* fhandler.cc (fhandler_base::write): Don't attempt to sparsify

	an already sparse file.  Drop check for FILE_SUPPORTS_SPARSE_FILES
	flag.  Explicitely set FILE_ATTRIBUTE_SPARSE_FILE attribute in
	cached attributes.
	(fhandler_base::lseek): Only set did_lseek if sparseness is supported.
	* fhandler_disk_file.cc (fhandler_disk_file::ftruncate): Don't attempt
	to sparsify an already sparse file.  Explicitely set
	FILE_ATTRIBUTE_SPARSE_FILE attribute in cached attributes.
	* mount.cc (oopt): Add "sparse" flag.
	(fillout_mntent): Ditto.
	* path.h (enum path_types): Add PATH_SPARSE.
	(path_conv::support_sparse): New method.
	(path_conv::fs_flags): Constify.
	(path_conv::fs_name_len): Ditto.
	include/sys/mount.h: Replace unused MOUNT_MIXED flag with MOUNT_SPARSE.

6 files changed, 48 insertions, 12 deletions

diff --git a/winsup/cygwin/ChangeLog b/winsup/cygwin/ChangeLog
index f9bca392e..9311dd863 100644
--- a/winsup/cygwin/ChangeLog
+++ b/winsup/cygwin/ChangeLog
@@ -1,3 +1,21 @@
+2012-12-14  Corinna Vinschen  <corinna@vinschen.de>
+
+	* fhandler.cc (fhandler_base::write): Don't attempt to sparsify
+	an already sparse file.  Drop check for FILE_SUPPORTS_SPARSE_FILES
+	flag.  Explicitely set FILE_ATTRIBUTE_SPARSE_FILE attribute in
+	cached attributes.
+	(fhandler_base::lseek): Only set did_lseek if sparseness is supported.
+	* fhandler_disk_file.cc (fhandler_disk_file::ftruncate): Don't attempt
+	to sparsify an already sparse file.  Explicitely set
+	FILE_ATTRIBUTE_SPARSE_FILE attribute in cached attributes.
+	* mount.cc (oopt): Add "sparse" flag.
+	(fillout_mntent): Ditto.
+	* path.h (enum path_types): Add PATH_SPARSE.
+	(path_conv::support_sparse): New method.
+	(path_conv::fs_flags): Constify.
+	(path_conv::fs_name_len): Ditto.
+	include/sys/mount.h: Replace unused MOUNT_MIXED flag with MOUNT_SPARSE.
+
 2012-12-10  Christopher Faylor  <me.cygwin2012@cgf.cx>
 
 	* sigproc.h (sig_send): Accept tid as argument #3.  Default to NULL.
diff --git a/winsup/cygwin/fhandler.cc b/winsup/cygwin/fhandler.cc
index b84263db5..169ff95be 100644
--- a/winsup/cygwin/fhandler.cc
+++ b/winsup/cygwin/fhandler.cc
@@ -817,15 +817,17 @@ ssize_t __stdcall
 fhandler_base::write (const void *ptr, size_t len)
 {
   int res;
-  IO_STATUS_BLOCK io;
-  FILE_POSITION_INFORMATION fpi;
-  FILE_STANDARD_INFORMATION fsi;
 
   if (did_lseek ())
     {
+      IO_STATUS_BLOCK io;
+      FILE_POSITION_INFORMATION fpi;
+      FILE_STANDARD_INFORMATION fsi;
+
       did_lseek (false); /* don't do it again */
 
       if (!(get_flags () & O_APPEND)
+	  && !has_attribute (FILE_ATTRIBUTE_SPARSE_FILE)
 	  && NT_SUCCESS (NtQueryInformationFile (get_output_handle (),
 						 &io, &fsi, sizeof fsi,
 						 FileStandardInformation))
@@ -833,8 +835,7 @@ fhandler_base::write (const void *ptr, size_t len)
 						 &io, &fpi, sizeof fpi,
 						 FilePositionInformation))
 	  && fpi.CurrentByteOffset.QuadPart
-	     >= fsi.EndOfFile.QuadPart + (128 * 1024)
-	  && (pc.fs_flags () & FILE_SUPPORTS_SPARSE_FILES))
+	     >= fsi.EndOfFile.QuadPart + (128 * 1024))
 	{
 	  /* If the file system supports sparse files and the application
 	     is writing after a long seek beyond EOF, convert the file to
@@ -842,6 +843,9 @@ fhandler_base::write (const void *ptr, size_t len)
 	  NTSTATUS status;
 	  status = NtFsControlFile (get_output_handle (), NULL, NULL, NULL,
 				    &io, FSCTL_SET_SPARSE, NULL, 0, NULL, 0);
+	  if (NT_SUCCESS (status))
+	    pc.file_attributes (pc.file_attributes ()
+				| FILE_ATTRIBUTE_SPARSE_FILE);
 	  debug_printf ("%p = NtFsControlFile(%S, FSCTL_SET_SPARSE)",
 			status, pc.get_nt_native_path ());
 	}
@@ -1071,7 +1075,8 @@ fhandler_base::lseek (_off64_t offset, int whence)
 
   /* When next we write(), we will check to see if *this* seek went beyond
      the end of the file and if so, potentially sparsify the file. */
-  did_lseek (true);
+  if (pc.support_sparse ())
+    did_lseek (true);
 
   /* If this was a SEEK_CUR with offset 0, we still might have
      readahead that we have to take into account when calculating
diff --git a/winsup/cygwin/fhandler_disk_file.cc b/winsup/cygwin/fhandler_disk_file.cc
index 92bb589cb..ca4f90286 100644
--- a/winsup/cygwin/fhandler_disk_file.cc
+++ b/winsup/cygwin/fhandler_disk_file.cc
@@ -1189,12 +1189,15 @@ fhandler_disk_file::ftruncate (_off64_t length, bool allow_truncate)
       feofi.EndOfFile.QuadPart = length;
       /* Create sparse files only when called through ftruncate, not when
 	 called through posix_fallocate. */
-      if (allow_truncate
-	  && (pc.fs_flags () & FILE_SUPPORTS_SPARSE_FILES)
+      if (allow_truncate && pc.support_sparse ()
+	  && !has_attribute (FILE_ATTRIBUTE_SPARSE_FILE)
 	  && length >= fsi.EndOfFile.QuadPart + (128 * 1024))
 	{
 	  status = NtFsControlFile (get_handle (), NULL, NULL, NULL, &io,
 				    FSCTL_SET_SPARSE, NULL, 0, NULL, 0);
+	  if (NT_SUCCESS (status))
+	    pc.file_attributes (pc.file_attributes ()
+				| FILE_ATTRIBUTE_SPARSE_FILE);
 	  syscall_printf ("%p = NtFsControlFile(%S, FSCTL_SET_SPARSE)",
 			  status, pc.get_nt_native_path ());
 	}
diff --git a/winsup/cygwin/include/sys/mount.h b/winsup/cygwin/include/sys/mount.h
index 0680e4562..94620f998 100644
--- a/winsup/cygwin/include/sys/mount.h
+++ b/winsup/cygwin/include/sys/mount.h
@@ -26,8 +26,8 @@ enum
 					   device mount */
   MOUNT_CYGWIN_EXEC =	0x00040,	/* file or directory is or contains a
 					   cygwin executable */
-  MOUNT_MIXED	=	0x00080,	/* reads are text, writes are binary
-					   not yet implemented */
+  MOUNT_SPARSE	=	0x00080,	/* Support automatic sparsifying of
+					   files. */
   MOUNT_NOTEXEC =	0x00100,	/* don't check files for executable magic */
   MOUNT_DEVFS =		0x00200,	/* /device "filesystem" */
   MOUNT_PROC =		0x00400,	/* /proc "filesystem" */
diff --git a/winsup/cygwin/mount.cc b/winsup/cygwin/mount.cc
index 70603d7ed..160fc4d83 100644
--- a/winsup/cygwin/mount.cc
+++ b/winsup/cygwin/mount.cc
@@ -1028,6 +1028,7 @@ struct opt
   {"override", MOUNT_OVERRIDE, 0},
   {"posix=0", MOUNT_NOPOSIX, 0},
   {"posix=1", MOUNT_NOPOSIX, 1},
+  {"sparse", MOUNT_SPARSE, 0},
   {"text", MOUNT_BINARY, 1},
   {"user", MOUNT_SYSTEM, 1}
 };
@@ -1667,6 +1668,9 @@ fillout_mntent (const char *native_path, const char *posix_path, unsigned flags)
   if (flags & MOUNT_NOPOSIX)
     strcat (_my_tls.locals.mnt_opts, (char *) ",posix=0");
 
+  if (flags & MOUNT_SPARSE)
+    strcat (_my_tls.locals.mnt_opts, (char *) ",sparse");
+
   if (!(flags & MOUNT_SYSTEM))		/* user mount */
     strcat (_my_tls.locals.mnt_opts, (char *) ",user");
 
diff --git a/winsup/cygwin/path.h b/winsup/cygwin/path.h
index cb7480a58..a9e8b7c4a 100644
--- a/winsup/cygwin/path.h
+++ b/winsup/cygwin/path.h
@@ -70,6 +70,7 @@ enum path_types
   PATH_EXEC		= MOUNT_EXEC,
   PATH_NOTEXEC		= MOUNT_NOTEXEC,
   PATH_CYGWIN_EXEC	= MOUNT_CYGWIN_EXEC,
+  PATH_SPARSE		= MOUNT_SPARSE,
   PATH_RO		= MOUNT_RO,
   PATH_NOACL		= MOUNT_NOACL,
   PATH_NOPOSIX		= MOUNT_NOPOSIX,
@@ -153,6 +154,11 @@ class path_conv
   bool has_acls () const {return !(path_flags & PATH_NOACL) && fs.has_acls (); }
   bool hasgood_inode () const {return !(path_flags & PATH_IHASH); }
   bool isgood_inode (__ino64_t ino) const;
+  bool support_sparse () const
+  {
+    return (path_flags & PATH_SPARSE)
+	   && (fs_flags () & FILE_SUPPORTS_SPARSE_FILES);
+  }
   int has_symlinks () const {return path_flags & PATH_HAS_SYMLINKS;}
   int has_dos_filenames_only () const {return path_flags & PATH_DOS;}
   int has_buggy_open () const {return fs.has_buggy_open ();}
@@ -342,8 +348,8 @@ class path_conv
   short get_unitn () const {return dev.get_minor ();}
   DWORD file_attributes () const {return fileattr;}
   void file_attributes (DWORD new_attr) {fileattr = new_attr;}
-  DWORD fs_flags () {return fs.flags ();}
-  DWORD fs_name_len () {return fs.name_len ();}
+  DWORD fs_flags () const {return fs.flags ();}
+  DWORD fs_name_len () const {return fs.name_len ();}
   bool fs_got_fs () const { return fs.got_fs (); }
   bool fs_is_fat () const {return fs.is_fat ();}
   bool fs_is_ntfs () const {return fs.is_ntfs ();}