dont-update-s_rev_level-if-not-required

   1 ext4: don't update s_rev_level if not required
   2
   3 From: Andreas Dilger <adilger@dilger.ca>
   4
   5 Don't update the superblock s_rev_level during mount if it isn't
   6 actually necessary, only if superblock features are being set by
   7 the kernel.  This was originally added for ext3 since it always
   8 set the INCOMPAT_RECOVER and HAS_JOURNAL features during mount,
   9 but this is not needed since no journal mode was added to ext4.
  10
  11 That will allow Geert to mount his 20-year-old ext2 rev 0.0 m68k
  12 filesystem, as a testament of the backward compatibility of ext4.
  13
  14 Fixes: 0390131ba84f ("ext4: Allow ext4 to run without a journal")
  15 Signed-off-by: Andreas Dilger <adilger@dilger.ca>
  16 Signed-off-by: Theodore Ts'o <tytso@mit.edu>
  17 ---
  18  fs/ext4/ext4.h  | 6 +++++-
  19  fs/ext4/inode.c | 1 -
  20  fs/ext4/super.c | 1 -
  21  3 files changed, 5 insertions(+), 3 deletions(-)
  22
  23 diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
  24 index 508a37ec9271..b8fde74ff76d 100644
  25 --- a/fs/ext4/ext4.h
  26 +++ b/fs/ext4/ext4.h
  27 @@ -1665,6 +1665,8 @@ static inline void ext4_clear_state_flags(struct ext4_inode_info *ei)
  28  #define EXT4_FEATURE_INCOMPAT_INLINE_DATA      0x8000 /* data in inode */
  29  #define EXT4_FEATURE_INCOMPAT_ENCRYPT          0x10000
  30
  31 +extern void ext4_update_dynamic_rev(struct super_block *sb);
  32 +
  33  #define EXT4_FEATURE_COMPAT_FUNCS(name, flagname) \
  34  static inline bool ext4_has_feature_##name(struct super_block *sb) \
  35  { \
  36 @@ -1673,6 +1675,7 @@ static inline bool ext4_has_feature_##name(struct super_block *sb) \
  37  } \
  38  static inline void ext4_set_feature_##name(struct super_block *sb) \
  39  { \
  40 +       ext4_update_dynamic_rev(sb); \
  41         EXT4_SB(sb)->s_es->s_feature_compat |= \
  42                 cpu_to_le32(EXT4_FEATURE_COMPAT_##flagname); \
  43  } \
  44 @@ -1690,6 +1693,7 @@ static inline bool ext4_has_feature_##name(struct super_block *sb) \
  45  } \
  46  static inline void ext4_set_feature_##name(struct super_block *sb) \
  47  { \
  48 +       ext4_update_dynamic_rev(sb); \
  49         EXT4_SB(sb)->s_es->s_feature_ro_compat |= \
  50                 cpu_to_le32(EXT4_FEATURE_RO_COMPAT_##flagname); \
  51  } \
  52 @@ -1707,6 +1711,7 @@ static inline bool ext4_has_feature_##name(struct super_block *sb) \
  53  } \
  54  static inline void ext4_set_feature_##name(struct super_block *sb) \
  55  { \
  56 +       ext4_update_dynamic_rev(sb); \
  57         EXT4_SB(sb)->s_es->s_feature_incompat |= \
  58                 cpu_to_le32(EXT4_FEATURE_INCOMPAT_##flagname); \
  59  } \
  60 @@ -2675,7 +2680,6 @@ do {                                                                      \
  61
  62  #endif
  63
  64 -extern void ext4_update_dynamic_rev(struct super_block *sb);
  65  extern int ext4_update_compat_feature(handle_t *handle, struct super_block *sb,
  66                                         __u32 compat);
  67  extern int ext4_update_rocompat_feature(handle_t *handle,
  68 diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
  69 index 9c3402ec85bc..2b6eefbc3b34 100644
  70 --- a/fs/ext4/inode.c
  71 +++ b/fs/ext4/inode.c
  72 @@ -5345,7 +5345,6 @@ static int ext4_do_update_inode(handle_t *handle,
  73                 err = ext4_journal_get_write_access(handle, EXT4_SB(sb)->s_sbh);
  74                 if (err)
  75                         goto out_brelse;
  76 -               ext4_update_dynamic_rev(sb);
  77                 ext4_set_feature_large_file(sb);
  78                 ext4_handle_sync(handle);
  79                 err = ext4_handle_dirty_super(handle, sb);
  80 diff --git a/fs/ext4/super.c b/fs/ext4/super.c
  81 index fb12d3c17c1b..6e4cac646345 100644
  82 --- a/fs/ext4/super.c
  83 +++ b/fs/ext4/super.c
  84 @@ -2249,7 +2249,6 @@ static int ext4_setup_super(struct super_block *sb, struct ext4_super_block *es,
  85                 es->s_max_mnt_count = cpu_to_le16(EXT4_DFL_MAX_MNT_COUNT);
  86         le16_add_cpu(&es->s_mnt_count, 1);
  87         ext4_update_tstamp(es, s_mtime);
  88 -       ext4_update_dynamic_rev(sb);
  89         if (sbi->s_journal)
  90                 ext4_set_feature_journal_needs_recovery(sb);
  91