From: Thomas Bertschinger Date: Sun, 26 May 2024 19:08:20 +0000 (-0600) Subject: bcachefs: don't expose "read_only" as a mount option X-Git-Tag: v6.11-rc1~120^2~102 X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=babe30fe8db62b79f7e3df4144acc344b3672f60;p=thirdparty%2Fkernel%2Flinux.git bcachefs: don't expose "read_only" as a mount option When "read_only" is exposed as a mount option, it is redundant with the standard option "ro" and gives users multiple ways to specify that a bcachefs filesystem should be mounted read-only. This presents the risk of having inconsistent options specified. This can be seen when remounting a read-only filesystem in read-write mode, using mount(8) from util-linux. Because mount(8) parses the existing mount options from `/proc/mounts` and applies them when remounting, it can end up applying both "read_only" and "rw": $ mount img -o ro /mnt $ strace mount -o remount,rw /mnt ... fsconfig(4, FSCONFIG_SET_FLAG, "read_only", NULL, 0) = 0 fsconfig(4, FSCONFIG_SET_FLAG, "rw", NULL, 0) = 0 ... Making "read_only" no longer a mount option means this edge case cannot occur. Fixes: 62719cf33c3a ("bcachefs: Fix nochanges/read_only interaction") Signed-off-by: Thomas Bertschinger Signed-off-by: Kent Overstreet --- diff --git a/fs/bcachefs/opts.h b/fs/bcachefs/opts.h index b197ec90d4cb0..c9da6267894b6 100644 --- a/fs/bcachefs/opts.h +++ b/fs/bcachefs/opts.h @@ -406,7 +406,7 @@ enum fsck_err_opts { BCH2_NO_SB_OPT, BCH_SB_SECTOR, \ "offset", "Sector offset of superblock") \ x(read_only, u8, \ - OPT_FS|OPT_MOUNT, \ + OPT_FS, \ OPT_BOOL(), \ BCH2_NO_SB_OPT, false, \ NULL, NULL) \