[PATCH] fuse2fs: open read-only when ro option and image non-writable

Dave Dykstra
2025-10-16T20:02:24Z

This opens the image read-only when an ro option is given and the
image is not writable. If it is then found that a journal recovery
is needed, an error is returned then.

The ret value is set to 4 after the option checks so that if there's
an error resulting in "goto out" it won't print an error about
unrecognized options.

Also submitted as PR https://github.com/tytso/e2fsprogs/pull/250
for the issue https://github.com/tytso/e2fsprogs/issues/244.

Replaces
https://lore.kernel.org/linux-ext4/20251010214735.22683-1-dave.dykstra@cern.ch/T/#u
https://lore.kernel.org/linux-ext4/175798064776.350013.6744611652039454651.stgit@frogsfrogsfrogs/#t

Signed-off-by: Dave Dykstra <2129743+DrDaveD@users.noreply.github.com>
---
misc/fuse2fs.c | 27 +++++++++++++++++++++++----
1 file changed, 23 insertions(+), 4 deletions(-)

diff --git a/misc/fuse2fs.c b/misc/fuse2fs.c
index cb5620c7..2ae2fc1a 100644
--- a/misc/fuse2fs.c
+++ b/misc/fuse2fs.c
@@ -4696,9 +4696,19 @@ int main(int argc, char *argv[])
err = ext2fs_open2(fctx.device, options, flags, 0, 0, unix_io_manager,
&global_fs);
if (err) {
- err_printf(&fctx, "%s.\n", error_message(err));
- err_printf(&fctx, "%s\n", _("Please run e2fsck -fy."));
- goto out;
+ if (((err == EACCES) || (err == EPERM)) && fctx.ro) {
+ // read-only requested and don't have write access
+ dbg_printf(&fctx, "%s: %s\n", __func__,
+ _("Permission denied with writable, trying without.\n"));
+ flags &= ~EXT2_FLAG_RW;
+ err = ext2fs_open2(fctx.device, options, flags, 0, 0,
+ unix_io_manager, &global_fs);
+ }
+ if (err) {
+ err_printf(&fctx, "%s.\n", error_message(err));
+ err_printf(&fctx, "%s\n", _("Please run e2fsck -fy."));
+ goto out;
+ }
}
fctx.fs = global_fs;
global_fs->priv_data = &fctx;
@@ -4741,6 +4751,8 @@ int main(int argc, char *argv[])
goto out;
}

+ ret = 4;
+
if (global_fs->super->s_state & EXT2_ERROR_FS) {
err_printf(&fctx, "%s\n",
_("Errors detected; running e2fsck is required."));
@@ -4760,6 +4772,11 @@ int main(int argc, char *argv[])
_("Mounting read-only without recovering journal."));
fctx.ro = 1;
global_fs->flags &= ~EXT2_FLAG_RW;
+ } else if (fctx.ro && !(flags & EXT2_FLAG_RW)) {
+ err_printf(&fctx, "%s\n",
+ _("Journal needs recovery but filesystem could not be opened read-write."));
+ err_printf(&fctx, "%s\n", _("Please run e2fsck -fy."));
+ goto out;
} else {
log_printf(&fctx, "%s\n", _("Recovering journal."));
err = ext2fs_run_ext3_journal(&global_fs);
@@ -4833,8 +4850,10 @@ int main(int argc, char *argv[])
if (fctx.no_default_opts == 0)
fuse_opt_add_arg(&args, extra_args);

- if (fctx.ro)
+ if (fctx.ro) {
+ /* This is in case ro was implied above and not passed in */
fuse_opt_add_arg(&args, "-oro");
+ }

if (fctx.fakeroot) {
#ifdef HAVE_MOUNT_NODEV
--
2.43.5