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scripts: Added simple mroot cycle detectors to dbg scripts

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These work by keeping a set of all seen mroots as we descend down the
mroot chain. Simple, but it works.

The downside of this approach is that the mroot set grows unbounded, but
it's unlikely we'll ever have enough mroots in a system for this to
really matter.

This fixes scripts like dbgbmap.py getting stuck on intentional mroot
cycles created for testing. It's not a problem for a foreground script
to get stuck in an infinite loop, since you can just kill it, but a
background script getting stuck at 100% CPU is a bit more annoying.
This commit is contained in:
Christopher Haster
2024-11-07 02:14:54 -06:00
parent b08c66e387
commit e3fdc3dbd7
9 changed files with 173 additions and 126 deletions
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52
scripts/dbgbmap.py
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@@ -92,10 +92,10 @@ def bdgeom(s):
return int(s, b)
# parse some rbyd addr encodings
# 0xa -> [0xa]
# 0xa.c -> [(0xa, 0xc)]
# 0x{a,b} -> [0xa, 0xb]
# 0x{a,b}.c -> [(0xa, 0xc), (0xb, 0xc)]
# 0xa -> (0xa,)
# 0xa.c -> ((0xa, 0xc),)
# 0x{a,b} -> (0xa, 0xb)
# 0x{a,b}.c -> ((0xa, 0xc), (0xb, 0xc))
def rbydaddr(s):
s = s.strip()
b = 10
@@ -126,7 +126,7 @@ def rbydaddr(s):
else:
addr.append(int(s, b))
return addr
return tuple(addr)
def crc32c(data, crc=0):
crc ^= 0xffffffff
@@ -168,7 +168,7 @@ def frommdir(data):
block, d_ = fromleb128(data[d:])
blocks.append(block)
d += d_
return blocks
return tuple(blocks)
def fromshrub(data):
d = 0
@@ -591,33 +591,34 @@ class Bmap:
# our core rbyd type
class Rbyd:
def __init__(self, block, data, rev, eoff, trunk, weight, cksum):
self.block = block
def __init__(self, blocks, data, rev, eoff, trunk, weight, cksum):
if isinstance(blocks, int):
blocks = (blocks,)
self.blocks = tuple(blocks)
self.data = data
self.rev = rev
self.eoff = eoff
self.trunk = trunk
self.weight = weight
self.cksum = cksum
self.redund_blocks = []
@property
def blocks(self):
return (self.block, *self.redund_blocks)
def block(self):
return self.blocks[0]
def addr(self):
if not self.redund_blocks:
if len(self.blocks) == 1:
return '0x%x.%x' % (self.block, self.trunk)
else:
return '0x{%x,%s}.%x' % (
self.block,
','.join('%x' % block for block in self.redund_blocks),
return '0x{%s}.%x' % (
','.join('%x' % block for block in self.blocks),
self.trunk)
@classmethod
def fetch(cls, f, block_size, blocks, trunk=None):
if isinstance(blocks, int):
blocks = [blocks]
blocks = (blocks,)
if len(blocks) > 1:
# fetch all blocks
@@ -635,9 +636,9 @@ class Rbyd:
i = i_
# keep track of the other blocks
rbyd = rbyds[i]
rbyd.redund_blocks = [
rbyd.blocks += tuple(
rbyds[(i+1+j) % len(rbyds)].block
for j in range(len(rbyds)-1)]
for j in range(len(rbyds)-1))
return rbyd
else:
# block may encode a trunk
@@ -982,13 +983,13 @@ def main(disk, mroots=None, *,
off, = size
size = None
if any(isinstance(b, list) and len(b) > 1 for b in block):
if any(isinstance(b, tuple) and len(b) > 1 for b in block):
print("error: more than one block address?",
file=sys.stderr)
sys.exit(-1)
if isinstance(block[0], list):
if isinstance(block[0], tuple):
block = (block[0][0], *block[1:])
if len(block) > 1 and isinstance(block[1], list):
if len(block) > 1 and isinstance(block[1], tuple):
block = (block[0], block[1][0])
if isinstance(block[0], tuple):
block, off_ = (block[0][0], *block[1:]), block[0][1]
@@ -1058,7 +1059,7 @@ def main(disk, mroots=None, *,
# flatten mroots, default to 0x{0,1}
if not mroots:
mroots = [[0,1]]
mroots = [(0,1)]
mroots = [block for mroots_ in mroots for block in mroots_]
# we seek around a bunch, so just keep the disk open
@@ -1087,11 +1088,18 @@ def main(disk, mroots=None, *,
btrees__ = []
mroot = Rbyd.fetch(f, block_size, mroots)
mdepth = 1
mseen = set()
while True:
# corrupted?
if not mroot:
corrupted = True
break
# cycle detected
elif mroot.blocks in mseen:
corrupted = True
break
mseen.add(mroot.blocks)
# mark mroots in our bmap
for block in mroot.blocks: