xfs: allocate xfs_da_args to reduce stack footprint

The struct xfs_da_args used to pass directory/attribute operation
information to the lower layers is 128 bytes in size and is
allocated on the stack. Dynamically allocate them to reduce the
stack footprint of directory operations.
Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Brian Foster <bfoster@redhat.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>

fs/xfs/xfs_dir2.c

@@ -180,16 +180,23 @@ xfs_dir_init(
 	xfs_inode_t	*dp,
 	xfs_inode_t	*pdp)
 {
-	xfs_da_args_t	args;
+	struct xfs_da_args *args;
 	int		error;
 
-	memset((char *)&args, 0, sizeof(args));
-	args.dp = dp;
-	args.trans = tp;
 	ASSERT(S_ISDIR(dp->i_d.di_mode));
-	if ((error = xfs_dir_ino_validate(tp->t_mountp, pdp->i_ino)))
+	error = xfs_dir_ino_validate(tp->t_mountp, pdp->i_ino);
+	if (error)
 		return error;
-	return xfs_dir2_sf_create(&args, pdp->i_ino);
+
+	args = kmem_zalloc(sizeof(*args), KM_SLEEP | KM_NOFS);
+	if (!args)
+		return ENOMEM;
+
+	args->dp = dp;
+	args->trans = tp;
+	error = xfs_dir2_sf_create(args, pdp->i_ino);
+	kmem_free(args);
+	return error;
 }
 
 /*
@@ -205,41 +212,56 @@ xfs_dir_createname(
 	xfs_bmap_free_t		*flist,		/* bmap's freeblock list */
 	xfs_extlen_t		total)		/* bmap's total block count */
 {
-	xfs_da_args_t		args;
+	struct xfs_da_args	*args;
 	int			rval;
 	int			v;		/* type-checking value */
 
 	ASSERT(S_ISDIR(dp->i_d.di_mode));
-	if ((rval = xfs_dir_ino_validate(tp->t_mountp, inum)))
+	rval = xfs_dir_ino_validate(tp->t_mountp, inum);
+	if (rval)
 		return rval;
 	XFS_STATS_INC(xs_dir_create);
 
-	memset(&args, 0, sizeof(xfs_da_args_t));
-	args.name = name->name;
-	args.namelen = name->len;
-	args.filetype = name->type;
-	args.hashval = dp->i_mount->m_dirnameops->hashname(name);
-	args.inumber = inum;
-	args.dp = dp;
-	args.firstblock = first;
-	args.flist = flist;
-	args.total = total;
-	args.whichfork = XFS_DATA_FORK;
-	args.trans = tp;
-	args.op_flags = XFS_DA_OP_ADDNAME | XFS_DA_OP_OKNOENT;
-
-	if (dp->i_d.di_format == XFS_DINODE_FMT_LOCAL)
-		rval = xfs_dir2_sf_addname(&args);
-	else if ((rval = xfs_dir2_isblock(tp, dp, &v)))
-		return rval;
-	else if (v)
-		rval = xfs_dir2_block_addname(&args);
-	else if ((rval = xfs_dir2_isleaf(tp, dp, &v)))
-		return rval;
-	else if (v)
-		rval = xfs_dir2_leaf_addname(&args);
+	args = kmem_zalloc(sizeof(*args), KM_SLEEP | KM_NOFS);
+	if (!args)
+		return ENOMEM;
+
+	args->name = name->name;
+	args->namelen = name->len;
+	args->filetype = name->type;
+	args->hashval = dp->i_mount->m_dirnameops->hashname(name);
+	args->inumber = inum;
+	args->dp = dp;
+	args->firstblock = first;
+	args->flist = flist;
+	args->total = total;
+	args->whichfork = XFS_DATA_FORK;
+	args->trans = tp;
+	args->op_flags = XFS_DA_OP_ADDNAME | XFS_DA_OP_OKNOENT;
+
+	if (dp->i_d.di_format == XFS_DINODE_FMT_LOCAL) {
+		rval = xfs_dir2_sf_addname(args);
+		goto out_free;
+	}
+
+	rval = xfs_dir2_isblock(tp, dp, &v);
+	if (rval)
+		goto out_free;
+	if (v) {
+		rval = xfs_dir2_block_addname(args);
+		goto out_free;
+	}
+
+	rval = xfs_dir2_isleaf(tp, dp, &v);
+	if (rval)
+		goto out_free;
+	if (v)
+		rval = xfs_dir2_leaf_addname(args);
 	else
-		rval = xfs_dir2_node_addname(&args);
+		rval = xfs_dir2_node_addname(args);
+
+out_free:
+	kmem_free(args);
 	return rval;
 }
 
@@ -282,46 +304,66 @@ xfs_dir_lookup(
 	xfs_ino_t	*inum,		/* out: inode number */
 	struct xfs_name *ci_name)	/* out: actual name if CI match */
 {
-	xfs_da_args_t	args;
+	struct xfs_da_args *args;
 	int		rval;
 	int		v;		/* type-checking value */
 
 	ASSERT(S_ISDIR(dp->i_d.di_mode));
 	XFS_STATS_INC(xs_dir_lookup);
 
-	memset(&args, 0, sizeof(xfs_da_args_t));
-	args.name = name->name;
-	args.namelen = name->len;
-	args.filetype = name->type;
-	args.hashval = dp->i_mount->m_dirnameops->hashname(name);
-	args.dp = dp;
-	args.whichfork = XFS_DATA_FORK;
-	args.trans = tp;
-	args.op_flags = XFS_DA_OP_OKNOENT;
+	/*
+	 * We need to use KM_NOFS here so that lockdep will not throw false
+	 * positive deadlock warnings on a non-transactional lookup path. It is
+	 * safe to recurse into inode recalim in that case, but lockdep can't
+	 * easily be taught about it. Hence KM_NOFS avoids having to add more
+	 * lockdep Doing this avoids having to add a bunch of lockdep class
+	 * annotations into the reclaim path for the ilock.
+	 */
+	args = kmem_zalloc(sizeof(*args), KM_SLEEP | KM_NOFS);
+	args->name = name->name;
+	args->namelen = name->len;
+	args->filetype = name->type;
+	args->hashval = dp->i_mount->m_dirnameops->hashname(name);
+	args->dp = dp;
+	args->whichfork = XFS_DATA_FORK;
+	args->trans = tp;
+	args->op_flags = XFS_DA_OP_OKNOENT;
 	if (ci_name)
-		args.op_flags |= XFS_DA_OP_CILOOKUP;
+		args->op_flags |= XFS_DA_OP_CILOOKUP;
 
-	if (dp->i_d.di_format == XFS_DINODE_FMT_LOCAL)
-		rval = xfs_dir2_sf_lookup(&args);
-	else if ((rval = xfs_dir2_isblock(tp, dp, &v)))
-		return rval;
-	else if (v)
-		rval = xfs_dir2_block_lookup(&args);
-	else if ((rval = xfs_dir2_isleaf(tp, dp, &v)))
-		return rval;
-	else if (v)
-		rval = xfs_dir2_leaf_lookup(&args);
+	if (dp->i_d.di_format == XFS_DINODE_FMT_LOCAL) {
+		rval = xfs_dir2_sf_lookup(args);
+		goto out_check_rval;
+	}
+
+	rval = xfs_dir2_isblock(tp, dp, &v);
+	if (rval)
+		goto out_free;
+	if (v) {
+		rval = xfs_dir2_block_lookup(args);
+		goto out_check_rval;
+	}
+
+	rval = xfs_dir2_isleaf(tp, dp, &v);
+	if (rval)
+		goto out_free;
+	if (v)
+		rval = xfs_dir2_leaf_lookup(args);
 	else
-		rval = xfs_dir2_node_lookup(&args);
+		rval = xfs_dir2_node_lookup(args);
+
+out_check_rval:
 	if (rval == EEXIST)
 		rval = 0;
 	if (!rval) {
-		*inum = args.inumber;
+		*inum = args->inumber;
 		if (ci_name) {
-			ci_name->name = args.value;
-			ci_name->len = args.valuelen;
+			ci_name->name = args->value;
+			ci_name->len = args->valuelen;
 		}
 	}
+out_free:
+	kmem_free(args);
 	return rval;
 }
 
@@ -338,38 +380,51 @@ xfs_dir_removename(
 	xfs_bmap_free_t	*flist,		/* bmap's freeblock list */
 	xfs_extlen_t	total)		/* bmap's total block count */
 {
-	xfs_da_args_t	args;
+	struct xfs_da_args *args;
 	int		rval;
 	int		v;		/* type-checking value */
 
 	ASSERT(S_ISDIR(dp->i_d.di_mode));
 	XFS_STATS_INC(xs_dir_remove);
 
-	memset(&args, 0, sizeof(xfs_da_args_t));
-	args.name = name->name;
-	args.namelen = name->len;
-	args.filetype = name->type;
-	args.hashval = dp->i_mount->m_dirnameops->hashname(name);
-	args.inumber = ino;
-	args.dp = dp;
-	args.firstblock = first;
-	args.flist = flist;
-	args.total = total;
-	args.whichfork = XFS_DATA_FORK;
-	args.trans = tp;
-
-	if (dp->i_d.di_format == XFS_DINODE_FMT_LOCAL)
-		rval = xfs_dir2_sf_removename(&args);
-	else if ((rval = xfs_dir2_isblock(tp, dp, &v)))
-		return rval;
-	else if (v)
-		rval = xfs_dir2_block_removename(&args);
-	else if ((rval = xfs_dir2_isleaf(tp, dp, &v)))
-		return rval;
-	else if (v)
-		rval = xfs_dir2_leaf_removename(&args);
+	args = kmem_zalloc(sizeof(*args), KM_SLEEP | KM_NOFS);
+	if (!args)
+		return ENOMEM;
+
+	args->name = name->name;
+	args->namelen = name->len;
+	args->filetype = name->type;
+	args->hashval = dp->i_mount->m_dirnameops->hashname(name);
+	args->inumber = ino;
+	args->dp = dp;
+	args->firstblock = first;
+	args->flist = flist;
+	args->total = total;
+	args->whichfork = XFS_DATA_FORK;
+	args->trans = tp;
+
+	if (dp->i_d.di_format == XFS_DINODE_FMT_LOCAL) {
+		rval = xfs_dir2_sf_removename(args);
+		goto out_free;
+	}
+
+	rval = xfs_dir2_isblock(tp, dp, &v);
+	if (rval)
+		goto out_free;
+	if (v) {
+		rval = xfs_dir2_block_removename(args);
+		goto out_free;
+	}
+
+	rval = xfs_dir2_isleaf(tp, dp, &v);
+	if (rval)
+		goto out_free;
+	if (v)
+		rval = xfs_dir2_leaf_removename(args);
 	else
-		rval = xfs_dir2_node_removename(&args);
+		rval = xfs_dir2_node_removename(args);
+out_free:
+	kmem_free(args);
 	return rval;
 }
 
@@ -386,40 +441,54 @@ xfs_dir_replace(
 	xfs_bmap_free_t	*flist,		/* bmap's freeblock list */
 	xfs_extlen_t	total)		/* bmap's total block count */
 {
-	xfs_da_args_t	args;
+	struct xfs_da_args *args;
 	int		rval;
 	int		v;		/* type-checking value */
 
 	ASSERT(S_ISDIR(dp->i_d.di_mode));
 
-	if ((rval = xfs_dir_ino_validate(tp->t_mountp, inum)))
+	rval = xfs_dir_ino_validate(tp->t_mountp, inum);
+	if (rval)
 		return rval;
 
-	memset(&args, 0, sizeof(xfs_da_args_t));
-	args.name = name->name;
-	args.namelen = name->len;
-	args.filetype = name->type;
-	args.hashval = dp->i_mount->m_dirnameops->hashname(name);
-	args.inumber = inum;
-	args.dp = dp;
-	args.firstblock = first;
-	args.flist = flist;
-	args.total = total;
-	args.whichfork = XFS_DATA_FORK;
-	args.trans = tp;
-
-	if (dp->i_d.di_format == XFS_DINODE_FMT_LOCAL)
-		rval = xfs_dir2_sf_replace(&args);
-	else if ((rval = xfs_dir2_isblock(tp, dp, &v)))
-		return rval;
-	else if (v)
-		rval = xfs_dir2_block_replace(&args);
-	else if ((rval = xfs_dir2_isleaf(tp, dp, &v)))
-		return rval;
-	else if (v)
-		rval = xfs_dir2_leaf_replace(&args);
+	args = kmem_zalloc(sizeof(*args), KM_SLEEP | KM_NOFS);
+	if (!args)
+		return ENOMEM;
+
+	args->name = name->name;
+	args->namelen = name->len;
+	args->filetype = name->type;
+	args->hashval = dp->i_mount->m_dirnameops->hashname(name);
+	args->inumber = inum;
+	args->dp = dp;
+	args->firstblock = first;
+	args->flist = flist;
+	args->total = total;
+	args->whichfork = XFS_DATA_FORK;
+	args->trans = tp;
+
+	if (dp->i_d.di_format == XFS_DINODE_FMT_LOCAL) {
+		rval = xfs_dir2_sf_replace(args);
+		goto out_free;
+	}
+
+	rval = xfs_dir2_isblock(tp, dp, &v);
+	if (rval)
+		goto out_free;
+	if (v) {
+		rval = xfs_dir2_block_replace(args);
+		goto out_free;
+	}
+
+	rval = xfs_dir2_isleaf(tp, dp, &v);
+	if (rval)
+		goto out_free;
+	if (v)
+		rval = xfs_dir2_leaf_replace(args);
 	else
-		rval = xfs_dir2_node_replace(&args);
+		rval = xfs_dir2_node_replace(args);
+out_free:
+	kmem_free(args);
 	return rval;
 }
 
@@ -434,7 +503,7 @@ xfs_dir_canenter(
 	struct xfs_name	*name,		/* name of entry to add */
 	uint		resblks)
 {
-	xfs_da_args_t	args;
+	struct xfs_da_args *args;
 	int		rval;
 	int		v;		/* type-checking value */
 
@@ -443,29 +512,42 @@ xfs_dir_canenter(
 
 	ASSERT(S_ISDIR(dp->i_d.di_mode));
 
-	memset(&args, 0, sizeof(xfs_da_args_t));
-	args.name = name->name;
-	args.namelen = name->len;
-	args.filetype = name->type;
-	args.hashval = dp->i_mount->m_dirnameops->hashname(name);
-	args.dp = dp;
-	args.whichfork = XFS_DATA_FORK;
-	args.trans = tp;
-	args.op_flags = XFS_DA_OP_JUSTCHECK | XFS_DA_OP_ADDNAME |
+	args = kmem_zalloc(sizeof(*args), KM_SLEEP | KM_NOFS);
+	if (!args)
+		return ENOMEM;
+
+	args->name = name->name;
+	args->namelen = name->len;
+	args->filetype = name->type;
+	args->hashval = dp->i_mount->m_dirnameops->hashname(name);
+	args->dp = dp;
+	args->whichfork = XFS_DATA_FORK;
+	args->trans = tp;
+	args->op_flags = XFS_DA_OP_JUSTCHECK | XFS_DA_OP_ADDNAME |
 							XFS_DA_OP_OKNOENT;
 
-	if (dp->i_d.di_format == XFS_DINODE_FMT_LOCAL)
-		rval = xfs_dir2_sf_addname(&args);
-	else if ((rval = xfs_dir2_isblock(tp, dp, &v)))
-		return rval;
-	else if (v)
-		rval = xfs_dir2_block_addname(&args);
-	else if ((rval = xfs_dir2_isleaf(tp, dp, &v)))
-		return rval;
-	else if (v)
-		rval = xfs_dir2_leaf_addname(&args);
+	if (dp->i_d.di_format == XFS_DINODE_FMT_LOCAL) {
+		rval = xfs_dir2_sf_addname(args);
+		goto out_free;
+	}
+
+	rval = xfs_dir2_isblock(tp, dp, &v);
+	if (rval)
+		goto out_free;
+	if (v) {
+		rval = xfs_dir2_block_addname(args);
+		goto out_free;
+	}
+
+	rval = xfs_dir2_isleaf(tp, dp, &v);
+	if (rval)
+		goto out_free;
+	if (v)
+		rval = xfs_dir2_leaf_addname(args);
 	else
-		rval = xfs_dir2_node_addname(&args);
+		rval = xfs_dir2_node_addname(args);
+out_free:
+	kmem_free(args);
 	return rval;
 }