io: Avoid running some tests if the file system does not support holes
Commit Message
Otherwise, these tests fills up the entire disk (or just run very slowly
and eventually time out).
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.
Comments
On 13/07/2018 09:10, Florian Weimer wrote:
> Otherwise, these tests fills up the entire disk (or just run very slowly
> and eventually time out).
>
> 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.
LGTM with just a clarification below.
>
> diff --git a/io/test-lfs.c b/io/test-lfs.c
> index f7721a5995..52120e9bca 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 3d531a1937..e5b46f91db 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 652d2cdf69..9063046c23 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 b61fe0735c..34ae6e10cd 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 0000000000..b04498664e
> --- /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,
Is this number based on 512 physical block size with a 4kb page size?
If so, shouldn't we try to determine this at runtime?
> + };
> +
> + 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 a6ba403c62..bc54cf5134 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
>
>
* Adhemerval Zanella:
>> + /* Our write may add this number of additional blocks. */
>> + block_headroom = 8,
>
> Is this number based on 512 physical block size with a 4kb page size?
> If so, shouldn't we try to determine this at runtime?
It's just an arbitrary number in case the file system needs blocks to
store large holes or something like that. I can make the number 11 to
make this more obvious, and expand the comment.
timezone/tst-tzset.c needs a similar check, so I have to send a new
patch anyway.
@@ -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)
@@ -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. */
@@ -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 \
@@ -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. */
new file mode 100644
@@ -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;
+}
@@ -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