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bmap: Initial scaffolding for on-disk block map

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This is pretty exploratory work, so I'm going to try to be less thorough
in commit messages until the dust settles.

---

New tag for gbmapdelta:

  LFS3_TAG_GBMAPDELTA   0x0104  v--- ---1 ---- -1rr

New tags for in-bmap block types:

  LFS3_TAG_BMRANGE      0x033u  v--- --11 --11 uuuu
  LFS3_TAG_BMFREE       0x0330  v--- --11 --11 ----
  LFS3_TAG_BMINFLIGHT   0x0331  v--- --11 --11 ---1
  LFS3_TAG_BMINUSE      0x0332  v--- --11 --11 --1-
  LFS3_TAG_BMBAD        0x0333  v--- --11 --11 --11
  LFS3_TAG_BMERASED     0x0334  v--- --11 --11 -1--

New gstate decoding for gbmap:

  .---+- -+- -+- -+- -. cursor: 1 leb128  <=5 bytes
  | cursor            | known:  1 leb128  <=5 bytes
  +---+- -+- -+- -+- -+ block:  1 leb128  <=5 bytes
  | known             | trunk:  1 leb128  <=4 bytes
  +---+- -+- -+- -+- -+ cksum:  1 le32    4 bytes
  | block             | total:            23 bytes
  +---+- -+- -+- -+- -'
  | trunk         |
  +---+- -+- -+- -+
  |     cksum     |
  '---+---+---+---'

New bmap node revdbg string:

  vvv---- -111111- -11---1- -11---1-  (62 62 7e v0  bb~r)  bmap node

New mount/format/info flags (still unsure about these):

  LFS3_M_BMAPMODE     0x03000000  On-disk block map mode
  LFS3_M_BMAPNONE     0x00000000  Don't use the bmap
  LFS3_M_BMAPCACHE    0x01000000  Use the bmap to cache lookahead scans
  LFS3_M_BMAPSLOW     0x02000000  Use the slow bmap algorithm
  LFS3_M_BMAPFAST     0x03000000  Use the fast bmap algorithm

New gbmap wcompat flag:

  LFS3_WCOMPAT_GBMAP  0x00002000  Global block-map in use
This commit is contained in:
Christopher Haster
2025-07-23 15:32:35 -05:00
parent 238dbc705d
commit 88180b6081
13 changed files with 755 additions and 58 deletions
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scripts/dbgflags.py
+22 -1
View File
@@ -72,6 +72,12 @@ FLAGS = [
('F_CKMETA', 0x00001000, "Check metadata checksums" ),
('F_CKDATA', 0x00002000, "Check metadata + data checksums" ),
('F_BMAPMODE', 0x03000000, "On-disk block map mode" ),
('^_BMAPNONE', 0x00000000, "Don't use the bmap" ),
('^_BMAPCACHE', 0x01000000, "Use the bmap to cache lookahead scans" ),
('^_BMAPSLOW', 0x02000000, "Use the slow bmap algorithm" ),
('^_BMAPFAST', 0x03000000, "Use the fast bmap algorithm" ),
# Filesystem mount flags
('M_MODE', 1, "Mount's access mode" ),
('^_RDWR', 0, "Mount the filesystem as read and write" ),
@@ -91,6 +97,12 @@ FLAGS = [
('M_CKMETA', 0x00001000, "Check metadata checksums" ),
('M_CKDATA', 0x00002000, "Check metadata + data checksums" ),
('M_BMAPMODE', 0x03000000, "On-disk block map mode" ),
('^_BMAPNONE', 0x00000000, "Don't use the bmap" ),
('^_BMAPCACHE', 0x01000000, "Use the bmap to cache lookahead scans" ),
('^_BMAPSLOW', 0x02000000, "Use the slow bmap algorithm" ),
('^_BMAPFAST', 0x03000000, "Use the fast bmap algorithm" ),
# GC flags
('GC_MKCONSISTENT',0x00000100, "Make the filesystem consistent" ),
('GC_LOOKAHEAD', 0x00000200, "Populate lookahead buffer" ),
@@ -115,7 +127,15 @@ FLAGS = [
('I_CKMETA', 0x00001000, "Metadata checksums not checked recently" ),
('I_CKDATA', 0x00002000, "Data checksums not checked recently" ),
('i_INMTREE', 0x08000000, "Committing to mtree" ),
('I_BMAPMODE', 0x03000000, "On-disk block map mode" ),
('^_BMAPNONE', 0x00000000, "Mounted with LFS3_M_BMAPNONE" ),
('^_BMAPCACHE', 0x01000000, "Mounted with LFS3_M_BMAPCACHE" ),
('^_BMAPSLOW', 0x02000000, "Mounted with LFS3_M_BMAPSLOW" ),
('^_BMAPFAST', 0x03000000, "Mounted with LFS3_M_BMAPFAST" ),
('i_INMTREE', 0x00030000, "Committing to mtree" ),
('^_INMTREE', 0x00010000, "Committing to mtree" ),
('^_INBMAP', 0x00020000, "Committing to bmap" ),
# Traversal flags
('T_MODE', 1, "The traversal's access mode" ),
@@ -181,6 +201,7 @@ FLAGS = [
('WCOMPAT_RDONLY', 0x00000002, "Writing is disallowed" ),
('WCOMPAT_DIR', 0x00000010, "Directory file types in use" ),
('WCOMPAT_GCKSUM', 0x00001000, "Global-checksum in use" ),
('WCOMPAT_GBMAP', 0x00002000, "Global block-map in use" ),
('wcompat_OVERFLOW',
0x80000000, "Can't represent all flags" ),