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add link_cow feature

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When enabled if a regular file is opened which has a link count > 1 it will
copy the file to a temporary file and rename over the original. Effectively
breaking the link. This behavior is similar to cow-shell and other LD_PRELOAD
based "CoW" solutions.
This commit is contained in:
Antonio SJ Musumeci 2018-10-02 14:22:37 -04:00
parent 19a7d43b31
commit 93f7d7d927
18 changed files with 424 additions and 127 deletions
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57
src/open.cpp
View file

@ -16,61 +16,67 @@
#include <fuse.h>
#include <fcntl.h>
#include <string>
#include <vector>
#include "config.hpp"
#include "errno.hpp"
#include "fileinfo.hpp"
#include "fs_base_open.hpp"
#include "fs_cow.hpp"
#include "fs_path.hpp"
#include "rwlock.hpp"
#include "ugid.hpp"
#include <fcntl.h>
#include <string>
#include <vector>
using std::string;
using std::vector;
using mergerfs::Policy;
static
int
_open_core(const string *basepath,
const char *fusepath,
const int flags,
uint64_t &fh)
_open_core(const string *basepath_,
const char *fusepath_,
const int flags_,
const bool link_cow_,
uint64_t &fh_)
{
int fd;
string fullpath;
fs::path::make(basepath,fusepath,fullpath);
fs::path::make(basepath_,fusepath_,fullpath);
fd = fs::open(fullpath,flags);
if(link_cow_ && fs::cow::is_eligible(fullpath.c_str(),flags_))
fs::cow::break_link(fullpath.c_str());
fd = fs::open(fullpath,flags_);
if(fd == -1)
return -errno;
fh = reinterpret_cast<uint64_t>(new FileInfo(fd,fusepath));
fh_ = reinterpret_cast<uint64_t>(new FileInfo(fd,fusepath_));
return 0;
}
static
int
_open(Policy::Func::Search searchFunc,
const vector<string> &srcmounts,
const uint64_t minfreespace,
const char *fusepath,
const int flags,
uint64_t &fh)
_open(Policy::Func::Search searchFunc_,
const vector<string> &srcmounts_,
const uint64_t minfreespace_,
const char *fusepath_,
const int flags_,
const bool link_cow_,
uint64_t &fh_)
{
int rv;
vector<const string*> basepaths;
rv = searchFunc(srcmounts,fusepath,minfreespace,basepaths);
rv = searchFunc_(srcmounts_,fusepath_,minfreespace_,basepaths);
if(rv == -1)
return -errno;
return _open_core(basepaths[0],fusepath,flags,fh);
return _open_core(basepaths[0],fusepath_,flags_,link_cow_,fh_);
}
namespace mergerfs
@ -78,8 +84,8 @@ namespace mergerfs
namespace fuse
{
int
open(const char *fusepath,
fuse_file_info *ffi)
open(const char *fusepath_,
fuse_file_info *ffi_)
{
const fuse_context *fc = fuse_get_context();
const Config &config = Config::get(fc);
@ -89,9 +95,10 @@ namespace mergerfs
return _open(config.open,
config.srcmounts,
config.minfreespace,
fusepath,
ffi->flags,
ffi->fh);
fusepath_,
ffi_->flags,
config.link_cow,
ffi_->fh);
}
}
}