xfs: use ->t_firstblock in xattr ops

Similar to the dirops code, the xattr code uses an on-stack
firstblock variable for the various operations. This code rolls the
underlying transaction in various places, however, which means we
cannot simply replace the local firstblock vars with ->t_firstblock.
Doing so (without further changes) would invalidate the memory
pointed to by xfs_da_args.firstblock as soon as the first
transaction rolls.

To avoid this problem, remove xfs_da_args.firstblock and replace all
such accesses with ->t_firstblock at the same time. This ensures
that accesses to the current firstblock always occur through the
current transaction rather than a potentially invalid xfs_da_args
pointer.
Signed-off-by: Brian Foster <bfoster@redhat.com>
Reviewed-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_attr.c

@@ -204,7 +204,6 @@ xfs_attr_set(
 	struct xfs_da_args	args;
 	struct xfs_defer_ops	dfops;
 	struct xfs_trans_res	tres;
-	xfs_fsblock_t		firstblock;
 	int			rsvd = (flags & ATTR_ROOT) != 0;
 	int			error, err2, local;
 
@@ -219,7 +218,6 @@ xfs_attr_set(
 
 	args.value = value;
 	args.valuelen = valuelen;
-	args.firstblock = &firstblock;
 	args.op_flags = XFS_DA_OP_ADDNAME | XFS_DA_OP_OKNOENT;
 	args.total = xfs_attr_calc_size(&args, &local);
 
@@ -253,7 +251,7 @@ xfs_attr_set(
 			rsvd ? XFS_TRANS_RESERVE : 0, &args.trans);
 	if (error)
 		return error;
-	xfs_defer_init(args.trans, &dfops, &firstblock);
+	xfs_defer_init(args.trans, &dfops, &args.trans->t_firstblock);
 
 	xfs_ilock(dp, XFS_ILOCK_EXCL);
 	error = xfs_trans_reserve_quota_nblks(args.trans, dp, args.total, 0,
@@ -392,7 +390,6 @@ xfs_attr_remove(
 	struct xfs_mount	*mp = dp->i_mount;
 	struct xfs_da_args	args;
 	struct xfs_defer_ops	dfops;
-	xfs_fsblock_t		firstblock;
 	int			error;
 
 	XFS_STATS_INC(mp, xs_attr_remove);
@@ -404,8 +401,6 @@ xfs_attr_remove(
 	if (error)
 		return error;
 
-	args.firstblock = &firstblock;
-
 	/*
 	 * we have no control over the attribute names that userspace passes us
 	 * to remove, so we have to allow the name lookup prior to attribute
@@ -427,7 +422,7 @@ xfs_attr_remove(
 			&args.trans);
 	if (error)
 		return error;
-	xfs_defer_init(args.trans, &dfops, &firstblock);
+	xfs_defer_init(args.trans, &dfops, &args.trans->t_firstblock);
 
 	xfs_ilock(dp, XFS_ILOCK_EXCL);
 	/*
@@ -598,7 +593,8 @@ xfs_attr_leaf_addname(
 		 * Commit that transaction so that the node_addname() call
 		 * can manage its own transactions.
 		 */
-		xfs_defer_init(NULL, args->trans->t_dfops, args->firstblock);
+		xfs_defer_init(args->trans, args->trans->t_dfops,
+			       &args->trans->t_firstblock);
 		error = xfs_attr3_leaf_to_node(args);
 		if (error)
 			goto out_defer_cancel;
@@ -687,8 +683,8 @@ xfs_attr_leaf_addname(
 		 * If the result is small enough, shrink it all into the inode.
 		 */
 		if ((forkoff = xfs_attr_shortform_allfit(bp, dp))) {
-			xfs_defer_init(NULL, args->trans->t_dfops,
-				       args->firstblock);
+			xfs_defer_init(args->trans, args->trans->t_dfops,
+				       &args->trans->t_firstblock);
 			error = xfs_attr3_leaf_to_shortform(bp, args, forkoff);
 			/* bp is gone due to xfs_da_shrink_inode */
 			if (error)
@@ -753,7 +749,8 @@ xfs_attr_leaf_removename(
 	 * If the result is small enough, shrink it all into the inode.
 	 */
 	if ((forkoff = xfs_attr_shortform_allfit(bp, dp))) {
-		xfs_defer_init(NULL, args->trans->t_dfops, args->firstblock);
+		xfs_defer_init(args->trans, args->trans->t_dfops,
+			       &args->trans->t_firstblock);
 		error = xfs_attr3_leaf_to_shortform(bp, args, forkoff);
 		/* bp is gone due to xfs_da_shrink_inode */
 		if (error)
@@ -882,8 +879,8 @@ xfs_attr_node_addname(
 			 */
 			xfs_da_state_free(state);
 			state = NULL;
-			xfs_defer_init(NULL, args->trans->t_dfops,
-				       args->firstblock);
+			xfs_defer_init(args->trans, args->trans->t_dfops,
+				       &args->trans->t_firstblock);
 			error = xfs_attr3_leaf_to_node(args);
 			if (error)
 				goto out_defer_cancel;
@@ -910,7 +907,8 @@ xfs_attr_node_addname(
 		 * in the index/blkno/rmtblkno/rmtblkcnt fields and
 		 * in the index2/blkno2/rmtblkno2/rmtblkcnt2 fields.
 		 */
-		xfs_defer_init(NULL, args->trans->t_dfops, args->firstblock);
+		xfs_defer_init(args->trans, args->trans->t_dfops,
+			       &args->trans->t_firstblock);
 		error = xfs_da3_split(state);
 		if (error)
 			goto out_defer_cancel;
@@ -1008,8 +1006,8 @@ xfs_attr_node_addname(
 		 * Check to see if the tree needs to be collapsed.
 		 */
 		if (retval && (state->path.active > 1)) {
-			xfs_defer_init(NULL, args->trans->t_dfops,
-				       args->firstblock);
+			xfs_defer_init(args->trans, args->trans->t_dfops,
+				       &args->trans->t_firstblock);
 			error = xfs_da3_join(state);
 			if (error)
 				goto out_defer_cancel;
@@ -1134,7 +1132,8 @@ xfs_attr_node_removename(
 	 * Check to see if the tree needs to be collapsed.
 	 */
 	if (retval && (state->path.active > 1)) {
-		xfs_defer_init(NULL, args->trans->t_dfops, args->firstblock);
+		xfs_defer_init(args->trans, args->trans->t_dfops,
+			       &args->trans->t_firstblock);
 		error = xfs_da3_join(state);
 		if (error)
 			goto out_defer_cancel;
@@ -1166,8 +1165,8 @@ xfs_attr_node_removename(
 			goto out;
 
 		if ((forkoff = xfs_attr_shortform_allfit(bp, dp))) {
-			xfs_defer_init(NULL, args->trans->t_dfops,
-				       args->firstblock);
+			xfs_defer_init(args->trans, args->trans->t_dfops,
+				       &args->trans->t_firstblock);
 			error = xfs_attr3_leaf_to_shortform(bp, args, forkoff);
 			/* bp is gone due to xfs_da_shrink_inode */
 			if (error)

fs/xfs/libxfs/xfs_attr_leaf.c

@@ -802,7 +802,6 @@ xfs_attr_shortform_to_leaf(
 	memset((char *)&nargs, 0, sizeof(nargs));
 	nargs.dp = dp;
 	nargs.geo = args->geo;
-	nargs.firstblock = args->firstblock;
 	nargs.total = args->total;
 	nargs.whichfork = XFS_ATTR_FORK;
 	nargs.trans = args->trans;
@@ -1005,7 +1004,6 @@ xfs_attr3_leaf_to_shortform(
 	memset((char *)&nargs, 0, sizeof(nargs));
 	nargs.geo = args->geo;
 	nargs.dp = dp;
-	nargs.firstblock = args->firstblock;
 	nargs.total = args->total;
 	nargs.whichfork = XFS_ATTR_FORK;
 	nargs.trans = args->trans;

fs/xfs/libxfs/xfs_attr_remote.c

@@ -480,11 +480,13 @@ xfs_attr_rmtval_set(
 		 * extent and then crash then the block may not contain the
 		 * correct metadata after log recovery occurs.
 		 */
-		xfs_defer_init(NULL, args->trans->t_dfops, args->firstblock);
+		xfs_defer_init(args->trans, args->trans->t_dfops,
+			       &args->trans->t_firstblock);
 		nmap = 1;
 		error = xfs_bmapi_write(args->trans, dp, (xfs_fileoff_t)lblkno,
-				  blkcnt, XFS_BMAPI_ATTRFORK, args->firstblock,
-				  args->total, &map, &nmap);
+				  blkcnt, XFS_BMAPI_ATTRFORK,
+				  &args->trans->t_firstblock, args->total, &map,
+				  &nmap);
 		if (error)
 			goto out_defer_cancel;
 		xfs_defer_ijoin(args->trans->t_dfops, dp);
@@ -522,7 +524,8 @@ xfs_attr_rmtval_set(
 
 		ASSERT(blkcnt > 0);
 
-		xfs_defer_init(NULL, args->trans->t_dfops, args->firstblock);
+		xfs_defer_init(args->trans, args->trans->t_dfops,
+			       &args->trans->t_firstblock);
 		nmap = 1;
 		error = xfs_bmapi_read(dp, (xfs_fileoff_t)lblkno,
 				       blkcnt, &map, &nmap,
@@ -626,10 +629,11 @@ xfs_attr_rmtval_remove(
 	blkcnt = args->rmtblkcnt;
 	done = 0;
 	while (!done) {
-		xfs_defer_init(NULL, args->trans->t_dfops, args->firstblock);
+		xfs_defer_init(args->trans, args->trans->t_dfops,
+			       &args->trans->t_firstblock);
 		error = xfs_bunmapi(args->trans, args->dp, lblkno, blkcnt,
-				    XFS_BMAPI_ATTRFORK, 1, args->firstblock,
-				    &done);
+				    XFS_BMAPI_ATTRFORK, 1,
+				    &args->trans->t_firstblock, &done);
 		if (error)
 			goto out_defer_cancel;
 		xfs_defer_ijoin(args->trans->t_dfops, args->dp);

fs/xfs/libxfs/xfs_bmap.c

@@ -1000,7 +1000,6 @@ xfs_bmap_add_attrfork_local(
 		memset(&dargs, 0, sizeof(dargs));
 		dargs.geo = ip->i_mount->m_dir_geo;
 		dargs.dp = ip;
-		dargs.firstblock = &tp->t_firstblock;
 		dargs.total = dargs.geo->fsbcount;
 		dargs.whichfork = XFS_DATA_FORK;
 		dargs.trans = tp;

fs/xfs/libxfs/xfs_da_btree.c

@@ -2059,10 +2059,9 @@ xfs_da_grow_inode_int(
 	 * Try mapping it in one filesystem block.
 	 */
 	nmap = 1;
-	ASSERT(args->firstblock != NULL);
 	error = xfs_bmapi_write(tp, dp, *bno, count,
 			xfs_bmapi_aflag(w)|XFS_BMAPI_METADATA|XFS_BMAPI_CONTIG,
-			args->firstblock, args->total, &map, &nmap);
+			&tp->t_firstblock, args->total, &map, &nmap);
 	if (error)
 		return error;
 
@@ -2084,7 +2083,7 @@ xfs_da_grow_inode_int(
 			c = (int)(*bno + count - b);
 			error = xfs_bmapi_write(tp, dp, b, c,
 					xfs_bmapi_aflag(w)|XFS_BMAPI_METADATA,
-					args->firstblock, args->total,
+					&tp->t_firstblock, args->total,
 					&mapp[mapi], &nmap);
 			if (error)
 				goto out_free_map;
@@ -2394,7 +2393,7 @@ xfs_da_shrink_inode(
 		 * the last block to the place we want to kill.
 		 */
 		error = xfs_bunmapi(tp, dp, dead_blkno, count,
-				    xfs_bmapi_aflag(w), 0, args->firstblock,
+				    xfs_bmapi_aflag(w), 0, &tp->t_firstblock,
 				    &done);
 		if (error == -ENOSPC) {
 			if (w != XFS_DATA_FORK)

fs/xfs/libxfs/xfs_da_btree.h

@@ -57,7 +57,6 @@ typedef struct xfs_da_args {
 	xfs_dahash_t	hashval;	/* hash value of name */
 	xfs_ino_t	inumber;	/* input/output inode number */
 	struct xfs_inode *dp;		/* directory inode to manipulate */
-	xfs_fsblock_t	*firstblock;	/* ptr to firstblock for bmap calls */
 	struct xfs_trans *trans;	/* current trans (changes over time) */
 	xfs_extlen_t	total;		/* total blocks needed, for 1st bmap */
 	int		whichfork;	/* data or attribute fork */

fs/xfs/libxfs/xfs_dir2.c

@@ -272,7 +272,6 @@ xfs_dir_createname(
 	args->total = total;
 	args->whichfork = XFS_DATA_FORK;
 	args->trans = tp;
-	args->firstblock = &tp->t_firstblock;
 	args->op_flags = XFS_DA_OP_ADDNAME | XFS_DA_OP_OKNOENT;
 	if (!inum)
 		args->op_flags |= XFS_DA_OP_JUSTCHECK;
@@ -439,7 +438,6 @@ xfs_dir_removename(
 	args->hashval = dp->i_mount->m_dirnameops->hashname(name);
 	args->inumber = ino;
 	args->dp = dp;
-	args->firstblock = &tp->t_firstblock;
 	args->total = total;
 	args->whichfork = XFS_DATA_FORK;
 	args->trans = tp;
@@ -502,7 +500,6 @@ xfs_dir_replace(
 	args->hashval = dp->i_mount->m_dirnameops->hashname(name);
 	args->inumber = inum;
 	args->dp = dp;
-	args->firstblock = &tp->t_firstblock;
 	args->total = total;
 	args->whichfork = XFS_DATA_FORK;
 	args->trans = tp;
@@ -660,7 +657,7 @@ xfs_dir2_shrink_inode(
 
 	/* Unmap the fsblock(s). */
 	error = xfs_bunmapi(tp, dp, da, args->geo->fsbcount, 0, 0,
-			    args->firstblock, &done);
+			    &tp->t_firstblock, &done);
 	if (error) {
 		/*
 		 * ENOSPC actually can happen if we're in a removename with no