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#!/usr/bin/python3
#
# Copyright (C) 2017 Hans van Kranenburg <hans@knorrie.org>
#
# Permission is hereby granted, free of charge, to any person obtaining
# a copy of this software and associated documentation files (the
# "Software"), to deal in the Software without restriction, including
# without limitation the rights to use, copy, modify, merge, publish,
# distribute, sublicense, and/or sell copies of the Software, and to
# permit persons to whom the Software is furnished to do so, subject to
# the following conditions:
#
# The above copyright notice and this permission notice shall be included
# in all copies or substantial portions of the Software.
#
# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
# EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
# MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
# IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
# CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
# TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
# SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
import argparse
import btrfs
import errno
import heapq
import sys
import time
class Bork(Exception):
pass
def load_block_groups(fs, max_used_pct):
min_used_pct = 101
block_groups = []
print("Loading block group objects with used_pct <= {} ...".format(max_used_pct),
end='', flush=True)
for chunk in fs.chunks():
if not (chunk.type & btrfs.BLOCK_GROUP_DATA):
continue
try:
block_group = fs.block_group(chunk.vaddr, chunk.length)
if block_group.used_pct <= max_used_pct:
block_groups.append((block_group.used_pct, block_group))
if block_group.used_pct < min_used_pct:
min_used_pct = block_group.used_pct
except IndexError:
continue
heapq.heapify(block_groups)
print(" found {}".format(len(block_groups)))
return min_used_pct, block_groups
def balance_one_block_group(fs, block_groups, max_used_pct):
next_used_pct, next_block_group = block_groups[0]
try:
block_group = fs.block_group(next_block_group.vaddr, next_block_group.length)
except IndexError:
heapq.heappop(block_groups)
return
vaddr = block_group.vaddr
used_pct = block_group.used_pct
if used_pct > next_used_pct:
if used_pct > max_used_pct:
print("Ignoring block group vaddr {} used_pct changed {} -> {}".format(
vaddr, next_used_pct, used_pct))
heapq.heappop(block_groups)
else:
print("Postponing block group vaddr {} used_pct changed {} -> {}".format(
vaddr, next_used_pct, used_pct))
heapq.heapreplace(block_groups, (used_pct, block_group))
return
start_time = time.time()
heapq.heappop(block_groups)
args = btrfs.ioctl.BalanceArgs(vstart=vaddr, vend=vaddr+1)
print("Balance block group vaddr {} used_pct {} ...".format(
vaddr, used_pct), end='', flush=True)
try:
progress = btrfs.ioctl.balance_v2(fs.fd, data_args=args)
end_time = time.time()
print(" duration {} sec total {}".format(int(end_time - start_time), progress.considered))
except KeyboardInterrupt:
end_time = time.time()
print(" duration {} sec".format(int(end_time - start_time)))
raise
def parse_args():
parser = argparse.ArgumentParser()
parser.add_argument(
'-u',
'--usage',
type=int,
default=100,
help="Only consider block groups with less than this percentage used",
)
parser.add_argument(
'mountpoint',
help="Btrfs filesystem mountpoint",
)
return parser.parse_args()
def permission_check(fs):
"""This is a simple canary function that explodes if the user does not have
enough permissions to use the search ioctl.
"""
fs.top_level()
def main():
args = parse_args()
max_used_pct = args.usage
path = args.mountpoint
try:
with btrfs.FileSystem(path) as fs:
permission_check(fs)
min_used_pct, block_groups = load_block_groups(fs, max_used_pct)
if len(block_groups) == 0:
print("Nothing to do, least used block group has used_pct {}".format(min_used_pct))
return
while len(block_groups) > 0:
balance_one_block_group(fs, block_groups, max_used_pct)
except OSError as e:
if e.errno == errno.EPERM:
raise Bork("Insufficient permissions to use the btrfs kernel API.\n"
"Hint: Try running the script as root user.".format(e))
elif e.errno == errno.ENOTTY:
raise Bork("Unable to retrieve data. Hint: Not a mounted btrfs file system?")
raise
if __name__ == '__main__':
try:
main()
except KeyboardInterrupt:
print("Exiting...")
sys.exit(130) # 128 + SIGINT
except Bork as e:
print("Error: {0}".format(e), file=sys.stderr)
sys.exit(1)
except Exception as e:
print(e)
sys.exit(1)
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