bug#63554: 63554

[andy]

Also&nbsp;had&nbsp;this&nbsp;exact&nbsp;same&nbsp;problem.&nbsp;Looking&nbsp;at&nbsp;patch&nbsp;#56880,&nbsp;it&nbsp;tried&nbsp;to&nbsp;add&nbsp;the&nbsp;shared&nbsp;option,&nbsp;but&nbsp;found&nbsp;that&nbsp;the&nbsp;`mount(2)`&nbsp;syscall&nbsp;had&nbsp;to&nbsp;be&nbsp;called&nbsp;twice,&nbsp;once&nbsp;to&nbsp;mount&nbsp;it,&nbsp;then&nbsp;once&nbsp;to&nbsp;make&nbsp;the&nbsp;already&nbsp;existing&nbsp;mount&nbsp;shared,&nbsp;so&nbsp;just&nbsp;adding&nbsp;the&nbsp;bit-flag&nbsp;`MS_SHARED`&nbsp;to&nbsp;that&nbsp;syscall&nbsp;didn&#39;t&nbsp;work.&nbsp;The&nbsp;patch&nbsp;seems&nbsp;to&nbsp;not&nbsp;include&nbsp;that&nbsp;bitflag&nbsp;until&nbsp;someone&nbsp;needed&nbsp;it&nbsp;enough&nbsp;to&nbsp;implement&nbsp;calling&nbsp;`mount(2)`&nbsp;twice.&nbsp;Pretty&nbsp;sure&nbsp;the&nbsp;option&nbsp;doesn&#39;t&nbsp;do&nbsp;anything&nbsp;because&nbsp;it&nbsp;doesn&#39;t&nbsp;change&nbsp;the&nbsp;bit-flag&nbsp;in&nbsp;the&nbsp;`mount-flags-&amp;gt;bit-mask`&nbsp;procedure&nbsp;at&nbsp;https://git.savannah.gnu.org/cgit/guix.git/tree/gnu/build/file-systems.scm#n1155<br/><br/>So&nbsp;the&nbsp;bug&nbsp;seems&nbsp;to&nbsp;be&nbsp;intentional,&nbsp;and&nbsp;a&nbsp;fix&nbsp;would&nbsp;have&nbsp;to&nbsp;have&nbsp;guix&nbsp;first&nbsp;mount&nbsp;the&nbsp;filesystem&nbsp;normally,&nbsp;then&nbsp;change&nbsp;it&nbsp;to&nbsp;a&nbsp;shared&nbsp;mount.