[newlib-cygwin/main] Cygwin: sparse support: enable automatic sparsifying of files on SSDs

[newlib-cygwin/main] Cygwin: sparse support: enable automatic sparsifying of files on SSDs

[Corinna Vinschen]

https://sourceware.org/git/gitweb.cgi?p=newlib-cygwin.git;h=832e91422c4ae9b2dcd0c307779f3dd53ee9c0ac

commit 832e91422c4ae9b2dcd0c307779f3dd53ee9c0ac
Author:     Corinna Vinschen <corinna@vinschen.de>
AuthorDate: Thu Nov 30 22:36:35 2023 +0100
Commit:     Corinna Vinschen <corinna@vinschen.de>
CommitDate: Thu Nov 30 22:37:35 2023 +0100

    Cygwin: sparse support: enable automatic sparsifying of files on SSDs
    
    Given that SSDs don't have a seek penalty, we can enable
    automatic sparsifying of files on SSDs, even if the "sparse"
    mount option is not set.
    
    Signed-off-by: Corinna Vinschen <corinna@vinschen.de>

Diff:
---
 winsup/cygwin/local_includes/path.h | 4 ++--
 winsup/cygwin/release/3.5.0         | 3 +++
 winsup/doc/new-features.xml         | 5 +++++
 winsup/doc/utils.xml                | 1 +
 4 files changed, 11 insertions(+), 2 deletions(-)

diff --git a/winsup/cygwin/local_includes/path.h b/winsup/cygwin/local_includes/path.h
index c7f113f8746a..d19721e0cd3f 100644
--- a/winsup/cygwin/local_includes/path.h
+++ b/winsup/cygwin/local_includes/path.h
@@ -174,8 +174,8 @@ class path_conv
   bool isgood_inode (ino_t ino) const;
   bool support_sparse () const
   {
-    return (mount_flags & MOUNT_SPARSE)
-	   && (fs_flags () & FILE_SUPPORTS_SPARSE_FILES);
+    return (fs_flags () & FILE_SUPPORTS_SPARSE_FILES)
+	   && (fs.is_ssd () || (mount_flags & MOUNT_SPARSE));
   }
   int has_dos_filenames_only () const {return mount_flags & MOUNT_DOS;}
   int has_buggy_reopen () const {return fs.has_buggy_reopen ();}
diff --git a/winsup/cygwin/release/3.5.0 b/winsup/cygwin/release/3.5.0
index 3b6df951d4d3..d0a6c2fc8302 100644
--- a/winsup/cygwin/release/3.5.0
+++ b/winsup/cygwin/release/3.5.0
@@ -55,3 +55,6 @@ What changed:
   https://www.austingroupbugs.net/view.php?id=1674
 
 - FIFOs now also work over NFS.
+
+- Enable automatic sparsifying of files on SSDs, independent of the
+  "sparse" mount mode.
diff --git a/winsup/doc/new-features.xml b/winsup/doc/new-features.xml
index c5e6cdd7f2dc..56509bdc38cf 100644
--- a/winsup/doc/new-features.xml
+++ b/winsup/doc/new-features.xml
@@ -82,6 +82,11 @@ New API call: fallocate (Linux-specific).
 FIFOs now also work over NFS.
 </para></listitem>
 
+<listitem><para>
+Enable automatic sparsifying of files on SSDs, independent of the
+"sparse" mount mode.
+</para></listitem>
+
 </itemizedlist>
 
 </sect2>
diff --git a/winsup/doc/utils.xml b/winsup/doc/utils.xml
index ad17c979663f..f79a928df2c7 100644
--- a/winsup/doc/utils.xml
+++ b/winsup/doc/utils.xml
@@ -1933,6 +1933,7 @@ D: on /d type fat (binary,user,noumount)
                (default).
   sparse     - Switch on support for sparse files.  This option only makes
                sense on NTFS and then only if you really need sparse files.
+	       This flag is always silently enabled on SSD drives.
   text       - Files default to CRLF text mode line endings.
 </screen>