where is remount?

where is remount?

[Steve French]

Was noticing a strange ioctl coming into the cifs code when I issue
"remount" on a cifs mount and was trying to trace it but although
remount appears to be in the path, neither "strace" nor "which" can
find a command named remount (bash command completion can, and it must
exist because the command calls into mount).

Is this some strange built in bash alias?  I don't see it when
grepping my root user's home dir.

-- 
Thanks,

Steve

Re: where is remount?

[Tetsuo Handa]

Steve French wrote:
> Was noticing a strange ioctl coming into the cifs code when I issue
> "remount" on a cifs mount and was trying to trace it but although
> remount appears to be in the path, neither "strace" nor "which" can
> find a command named remount (bash command completion can, and it must
> exist because the command calls into mount).
> 
> Is this some strange built in bash alias?  I don't see it when
> grepping my root user's home dir.

You mean "/bin/mount -o remount" ?

Re: where is remount?

[Steve French]

It may be calling that ... but I was typing:  "remount" in bash and I
don't see a bash alias for it or a command in the path named that.

On Fri, May 16, 2008 at 8:18 PM, Tetsuo Handa
<penguin-kernel@i-love.sakura.ne.jp> wrote:
>
> Steve French wrote:
>> Was noticing a strange ioctl coming into the cifs code when I issue
>> "remount" on a cifs mount and was trying to trace it but although
>> remount appears to be in the path, neither "strace" nor "which" can
>> find a command named remount (bash command completion can, and it must
>> exist because the command calls into mount).
>>
>> Is this some strange built in bash alias?  I don't see it when
>> grepping my root user's home dir.
>
> You mean "/bin/mount -o remount" ?
>



-- 
Thanks,

Steve

Re: where is remount?

[Tetsuo Handa]

Steve French wrote:
> It may be calling that ... but I was typing:  "remount" in bash and I
> don't see a bash alias for it or a command in the path named that.
Didn't you see MS_REMOUNT in the output of "strace"?

# mount -t tmpfs none /dev/shm/
# strace mount -o remount,ro /dev/shm/ 2>&1 | grep mount
execve("/bin/mount", ["mount", "-o", "remount,ro", "/dev/shm/"], [/* 17 vars */]) = 0
open("/proc/mounts", O_RDONLY|O_LARGEFILE) = 3
stat64("/sbin/mount.tmpfs", 0xbffeb570) = -1 ENOENT (No such file or directory)
mount("none", "/dev/shm", 0x8c13d68, MS_MGC_VAL|MS_RDONLY|MS_REMOUNT, ""...) = 0

Re: where is remount?

[Steve French]

that is the point ... strace doesn't work on that command and I don't
even know the syntax of the utility "remount"  It seems to be
something builtin to bash - very odd ....

smfhome2:~ # mount /dev/sdb8 /mnt2
smfhome2:~ # remount -o ro /dev/sdb8
mount: you must specify the filesystem type
smfhome2:~ # remount -o ro /dev/sdb8 -t ext3
mount: /dev/sdb8 not mounted already, or bad option
smfhome2:~ # remount -t ext3 -o ro /dev/sdb8
mount: you must specify the filesystem type
smfhome2:~ # remount -o ro -t ext3 /dev/sdb8
mount: /dev/sdb8 not mounted already, or bad option
smfhome2:~ # strace -f remount -o ro -t ext3 /dev/sdb8
strace: remount: command not found
smfhome2:~ # which strace
/usr/bin/strace
smfhome2:~ # which remount
which: no remount in
(/home/stevef/bin:/usr/local/bin:/usr/bin:/sbin:/usr/sbin:/bin:/usr/bin/X11:/usr/X11R6/bin:/usr/games:/usr/lib/mit/bin:/usr/lib/mit/sbin:/usr/lib/qt3/bin)


On Fri, May 16, 2008 at 8:49 PM, Tetsuo Handa
<penguin-kernel@i-love.sakura.ne.jp> wrote:
> Steve French wrote:
>> It may be calling that ... but I was typing:  "remount" in bash and I
>> don't see a bash alias for it or a command in the path named that.
> Didn't you see MS_REMOUNT in the output of "strace"?
>
> # mount -t tmpfs none /dev/shm/
> # strace mount -o remount,ro /dev/shm/ 2>&1 | grep mount
> execve("/bin/mount", ["mount", "-o", "remount,ro", "/dev/shm/"], [/* 17 vars */]) = 0
> open("/proc/mounts", O_RDONLY|O_LARGEFILE) = 3
> stat64("/sbin/mount.tmpfs", 0xbffeb570) = -1 ENOENT (No such file or directory)
> mount("none", "/dev/shm", 0x8c13d68, MS_MGC_VAL|MS_RDONLY|MS_REMOUNT, ""...) = 0
>



-- 
Thanks,

Steve

Re: where is remount?

[Matthew Wilcox]

On Fri, May 16, 2008 at 09:51:51PM -0500, Steve French wrote:
> that is the point ... strace doesn't work on that command and I don't
> even know the syntax of the utility "remount"  It seems to be
> something builtin to bash - very odd ....

Assuming you're using bash, try type -a remount

(and then type 'help type' to see what it's telling you)

-- 
Intel are signing my paycheques ... these opinions are still mine
"Bill, look, we understand that you're interested in selling us this
operating system, but compare it to ours.  We can't possibly take such
a retrograde step."

Re: where is remount?

[Steve French]

Mystery solved ,,,

It is a bash function (although the bash function seems fairly
useless) ... Thank you .... Thank you ...

stevef@smfhome2:~> type -a remount
remount is a function
remount ()
{
    /bin/mount -o remount,${1+"$@"}
}


On Fri, May 16, 2008 at 10:01 PM, Matthew Wilcox <matthew@wil.cx> wrote:
> On Fri, May 16, 2008 at 09:51:51PM -0500, Steve French wrote:
>> that is the point ... strace doesn't work on that command and I don't
>> even know the syntax of the utility "remount"  It seems to be
>> something builtin to bash - very odd ....
>
> Assuming you're using bash, try type -a remount


-- 
Thanks,

Steve

Re: where is remount?

[Steve French]

By trying various combinations of options, I finally was able to find
one that stopped "remount" by pausing in the cifs mount helper
(prompting for a password), i can see a little more information:

Typing the command:
smfhome2:/home/stevef # remount /mnt /mnt1

I can see that "remount" invokes mount but with odd syntax
stevef@smfhome2:~> ps -Aelf | grep "mount"
0 S root     25024 25012  0  80   0 -  1779 wait   22:01 pts/4
00:00:00 /bin/mount -o remount,/mnt /mnt1



On Fri, May 16, 2008 at 9:51 PM, Steve French <smfrench@gmail.com> wrote:
> that is the point ... strace doesn't work on that command and I don't
> even know the syntax of the utility "remount"  It seems to be
> something builtin to bash - very odd ....
>
> smfhome2:~ # mount /dev/sdb8 /mnt2
> smfhome2:~ # remount -o ro /dev/sdb8
> mount: you must specify the filesystem type
> smfhome2:~ # remount -o ro /dev/sdb8 -t ext3
> mount: /dev/sdb8 not mounted already, or bad option
> smfhome2:~ # remount -t ext3 -o ro /dev/sdb8
> mount: you must specify the filesystem type
> smfhome2:~ # remount -o ro -t ext3 /dev/sdb8
> mount: /dev/sdb8 not mounted already, or bad option
> smfhome2:~ # strace -f remount -o ro -t ext3 /dev/sdb8
> strace: remount: command not found
> smfhome2:~ # which strace
> /usr/bin/strace
> smfhome2:~ # which remount
> which: no remount in
> (/home/stevef/bin:/usr/local/bin:/usr/bin:/sbin:/usr/sbin:/bin:/usr/bin/X11:/usr/X11R6/bin:/usr/games:/usr/lib/mit/bin:/usr/lib/mit/sbin:/usr/lib/qt3/bin)
>
>
> On Fri, May 16, 2008 at 8:49 PM, Tetsuo Handa
> <penguin-kernel@i-love.sakura.ne.jp> wrote:
>> Steve French wrote:
>>> It may be calling that ... but I was typing:  "remount" in bash and I
>>> don't see a bash alias for it or a command in the path named that.
>> Didn't you see MS_REMOUNT in the output of "strace"?
>>
>> # mount -t tmpfs none /dev/shm/
>> # strace mount -o remount,ro /dev/shm/ 2>&1 | grep mount
>> execve("/bin/mount", ["mount", "-o", "remount,ro", "/dev/shm/"], [/* 17 vars */]) = 0
>> open("/proc/mounts", O_RDONLY|O_LARGEFILE) = 3
>> stat64("/sbin/mount.tmpfs", 0xbffeb570) = -1 ENOENT (No such file or directory)
>> mount("none", "/dev/shm", 0x8c13d68, MS_MGC_VAL|MS_RDONLY|MS_REMOUNT, ""...) = 0
>>
>
>
>
> --
> Thanks,
>
> Steve
>



-- 
Thanks,

Steve