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Message-ID: <20140105061233.GA5849@thunk.org>
Date: Sun, 5 Jan 2014 01:12:33 -0500
From: Theodore Ts'o <tytso@....edu>
To: Baruch Siach <baruch@...s.co.il>
Cc: linux-ext4@...r.kernel.org
Subject: Re: [PATCH] e4defrag: choose the best available posix_fadvise variant
On Fri, Jan 03, 2014 at 11:23:44AM -0500, Theodore Ts'o wrote:
>
> Oh, oops. I'll find the other version of the patch and fix it up.
Here is the revised version of your patch which I currently have in my
sources. Let me know what you think.
- Ted
commit e47e7100a357ed9ba1575a6a8caca9258b1aab77
Author: Baruch Siach <baruch@...s.co.il>
Date: Thu Jan 2 13:05:37 2014 -0500
e4defrag: choose the best available posix_fadvise variant
Use posix_fadvise64() when available. This allows 64bit offsets on 32bit
systems.
Rename the internal posix_fadvise() implementation to avoid collision with the
C library signature that is sometimes present event when the implementation
itself is not. This fixes build errors like:
e4defrag.c:189:2: warning: #warning Using locally defined posix_fadvise interface. [-Wcpp
e4defrag.c:203:12: error: conflicting types for ‘posix_fadvise’
[ Modified by tytso to try to use fadvise64 as well, and to remove the
attempt to use the syscall directly, since between fadvise64,
fadvise64_64, and complexities caused by required dummy arguments on
some architectures, it's not worth the hair. ]
Signed-off-by: Baruch Siach <baruch@...s.co.il>
Signed-off-by: Theodore Ts'o <tytso@....edu>
diff --git a/configure b/configure
index 6f8f1ab..5943849 100755
--- a/configure
+++ b/configure
@@ -11051,7 +11051,7 @@ if test "$ac_res" != no; then :
fi
fi
-for ac_func in __secure_getenv backtrace blkid_probe_get_topology chflags fallocate fallocate64 fchown fdatasync fstat64 ftruncate64 futimes getdtablesize getmntinfo getpwuid_r getrlimit getrusage jrand48 llseek lseek64 mallinfo mbstowcs memalign mmap msync nanosleep open64 pathconf posix_fadvise posix_memalign prctl secure_getenv setmntent setresgid setresuid srandom strcasecmp strdup strnlen strptime strtoull sync_file_range sysconf usleep utime valloc
+for ac_func in __secure_getenv backtrace blkid_probe_get_topology chflags fadvise64 fallocate fallocate64 fchown fdatasync fstat64 ftruncate64 futimes getdtablesize getmntinfo getpwuid_r getrlimit getrusage jrand48 llseek lseek64 mallinfo mbstowcs memalign mmap msync nanosleep open64 pathconf posix_fadvise posix_fadvise64 posix_memalign prctl secure_getenv setmntent setresgid setresuid srandom strcasecmp strdup strnlen strptime strtoull sync_file_range sysconf usleep utime valloc
do :
as_ac_var=`$as_echo "ac_cv_func_$ac_func" | $as_tr_sh`
ac_fn_c_check_func "$LINENO" "$ac_func" "$as_ac_var"
diff --git a/configure.in b/configure.in
index b70a3f9..214d3f6 100644
--- a/configure.in
+++ b/configure.in
@@ -1026,6 +1026,7 @@ AC_CHECK_FUNCS(m4_flatten([
backtrace
blkid_probe_get_topology
chflags
+ fadvise64
fallocate
fallocate64
fchown
@@ -1050,6 +1051,7 @@ AC_CHECK_FUNCS(m4_flatten([
open64
pathconf
posix_fadvise
+ posix_fadvise64
posix_memalign
prctl
secure_getenv
diff --git a/lib/config.h.in b/lib/config.h.in
index ef2e664..0197b56 100644
--- a/lib/config.h.in
+++ b/lib/config.h.in
@@ -103,6 +103,9 @@
/* Define to 1 if Ext2 ioctls present */
#undef HAVE_EXT2_IOCTLS
+/* Define to 1 if you have the `fadvise64' function. */
+#undef HAVE_FADVISE64
+
/* Define to 1 if you have the `fallocate' function. */
#undef HAVE_FALLOCATE
@@ -287,6 +290,9 @@
/* Define to 1 if you have the `posix_fadvise' function. */
#undef HAVE_POSIX_FADVISE
+/* Define to 1 if you have the `posix_fadvise64' function. */
+#undef HAVE_POSIX_FADVISE64
+
/* Define to 1 if you have the `posix_memalign' function. */
#undef HAVE_POSIX_MEMALIGN
diff --git a/misc/e4defrag.c b/misc/e4defrag.c
index c6a5f0d..65933b1 100644
--- a/misc/e4defrag.c
+++ b/misc/e4defrag.c
@@ -34,13 +34,11 @@
#include <unistd.h>
#include <ext2fs/ext2_types.h>
#include <ext2fs/ext2fs.h>
-#include <linux/fs.h>
#include <sys/ioctl.h>
#include <ext2fs/fiemap.h>
#include <sys/mman.h>
#include <sys/stat.h>
#include <sys/statfs.h>
-#include <sys/syscall.h>
#include <sys/vfs.h>
/* A relatively new ioctl interface ... */
@@ -183,28 +181,21 @@ static ext4_fsblk_t files_block_count;
static struct frag_statistic_ino frag_rank[SHOW_FRAG_FILES];
-/* Local definitions of some syscalls glibc may not yet have */
-
-#ifndef HAVE_POSIX_FADVISE
-#warning Using locally defined posix_fadvise interface.
-
-#ifndef __NR_fadvise64_64
-#error Your kernel headers dont define __NR_fadvise64_64
-#endif
-
-/*
- * fadvise() - Give advice about file access.
+/* Local definitions of some syscalls glibc may not yet have
*
- * @fd: defrag target file's descriptor.
- * @offset: file offset.
- * @len: area length.
- * @advise: process flag.
+ * We prefer posix_fadvise64 when available, as it allows 64bit offset on
+ * 32bit systems
*/
-static int posix_fadvise(int fd, loff_t offset, size_t len, int advise)
-{
- return syscall(__NR_fadvise64_64, fd, offset, len, advise);
-}
-#endif /* ! HAVE_FADVISE64_64 */
+
+#if defined(HAVE_POSIX_FADVISE64)
+#define posix_fadvise posix_fadvise64
+#elif defined(HAVE_FADVISE64)
+#define posix_fadvise fadvise64
+#elif defined(HAVE_POSIX_FADVISE)
+#define posix_fadvise posix_fadvise
+#else
+#error posix_fadvise not available!
+#endif
#ifndef HAVE_SYNC_FILE_RANGE
#warning Using locally defined sync_file_range interface.
--
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