ovl: fix regression in parsing of mount options with escaped comma
Ever since commit
91c77947133f ("ovl: allow filenames with comma"), the
following example was legit overlayfs mount options:
mount -t overlay overlay -o 'lowerdir=/tmp/a\,b/lower' /mnt
The conversion to new mount api moved to using the common helper
generic_parse_monolithic() and discarded the specialized ovl_next_opt()
option separator.
Bring back ovl_next_opt() and use vfs_parse_monolithic_sep() to fix the
regression.
Reported-by: Ryan Hendrickson <ryan.hendrickson@alum.mit.edu>
Closes: https://lore.kernel.org/r/
8da307fb-9318-cf78-8a27-
ba5c5a0aef6d@alum.mit.edu/
Fixes:
1784fbc2ed9c ("ovl: port to new mount api")
Signed-off-by: Amir Goldstein <amir73il@gmail.com>