[PATCH 4/8] smb: client: reduce stack usage in smb2_set_ea()

[Paulo Alcantara <pc@xxxxxxxxxxxxx>]

Clang warns about exceeded stack frame size

  fs/smb/client/smb2ops.c:1080:1: warning: stack frame size (1432)
  exceeds limit (1024) in 'smb2_set_ea' [-Wframe-larger-than]

Fix this by allocating a set_ea_vars structure that will hold most of
the large structures.

Signed-off-by: Paulo Alcantara (SUSE) <pc@xxxxxxxxxxxxx>
---
 fs/smb/client/smb2ops.c | 40 +++++++++++++++++++++++++---------------
 1 file changed, 25 insertions(+), 15 deletions(-)

diff --git a/fs/smb/client/smb2ops.c b/fs/smb/client/smb2ops.c
index 0f62bc373ad0..5c8bcaf41556 100644
--- a/fs/smb/client/smb2ops.c
+++ b/fs/smb/client/smb2ops.c
@@ -1075,6 +1075,13 @@ smb2_query_eas(const unsigned int xid, struct cifs_tcon *tcon,
 	return rc;
 }
 
+struct set_ea_vars {
+	struct smb_rqst rqst[3];
+	struct kvec rsp_iov[3];
+	struct kvec open_iov[SMB2_CREATE_IOV_SIZE];
+	struct kvec si_iov[SMB2_SET_INFO_IOV_SIZE];
+	struct kvec close_iov;
+};
 
 static int
 smb2_set_ea(const unsigned int xid, struct cifs_tcon *tcon,
@@ -1082,25 +1089,23 @@ smb2_set_ea(const unsigned int xid, struct cifs_tcon *tcon,
 	    const __u16 ea_value_len, const struct nls_table *nls_codepage,
 	    struct cifs_sb_info *cifs_sb)
 {
+	struct smb2_query_info_rsp *rsp;
 	struct cifs_ses *ses = tcon->ses;
+	struct set_ea_vars *vars;
 	struct TCP_Server_Info *server = cifs_pick_channel(ses);
+	struct smb_rqst *rqst;
+	struct kvec *rsp_iov;
 	__le16 *utf16_path = NULL;
 	int ea_name_len = strlen(ea_name);
 	int flags = CIFS_CP_CREATE_CLOSE_OP;
 	int len;
-	struct smb_rqst rqst[3];
 	int resp_buftype[3];
-	struct kvec rsp_iov[3];
-	struct kvec open_iov[SMB2_CREATE_IOV_SIZE];
 	struct cifs_open_parms oparms;
 	__u8 oplock = SMB2_OPLOCK_LEVEL_NONE;
 	struct cifs_fid fid;
-	struct kvec si_iov[SMB2_SET_INFO_IOV_SIZE];
 	unsigned int size[1];
 	void *data[1];
 	struct smb2_file_full_ea_info *ea = NULL;
-	struct kvec close_iov[1];
-	struct smb2_query_info_rsp *rsp;
 	int rc, used_len = 0;
 
 	if (smb3_encryption_required(tcon))
@@ -1113,9 +1118,15 @@ smb2_set_ea(const unsigned int xid, struct cifs_tcon *tcon,
 	if (!utf16_path)
 		return -ENOMEM;
 
-	memset(rqst, 0, sizeof(rqst));
 	resp_buftype[0] = resp_buftype[1] = resp_buftype[2] = CIFS_NO_BUFFER;
-	memset(rsp_iov, 0, sizeof(rsp_iov));
+
+	vars = kzalloc(sizeof(*vars), GFP_KERNEL);
+	if (!vars) {
+		rc = -ENOMEM;
+		goto out_free_path;
+	}
+	rqst = vars->rqst;
+	rsp_iov = vars->rsp_iov;
 
 	if (ses->server->ops->query_all_EAs) {
 		if (!ea_value) {
@@ -1160,8 +1171,7 @@ smb2_set_ea(const unsigned int xid, struct cifs_tcon *tcon,
 	}
 
 	/* Open */
-	memset(&open_iov, 0, sizeof(open_iov));
-	rqst[0].rq_iov = open_iov;
+	rqst[0].rq_iov = vars->open_iov;
 	rqst[0].rq_nvec = SMB2_CREATE_IOV_SIZE;
 
 	oparms = (struct cifs_open_parms) {
@@ -1181,8 +1191,7 @@ smb2_set_ea(const unsigned int xid, struct cifs_tcon *tcon,
 
 
 	/* Set Info */
-	memset(&si_iov, 0, sizeof(si_iov));
-	rqst[1].rq_iov = si_iov;
+	rqst[1].rq_iov = vars->si_iov;
 	rqst[1].rq_nvec = 1;
 
 	len = sizeof(*ea) + ea_name_len + ea_value_len + 1;
@@ -1212,8 +1221,7 @@ smb2_set_ea(const unsigned int xid, struct cifs_tcon *tcon,
 
 
 	/* Close */
-	memset(&close_iov, 0, sizeof(close_iov));
-	rqst[2].rq_iov = close_iov;
+	rqst[2].rq_iov = &vars->close_iov;
 	rqst[2].rq_nvec = 1;
 	rc = SMB2_close_init(tcon, server,
 			     &rqst[2], COMPOUND_FID, COMPOUND_FID, false);
@@ -1228,13 +1236,15 @@ smb2_set_ea(const unsigned int xid, struct cifs_tcon *tcon,
 
  sea_exit:
 	kfree(ea);
-	kfree(utf16_path);
 	SMB2_open_free(&rqst[0]);
 	SMB2_set_info_free(&rqst[1]);
 	SMB2_close_free(&rqst[2]);
 	free_rsp_buf(resp_buftype[0], rsp_iov[0].iov_base);
 	free_rsp_buf(resp_buftype[1], rsp_iov[1].iov_base);
 	free_rsp_buf(resp_buftype[2], rsp_iov[2].iov_base);
+	kfree(vars);
+out_free_path:
+	kfree(utf16_path);
 	return rc;
 }
 #endif
-- 
2.41.0