fuse2fs: make "ro" behavior consistent with the kernel

Make the behavior of the "ro" mount option consistent with the kernel:
User programs cannot change the files in the filesystem, but the driver
itself is allowed to update the filesystem metadata.  This means that ro
mounts can recover the journal.

Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Link: https://lore.kernel.org/r/174553064727.1160289.10466952108264302412.stgit@frogsfrogsfrogs
Signed-off-by: Theodore Ts'o <tytso@mit.edu>

diff --git a/misc/fuse2fs.c b/misc/fuse2fs.c
index 9ffc47c..28443fc 100644 (file)
--- a/misc/fuse2fs.c
+++ b/misc/fuse2fs.c
@@ -3739,6 +3739,7 @@ enum {
 
 static struct fuse_opt fuse2fs_opts[] = {
        FUSE2FS_OPT("ro",               ro,                     1),
+       FUSE2FS_OPT("rw",               ro,                     0),
        FUSE2FS_OPT("errors=panic",     panic_on_error,         1),
        FUSE2FS_OPT("minixdf",          minixdf,                1),
        FUSE2FS_OPT("fakeroot",         fakeroot,               1),
@@ -3784,13 +3785,12 @@ static int fuse2fs_opt_proc(void *data, const char *arg,
        "    -V   --version   print version\n"
        "\n"
        "fuse2fs options:\n"
-       "    -o ro                  read-only mount\n"
        "    -o errors=panic        dump core on error\n"
        "    -o minixdf             minix-style df\n"
        "    -o fakeroot            pretend to be root for permission checks\n"
        "    -o no_default_opts     do not include default fuse options\n"
        "    -o offset=<bytes>      similar to mount -o offset=<bytes>, mount the partition starting at <bytes>\n"
-       "    -o norecovery          don't replay the journal (implies ro)\n"
+       "    -o norecovery          don't replay the journal\n"
        "    -o fuse2fs_debug       enable fuse2fs debugging\n"
        "\n",
                        outargs->argv[0]);
@@ -3838,7 +3838,8 @@ int main(int argc, char *argv[])
        char *logfile;
        char extra_args[BUFSIZ];
        int ret = 0;
-       int flags = EXT2_FLAG_64BITS | EXT2_FLAG_THREADS | EXT2_FLAG_EXCLUSIVE;
+       int flags = EXT2_FLAG_64BITS | EXT2_FLAG_THREADS | EXT2_FLAG_EXCLUSIVE |
+                   EXT2_FLAG_RW;
 
        memset(&fctx, 0, sizeof(fctx));
        fctx.magic = FUSE2FS_MAGIC;
@@ -3857,11 +3858,6 @@ int main(int argc, char *argv[])
        else
                fctx.shortdev = fctx.device;
 
-       if (fctx.norecovery)
-               fctx.ro = 1;
-       if (fctx.ro)
-               log_printf(&fctx, "%s\n", _("Mounting read-only."));
-
 #ifdef ENABLE_NLS
        setlocale(LC_MESSAGES, "");
        setlocale(LC_CTYPE, "");
@@ -3892,8 +3888,6 @@ int main(int argc, char *argv[])
 
        /* Start up the fs (while we still can use stdout) */
        ret = 2;
-       if (!fctx.ro)
-               flags |= EXT2_FLAG_RW;
        char options[50];
        sprintf(options, "offset=%lu", fctx.offset);
        err = ext2fs_open2(fctx.device, options, flags, 0, 0, unix_io_manager,
@@ -3913,7 +3907,9 @@ int main(int argc, char *argv[])
                        log_printf(&fctx, "%s\n",
                                   _("Mounting read-only without "
                                     "recovering journal."));
-               } else if (!fctx.ro) {
+                       fctx.ro = 1;
+                       global_fs->flags &= ~EXT2_FLAG_RW;
+               } else {
                        log_printf(&fctx, "%s\n", _("Recovering journal."));
                        err = ext2fs_run_ext3_journal(&global_fs);
                        if (err) {
@@ -3924,14 +3920,10 @@ int main(int argc, char *argv[])
                        }
                        ext2fs_clear_feature_journal_needs_recovery(global_fs->super);
                        ext2fs_mark_super_dirty(global_fs);
-               } else {
-                       err_printf(&fctx, "%s\n",
- _("Journal needs recovery; running `e2fsck -E journal_only' is required."));
-                       goto out;
                }
        }
 
-       if (!fctx.ro) {
+       if (global_fs->flags & EXT2_FLAG_RW) {
                if (ext2fs_has_feature_journal(global_fs->super))
                        log_printf(&fctx, "%s\n",
                                   _("Warning: fuse2fs does not support "
@@ -3985,6 +3977,9 @@ int main(int argc, char *argv[])
        if (fctx.no_default_opts == 0)
                fuse_opt_add_arg(&args, extra_args);
 
+       if (fctx.ro)
+               fuse_opt_add_arg(&args, "-oro");
+
        if (fctx.fakeroot) {
 #ifdef HAVE_MOUNT_NODEV
                fuse_opt_add_arg(&args,"-onodev");