Date: Thu, 28 Jan 1999 17:34:10 -0500 (EST) From: Erez Zadok <ezk@ape.mcl.cs.columbia.edu> To: FreeBSD-gnats-submit@FreeBSD.ORG Cc: ezk@ape.mcl.cs.columbia.edu Subject: kern/9764: patches to support "ignore" mount flag Message-ID: <199901282234.RAA01770@ape.mcl.cs.columbia.edu>
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>Number: 9764
>Category: kern
>Synopsis: allow /bin/df not to list certain entries (made by automounter)
>Confidential: no
>Severity: non-critical
>Priority: low
>Responsible: freebsd-bugs
>State: open
>Quarter:
>Keywords:
>Date-Required:
>Class: change-request
>Submitter-Id: current-users
>Arrival-Date: Thu Jan 28 14:40:00 PST 1999
>Closed-Date:
>Last-Modified:
>Originator: Erez Zadok
>Release: FreeBSD 3.0-CURRENT i386
>Organization:
Columbia University Department of Computer Science.
>Environment:
Vanilla 3.0-RELEASE system, with elf kernel and boot blocks off of
-current, and running amd from the am-utils-6.0 distribution or
a later distribution (which I maintain.)
>Description:
Most modern OSs have the ability to flag certain mounts as ones to
be ignored by default by the df(1) program. This is used mostly to
avoid stat()-ing entries that do not represent "real" disk mount
points (such as those made by an automounter such as amd.) It is
also useful not to have to stat() these entries because it takes
longer to report them that for other file systems, being that these
mount points are served by a user-level file server and resulting in
several context switches. Worse, if the automounter is down
unexpectedly, a causal df(1) will hang in an interruptible way.
Finally, amd normally has nothing to report for its own mount point,
so seeing output like:
Filesystem 1K-blocks Used Avail Capacity Mounted on
pid204@ape:/proj 0 0 0 100% /proj
only clutters the rest of the listing. The patch below adds a new
flag MNT_IGNORE to the system, and tells the kernel to report it
back to a statfs() call. Then /bin/df is modified so that by
default it does not list any entries with the MNT_IGNORE flag on,
unless df -a is used. This is comparable behavior to the df program
elsewhere: Solaris/SunOS, linux, GNU df, and more.
With this patch in place, am-utils is able to automatically detect
the existence of the MNT_IGNORE flag during the configure run, and
use it at run-time as it does with other OSs.
>How-To-Repeat:
Since this is not a bug, there isn't much to repeat. It is clear
when using amd that all of the automounter mount points themselves
are stat()-ed and listed by df(1).
>Fix:
Apply the following patch. It creates a new mount flag MNT_IGNORE,
makes sure that the kernel reports it back via statfs, and makes
/bin/df ignore entries with the MNT_IGNORE flag set unless a -a
(new) flag is set. I've tested this for over a week now without a
single adverse effect.
Index: src/bin/df/df.1
===================================================================
RCS file: /proj/bank/fist/freebsd/cvsroot/src/bin/df/df.1,v
retrieving revision 1.13
diff -c -r1.13 df.1
*** df.1 1998/05/13 07:56:58 1.13
--- df.1 1999/01/27 19:46:46
***************
*** 40,46 ****
.Nd display free disk space
.Sh SYNOPSIS
.Nm df
! .Op Fl ikn
.Op Fl t Ar type
.Op Ar file | Ar filesystem ...
.Sh DESCRIPTION
--- 40,46 ----
.Nd display free disk space
.Sh SYNOPSIS
.Nm df
! .Op Fl aikn
.Op Fl t Ar type
.Op Ar file | Ar filesystem ...
.Sh DESCRIPTION
***************
*** 59,64 ****
--- 59,67 ----
.Pp
The following options are available:
.Bl -tag -width Ds
+ .It Fl a
+ Show all mount points, including those that were mounted with the MNT_IGNORE
+ flag.
.It Fl i
Include statistics on the number of free inodes.
.It Fl k
Index: src/bin/df/df.c
===================================================================
RCS file: /proj/bank/fist/freebsd/cvsroot/src/bin/df/df.c,v
retrieving revision 1.20
diff -c -r1.20 df.c
*** df.c 1998/12/16 05:29:09 1.20
--- df.c 1999/01/27 19:46:37
***************
*** 73,79 ****
int ufs_df __P((char *, int));
void usage __P((void));
! int iflag, nflag;
struct ufs_args mdev;
int
--- 73,79 ----
int ufs_df __P((char *, int));
void usage __P((void));
! int aflag = 0, iflag, nflag;
struct ufs_args mdev;
int
***************
*** 88,95 ****
char *mntpt, *mntpath, **vfslist;
vfslist = NULL;
! while ((ch = getopt(argc, argv, "iknt:")) != -1)
switch (ch) {
case 'i':
iflag = 1;
break;
--- 88,98 ----
char *mntpt, *mntpath, **vfslist;
vfslist = NULL;
! while ((ch = getopt(argc, argv, "aiknt:")) != -1)
switch (ch) {
+ case 'a':
+ aflag = 1;
+ break;
case 'i':
iflag = 1;
break;
***************
*** 129,137 ****
if (width > maxwidth)
maxwidth = width;
}
}
- for (i = 0; i < mntsize; i++)
- prtstat(&mntbuf[i], maxwidth);
exit(rv);
}
--- 132,142 ----
if (width > maxwidth)
maxwidth = width;
}
+ }
+ for (i = 0; i < mntsize; i++) {
+ if (aflag || (mntbuf[i].f_flags & MNT_IGNORE) == 0)
+ prtstat(&mntbuf[i], maxwidth);
}
exit(rv);
}
***************
*** 377,382 ****
usage()
{
(void)fprintf(stderr,
! "usage: df [-ikn] [-t type] [file | filesystem ...]\n");
exit(1);
}
--- 382,387 ----
usage()
{
(void)fprintf(stderr,
! "usage: df [-aikn] [-t type] [file | filesystem ...]\n");
exit(1);
}
Index: src/sys/kern/vfs_syscalls.c
===================================================================
RCS file: /proj/bank/fist/freebsd/cvsroot/src/sys/kern/vfs_syscalls.c,v
retrieving revision 1.112
diff -c -r1.112 vfs_syscalls.c
*** vfs_syscalls.c 1999/01/05 18:49:55 1.112
--- vfs_syscalls.c 1999/01/27 23:17:41
***************
*** 293,303 ****
mp->mnt_kern_flag |= MNTK_WANTRDWR;
mp->mnt_flag &=~ (MNT_NOSUID | MNT_NOEXEC | MNT_NODEV |
MNT_SYNCHRONOUS | MNT_UNION | MNT_ASYNC | MNT_NOATIME |
! MNT_NOSYMFOLLOW |
MNT_NOCLUSTERR | MNT_NOCLUSTERW | MNT_SUIDDIR);
mp->mnt_flag |= SCARG(uap, flags) & (MNT_NOSUID | MNT_NOEXEC |
MNT_NODEV | MNT_SYNCHRONOUS | MNT_UNION | MNT_ASYNC | MNT_FORCE |
! MNT_NOSYMFOLLOW |
MNT_NOATIME | MNT_NOCLUSTERR | MNT_NOCLUSTERW | MNT_SUIDDIR);
/*
* Mount the filesystem.
--- 293,303 ----
mp->mnt_kern_flag |= MNTK_WANTRDWR;
mp->mnt_flag &=~ (MNT_NOSUID | MNT_NOEXEC | MNT_NODEV |
MNT_SYNCHRONOUS | MNT_UNION | MNT_ASYNC | MNT_NOATIME |
! MNT_NOSYMFOLLOW | MNT_IGNORE |
MNT_NOCLUSTERR | MNT_NOCLUSTERW | MNT_SUIDDIR);
mp->mnt_flag |= SCARG(uap, flags) & (MNT_NOSUID | MNT_NOEXEC |
MNT_NODEV | MNT_SYNCHRONOUS | MNT_UNION | MNT_ASYNC | MNT_FORCE |
! MNT_NOSYMFOLLOW | MNT_IGNORE |
MNT_NOATIME | MNT_NOCLUSTERR | MNT_NOCLUSTERW | MNT_SUIDDIR);
/*
* Mount the filesystem.
Index: src/sys/sys/mount.h
===================================================================
RCS file: /proj/bank/fist/freebsd/cvsroot/src/sys/sys/mount.h,v
retrieving revision 1.73
diff -c -r1.73 mount.h
*** mount.h 1998/11/15 15:12:58 1.73
--- mount.h 1999/01/27 20:17:13
***************
*** 141,146 ****
--- 141,147 ----
#define MNT_QUOTA 0x00002000 /* quotas are enabled on filesystem */
#define MNT_ROOTFS 0x00004000 /* identifies the root filesystem */
#define MNT_USER 0x00008000 /* mounted by a user */
+ #define MNT_IGNORE 0x00800000 /* do not show entry in df */
/*
* Mask of flags that are visible to statfs()
***************
*** 154,160 ****
MNT_DEFEXPORTED | MNT_EXPORTANON| MNT_EXKERB | \
MNT_LOCAL | MNT_USER | MNT_QUOTA | \
MNT_ROOTFS | MNT_NOATIME | MNT_NOCLUSTERR| \
! MNT_NOCLUSTERW | MNT_SUIDDIR | MNT_SOFTDEP \
/* | MNT_EXPUBLIC */)
/*
* External filesystem command modifier flags.
--- 155,162 ----
MNT_DEFEXPORTED | MNT_EXPORTANON| MNT_EXKERB | \
MNT_LOCAL | MNT_USER | MNT_QUOTA | \
MNT_ROOTFS | MNT_NOATIME | MNT_NOCLUSTERR| \
! MNT_NOCLUSTERW | MNT_SUIDDIR | MNT_SOFTDEP | \
! MNT_IGNORE \
/* | MNT_EXPUBLIC */)
/*
* External filesystem command modifier flags.
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