xfs: remove if_real_bytes

The field is only used for asserts, and to track if we really need to do
realloc when growing the inode fork data.  But the krealloc function
already performs this check internally, so there is no need to keep track
of the real allocation size.

This will free space in the inode fork for keeping a sequence counter of
changes to the extent list.
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_inode_fork.c

@@ -158,7 +158,6 @@ xfs_init_local_fork(
 	}
 
 	ifp->if_bytes = size;
-	ifp->if_real_bytes = real_size;
 	ifp->if_flags &= ~(XFS_IFEXTENTS | XFS_IFBROOT);
 	ifp->if_flags |= XFS_IFINLINE;
 }
@@ -226,7 +225,6 @@ xfs_iformat_extents(
 		return -EFSCORRUPTED;
 	}
 
-	ifp->if_real_bytes = 0;
 	ifp->if_bytes = 0;
 	ifp->if_u1.if_root = NULL;
 	ifp->if_height = 0;
@@ -317,7 +315,6 @@ xfs_iformat_btree(
 	ifp->if_flags &= ~XFS_IFEXTENTS;
 	ifp->if_flags |= XFS_IFBROOT;
 
-	ifp->if_real_bytes = 0;
 	ifp->if_bytes = 0;
 	ifp->if_u1.if_root = NULL;
 	ifp->if_height = 0;
@@ -501,7 +498,6 @@ xfs_idata_realloc(
 		 */
 		real_size = roundup(new_size, 4);
 		if (ifp->if_u1.if_data == NULL) {
-			ASSERT(ifp->if_real_bytes == 0);
 			ifp->if_u1.if_data = kmem_alloc(real_size,
 							KM_SLEEP | KM_NOFS);
 		} else {
@@ -509,15 +505,12 @@ xfs_idata_realloc(
 			 * Only do the realloc if the underlying size
 			 * is really changing.
 			 */
-			if (ifp->if_real_bytes != real_size) {
-				ifp->if_u1.if_data =
-					kmem_realloc(ifp->if_u1.if_data,
-							real_size,
-							KM_SLEEP | KM_NOFS);
-			}
+			ifp->if_u1.if_data =
+				kmem_realloc(ifp->if_u1.if_data,
+						real_size,
+						KM_SLEEP | KM_NOFS);
 		}
 	}
-	ifp->if_real_bytes = real_size;
 	ifp->if_bytes = new_size;
 	ASSERT(ifp->if_bytes <= XFS_IFORK_SIZE(ip, whichfork));
 }
@@ -543,17 +536,13 @@ xfs_idestroy_fork(
 	 */
 	if (XFS_IFORK_FORMAT(ip, whichfork) == XFS_DINODE_FMT_LOCAL) {
 		if (ifp->if_u1.if_data != NULL) {
-			ASSERT(ifp->if_real_bytes != 0);
 			kmem_free(ifp->if_u1.if_data);
 			ifp->if_u1.if_data = NULL;
-			ifp->if_real_bytes = 0;
 		}
 	} else if ((ifp->if_flags & XFS_IFEXTENTS) && ifp->if_height) {
 		xfs_iext_destroy(ifp);
 	}
 
-	ASSERT(ifp->if_real_bytes == 0);
-
 	if (whichfork == XFS_ATTR_FORK) {
 		kmem_zone_free(xfs_ifork_zone, ip->i_afp);
 		ip->i_afp = NULL;

fs/xfs/libxfs/xfs_inode_fork.h

@@ -14,7 +14,6 @@ struct xfs_dinode;
  */
 typedef struct xfs_ifork {
 	int			if_bytes;	/* bytes in if_u1 */
-	int			if_real_bytes;	/* bytes allocated in if_u1 */
 	struct xfs_btree_block	*if_broot;	/* file's incore btree root */
 	short			if_broot_bytes;	/* bytes allocated for root */
 	unsigned char		if_flags;	/* per-fork flags */

fs/xfs/xfs_inode.c

@@ -927,7 +927,7 @@ xfs_ialloc(
 	case S_IFLNK:
 		ip->i_d.di_format = XFS_DINODE_FMT_EXTENTS;
 		ip->i_df.if_flags = XFS_IFEXTENTS;
-		ip->i_df.if_bytes = ip->i_df.if_real_bytes = 0;
+		ip->i_df.if_bytes = 0;
 		ip->i_df.if_u1.if_root = NULL;
 		break;
 	default:
@@ -1841,7 +1841,6 @@ xfs_inactive(
 	 * to clean up here.
 	 */
 	if (VFS_I(ip)->i_mode == 0) {
-		ASSERT(ip->i_df.if_real_bytes == 0);
 		ASSERT(ip->i_df.if_broot_bytes == 0);
 		return;
 	}

fs/xfs/xfs_inode_item.c

@@ -194,8 +194,6 @@ xfs_inode_item_format_data_fork(
 			 * to be there by xfs_idata_realloc().
 			 */
 			data_bytes = roundup(ip->i_df.if_bytes, 4);
-			ASSERT(ip->i_df.if_real_bytes == 0 ||
-			       ip->i_df.if_real_bytes >= data_bytes);
 			ASSERT(ip->i_df.if_u1.if_data != NULL);
 			ASSERT(ip->i_d.di_size > 0);
 			xlog_copy_iovec(lv, vecp, XLOG_REG_TYPE_ILOCAL,
@@ -280,8 +278,6 @@ xfs_inode_item_format_attr_fork(
 			 * to be there by xfs_idata_realloc().
 			 */
 			data_bytes = roundup(ip->i_afp->if_bytes, 4);
-			ASSERT(ip->i_afp->if_real_bytes == 0 ||
-			       ip->i_afp->if_real_bytes >= data_bytes);
 			ASSERT(ip->i_afp->if_u1.if_data != NULL);
 			xlog_copy_iovec(lv, vecp, XLOG_REG_TYPE_IATTR_LOCAL,
 					ip->i_afp->if_u1.if_data,