GNU bug report logs - #54286
[PATCH] Fix ls -l triggering automounts.

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Message #5 received at submit <at> debbugs.gnu.org (full text, mbox):

From: Rohan Sable <rsable <at> redhat.com>
To: bug-coreutils <at> gnu.org
Cc: ikent <at> redhat.com, rohanjsable <at> gmail.com, kdudka <at> redhat.com
Subject: [PATCH] Fix ls -l triggering automounts.
Date: Mon, 7 Mar 2022 13:24:02 +0530

Running ls -l on a path that has autofs mounts,
triggers a mount or in case of unmountable shares,
triggers errors :
~~~
[root <at> rsablerhel85 mnt2]# ll
ls: cannot access 'testshare2': No such file or directory     <<<<< Error
total 0
drwxrwxrwx. 3 1000 1000 15 Jan 17 12:08 testshare             <<<<< mount is triggerd for testshare
d?????????? ? ?    ?     ?            ? testshare2            <<<<< Path we know that is inaccessible throws an error

[root <at> rsablerhel85 mnt2]# mount | grep -i test
rsable76server:/testshare on /mnt2/testshare type nfs (rw,relatime,vers=3,rsize=32768,wsize=32768,namlen=255,hard,proto=tcp,timeo=600,retrans=6,sec=sys,mountaddr=192.168.122.58,mountvers=3,mountport=20048,mountproto=tcp,local_lock=none,addr=192.168.122.58)
~~~

Added AT_NO_AUTOMOUNT flag to do_lstat to fix this behavior.

Signed-off-by: Rohan Sable <rsable <at> redhat.com>
---
 src/ls.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/ls.c b/src/ls.c
index 1930e4abb..bf79ef8b9 100644
--- a/src/ls.c
+++ b/src/ls.c
@@ -1204,7 +1204,7 @@ do_stat (char const *name, struct stat *st)
 static int
 do_lstat (char const *name, struct stat *st)
 {
-  return do_statx (AT_FDCWD, name, st, AT_SYMLINK_NOFOLLOW, calc_req_mask ());
+  return do_statx (AT_FDCWD, name, st, AT_SYMLINK_NOFOLLOW | AT_NO_AUTOMOUNT, calc_req_mask ());
 }
 
 static int
-- 
2.34.1

Message #8 received at 54286 <at> debbugs.gnu.org (full text, mbox):

From: Pádraig Brady <P <at> draigBrady.com>
To: Rohan Sable <rsable <at> redhat.com>, 54286 <at> debbugs.gnu.org
Cc: ikent <at> redhat.com, rohanjsable <at> gmail.com, kdudka <at> redhat.com
Subject: Re: bug#54286: [PATCH] Fix ls -l triggering automounts.
Date: Mon, 7 Mar 2022 13:33:43 +0000

On 07/03/2022 07:54, Rohan Sable wrote:
> Running ls -l on a path that has autofs mounts,
> triggers a mount or in case of unmountable shares,
> triggers errors :
> ~~~
> [root <at> rsablerhel85 mnt2]# ll
> ls: cannot access 'testshare2': No such file or directory     <<<<< Error
> total 0
> drwxrwxrwx. 3 1000 1000 15 Jan 17 12:08 testshare             <<<<< mount is triggerd for testshare
> d?????????? ? ?    ?     ?            ? testshare2            <<<<< Path we know that is inaccessible throws an error
> 
> [root <at> rsablerhel85 mnt2]# mount | grep -i test
> rsable76server:/testshare on /mnt2/testshare type nfs (rw,relatime,vers=3,rsize=32768,wsize=32768,namlen=255,hard,proto=tcp,timeo=600,retrans=6,sec=sys,mountaddr=192.168.122.58,mountvers=3,mountport=20048,mountproto=tcp,local_lock=none,addr=192.168.122.58)
> ~~~
> 
> Added AT_NO_AUTOMOUNT flag to do_lstat to fix this behavior.

Yes we should handle this, but a bit differently I think.

In this and the stat(1) patch you're only doing the adjustment for lstat().
I'd be more inclined to do this for all statx() uses because:
 - stat() and lstat() behave as if AT_NO_AUTOMOUNT is set
   - stat can be significant here for ondemand dirs, bind mounted entries, or network contexts etc.
 - ls(1) and stat(1) are operating on meta-data so should avoid mounts by default

Also we have to provide some ifdef protection around AT_NO_AUTOMOUNT use.
That's best done in gnulib in fcntl.in.h

Also we have related control in the --cached=never option in stat(1),
which is meant to ensure we go the whole way to the source file system,
which maps well with _not_ setting AT_NO_AUTOMOUNT for that case only.

I'll follow up with some patches along those lines.

thanks,
Pádraig

Message #11 received at 54286 <at> debbugs.gnu.org (full text, mbox):

From: Pádraig Brady <P <at> draigBrady.com>
To: bug-gnulib <at> gnu.org
Cc: 54286 <at> debbugs.gnu.org, Pádraig Brady <P <at> draigBrady.com>
Subject: [PATCH] fcntl-h: add AT_NO_AUTOMOUNT
Date: Mon,  7 Mar 2022 14:08:51 +0000

* lib/fcntl.in.h: Define AT_NO_AUTOMOUNT to 0 where not defined.
This is available on Linux since 2.6.38.
---
 ChangeLog      | 6 ++++++
 lib/fcntl.in.h | 4 ++++
 2 files changed, 10 insertions(+)

diff --git a/ChangeLog b/ChangeLog
index c5a80fd3f3..e3f0ed216c 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,9 @@
+2022-03-07  Pádraig Brady  <P <at> draigBrady.com>
+
+	fcntl-h: add AT_NO_AUTOMOUNT
+	* lib/fcntl.in.h: Define AT_NO_AUTOMOUNT to 0 where not defined.
+	This is available on Linux since 2.6.38.
+
 2022-03-01  Paul Eggert  <eggert <at> cs.ucla.edu>
 
 	Create lib/Makefile.am after gnulib-comp.m4
diff --git a/lib/fcntl.in.h b/lib/fcntl.in.h
index 3e0c302af3..9270ced897 100644
--- a/lib/fcntl.in.h
+++ b/lib/fcntl.in.h
@@ -435,6 +435,10 @@ _GL_WARN_ON_USE (openat, "openat is not portable - "
 # define AT_EACCESS 4
 #endif
 
+/* Ignore this flag if not supported.  */
+#ifndef AT_NO_AUTOMOUNT
+# define AT_NO_AUTOMOUNT 0
+#endif
 
 #endif /* _ <at> GUARD_PREFIX <at> _FCNTL_H */
 #endif /* _ <at> GUARD_PREFIX <at> _FCNTL_H */
-- 
2.26.2

Message #14 received at 54286 <at> debbugs.gnu.org (full text, mbox):

From: Pádraig Brady <P <at> draigBrady.com>
To: Rohan Sable <rsable <at> redhat.com>, 54286 <at> debbugs.gnu.org
Cc: ikent <at> redhat.com, rohanjsable <at> gmail.com, kdudka <at> redhat.com
Subject: Re: bug#54286: [PATCH] Fix ls -l triggering automounts.
Date: Mon, 7 Mar 2022 14:26:27 +0000

[Message part 1 (text/plain, inline)]

Updated patch for ls attached as per discussion.
Added a NEWS entry.

[ls-no-automount.patch (text/x-patch, attachment)]

Message #17 received at 54286 <at> debbugs.gnu.org (full text, mbox):

From: Kamil Dudka <kdudka <at> redhat.com>
To: Rohan Sable <rsable <at> redhat.com>, 54286 <at> debbugs.gnu.org,
 Pádraig Brady <P <at> draigbrady.com>
Cc: ikent <at> redhat.com, rohanjsable <at> gmail.com
Subject: Re: bug#54286: [PATCH] Fix ls -l triggering automounts.
Date: Mon, 07 Mar 2022 16:51:18 +0100

On Monday, March 7, 2022 3:26:27 PM CET Pádraig Brady wrote:
> Updated patch for ls attached as per discussion.
> Added a NEWS entry.

Works as expected.  Thank you both!

Kamil

Message #20 received at 54286 <at> debbugs.gnu.org (full text, mbox):

From: Paul Eggert <eggert <at> cs.ucla.edu>
To: Pádraig Brady <P <at> draigBrady.com>
Cc: 54286 <at> debbugs.gnu.org, bug-gnulib <at> gnu.org
Subject: Re: [PATCH] fcntl-h: add AT_NO_AUTOMOUNT
Date: Mon, 7 Mar 2022 09:14:49 -0800

On 3/7/22 06:08, Pádraig Brady wrote:
> * lib/fcntl.in.h: Define AT_NO_AUTOMOUNT to 0 where not defined.
> This is available on Linux since 2.6.38.

Looks good.

Please feel free to install this sort of thing without waiting for review.

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