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mergerfs/src/config.cpp
Grioghar 5f6275baea qos: match on cmdline, and never throttle critical dependencies 
Two gaps found while using this against a real media server.

Some programs do very different jobs under one name. Plex runs credits
detection with the same 'Plex Transcoder' binary that serves playback,
reading the same file, so neither comm nor path separates them. Adds a
cmdline match field, and quoting so a pattern can contain spaces --
without which 'Plex Transcoder' cannot be written down at all.

Adds a 'critical' class flag for services playback synchronously waits
on. Plex's EasyAudioEncoder is the case: a transcode of EAC3 audio
writes to EAE and blocks. Such a helper looks like background work, so
a governor protecting playback will throttle or suspend it and hang the
stream waiting behind it. A critical class is never delayed.

Also fixes qos.max-sleepers auto-sizing, which read the requested
thread count rather than the resolved one and so capped at 1.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
2026-09-09 17:21:57 -05:00

534 lines
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/*
ISC License
Copyright (c) 2026, Antonio SJ Musumeci <trapexit@spawn.link>
Permission to use, copy, modify, and/or distribute this software for any
purpose with or without fee is hereby granted, provided that the above
copyright notice and this permission notice appear in all copies.
THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*/
#include "config.hpp"
#include "errno.hpp"
#include "fmt/core.h"
#include "fs_path.hpp"
#include "nonstd/string.hpp"
#include "str.hpp"
#include "version.hpp"
#include <fstream>
#include <string>
#include <string.h>
constexpr const char CACHE_FILES_PROCESS_NAMES_DEFAULT[] =
"rtorrent|"
"qbittorrent-nox";
Config cfg;
thread_local int Config::CfgConfigFile::_depth = 0;
Config::CfgConfigFile::CfgConfigFile()
{
}
int
Config::CfgConfigFile::from_string(const std::string_view s_)
{
int rv;
fs::path cfg_file;
if(_depth > 5)
return -ELOOP;
_depth++;
struct DepthGuard { int &d; ~DepthGuard() { --d; } } guard{_depth};
cfg_file = (s_.empty() ? _cfg_file : s_);
rv = cfg.from_file(cfg_file);
if(rv == 0)
_cfg_file = cfg_file;
return rv;
}
std::string
Config::CfgConfigFile::to_string() const
{
return _cfg_file;
}
Config::Config()
:
allow_idmap(true),
async_read(true),
branches(),
branches_mount_timeout(0),
branches_mount_timeout_fail(false),
cache_attr(1),
cache_entry(1),
cache_files(CacheFiles::ENUM::OFF),
cache_files_process_names(CACHE_FILES_PROCESS_NAMES_DEFAULT),
cache_negative_entry(0),
cache_readdir(false),
cache_statfs(0),
cache_symlinks(false),
cache_writeback(false),
category(func),
config_file(),
direct_io_allow_mmap(true),
dropcacheonclose(false),
export_support(true),
flushonclose(FlushOnClose::ENUM::OPENED_FOR_WRITE),
follow_symlinks(FollowSymlinks::ENUM::NEVER),
fsname(),
func(),
fuse_msg_size("1M"),
handle_killpriv(true),
handle_killpriv_v2(true),
ignorepponrename(false),
inodecalc("hybrid-hash"),
kernel_permissions_check(true),
lazy_umount_mountpoint(false),
link_cow(false),
link_exdev(LinkEXDEV::ENUM::PASSTHROUGH),
log_file({}),
minfreespace(branches.minfreespace),
mountpoint(),
moveonenospc(true),
nfsopenhack(NFSOpenHack::ENUM::OFF),
nullrw(false),
parallel_direct_writes(true),
passthrough_io(PassthroughIO::ENUM::OFF),
passthrough_max_stack_depth(fuse_cfg.passthrough_max_stack_depth),
pin_threads(fuse_cfg.pin_threads),
posix_acl(false),
process_thread_count(fuse_cfg.process_thread_count),
process_thread_queue_depth(fuse_cfg.process_thread_queue_depth),
proxy_ioprio(false),
qos(false),
read_thread_count(fuse_cfg.read_thread_count),
readahead(0),
readdir("seq"),
rename_exdev(RenameEXDEV::ENUM::PASSTHROUGH),
scheduling_priority(-10),
security_capability(true),
statfs(StatFS::ENUM::BASE),
statfs_ignore(StatFSIgnore::ENUM::NONE),
symlinkify(false),
symlinkify_timeout(3600),
xattr(XAttr::ENUM::PASSTHROUGH),
_congestion_threshold(fuse_cfg.congestion_threshold),
_debug(false),
_gid(fuse_cfg.gid),
_max_background(fuse_cfg.max_background),
_mount(mountpoint),
_mountpoint(mountpoint),
_srcmounts(branches),
_threads(fuse_cfg.read_thread_count),
_uid(fuse_cfg.uid),
_umask(fuse_cfg.umask),
_version(MERGERFS_VERSION),
_initialized(false)
{
_congestion_threshold.ro =
_max_background.ro =
_mount.ro =
_mountpoint.ro =
_never_forget_nodes.ro =
_noforget.ro =
_remember.ro =
_remember_nodes.ro =
_srcmounts.ro =
_version.ro =
allow_idmap.ro =
async_read.ro =
branches_mount_timeout.ro =
branches_mount_timeout_fail.ro =
cache_symlinks.ro =
cache_writeback.ro =
direct_io_allow_mmap.ro =
export_support.ro =
fsname.ro =
fuse_msg_size.ro =
handle_killpriv.ro =
handle_killpriv_v2.ro =
kernel_permissions_check.ro =
nullrw.ro =
pid.ro =
pin_threads.ro =
posix_acl.ro =
process_thread_count.ro =
process_thread_queue_depth.ro =
read_thread_count.ro =
scheduling_priority.ro =
true;
_congestion_threshold.display =
_gid.display =
_max_background.display =
_mount.display =
_noforget.display =
_remember.display =
_remember_nodes.display =
_srcmounts.display =
_threads.display =
_uid.display =
_umask.display =
false;
_map["allow-idmap"] = &allow_idmap;
_map["async-read"] = &async_read;
_map["atomic-o-trunc"] = &_dummy;
_map["auto-cache"] = &_dummy;
_map["big-writes"] = &_dummy;
_map["branches"] = &branches;
_map["branches-mount-timeout"] = &branches_mount_timeout;
_map["branches-mount-timeout-fail"] = &branches_mount_timeout_fail;
_map["cache.attr"] = &cache_attr;
_map["cache.entry"] = &cache_entry;
_map["cache.files"] = &cache_files;
_map["cache.files.process-names"] = &cache_files_process_names;
_map["cache.negative-entry"] = &cache_negative_entry;
_map["cache.open"] = &_dummy;
_map["cache.readdir"] = &cache_readdir;
_map["cache.statfs"] = &cache_statfs;
_map["cache.symlinks"] = &cache_symlinks;
_map["cache.writeback"] = &cache_writeback;
_map["category.action"] = &category.action;
_map["category.create"] = &category.create;
_map["category.search"] = &category.search;
_map["config"] = &config_file;
_map["debug"] = &_debug;
_map["defaults"] = &_dummy;
_map["direct-io"] = &_dummy;
_map["direct-io-allow-mmap"] = &direct_io_allow_mmap;
_map["dropcacheonclose"] = &dropcacheonclose;
_map["export-support"] = &export_support;
_map["flush-on-close"] = &flushonclose;
_map["follow-symlinks"] = &follow_symlinks;
_map["fsname"] = &fsname;
_map["func.access"] = &func.access;
_map["func.chmod"] = &func.chmod;
_map["func.chown"] = &func.chown;
_map["func.create"] = &func.create;
_map["func.getattr"] = &func.getattr;
_map["func.getxattr"] = &func.getxattr;
_map["func.link"] = &func.link;
_map["func.listxattr"] = &func.listxattr;
_map["func.mkdir"] = &func.mkdir;
_map["func.mknod"] = &func.mknod;
_map["func.open"] = &func.open;
_map["func.readdir"] = &readdir;
_map["func.readlink"] = &func.readlink;
_map["func.removexattr"] = &func.removexattr;
_map["func.rename"] = &func.rename;
_map["func.rmdir"] = &func.rmdir;
_map["func.setxattr"] = &func.setxattr;
_map["func.symlink"] = &func.symlink;
_map["func.truncate"] = &func.truncate;
_map["func.unlink"] = &func.unlink;
_map["func.utimens"] = &func.utimens;
_map["fuse-msg-size"] = &fuse_msg_size;
_map["gid"] = &_gid;
_map["gid-cache.expire-timeout"] = &_dummy;
_map["gid-cache.remove-timeout"] = &_dummy;
_map["handle-killpriv"] = &handle_killpriv;
_map["handle-killpriv-v2"] = &handle_killpriv_v2;
_map["hard-remove"] = &_dummy;
_map["ignorepponrename"] = &ignorepponrename;
_map["inodecalc"] = &inodecalc;
_map["kernel-cache"] = &_dummy;
_map["kernel-permissions-check"] = &kernel_permissions_check;
_map["lazy-umount-mountpoint"] = &lazy_umount_mountpoint;
_map["link-cow"] = &link_cow;
_map["link-exdev"] = &link_exdev;
_map["log.file"] = &log_file;
_map["minfreespace"] = &minfreespace;
_map["mount"] = &_mount;
_map["mountpoint"] = &_mountpoint;
_map["moveonenospc"] = &moveonenospc;
_map["negative-entry"] = &_dummy;
_map["never-forget-nodes"] = &_never_forget_nodes;
_map["nfsopenhack"] = &nfsopenhack;
_map["no-splice-move"] = &_dummy;
_map["no-splice-read"] = &_dummy;
_map["no-splice-write"] = &_dummy;
_map["noforget"] = &_noforget;
_map["nonempty"] = &_dummy;
_map["nullrw"] = &nullrw;
_map["parallel-direct-writes"] = &parallel_direct_writes;
_map["passthrough.io"] = &passthrough_io;
_map["passthrough.max-stack-depth"] = &passthrough_max_stack_depth;
_map["pid"] = &pid;
_map["pin-threads"] = &pin_threads;
_map["posix-acl"] = &posix_acl;
_map["process-thread-count"] = &process_thread_count;
_map["process-thread-queue-depth"] = &process_thread_queue_depth;
_map["proxy-ioprio"] = &proxy_ioprio;
_map["read-thread-count"] = &read_thread_count;
_map["readahead"] = &readahead;
_map["remember"] = &_remember;
_map["remember-nodes"] = &_remember_nodes;
_map["qos"] = &qos;
_map["qos.distress-factor"] = &qos_distress_factor;
_map["qos.distress-ms"] = &qos_distress_ms;
_map["qos.max-sleep-ms"] = &qos_max_sleep_ms;
_map["qos.max-sleepers"] = &qos_max_sleepers;
_map["qos.rules"] = &qos_rules;
_map["qos.ruleset"] = &qos_ruleset;
_map["qos.stats"] = &qos_stats;
_map["rename-exdev"] = &rename_exdev;
_map["scheduling-priority"] = &scheduling_priority;
_map["security-capability"] = &security_capability;
_map["splice-move"] = &_dummy;
_map["splice-read"] = &_dummy;
_map["splice-write"] = &_dummy;
_map["srcmounts"] = &_srcmounts;
_map["statfs"] = &statfs;
_map["statfs-ignore"] = &statfs_ignore;
_map["symlinkify"] = &symlinkify;
_map["symlinkify-timeout"] = &symlinkify_timeout;
_map["threads"] = &_threads;
_map["uid"] = &_uid;
_map["umask"] = &_umask;
_map["use-ino"] = &_dummy;
_map["version"] = &_version;
_map["xattr"] = &xattr;
}
bool
Config::has_key(const std::string &key_) const
{
return _map.count(key_);
}
ssize_t
Config::keys_listxattr_size() const
{
ssize_t rv;
rv = 0;
for(const auto &[key,val] : _map)
{
if(val->display == false)
continue;
rv += sizeof("user.mergerfs.");
rv += key.size();
}
return rv;
}
ssize_t
Config::keys_listxattr(char *list_,
size_t size_) const
{
char *list = list_;
ssize_t size = size_;
if(size_ == 0)
return keys_listxattr_size();
for(const auto &[key,val] : _map)
{
if(val->display == false)
continue;
static constexpr std::string_view prefix = "user.mergerfs.";
ssize_t entry_size = (ssize_t)(prefix.size() + key.size() + 1);
if(entry_size > size)
return -ERANGE;
memcpy(list, prefix.data(), prefix.size());
list += prefix.size();
memcpy(list, key.data(), key.size());
list += key.size();
*list++ = '\0';
size -= entry_size;
}
return (list - list_);
}
int
Config::get(const std::string &key_,
std::string *val_) const
{
std::string key;
Str2TFStrMap::const_iterator i;
key = str::replace(key_,'_','-');
i = _map.find(key);
if(i == _map.end())
return -ENOATTR;
*val_ = i->second->to_string();
return 0;
}
int
Config::set(const std::string &key_,
const std::string &value_)
{
std::string key;
Str2TFStrMap::iterator i;
key = str::replace(key_,'_','-');
i = _map.find(key);
if(i == _map.end())
return -ENOATTR;
if(_initialized && i->second->ro)
return -EROFS;
return i->second->from_string(value_);
}
int
Config::set(const std::string &kv_)
{
auto [key, val] = str::splitkv(kv_,'=');
key = str::trim(key);
val = str::trim(val);
return set(key,val);
}
int
Config::from_stream(std::istream &istrm_)
{
std::string line;
Config::ErrVec new_errs;
while(std::getline(istrm_,line,'\n'))
{
line = str::trim(line);
if(line.empty() || (line[0] == '#'))
continue;
int rv = set(line);
if(rv < 0)
new_errs.push_back({-rv,line});
}
errs.insert(errs.end(),
new_errs.begin(),
new_errs.end());
return (new_errs.empty() ? 0 : -EINVAL);
}
int
Config::from_file(const std::string &filepath_)
{
std::ifstream ifstrm;
errno = 0;
ifstrm.open(filepath_);
if(!ifstrm.good())
{
errno = errno ? errno : EIO;
errs.push_back({errno,filepath_});
return -errno;
}
return from_stream(ifstrm);
}
void
Config::finish_initializing()
{
_initialized = true;
}
bool
Config::is_rootdir(const fs::path &fusepath_)
{
return fusepath_.empty();
}
bool
Config::is_ctrl_file(const fs::path &fusepath_)
{
return (fusepath_ == ".mergerfs");
}
bool
Config::is_mergerfs_xattr(const char *attrname_)
{
return str::startswith(attrname_,"user.mergerfs.");
}
bool
Config::is_cmd_xattr(const std::string_view &attrname_)
{
return nonstd::starts_with(attrname_,"user.mergerfs.cmd.");
}
std::string_view
Config::prune_ctrl_xattr(const std::string_view s_)
{
constexpr size_t offset = (sizeof("user.mergerfs.") - 1);
if(offset < s_.size())
return s_.substr(offset);
return {};
}
std::string_view
Config::prune_cmd_xattr(const std::string_view &s_)
{
constexpr size_t offset = (sizeof("user.mergerfs.cmd.") - 1);
if(offset < s_.size())
return s_.substr(offset);
return {};
}
std::string
Config::Err::to_string() const
{
std::string s;
switch(err)
{
case 0:
break;
case EINVAL:
s = "invalid value";
break;
case ENOATTR:
s = "unknown option";
break;
case EROFS:
s = "read-only option";
break;
case ELOOP:
s = "too many levels of config";
break;
case ENOENT:
s = "no value set";
break;
default:
s = strerror(err);
break;
}
return fmt::format("{} - {}",s,str);
}
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