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Rearranged flags a bit

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Mainly to make space for more shared open/mount flags that are future
planned.

The nice thing about our flags is they don't live on-disk, so we can
always change them whenever we need to.

It gets a bit messy, but this is what the current layout looks like:

              8     8     8     8
            .----++----++----++----.
            .----..-..-..----------.
  o_flags:  |type||f||t||    o     |
            |----||-|:-:'--.-.-----'
            |----||-|:-:---:-:-----.
  d_flags:  |type||f|: :   : :     |
            |----||-|:-:---:-:-----'
            |----||-|:-'--..-..----.
  t_flags:  |type||f|| t  ||f||tstt|
            '----''-'|----|'-''----'
            .--------|----|:-:-----.
  gc_flags: |        | t  |: :     |
            '--------|----|:-:-----'
            .----..-.|----|:-:.----.
  f_flags:  | f  ||m|| t  |: :| f  |
            '----'|-||----|:-:'----'
            .----.|-||----||-|.----.
  m_flags:  | i  ||m|| t  ||o|| m  |
            |----||-|'----'|-||----|
            |----||-|------|-||----|
  i_flags:  | i  ||m|      |o|| m  |
            '----''-'------'-''----'

The main downside of this layout is that some of the traversal flags,
LFS_T_DIRTY/MUTATED, now risk ambiguity with open/mount flags. But I
don't think this is really avoidable as traversals are already using
almost the entire 32-bit encoding space...

No code changes:

           code          stack
  before: 36480           2680
  after:  36480 (+0.0%)   2680 (+0.0%)
This commit is contained in:
Christopher Haster
2024-08-12 16:54:10 -05:00
parent 80ef963bec
commit e536300606
2 changed files with 40 additions and 40 deletions
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lfs.c
+4 -4
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@@ -6672,8 +6672,8 @@ static inline bool lfsr_t_ismutated(uint32_t flags) {
}
static inline uint32_t lfsr_t_swapdirty(uint32_t flags) {
uint32_t x = ((flags >> 19) ^ (flags >> 18)) & 0x1;
return flags ^ (x << 19) ^ (x << 18);
uint32_t x = ((flags >> 9) ^ (flags >> 8)) & 0x1;
return flags ^ (x << 9) ^ (x << 8);
}
// mount flags
@@ -13831,7 +13831,7 @@ int lfsr_fs_gc(lfs_t *lfs, lfs_soff_t steps, uint32_t flags) {
uint32_t pending = flags & (
((lfs->flags & (
LFS_I_HASORPHANS
| LFS_I_UNCOMPACTED)) >> 16)
| LFS_I_UNCOMPACTED)) >> 12)
| ((lfsr_fs_canlookahead(lfs)) ? LFS_GC_LOOKAHEAD : 0)
| LFS_GC_CKMETA
| LFS_GC_CKDATA);
@@ -13896,7 +13896,7 @@ int lfsr_fs_gc(lfs_t *lfs, lfs_soff_t steps, uint32_t flags) {
pending &= (
((lfs->flags & (
LFS_I_HASORPHANS
| LFS_I_UNCOMPACTED)) >> 16)
| LFS_I_UNCOMPACTED)) >> 12)
| ((lfsr_fs_canlookahead(lfs)) ? LFS_GC_LOOKAHEAD : 0)
// only consider our filesystem checked if we
// weren't mutated