GNU C Library master sources branch fw/holes created. glibc-2.27.9000-570-g118564f

[fw at sourceware dot org]

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The branch, fw/holes has been created
        at  118564fd93a217b4839c690959ef452ba6109819 (commit)

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http://sourceware.org/git/gitweb.cgi?p=glibc.git;a=commitdiff;h=118564fd93a217b4839c690959ef452ba6109819

commit 118564fd93a217b4839c690959ef452ba6109819
Author: Florian Weimer <fweimer@redhat.com>
Date:   Fri Jul 13 14:08:08 2018 +0200

    io/tst-copy_file_range: Require that file system supports holes
    
    Otherwise, the test fills up the entire disk.

diff --git a/ChangeLog b/ChangeLog
index e9dd4ae..04e0bf2 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,15 @@
+2018-07-13  Florian Weimer  <fweimer@redhat.com>
+
+	* support/support_descriptor_supports_holes.c: New file.
+	* support/Makefile (libsupport-routines): Add
+	support_descriptor_supports_holes.
+	* support/support.h (support_descriptor_supports_holes): Declare.
+	* io/tst-copy_file_range.c: Call support_descriptor_supports_holes
+	and stop testing if holes are not supported.
+	* io/test-lfs.c (do_prepare): Likewise.
+	* sysdeps/unix/sysv/linux/tst-fallocate-common.c (do_prepare):
+	Likewise.
+
 2018-07-12  Florian Weimer  <fweimer@redhat.com>
 
 	* nptl/allocatestack.c [_STACK_GROWS_UP] (allocate_stack): Call
diff --git a/io/test-lfs.c b/io/test-lfs.c
index f7721a5..52120e9 100644
--- a/io/test-lfs.c
+++ b/io/test-lfs.c
@@ -25,6 +25,7 @@
 #include <error.h>
 #include <errno.h>
 #include <sys/resource.h>
+#include <support/check.h>
 
 /* Prototype for our test function.  */
 extern void do_prepare (int argc, char *argv[]);
@@ -70,6 +71,8 @@ do_prepare (int argc, char *argv[])
       else
 	error (EXIT_FAILURE, errno, "cannot create temporary file");
     }
+  if (!support_descriptor_supports_holes (fd))
+    FAIL_UNSUPPORTED ("File %s does not support holes", name);
   add_temp_file (name);
 
   if (getrlimit64 (RLIMIT_FSIZE, &rlim) != 0)
diff --git a/io/tst-copy_file_range.c b/io/tst-copy_file_range.c
index 3d531a1..e5b46f9 100644
--- a/io/tst-copy_file_range.c
+++ b/io/tst-copy_file_range.c
@@ -739,7 +739,12 @@ do_test (void)
     *p = rand () >> 24;
 
   infd = create_temp_file ("tst-copy_file_range-in-", &infile);
-  xclose (create_temp_file ("tst-copy_file_range-out-", &outfile));
+  {
+    int outfd = create_temp_file ("tst-copy_file_range-out-", &outfile);
+    if (!support_descriptor_supports_holes (outfd))
+      FAIL_UNSUPPORTED ("File %s does not support holes", outfile);
+    xclose (outfd);
+  }
 
   /* Try to find a different directory from the default input/output
      file.  */
diff --git a/support/Makefile b/support/Makefile
index 652d2cd..9063046 100644
--- a/support/Makefile
+++ b/support/Makefile
@@ -43,6 +43,7 @@ libsupport-routines = \
   support_capture_subprocess \
   support_capture_subprocess_check \
   support_chroot \
+  support_descriptor_supports_holes \
   support_enter_mount_namespace \
   support_enter_network_namespace \
   support_format_address_family \
diff --git a/support/support.h b/support/support.h
index b61fe07..34ae6e1 100644
--- a/support/support.h
+++ b/support/support.h
@@ -65,6 +65,12 @@ void support_write_file_string (const char *path, const char *contents);
    the result).  */
 char *support_quote_blob (const void *blob, size_t length);
 
+/* Returns non-zero if the file descriptor is a regular file on a file
+   system which supports holes (that is, seeking and writing does not
+   allocate storage for the range of zeros).  FD must refer to a
+   regular file open for writing, and initially empty.  */
+int support_descriptor_supports_holes (int fd);
+
 /* Error-checking wrapper functions which terminate the process on
    error.  */
 
diff --git a/support/support_descriptor_supports_holes.c b/support/support_descriptor_supports_holes.c
new file mode 100644
index 0000000..b044986
--- /dev/null
+++ b/support/support_descriptor_supports_holes.c
@@ -0,0 +1,80 @@
+/* Test for file system hole support.
+   Copyright (C) 2018 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+#include <stdbool.h>
+#include <support.h>
+#include <support/check.h>
+#include <sys/stat.h>
+#include <xunistd.h>
+
+int
+support_descriptor_supports_holes (int fd)
+{
+  enum
+    {
+      /* Write offset for the enlarged file.  This value is arbitrary
+         and hopefully large enough to trigger the creation of holes.
+         We cannot use the file system block size as a reference here
+         because it is incorrect for network file systems.  */
+      write_offset = 16 * 1024 * 1024,
+
+      /* Our write may add this number of additional blocks.  */
+      block_headroom = 8,
+    };
+
+  struct stat64 st;
+  xfstat (fd, &st);
+  if (!S_ISREG (st.st_mode))
+    FAIL_EXIT1 ("descriptor %d does not refer to a regular file", fd);
+  if (st.st_size != 0)
+    FAIL_EXIT1 ("descriptor %d does not refer to an empty file", fd);
+  if (st.st_blocks > block_headroom)
+    FAIL_EXIT1 ("descriptor %d refers to a pre-allocated file (%lld blocks)",
+                fd, (long long int) st.st_blocks);
+
+  /* Write a single byte at the start of the file to compute the block
+     usage for a single byte.  */
+  xlseek (fd, 0, SEEK_SET);
+  char b = '@';
+  xwrite (fd, &b, 1);
+  /* Attempt to bypass delayed allocation.  */
+  TEST_COMPARE (fsync (fd), 0);
+  xfstat (fd, &st);
+  unsigned long long int block_limit = 2 * st.st_blocks + block_headroom;
+
+  /* Write a single byte at 16 megabytes.  */
+  xlseek (fd, write_offset, SEEK_SET);
+  xwrite (fd, &b, 1);
+  /* Attempt to bypass delayed allocation.  */
+  TEST_COMPARE (fsync (fd), 0);
+  xfstat (fd, &st);
+  bool supports_holes = st.st_blocks <= block_limit;
+
+  /* Also check that extending the file does not fill up holes.  */
+  xftruncate (fd, 2 * write_offset);
+  /* Attempt to bypass delayed allocation.  */
+  TEST_COMPARE (fsync (fd), 0);
+  xfstat (fd, &st);
+  supports_holes = supports_holes && st.st_blocks <= block_limit;
+
+  /* Return to a zero-length file.  */
+  xftruncate (fd, 0);
+  xlseek (fd, 0, SEEK_SET);
+
+  return supports_holes;
+}
diff --git a/sysdeps/unix/sysv/linux/tst-fallocate-common.c b/sysdeps/unix/sysv/linux/tst-fallocate-common.c
index a6ba403..bc54cf5 100644
--- a/sysdeps/unix/sysv/linux/tst-fallocate-common.c
+++ b/sysdeps/unix/sysv/linux/tst-fallocate-common.c
@@ -41,6 +41,8 @@ do_prepare (int argc, char **argv)
   temp_fd = create_temp_file ("tst-fallocate.", &temp_filename);
   if (temp_fd == -1)
     FAIL_EXIT1 ("cannot create temporary file: %m");
+  if (!support_descriptor_supports_holes (temp_fd))
+    FAIL_UNSUPPORTED ("File %s does not support holes", temp_filename);
 }
 #define PREPARE do_prepare
 

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