Date: Sun, 23 Jan 2000 17:30:44 -0800 (PST) From: krentel@dreamscape.com To: freebsd-gnats-submit@FreeBSD.org Subject: bin/16320: fstat -f confuses some partitions Message-ID: <20000124013044.9D06C14E03@hub.freebsd.org>
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>Number: 16320
>Category: bin
>Synopsis: fstat -f confuses some partitions
>Confidential: no
>Severity: non-critical
>Priority: low
>Responsible: freebsd-bugs
>State: open
>Quarter:
>Keywords:
>Date-Required:
>Class: sw-bug
>Submitter-Id: current-users
>Arrival-Date: Sun Jan 23 17:40:00 PST 2000
>Closed-Date:
>Last-Modified:
>Originator: Mark W. Krentel
>Release: 3.4-Release
>Organization:
none
>Environment:
FreeBSD 3.4-RELEASE #0: Tue Jan 11 15:38:38 EST 2000
>Description:
The -f flag for /usr/bin/fstat is supposed to "Restrict examination to
files open in the same filesystems as the named file arguments."
But some partitions are considered equivalent, when they are not.
The problem happens whenever there are two partitions with the same
letter on different slices of the same disk. For example, I put /home
on a separate slice, so /usr and /home are both the "f" partition of
two slices:
# Device Mountpoint FStype Options Dump Pass
/dev/da0s2f /usr ufs rw 2 2
/dev/da0s3f /home ufs rw 2 2
% ls -l /dev/da0*f
brw-r----- 1 root operator 4, 5 Dec 24 20:06 /dev/da0f
brw-r----- 1 root operator 4, 0x00030005 Jul 1 1999 /dev/da0s2f
brw-r----- 1 root operator 4, 0x00040005 Jul 1 1999 /dev/da0s3f
In fstat.c, in ufs_filestat, the program computes a unique identifier
for the file system (fsid) as:
fsp->fsid = inode.i_dev & 0xffff;
The 0xffff mask erases the high-order bits of the device's minor number.
This makes fstat incorrectly think that da0s2f and da0s3f are the same
partition because they both have fsid == 0x0405. So, when I ask for
just /home, I get both /home and /usr:
% fstat -f /home
USER CMD PID FD MOUNT INUM MODE SZ|DV R/W
krentel fstat 10702 wd /home 315401 drwxr-xr-x 2048 r
krentel fstat 10702 text /usr 7946 -r-xr-sr-x 10160 r
...
I noticed this in 3.4-Release, but from looking at the CVS repository,
it's clear that current has the same behavior.
>How-To-Repeat:
Create two partitions with the same letter on different slices of the
same disk. For example,
/dev/da0s1f /foo
/dev/da0s2f /bar
Then, "fstat -f /foo" includes files on both /foo and /bar.
>Fix:
I suggest the following patch. It removes the 0xffff mask from fsid,
so fstat correctly distinguishes between da0s1f and da0s2f. Instead,
it puts the mask on the printf statement, so fstat -n continues to
display da0s2f as device 4,5 instead of 4,0x00030005.
Or, maybe da0s2f really should print as 4,0x00030005, I don't know.
I've never been that clear on Freebsd's use of the high-order bits
in the minor number.
This patch is for 3.4-Release (rev 1.16.2.2 of fstat.c), but it's
basically the same for current.
% diff -u fstat.c.orig fstat.c
--- fstat.c.orig Sun Aug 29 11:28:06 1999
+++ fstat.c Sat Jan 22 16:10:12 2000
@@ -441,7 +441,7 @@
return;
}
if (nflg)
- (void)printf(" %2d,%-2d", major(fst.fsid), minor(fst.fsid));
+ (void)printf(" %2d,%-2d", major(fst.fsid), minor(fst.fsid & 0xffff));
else
(void)printf(" %-8s", getmnton(vn.v_mount));
if (nflg)
@@ -487,7 +487,7 @@
(void *)VTOI(vp), Pid);
return 0;
}
- fsp->fsid = inode.i_dev & 0xffff;
+ fsp->fsid = inode.i_dev;
fsp->fileid = (long)inode.i_number;
fsp->mode = (mode_t)inode.i_mode;
fsp->size = (u_long)inode.i_size;
@@ -765,7 +765,7 @@
devs = cur;
cur->ino = statbuf.st_ino;
- cur->fsid = statbuf.st_dev & 0xffff;
+ cur->fsid = statbuf.st_dev;
cur->name = filename;
return(1);
}
>Release-Note:
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