[PATCH 19/43] xfs: enable CoW for realtime data

["Darrick J. Wong" <djwong@xxxxxxxxxx>]

From: Darrick J. Wong <djwong@xxxxxxxxxx>

Update our write paths to support copy on write on the rt volume.  This
works in more or less the same way as it does on the data device, with
the major exception that we never do delalloc on the rt volume.

Because we consider unwritten CoW fork staging extents to be incore
quota reservation, we update xfs_quota_reserve_blkres to support this
case.  Though xfs doesn't allow rt and quota together, the change is
trivial and we shouldn't leave a logic bomb here.

Signed-off-by: "Darrick J. Wong" <djwong@xxxxxxxxxx>
---
 fs/xfs/xfs_reflink.c |   36 ++++++++++++++++++++++++++++--------
 1 file changed, 28 insertions(+), 8 deletions(-)


diff --git a/fs/xfs/xfs_reflink.c b/fs/xfs/xfs_reflink.c
index 29574b015fddc0..24f545687b8730 100644
--- a/fs/xfs/xfs_reflink.c
+++ b/fs/xfs/xfs_reflink.c
@@ -439,20 +439,26 @@ xfs_reflink_fill_cow_hole(
 	struct xfs_mount	*mp = ip->i_mount;
 	struct xfs_trans	*tp;
 	xfs_filblks_t		resaligned;
-	xfs_extlen_t		resblks;
+	unsigned int		dblocks = 0, rblocks = 0;
 	int			nimaps;
 	int			error;
 	bool			found;
 
 	resaligned = xfs_aligned_fsb_count(imap->br_startoff,
 		imap->br_blockcount, xfs_get_cowextsz_hint(ip));
-	resblks = XFS_DIOSTRAT_SPACE_RES(mp, resaligned);
+	if (XFS_IS_REALTIME_INODE(ip)) {
+		dblocks = XFS_DIOSTRAT_SPACE_RES(mp, 0);
+		rblocks = resaligned;
+	} else {
+		dblocks = XFS_DIOSTRAT_SPACE_RES(mp, resaligned);
+		rblocks = 0;
+	}
 
 	xfs_iunlock(ip, *lockmode);
 	*lockmode = 0;
 
-	error = xfs_trans_alloc_inode(ip, &M_RES(mp)->tr_write, resblks, 0,
-			false, &tp);
+	error = xfs_trans_alloc_inode(ip, &M_RES(mp)->tr_write, dblocks,
+			rblocks, false, &tp);
 	if (error)
 		return error;
 
@@ -1212,7 +1218,7 @@ xfs_reflink_remap_extent(
 	struct xfs_trans	*tp;
 	xfs_off_t		newlen;
 	int64_t			qdelta = 0;
-	unsigned int		resblks;
+	unsigned int		dblocks, rblocks, resblks;
 	bool			quota_reserved = true;
 	bool			smap_real;
 	bool			dmap_written = xfs_bmap_is_written_extent(dmap);
@@ -1243,8 +1249,15 @@ xfs_reflink_remap_extent(
 	 * we're remapping.
 	 */
 	resblks = XFS_EXTENTADD_SPACE_RES(mp, XFS_DATA_FORK);
+	if (XFS_IS_REALTIME_INODE(ip)) {
+		dblocks = resblks;
+		rblocks = dmap->br_blockcount;
+	} else {
+		dblocks = resblks + dmap->br_blockcount;
+		rblocks = 0;
+	}
 	error = xfs_trans_alloc_inode(ip, &M_RES(mp)->tr_write,
-			resblks + dmap->br_blockcount, 0, false, &tp);
+			dblocks, rblocks, false, &tp);
 	if (error == -EDQUOT || error == -ENOSPC) {
 		quota_reserved = false;
 		error = xfs_trans_alloc_inode(ip, &M_RES(mp)->tr_write,
@@ -1324,8 +1337,15 @@ xfs_reflink_remap_extent(
 	 * done.
 	 */
 	if (!quota_reserved && !smap_real && dmap_written) {
-		error = xfs_trans_reserve_quota_nblks(tp, ip,
-				dmap->br_blockcount, 0, false);
+		if (XFS_IS_REALTIME_INODE(ip)) {
+			dblocks = 0;
+			rblocks = dmap->br_blockcount;
+		} else {
+			dblocks = dmap->br_blockcount;
+			rblocks = 0;
+		}
+		error = xfs_trans_reserve_quota_nblks(tp, ip, dblocks, rblocks,
+				false);
 		if (error)
 			goto out_cancel;
 	}