Attachment 1458628 Details for Bug 1358887 – Patch - set bind mount as propagation slave

[patch] Patch - set bind mount as propagation slave

autofs-5.1.4-set-bind-mount-as-propagation-slave.patch (text/plain), 2.12 KB, created by Ian Kent on 2018-07-13 04:34:58 UTC

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Creator: Ian Kent

Created: 2018-07-13 04:34:58 UTC

Size: 2.12 KB

patch

obsolete

>autofs-5.1.4 - set bind mount as propagation slave
>
>From: Ian Kent <raven@themaw.net>
>
>When using a multi-mount with mount targets that are on the
>local machine and resulting bind mounts are made to a file
>system that is mount propagation shared (such as the root
>file system on systemd managed systems) the autofs offset
>mount triggers made within the bind mount will be propagated
>back to the target file system.
>
>When this happens the target of the offset (the unwanted
>propagated mount) is itself an autofs trigger mount and
>accessing the path results in a deadlock.
>
>In order for these multi-mounts to function properly in this
>case bind mounts that contain mount triggers must be set to
>propagation shared or private so the backward propagation
>doesn't occur.
>
>Signed-off-by: Ian Kent <raven@themaw.net>
>---
> CHANGELOG            |    1 +
> modules/mount_bind.c |   16 +++++++++++++++-
> 2 files changed, 16 insertions(+), 1 deletion(-)
>
>--- autofs-5.0.7.orig/CHANGELOG
>+++ autofs-5.0.7/CHANGELOG
>@@ -301,6 +301,7 @@
> - add man page note about extra slashes in paths.
> - add units After line to include statd service.
> - use systemd sd_notify() at startup.
>+- set bind mount as propagation slave.
> 
> 25/07/2012 autofs-5.0.7
> =======================
>--- autofs-5.0.7.orig/modules/mount_bind.c
>+++ autofs-5.0.7/modules/mount_bind.c
>@@ -20,6 +20,7 @@
> #include <sys/param.h>
> #include <sys/types.h>
> #include <sys/stat.h>
>+#include <sys/mount.h>
> 
> #define MODULE_MOUNT
> #include "automount.h"
>@@ -184,8 +185,21 @@ int mount_mount(struct autofs_point *ap,
> 			debug(ap->logopt,
> 			      MODPREFIX "mounted %s type %s on %s",
> 			      what, fstype, fullpath);
>-			return 0;
> 		}
>+
>+		/* The bind mount has succeeded but if the target
>+		 * mount is propagation shared propagation of child
>+		 * mounts (autofs offset mounts for example) back to
>+		 * the target of the bind mount must be avoided or
>+		 * autofs trigger mounts will deadlock.
>+		 */
>+		err = mount(NULL, fullpath, NULL, MS_SLAVE, NULL);
>+		if (err)
>+			warn(ap->logopt,
>+			     "failed to set propagation type for %s",
>+			     fullpath);
>+
>+		return 0;
> 	} else {
> 		char *cp;
> 		char basepath[PATH_MAX];

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