use different read and write functions when using direct_io

src/config.cpp

@@ -39,6 +39,7 @@ namespace mergerfs
       srcmountslock(),
       minfreespace(MINFREESPACE_DEFAULT),
       moveonenospc(false),
+      direct_io(false),
       POLICYINIT(access),
       POLICYINIT(chmod),
       POLICYINIT(chown),

src/config.hpp

@@ -47,6 +47,7 @@ namespace mergerfs
     mutable pthread_rwlock_t srcmountslock;
     uint64_t                 minfreespace;
     bool                     moveonenospc;
+    bool                     direct_io;
 
   public:
     const Policy  *policies[FuseFunc::Enum::END];

src/mergerfs.cpp

@@ -78,7 +78,8 @@ namespace local
 
   static
   void
-  get_fuse_operations(struct fuse_operations &ops)
+  get_fuse_operations(struct fuse_operations &ops,
+                      const bool              direct_io)
   {
 #if FLAG_NOPATH
     ops.flag_nopath      = false;
@@ -115,7 +116,9 @@ namespace local
     ops.open        = mergerfs::fuse::open;
     ops.opendir     = mergerfs::fuse::opendir;
     ops.poll        = NULL;
-    ops.read        = mergerfs::fuse::read;
+    ops.read        = direct_io ?
+      mergerfs::fuse::read_direct_io :
+      mergerfs::fuse::read;
 #if READ_BUF
     ops.read_buf    = mergerfs::fuse::read_buf;
 #endif
@@ -133,7 +136,9 @@ namespace local
     ops.unlink      = mergerfs::fuse::unlink;
     ops.utime       = NULL;       /* deprecated; use utimens() */
     ops.utimens     = mergerfs::fuse::utimens;
-    ops.write       = mergerfs::fuse::write;
+    ops.write       = direct_io ?
+      mergerfs::fuse::write_direct_io :
+      mergerfs::fuse::write;
 #if WRITE_BUF
     ops.write_buf   = mergerfs::fuse::write_buf;
 #endif
@@ -172,7 +177,7 @@ namespace mergerfs
     mergerfs::options::parse(args,config);
 
     local::setup_resources();
-    local::get_fuse_operations(ops);
+    local::get_fuse_operations(ops,config.direct_io);
 
     return fuse_main(args.argc,
                      args.argv,

src/option_parser.cpp

@@ -140,10 +140,9 @@ parse_and_process_arg(Config            &config,
                       fuse_args         *outargs)
 {
   if(arg == "defaults")
-    {
-      set_default_options(*outargs);
-      return 0;
-    }
+    return (set_default_options(*outargs),0);
+  else if(arg == "direct_io")
+    return (config.direct_io=true,1);
 
   return 1;
 }

src/read.cpp

@@ -25,6 +25,7 @@
 #include "fs_base_read.hpp"
 
 static
+inline
 int
 _read(const int     fd,
       void         *buf,
@@ -34,8 +35,29 @@ _read(const int     fd,
   int rv;
 
   rv = fs::pread(fd,buf,count,offset);
+  if(rv == -1)
+    return -errno;
+  if(rv == 0)
+    return 0;
 
-  return ((rv == -1) ? -errno : rv);
+  return count;
+}
+
+static
+inline
+int
+_read_direct_io(const int     fd,
+                void         *buf,
+                const size_t  count,
+                const off_t   offset)
+{
+  int rv;
+
+  rv = fs::pread(fd,buf,count,offset);
+  if(rv == -1)
+    return -errno;
+
+  return rv;
 }
 
 namespace mergerfs
@@ -51,10 +73,19 @@ namespace mergerfs
     {
       FileInfo *fi = reinterpret_cast<FileInfo*>(ffi->fh);
 
-      return _read(fi->fd,
-                   buf,
-                   count,
-                   offset);
+      return _read(fi->fd,buf,count,offset);
+    }
+
+    int
+    read_direct_io(const char     *fusepath,
+                   char           *buf,
+                   size_t          count,
+                   off_t           offset,
+                   fuse_file_info *ffi)
+    {
+      FileInfo *fi = reinterpret_cast<FileInfo*>(ffi->fh);
+
+      return _read_direct_io(fi->fd,buf,count,offset);
     }
   }
 }

src/read.hpp

@@ -24,5 +24,12 @@ namespace mergerfs
          size_t          count,
          off_t           offset,
          fuse_file_info *fi);
+
+    int
+    read_direct_io(const char     *fusepath,
+                   char           *buf,
+                   size_t          count,
+                   off_t           offset,
+                   fuse_file_info *fi);
   }
 }

src/write.cpp

@@ -24,6 +24,10 @@
 #include "rwlock.hpp"
 #include "ugid.hpp"
 
+using namespace mergerfs;
+
+typedef int (*WriteFunc)(const int,const void*,const size_t,const off_t);
+
 static
 bool
 _out_of_space(const int error)
@@ -33,6 +37,7 @@ _out_of_space(const int error)
 }
 
 static
+inline
 int
 _write(const int     fd,
        const void   *buf,
@@ -42,25 +47,52 @@ _write(const int     fd,
   int rv;
 
   rv = fs::pwrite(fd,buf,count,offset);
+  if(rv == -1)
+    return -errno;
+  if(rv == 0)
+    return 0;
 
-  return ((rv == -1) ? -errno : rv);
+  return count;
 }
 
+static
+inline
+int
+_write_direct_io(const int     fd,
+                 const void   *buf,
+                 const size_t  count,
+                 const off_t   offset)
+{
+  int rv;
+
+  rv = fs::pwrite(fd,buf,count,offset);
+  if(rv == -1)
+    return -errno;
+
+  return rv;
+}
+
+
+
+
 namespace mergerfs
 {
   namespace fuse
   {
+    static
+    inline
     int
-    write(const char     *fusepath,
+    write(WriteFunc       func,
+          const char     *fusepath,
           const char     *buf,
-          size_t          count,
-          off_t           offset,
+          const size_t    count,
+          const off_t     offset,
           fuse_file_info *ffi)
     {
       int rv;
       FileInfo* fi = reinterpret_cast<FileInfo*>(ffi->fh);
 
-      rv = _write(fi->fd,buf,count,offset);
+      rv = func(fi->fd,buf,count,offset);
       if(_out_of_space(-rv))
         {
           const fuse_context *fc     = fuse_get_context();
@@ -75,11 +107,31 @@ namespace mergerfs
               if(rv == -1)
                 return -ENOSPC;
 
-              rv = _write(fi->fd,buf,count,offset);
+              rv = func(fi->fd,buf,count,offset);
             }
         }
 
       return rv;
     }
+
+    int
+    write(const char     *fusepath,
+          const char     *buf,
+          size_t          count,
+          off_t           offset,
+          fuse_file_info *ffi)
+    {
+      return write(_write,fusepath,buf,count,offset,ffi);
+    }
+
+    int
+    write_direct_io(const char     *fusepath,
+                    const char     *buf,
+                    size_t          count,
+                    off_t           offset,
+                    fuse_file_info *ffi)
+    {
+      return write(_write_direct_io,fusepath,buf,count,offset,ffi);
+    }
   }
 }

src/write.hpp

@@ -24,5 +24,12 @@ namespace mergerfs
           size_t          count,
           off_t           offset,
           fuse_file_info *fi);
+
+    int
+    write_direct_io(const char     *fusepath,
+                    const char     *buf,
+                    size_t          count,
+                    off_t           offset,
+                    fuse_file_info *fi);
   }
 }