[Samba] open() called from within Samba returns EROFS on a filesystem that was remounted R/W

Daniel Kamil Kozar dkk089 at gmail.com
Fri Dec 29 06:29:57 UTC 2017

I have a Samba share pointing to a mount point which is mounted
read-only on boot. It has since  been remounted as R/W. The share
itself is marked as writable in smb.conf :

path = /mnt/storage/
guest ok = yes
browseable = yes
writable = yes

After connecting to the share via CIFS as an authenticated user, I get
a "permission denied" message, with the error code being
NT_STATUS_ACCESS_DENIED. I straced the forked Samba process that's
running with the privileges of the user that I log in as, and saw that
open() returns EROFS :

getcwd("/mnt/storage", 4096)            = 13
open("a", O_RDWR|O_CREAT|O_EXCL|O_NOFOLLOW, 0644) = -1 EROFS
(Read-only file system)

Meanwhile, running a simple "touch" on said mount point, as the same
user as the one running the forked Samba process, works fine. Why does
Samba not seem to respect the remount? I tried restarting the smbd
daemon, but with no effect. Running Samba 4.7.3-Debian on Debian
unstable, kernel 4.14.7.

Thank you in advance,

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