bcachefs: make offline fsck set read_only fs flag

A subsequent change will remove "read_only" as a mount option in favor
of the standard option "ro", meaning the userspace fsck command cannot
pass it to the fsck ioctl. Instead, in offline fsck, set "read_only"
kernel-side without trying to parse it as a mount option.

For compatibility with versions of the "bcachefs fsck" command that try
to pass the "read_only" mount opt, remove it from the mount options
string prior to parsing when it is present.

Signed-off-by: Thomas Bertschinger <tahbertschinger@gmail.com>
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

diff --git a/fs/bcachefs/chardev.c b/fs/bcachefs/chardev.c
index 6d82e1165adc2da028f88f98d704f0ff7676b0d0..8c5b13cd3205c359fdc11a315ea3ef2706002aff 100644 (file)
--- a/fs/bcachefs/chardev.c
+++ b/fs/bcachefs/chardev.c
@@ -213,6 +213,18 @@ static long bch2_ioctl_fsck_offline(struct bch_ioctl_fsck_offline __user *user_a
 
        if (arg.opts) {
                char *optstr = strndup_user((char __user *)(unsigned long) arg.opts, 1 << 16);
+               char *ro, *rest;
+
+               /*
+                * If passed a "read_only" mount option, remove it because it is
+                * no longer a valid mount option, and the filesystem will be
+                * set "read_only" regardless.
+                */
+               ro = strstr(optstr, "read_only");
+               if (ro) {
+                       rest = ro + strlen("read_only");
+                       memmove(ro, rest, strlen(rest) + 1);
+               }
 
                ret =   PTR_ERR_OR_ZERO(optstr) ?:
                        bch2_parse_mount_opts(NULL, &thr->opts, optstr);
@@ -224,6 +236,7 @@ static long bch2_ioctl_fsck_offline(struct bch_ioctl_fsck_offline __user *user_a
        }
 
        opt_set(thr->opts, stdio, (u64)(unsigned long)&thr->thr.stdio);
+       opt_set(thr->opts, read_only, 1);
 
        /* We need request_key() to be called before we punt to kthread: */
        opt_set(thr->opts, nostart, true);