bcachefs: fix mounting read only block devices

4 files changed, 24 insertions, 12 deletions

diff --git a/fs/bcachefs/opts.h b/fs/bcachefs/opts.h
index 126056e60543..bc8fd46aeb23 100644
--- a/fs/bcachefs/opts.h
+++ b/fs/bcachefs/opts.h
@@ -171,7 +171,7 @@ static const struct bch_opts bch2_opts_default = {
 #define opt_defined(_opts, _name)	((_opts)._name##_defined)
 
 #define opt_get(_opts, _name)						\
-	(opt_defined(_opts, _name) ? _opts._name : bch2_opts_default._name)
+	(opt_defined(_opts, _name) ? (_opts)._name : bch2_opts_default._name)
 
 #define opt_set(_opts, _name, _v)					\
 do {									\
diff --git a/fs/bcachefs/super-io.c b/fs/bcachefs/super-io.c
index e49437c276ac..6c7f4166d3dd 100644
--- a/fs/bcachefs/super-io.c
+++ b/fs/bcachefs/super-io.c
@@ -531,10 +531,10 @@ reread:
 	return NULL;
 }
 
-int bch2_read_super(const char *path, struct bch_opts opts,
+int bch2_read_super(const char *path, struct bch_opts *opts,
 		    struct bch_sb_handle *sb)
 {
-	u64 offset = opt_get(opts, sb);
+	u64 offset = opt_get(*opts, sb);
 	struct bch_sb_layout layout;
 	const char *err;
 	__le64 *i;
@@ -543,13 +543,23 @@ int bch2_read_super(const char *path, struct bch_opts opts,
 	memset(sb, 0, sizeof(*sb));
 	sb->mode = FMODE_READ;
 
-	if (!opt_get(opts, noexcl))
+	if (!opt_get(*opts, noexcl))
 		sb->mode |= FMODE_EXCL;
 
-	if (!opt_get(opts, nochanges))
+	if (!opt_get(*opts, nochanges))
 		sb->mode |= FMODE_WRITE;
 
 	sb->bdev = blkdev_get_by_path(path, sb->mode, sb);
+	if (IS_ERR(sb->bdev) &&
+	    PTR_ERR(sb->bdev) == -EACCES &&
+	    opt_get(*opts, read_only)) {
+		sb->mode &= ~FMODE_WRITE;
+
+		sb->bdev = blkdev_get_by_path(path, sb->mode, sb);
+		if (!IS_ERR(sb->bdev))
+			opt_set(*opts, nochanges, true);
+	}
+
 	if (IS_ERR(sb->bdev))
 		return PTR_ERR(sb->bdev);
 
@@ -568,7 +578,7 @@ int bch2_read_super(const char *path, struct bch_opts opts,
 	if (!err)
 		goto got_super;
 
-	if (opt_defined(opts, sb))
+	if (opt_defined(*opts, sb))
 		goto err;
 
 	pr_err("error reading default superblock: %s", err);
@@ -601,7 +611,7 @@ int bch2_read_super(const char *path, struct bch_opts opts,
 	     i < layout.sb_offset + layout.nr_superblocks; i++) {
 		offset = le64_to_cpu(*i);
 
-		if (offset == opt_get(opts, sb))
+		if (offset == opt_get(*opts, sb))
 			continue;
 
 		err = read_one_super(sb, offset);
diff --git a/fs/bcachefs/super-io.h b/fs/bcachefs/super-io.h
index 32ac0e875fa0..69366a6f9581 100644
--- a/fs/bcachefs/super-io.h
+++ b/fs/bcachefs/super-io.h
@@ -94,7 +94,7 @@ int bch2_super_realloc(struct bch_sb_handle *, unsigned);
 
 const char *bch2_sb_validate(struct bch_sb_handle *);
 
-int bch2_read_super(const char *, struct bch_opts, struct bch_sb_handle *);
+int bch2_read_super(const char *, struct bch_opts *, struct bch_sb_handle *);
 void bch2_write_super(struct bch_fs *);
 
 /* BCH_SB_FIELD_journal: */
diff --git a/fs/bcachefs/super.c b/fs/bcachefs/super.c
index 6f541ddd6aa0..4cc4301ceae7 100644
--- a/fs/bcachefs/super.c
+++ b/fs/bcachefs/super.c
@@ -1432,6 +1432,7 @@ err:
 /* Add new device to running filesystem: */
 int bch2_dev_add(struct bch_fs *c, const char *path)
 {
+	struct bch_opts opts = bch2_opts_empty();
 	struct bch_sb_handle sb;
 	const char *err;
 	struct bch_dev *ca = NULL;
@@ -1440,7 +1441,7 @@ int bch2_dev_add(struct bch_fs *c, const char *path)
 	unsigned dev_idx, nr_devices, u64s;
 	int ret;
 
-	ret = bch2_read_super(path, bch2_opts_empty(), &sb);
+	ret = bch2_read_super(path, &opts, &sb);
 	if (ret)
 		return ret;
 
@@ -1542,6 +1543,7 @@ err:
 /* Hot add existing device to running filesystem: */
 int bch2_dev_online(struct bch_fs *c, const char *path)
 {
+	struct bch_opts opts = bch2_opts_empty();
 	struct bch_sb_handle sb = { NULL };
 	struct bch_dev *ca;
 	unsigned dev_idx;
@@ -1550,7 +1552,7 @@ int bch2_dev_online(struct bch_fs *c, const char *path)
 
 	mutex_lock(&c->state_lock);
 
-	ret = bch2_read_super(path, bch2_opts_empty(), &sb);
+	ret = bch2_read_super(path, &opts, &sb);
 	if (ret) {
 		mutex_unlock(&c->state_lock);
 		return ret;
@@ -1708,7 +1710,7 @@ struct bch_fs *bch2_fs_open(char * const *devices, unsigned nr_devices,
 		goto err;
 
 	for (i = 0; i < nr_devices; i++) {
-		ret = bch2_read_super(devices[i], opts, &sb[i]);
+		ret = bch2_read_super(devices[i], &opts, &sb[i]);
 		if (ret)
 			goto err;
 
@@ -1842,7 +1844,7 @@ const char *bch2_fs_open_incremental(const char *path)
 	struct bch_opts opts = bch2_opts_empty();
 	const char *err;
 
-	if (bch2_read_super(path, opts, &sb))
+	if (bch2_read_super(path, &opts, &sb))
 		return "error reading superblock";
 
 	err = __bch2_fs_open_incremental(&sb, opts);