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

   1 From eee53f6eb7561f516b9c4bac829ce31c48096130 Mon Sep 17 00:00:00 2001
   2 From: Fabian Frederick <fabf@skynet.be>
   3 Date: Tue, 9 May 2017 22:30:03 +0200
   4 Subject: [PATCH] jffs2: reduce stack usage in jffs2_build_xattr_subsystem()
   5
   6 Use kcalloc() for allocation/flush of 128 pointers table to
   7 reduce stack usage.
   8
   9 Function now returns -ENOMEM or 0 on success.
  10
  11 stackusage
  12 Before:
  13 ./fs/jffs2/xattr.c:775  jffs2_build_xattr_subsystem     1208
  14 dynamic,bounded
  15
  16 After:
  17 ./fs/jffs2/xattr.c:775  jffs2_build_xattr_subsystem     192
  18 dynamic,bounded
  19
  20 Also update definition when CONFIG_JFFS2_FS_XATTR is not enabled
  21
  22 Tested with an MTD mount point and some user set/getfattr.
  23
  24 Many current target on OpenWRT also suffer from a compilation warning
  25 (that become an error with CONFIG_WERROR) with the following output:
  26
  27 fs/jffs2/xattr.c: In function 'jffs2_build_xattr_subsystem':
  28 fs/jffs2/xattr.c:887:1: error: the frame size of 1088 bytes is larger than 1024 bytes [-Werror=frame-larger-than=]
  29   887 | }
  30       | ^
  31
  32 Using dynamic allocation fix this compilation warning.
  33
  34 Fixes: c9f700f840bd ("[JFFS2][XATTR] using 'delete marker' for xdatum/xref deletion")
  35 Reported-by: Tim Gardner <tim.gardner@canonical.com>
  36 Reported-by: kernel test robot <lkp@intel.com>
  37 Reported-by: Ron Economos <re@w6rz.net>
  38 Reported-by: Nathan Chancellor <nathan@kernel.org>
  39 Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
  40 Signed-off-by: Fabian Frederick <fabf@skynet.be>
  41 Signed-off-by: Christian Marangi <ansuelsmth@gmail.com>
  42 Cc: stable@vger.kernel.org
  43 ---
  44  fs/jffs2/build.c |  5 ++++-
  45  fs/jffs2/xattr.c | 13 +++++++++----
  46  fs/jffs2/xattr.h |  4 ++--
  47  3 files changed, 15 insertions(+), 7 deletions(-)
  48
  49 --- a/fs/jffs2/build.c
  50 +++ b/fs/jffs2/build.c
  51 @@ -211,7 +211,10 @@ static int jffs2_build_filesystem(struct
  52                 ic->scan_dents = NULL;
  53                 cond_resched();
  54         }
  55 -       jffs2_build_xattr_subsystem(c);
  56 +       ret = jffs2_build_xattr_subsystem(c);
  57 +       if (ret)
  58 +               goto exit;
  59 +
  60         c->flags &= ~JFFS2_SB_FLAG_BUILDING;
  61
  62         dbg_fsbuild("FS build complete\n");
  63 --- a/fs/jffs2/xattr.c
  64 +++ b/fs/jffs2/xattr.c
  65 @@ -772,10 +772,10 @@ void jffs2_clear_xattr_subsystem(struct
  66  }
  67
  68  #define XREF_TMPHASH_SIZE      (128)
  69 -void jffs2_build_xattr_subsystem(struct jffs2_sb_info *c)
  70 +int jffs2_build_xattr_subsystem(struct jffs2_sb_info *c)
  71  {
  72         struct jffs2_xattr_ref *ref, *_ref;
  73 -       struct jffs2_xattr_ref *xref_tmphash[XREF_TMPHASH_SIZE];
  74 +       struct jffs2_xattr_ref **xref_tmphash;
  75         struct jffs2_xattr_datum *xd, *_xd;
  76         struct jffs2_inode_cache *ic;
  77         struct jffs2_raw_node_ref *raw;
  78 @@ -784,9 +784,12 @@ void jffs2_build_xattr_subsystem(struct
  79
  80         BUG_ON(!(c->flags & JFFS2_SB_FLAG_BUILDING));
  81
  82 +       xref_tmphash = kcalloc(XREF_TMPHASH_SIZE,
  83 +                              sizeof(struct jffs2_xattr_ref *), GFP_KERNEL);
  84 +       if (!xref_tmphash)
  85 +               return -ENOMEM;
  86 +
  87         /* Phase.1 : Merge same xref */
  88 -       for (i=0; i < XREF_TMPHASH_SIZE; i++)
  89 -               xref_tmphash[i] = NULL;
  90         for (ref=c->xref_temp; ref; ref=_ref) {
  91                 struct jffs2_xattr_ref *tmp;
  92
  93 @@ -884,6 +887,8 @@ void jffs2_build_xattr_subsystem(struct
  94                      "%u of xref (%u dead, %u orphan) found.\n",
  95                      xdatum_count, xdatum_unchecked_count, xdatum_orphan_count,
  96                      xref_count, xref_dead_count, xref_orphan_count);
  97 +       kfree(xref_tmphash);
  98 +       return 0;
  99  }
 100
 101  struct jffs2_xattr_datum *jffs2_setup_xattr_datum(struct jffs2_sb_info *c,
 102 --- a/fs/jffs2/xattr.h
 103 +++ b/fs/jffs2/xattr.h
 104 @@ -71,7 +71,7 @@ static inline int is_xattr_ref_dead(stru
 105  #ifdef CONFIG_JFFS2_FS_XATTR
 106
 107  extern void jffs2_init_xattr_subsystem(struct jffs2_sb_info *c);
 108 -extern void jffs2_build_xattr_subsystem(struct jffs2_sb_info *c);
 109 +extern int jffs2_build_xattr_subsystem(struct jffs2_sb_info *c);
 110  extern void jffs2_clear_xattr_subsystem(struct jffs2_sb_info *c);
 111
 112  extern struct jffs2_xattr_datum *jffs2_setup_xattr_datum(struct jffs2_sb_info *c,
 113 @@ -103,7 +103,7 @@ extern ssize_t jffs2_listxattr(struct de
 114  #else
 115
 116  #define jffs2_init_xattr_subsystem(c)
 117 -#define jffs2_build_xattr_subsystem(c)
 118 +#define jffs2_build_xattr_subsystem(c)         (0)
 119  #define jffs2_clear_xattr_subsystem(c)
 120
 121  #define jffs2_xattr_do_crccheck_inode(c, ic)