	if (error)
-		return error;
-	XFS_WANT_CORRUPTED_RETURN(mp, i == 1);
+	xfs_iext_update_extent(ifp, *current_ext, &new);
 
-	got.br_startoff = startoff;
-	error = xfs_bmbt_update(cur, got.br_startoff, got.br_startblock,
-			got.br_blockcount, got.br_state);
-	if (error)
-		return error;
+	if (direction == SHIFT_LEFT)
+		(*current_ext)++;
+	else
+		(*current_ext)--;
 
-update_rmap:
 	/* update reverse mapping */
-	error = xfs_rmap_unmap_extent(mp, dfops, ip, whichfork, &adj_irec);
+	error = xfs_rmap_unmap_extent(mp, dfops, ip, whichfork, got);
 	if (error)
 		return error;
-	adj_irec.br_startoff = startoff;
-	return xfs_rmap_map_extent(mp, dfops, ip, whichfork, &adj_irec);
+	return xfs_rmap_map_extent(mp, dfops, ip, whichfork, &new);
 }
 
 /*
@@ -6100,7 +6099,6 @@ xfs_bmap_shift_extents(
 	int			num_exts)
 {
 	struct xfs_btree_cur		*cur = NULL;
-	struct xfs_bmbt_rec_host	*gotp;
 	struct xfs_bmbt_irec            got;
 	struct xfs_mount		*mp = ip->i_mount;
 	struct xfs_ifork		*ifp;
@@ -6161,33 +6159,33 @@ xfs_bmap_shift_extents(
 		ASSERT(direction == SHIFT_RIGHT);
 
 		current_ext = total_extents - 1;
-		gotp = xfs_iext_get_ext(ifp, current_ext);
-		xfs_bmbt_get_all(gotp, &got);
-		*next_fsb = got.br_startoff;
-		if (stop_fsb > *next_fsb) {
+		xfs_iext_get_extent(ifp, current_ext, &got);
+		if (stop_fsb > got.br_startoff) {
 			*done = 1;
 			goto del_cursor;
 		}
+		*next_fsb = got.br_startoff;
 	} else {
 		/*
 		 * Look up the extent index for the fsb where we start shifting. We can
 		 * henceforth iterate with current_ext as extent list changes are locked
 		 * out via ilock.
 		 *
-		 * gotp can be null in 2 cases: 1) if there are no extents or 2)
-		 * *next_fsb lies in a hole beyond which there are no extents. Either
-		 * way, we are done.
+		 * If next_fsb lies in a hole beyond which there are no extents we are
+		 * done.
 		 */
-		gotp = xfs_iext_bno_to_ext(ifp, *next_fsb, &current_ext);
-		if (!gotp) {
+		if (!xfs_iext_lookup_extent(ip, ifp, *next_fsb, &current_ext,
+				&got)) {
 			*done = 1;
 			goto del_cursor;
 		}
 	}
 
 	/* Lookup the extent index at which we have to stop */
 	if (direction == SHIFT_RIGHT) {
-		xfs_iext_bno_to_ext(ifp, stop_fsb, &stop_extent);
+		struct xfs_bmbt_irec s;
+
+		xfs_iext_lookup_extent(ip, ifp, stop_fsb, &stop_extent, &s);
 		/* Make stop_extent exclusive of shift range */
 		stop_extent--;
 		if (current_ext <= stop_extent) {
@@ -6204,7 +6202,7 @@ xfs_bmap_shift_extents(
 
 	while (nexts++ < num_exts) {
 		error = xfs_bmse_shift_one(ip, whichfork, offset_shift_fsb,
-					   &current_ext, gotp, cur, &logflags,
+					   &current_ext, &got, cur, &logflags,
 					   direction, dfops);
 		if (error)
 			goto del_cursor;
@@ -6222,13 +6220,11 @@ xfs_bmap_shift_extents(
 			*next_fsb = NULLFSBLOCK;
 			break;
 		}
-		gotp = xfs_iext_get_ext(ifp, current_ext);
+		xfs_iext_get_extent(ifp, current_ext, &got);
 	}
 
-	if (!*done) {
-		xfs_bmbt_get_all(gotp, &got);
+	if (!*done)
 		*next_fsb = got.br_startoff;
-	}
 
 del_cursor:
 	if (cur)