generic: 5.15: add pending patch fixing compilation warning in jffs2

Current gcc set a limit for each stack and complain if this limit is not
followed. JFSS2 in build_xattr function currently exceed the limit by
allocating a massive array of struct of 128 elements. Introduce a
pending patch that allocate this temp array dynamically fixing the
compilation warning:

fs/jffs2/xattr.c: In function 'jffs2_build_xattr_subsystem':
fs/jffs2/xattr.c:887:1: error: the frame size of 1088 bytes is larger than 1024 bytes [-Werror=frame-larger-than=]
  887 | }
      | ^

Affecting many target that require jffs2 support.

Signed-off-by: Christian Marangi <[email protected]>

target/linux/generic/pending-5.15/143-jffs2-reduce-stack-usage-in-jffs2_build_xattr_subsys.patch

@@ -0,0 +1,121 @@
+From eee53f6eb7561f516b9c4bac829ce31c48096130 Mon Sep 17 00:00:00 2001
+From: Fabian Frederick <[email protected]>
+Date: Tue, 9 May 2017 22:30:03 +0200
+Subject: [PATCH] jffs2: reduce stack usage in jffs2_build_xattr_subsystem()
+
+Use kcalloc() for allocation/flush of 128 pointers table to
+reduce stack usage.
+
+Function now returns -ENOMEM or 0 on success.
+
+stackusage
+Before:
+./fs/jffs2/xattr.c:775  jffs2_build_xattr_subsystem     1208
+dynamic,bounded
+
+After:
+./fs/jffs2/xattr.c:775  jffs2_build_xattr_subsystem     192
+dynamic,bounded
+
+Also update definition when CONFIG_JFFS2_FS_XATTR is not enabled
+
+Tested with an MTD mount point and some user set/getfattr.
+
+Many current target on OpenWRT also suffer from a compilation warning
+(that become an error with CONFIG_WERROR) with the following output:
+
+fs/jffs2/xattr.c: In function 'jffs2_build_xattr_subsystem':
+fs/jffs2/xattr.c:887:1: error: the frame size of 1088 bytes is larger than 1024 bytes [-Werror=frame-larger-than=]
+  887 | }
+      | ^
+
+Using dynamic allocation fix this compilation warning.
+
+Fixes: c9f700f840bd ("[JFFS2][XATTR] using 'delete marker' for xdatum/xref deletion")
+Reported-by: Tim Gardner <[email protected]>
+Reported-by: kernel test robot <[email protected]>
+Reported-by: Ron Economos <[email protected]>
+Reported-by: Nathan Chancellor <[email protected]>
+Reviewed-by: Nick Desaulniers <[email protected]>
+Signed-off-by: Fabian Frederick <[email protected]>
+Signed-off-by: Christian Marangi <[email protected]>
+Cc: [email protected]
+---
+ fs/jffs2/build.c |  5 ++++-
+ fs/jffs2/xattr.c | 13 +++++++++----
+ fs/jffs2/xattr.h |  4 ++--
+ 3 files changed, 15 insertions(+), 7 deletions(-)
+
+--- a/fs/jffs2/build.c
++++ b/fs/jffs2/build.c
+@@ -211,7 +211,10 @@ static int jffs2_build_filesystem(struct
+ 		ic->scan_dents = NULL;
+ 		cond_resched();
+ 	}
+-	jffs2_build_xattr_subsystem(c);
++	ret = jffs2_build_xattr_subsystem(c);
++	if (ret)
++		goto exit;
++
+ 	c->flags &= ~JFFS2_SB_FLAG_BUILDING;
+ 
+ 	dbg_fsbuild("FS build complete\n");
+--- a/fs/jffs2/xattr.c
++++ b/fs/jffs2/xattr.c
+@@ -772,10 +772,10 @@ void jffs2_clear_xattr_subsystem(struct
+ }
+ 
+ #define XREF_TMPHASH_SIZE	(128)
+-void jffs2_build_xattr_subsystem(struct jffs2_sb_info *c)
++int jffs2_build_xattr_subsystem(struct jffs2_sb_info *c)
+ {
+ 	struct jffs2_xattr_ref *ref, *_ref;
+-	struct jffs2_xattr_ref *xref_tmphash[XREF_TMPHASH_SIZE];
++	struct jffs2_xattr_ref **xref_tmphash;
+ 	struct jffs2_xattr_datum *xd, *_xd;
+ 	struct jffs2_inode_cache *ic;
+ 	struct jffs2_raw_node_ref *raw;
+@@ -784,9 +784,12 @@ void jffs2_build_xattr_subsystem(struct
+ 
+ 	BUG_ON(!(c->flags & JFFS2_SB_FLAG_BUILDING));
+ 
++	xref_tmphash = kcalloc(XREF_TMPHASH_SIZE,
++			       sizeof(struct jffs2_xattr_ref *), GFP_KERNEL);
++	if (!xref_tmphash)
++		return -ENOMEM;
++
+ 	/* Phase.1 : Merge same xref */
+-	for (i=0; i < XREF_TMPHASH_SIZE; i++)
+-		xref_tmphash[i] = NULL;
+ 	for (ref=c->xref_temp; ref; ref=_ref) {
+ 		struct jffs2_xattr_ref *tmp;
+ 
+@@ -884,6 +887,8 @@ void jffs2_build_xattr_subsystem(struct
+ 		     "%u of xref (%u dead, %u orphan) found.\n",
+ 		     xdatum_count, xdatum_unchecked_count, xdatum_orphan_count,
+ 		     xref_count, xref_dead_count, xref_orphan_count);
++	kfree(xref_tmphash);
++	return 0;
+ }
+ 
+ struct jffs2_xattr_datum *jffs2_setup_xattr_datum(struct jffs2_sb_info *c,
+--- a/fs/jffs2/xattr.h
++++ b/fs/jffs2/xattr.h
+@@ -71,7 +71,7 @@ static inline int is_xattr_ref_dead(stru
+ #ifdef CONFIG_JFFS2_FS_XATTR
+ 
+ extern void jffs2_init_xattr_subsystem(struct jffs2_sb_info *c);
+-extern void jffs2_build_xattr_subsystem(struct jffs2_sb_info *c);
++extern int jffs2_build_xattr_subsystem(struct jffs2_sb_info *c);
+ extern void jffs2_clear_xattr_subsystem(struct jffs2_sb_info *c);
+ 
+ extern struct jffs2_xattr_datum *jffs2_setup_xattr_datum(struct jffs2_sb_info *c,
+@@ -103,7 +103,7 @@ extern ssize_t jffs2_listxattr(struct de
+ #else
+ 
+ #define jffs2_init_xattr_subsystem(c)
+-#define jffs2_build_xattr_subsystem(c)
++#define jffs2_build_xattr_subsystem(c)		(0)
+ #define jffs2_clear_xattr_subsystem(c)
+ 
+ #define jffs2_xattr_do_crccheck_inode(c, ic)