On 05/11/2012 03:42 AM, Jim Meyering wrote:
it's not clear that there is even a problem with our
current use of statfs on glibc-based Linux systems.
Yes, I find it curious. GNU/Linux statvfs
simply invokes statfs internally, right?
So why should it matter whether df uses statvfs
or statfs? And yet from Nikolaus Rath's evidence
it does appear that we have a problem with current FUSE systems.
In the long run I'd rather have the Linux-based code
use statvfs, since that's the more-standard interface.
Nikolaus, does the attached hack fix things for you?
Basically, it transforms a configure-time test into a
run-time test. After applying this patch,
you'll need to run autoreconf + configure before 'make'.
diff --git a/lib/fsusage.c b/lib/fsusage.c
index 099b0aa..539f1a9 100644
--- a/lib/fsusage.c
+++ b/lib/fsusage.c
@@ -84,6 +84,33 @@
otherwise, use PROPAGATE_ALL_ONES. */
#define PROPAGATE_TOP_BIT(x) ((x) | ~ (EXTRACT_TOP_BIT (x) - 1))
+#ifdef STAT_STATVFS
+/* Return true if statvfs works. This is false for statvfs on systems
+ with GNU libc on Linux kernels before 2.6.36, which stats all
+ preceding entries in /proc/mounts; that makes df hang if even one
+ of the corresponding file systems is hard-mounted but not available. */
+# if ! (__linux__ && (__GLIBC__ || __UCLIBC__))
+static int statvfs_works (void) { return 1; }
+# else
+# include <string.h> /* for strverscmp */
+# include <sys/utsname.h>
+# include <sys/statfs.h>
+# define STAT_STATFS2_BSIZE 1
+
+static int
+statvfs_works (void)
+{
+ static int statvfs_works_cache = -1;
+ struct utsname name;
+ if (statvfs_works_cache < 0)
+ statvfs_works_cache = (uname (&name) == 0
+ && 0 <= strverscmp (name.release, "2.6.36"));
+ return statvfs_works_cache;
+}
+# endif
+#endif
+
+
/* Fill in the fields of FSP with information about space usage for
the file system on which FILE resides.
DISK is the device on which FILE is mounted, for space-getting
@@ -94,19 +121,32 @@
int
get_fs_usage (char const *file, char const *disk, struct fs_usage *fsp)
{
-#if defined STAT_STATVFS /* POSIX, except glibc/Linux */
+#ifdef STAT_STATVFS /* POSIX, except pre-2.6.36 glibc/Linux */
- struct statvfs fsd;
-
- if (statvfs (file, &fsd) < 0)
- return -1;
+ if (statvfs_works ())
+ {
+ struct statvfs vfsd;
+
+ if (statvfs (file, &vfsd) < 0)
+ return -1;
+
+ /* f_frsize isn't guaranteed to be supported. */
+ fsp->fsu_blocksize = (vfsd.f_frsize
+ ? PROPAGATE_ALL_ONES (vfsd.f_frsize)
+ : PROPAGATE_ALL_ONES (vfsd.f_bsize));
+
+ fsp->fsu_blocks = PROPAGATE_ALL_ONES (vfsd.f_blocks);
+ fsp->fsu_bfree = PROPAGATE_ALL_ONES (vfsd.f_bfree);
+ fsp->fsu_bavail = PROPAGATE_TOP_BIT (vfsd.f_bavail);
+ fsp->fsu_bavail_top_bit_set = EXTRACT_TOP_BIT (vfsd.f_bavail) != 0;
+ fsp->fsu_files = PROPAGATE_ALL_ONES (vfsd.f_files);
+ fsp->fsu_ffree = PROPAGATE_ALL_ONES (vfsd.f_ffree);
+ return 0;
+ }
- /* f_frsize isn't guaranteed to be supported. */
- fsp->fsu_blocksize = (fsd.f_frsize
- ? PROPAGATE_ALL_ONES (fsd.f_frsize)
- : PROPAGATE_ALL_ONES (fsd.f_bsize));
+#endif
-#elif defined STAT_STATVFS64 /* AIX */
+#if defined STAT_STATVFS64 /* AIX */
struct statvfs64 fsd;
@@ -235,7 +275,7 @@ get_fs_usage (char const *file, char const *disk, struct
fs_usage *fsp)
#endif
-#if (defined STAT_STATVFS || defined STAT_STATVFS64 \
+#if (defined STAT_STATVFS64 \
|| (!defined STAT_STATFS2_FS_DATA && !defined STAT_READ_FILSYS))
fsp->fsu_blocks = PROPAGATE_ALL_ONES (fsd.f_blocks);
diff --git a/m4/fsusage.m4 b/m4/fsusage.m4
index 519743f..f87834e 100644
--- a/m4/fsusage.m4
+++ b/m4/fsusage.m4
@@ -50,14 +50,6 @@ if test $ac_fsusage_space = no; then
# OpenBSD >= 4.4, AIX, HP-UX, IRIX, Solaris, Cygwin, Interix, BeOS.
AC_CACHE_CHECK([for statvfs function (SVR4)], [fu_cv_sys_stat_statvfs],
[AC_LINK_IFELSE([AC_LANG_PROGRAM([[#include <sys/types.h>
-#if (defined __GLIBC__ || defined __UCLIBC__) && defined __linux__
-Do not use statvfs on systems with GNU libc on Linux, because that function
-stats all preceding entries in /proc/mounts, and that makes df hang if even
-one of the corresponding file systems is hard-mounted, but not available.
-statvfs in GNU libc on Hurd, BeOS, Haiku operates differently: it only makes
-a system call.
-#endif
-
#ifdef __osf__
"Do not use Tru64's statvfs implementation"
#endif
