mergerfs/src/link.cpp
Antonio SJ Musumeci 5808ab7795 move on enospc when writing feature. closes #141
This feature mimics the standard mhddfs behavior but is more thorough.
If a write fails and the errno is set to ENOSPC then mergerfs will (if
the feature is enabled) attempt to move the file to the drive with
the most free space but only if it has enough room for the file plus
the amount to be written. If that transfer is successful it will then
unlink the original file and attempt the previously failed write again.

The copy includes copying the path and file including the acls, owners,
attributes, extended attributes, and timestamps.
2015-09-25 15:14:17 -04:00

129 lines
3.5 KiB
C++

/*
The MIT License (MIT)
Copyright (c) 2014 Antonio SJ Musumeci <trapexit@spawn.link>
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.
*/
#include <fuse.h>
#include <string>
#include <vector>
#include <errno.h>
#include <unistd.h>
#include "config.hpp"
#include "fs_clonepath.hpp"
#include "fs_path.hpp"
#include "rwlock.hpp"
#include "ugid.hpp"
using std::string;
using std::vector;
using mergerfs::Policy;
using namespace mergerfs;
static
int
_single_link(Policy::Func::Search searchFunc,
const vector<string> &srcmounts,
const size_t minfreespace,
const string &base,
const string &oldpath,
const string &newpath)
{
int rv;
const string fulloldpath = fs::path::make(base,oldpath);
const string fullnewpath = fs::path::make(base,newpath);
rv = ::link(fulloldpath.c_str(),fullnewpath.c_str());
if(rv == -1 && errno == ENOENT)
{
string newpathdir;
vector<string> foundpath;
newpathdir = fs::path::dirname(newpath);
rv = searchFunc(srcmounts,newpathdir,minfreespace,foundpath);
if(rv == -1)
return -1;
{
const ugid::SetRootGuard ugidGuard;
fs::clonepath(foundpath[0],base,newpathdir);
}
rv = ::link(fulloldpath.c_str(),fullnewpath.c_str());
}
return rv;
}
static
int
_link(Policy::Func::Search searchFunc,
Policy::Func::Action actionFunc,
const vector<string> &srcmounts,
const size_t minfreespace,
const string &oldpath,
const string &newpath)
{
int rv;
int error;
vector<string> oldpaths;
rv = actionFunc(srcmounts,oldpath,minfreespace,oldpaths);
if(rv == -1)
return -errno;
error = 0;
for(size_t i = 0, ei = oldpaths.size(); i != ei; i++)
{
rv = _single_link(searchFunc,srcmounts,minfreespace,oldpaths[i],oldpath,newpath);
if(rv == -1)
error = errno;
}
return -error;
}
namespace mergerfs
{
namespace fuse
{
int
link(const char *from,
const char *to)
{
const fuse_context *fc = fuse_get_context();
const Config &config = Config::get(fc);
const ugid::Set ugid(fc->uid,fc->gid);
const rwlock::ReadGuard readlock(&config.srcmountslock);
return _link(config.getattr,
config.link,
config.srcmounts,
config.minfreespace,
from,
to);
}
}
}