add-sysfs-bool-support

   1 ext4: add support for adding boolean toggles to ext4's sysfs directory
   2
   3 Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
   4 ---
   5  fs/ext4/super.c | 38 ++++++++++++++++++++++++++++++++++----
   6  1 file changed, 34 insertions(+), 4 deletions(-)
   7
   8 diff --git a/fs/ext4/super.c b/fs/ext4/super.c
   9 index bf1b8a8..2d294b7 100644
  10 --- a/fs/ext4/super.c
  11 +++ b/fs/ext4/super.c
  12 @@ -2535,6 +2535,7 @@ struct ext4_attr {
  13                 int offset;
  14                 int deprecated_val;
  15         } u;
  16 +       unsigned int mask;
  17  };
  18
  19  static int parse_strtoull(const char *buf,
  20 @@ -2677,7 +2678,33 @@ static ssize_t sbi_deprecated_show(struct ext4_attr *a,
  21         return snprintf(buf, PAGE_SIZE, "%d\n", a->u.deprecated_val);
  22  }
  23
  24 -#define EXT4_ATTR_OFFSET(_name,_mode,_show,_store,_elname) \
  25 +static ssize_t sbi_bool_show(struct ext4_attr *a,
  26 +                            struct ext4_sb_info *sbi, char *buf)
  27 +{
  28 +       unsigned int *ui = (unsigned int *) (((char *) sbi) + a->u.offset);
  29 +
  30 +       return snprintf(buf, PAGE_SIZE, "%d\n",
  31 +                       ((*ui & a->mask) == 0) ? 0 : 1);
  32 +}
  33 +
  34 +static ssize_t sbi_bool_store(struct ext4_attr *a,
  35 +                             struct ext4_sb_info *sbi,
  36 +                             const char *buf, size_t count)
  37 +{
  38 +       unsigned int *ui = (unsigned int *) (((char *) sbi) + a->u.offset);
  39 +       unsigned long long t;
  40 +
  41 +       if (parse_strtoull(buf, 0xffffffff, &t))
  42 +               return -EINVAL;
  43 +       if (t)
  44 +               *ui |= a->mask;
  45 +       else
  46 +               *ui &= ~a->mask;
  47 +
  48 +       return count;
  49 +}
  50 +
  51 +#define EXT4_ATTR_OFFSET(_name,_mode,_show,_store,_elname,_mask)\
  52  static struct ext4_attr ext4_attr_##_name = {                  \
  53         .attr = {.name = __stringify(_name), .mode = _mode },   \
  54         .show   = _show,                                        \
  55 @@ -2685,6 +2712,7 @@ static struct ext4_attr ext4_attr_##_name = {                     \
  56         .u = {                                                  \
  57                 .offset = offsetof(struct ext4_sb_info, _elname),\
  58         },                                                      \
  59 +       .mask   = (_mask),                                              \
  60  }
  61
  62  #define EXT4_ATTR_OFFSET_ES(_name,_mode,_show,_store,_elname)          \
  63 @@ -2707,8 +2735,10 @@ static struct ext4_attr ext4_attr_##name = __ATTR(name, mode, show, store)
  64  #define EXT4_RO_ATTR_ES_UI(name, elname)       \
  65         EXT4_ATTR_OFFSET_ES(name, 0444, es_ui_show, NULL, elname)
  66  #define EXT4_RW_ATTR_SBI_UI(name, elname)      \
  67 -       EXT4_ATTR_OFFSET(name, 0644, sbi_ui_show, sbi_ui_store, elname)
  68 -
  69 +       EXT4_ATTR_OFFSET(name, 0644, sbi_ui_show, sbi_ui_store, elname, 0)
  70 +#define EXT4_RW_ATTR_SBI_BOOL(name, elname, mask)                      \
  71 +       EXT4_ATTR_OFFSET(name, 0644, sbi_bool_show, sbi_bool_store,     \
  72 +                        elname, mask)
  73  #define ATTR_LIST(name) &ext4_attr_##name.attr
  74  #define EXT4_DEPRECATED_ATTR(_name, _val)      \
  75  static struct ext4_attr ext4_attr_##_name = {                  \
  76 @@ -2724,7 +2754,7 @@ EXT4_RO_ATTR(session_write_kbytes);
  77  EXT4_RO_ATTR(lifetime_write_kbytes);
  78  EXT4_RW_ATTR(reserved_clusters);
  79  EXT4_ATTR_OFFSET(inode_readahead_blks, 0644, sbi_ui_show,
  80 -                inode_readahead_blks_store, s_inode_readahead_blks);
  81 +                inode_readahead_blks_store, s_inode_readahead_blks, 0);
  82  EXT4_RW_ATTR_SBI_UI(inode_goal, s_inode_goal);
  83  EXT4_RW_ATTR_SBI_UI(mb_stats, s_mb_stats);
  84  EXT4_RW_ATTR_SBI_UI(mb_max_to_scan, s_mb_max_to_scan);