diff options
| -rw-r--r-- | fs/super.c | 94 | ||||
| -rw-r--r-- | include/linux/fs_context.h | 5 |
2 files changed, 99 insertions, 0 deletions
diff --git a/fs/super.c b/fs/super.c index 0220def9baba..da223b4cfbca 100644 --- a/fs/super.c +++ b/fs/super.c @@ -1222,6 +1222,7 @@ int get_tree_keyed(struct fs_context *fc, EXPORT_SYMBOL(get_tree_keyed); #ifdef CONFIG_BLOCK + static int set_bdev_super(struct super_block *s, void *data) { s->s_bdev = data; @@ -1231,6 +1232,99 @@ static int set_bdev_super(struct super_block *s, void *data) return 0; } +static int set_bdev_super_fc(struct super_block *s, struct fs_context *fc) +{ + return set_bdev_super(s, fc->sget_key); +} + +static int test_bdev_super_fc(struct super_block *s, struct fs_context *fc) +{ + return s->s_bdev == fc->sget_key; +} + +/** + * get_tree_bdev - Get a superblock based on a single block device + * @fc: The filesystem context holding the parameters + * @fill_super: Helper to initialise a new superblock + */ +int get_tree_bdev(struct fs_context *fc, + int (*fill_super)(struct super_block *, + struct fs_context *)) +{ + struct block_device *bdev; + struct super_block *s; + fmode_t mode = FMODE_READ | FMODE_EXCL; + int error = 0; + + if (!(fc->sb_flags & SB_RDONLY)) + mode |= FMODE_WRITE; + + if (!fc->source) + return invalf(fc, "No source specified"); + + bdev = blkdev_get_by_path(fc->source, mode, fc->fs_type); + if (IS_ERR(bdev)) { + errorf(fc, "%s: Can't open blockdev", fc->source); + return PTR_ERR(bdev); + } + + /* Once the superblock is inserted into the list by sget_fc(), s_umount + * will protect the lockfs code from trying to start a snapshot while + * we are mounting + */ + mutex_lock(&bdev->bd_fsfreeze_mutex); + if (bdev->bd_fsfreeze_count > 0) { + mutex_unlock(&bdev->bd_fsfreeze_mutex); + warnf(fc, "%pg: Can't mount, blockdev is frozen", bdev); + return -EBUSY; + } + + fc->sb_flags |= SB_NOSEC; + fc->sget_key = bdev; + s = sget_fc(fc, test_bdev_super_fc, set_bdev_super_fc); + mutex_unlock(&bdev->bd_fsfreeze_mutex); + if (IS_ERR(s)) + return PTR_ERR(s); + + if (s->s_root) { + /* Don't summarily change the RO/RW state. */ + if ((fc->sb_flags ^ s->s_flags) & SB_RDONLY) { + warnf(fc, "%pg: Can't mount, would change RO state", bdev); + deactivate_locked_super(s); + blkdev_put(bdev, mode); + return -EBUSY; + } + + /* + * s_umount nests inside bd_mutex during + * __invalidate_device(). blkdev_put() acquires + * bd_mutex and can't be called under s_umount. Drop + * s_umount temporarily. This is safe as we're + * holding an active reference. + */ + up_write(&s->s_umount); + blkdev_put(bdev, mode); + down_write(&s->s_umount); + } else { + s->s_mode = mode; + snprintf(s->s_id, sizeof(s->s_id), "%pg", bdev); + sb_set_blocksize(s, block_size(bdev)); + error = fill_super(s, fc); + if (error) { + deactivate_locked_super(s); + return error; + } + + s->s_flags |= SB_ACTIVE; + bdev->bd_super = s; + } + + BUG_ON(fc->root); + fc->root = dget(s->s_root); + return 0; +} +EXPORT_SYMBOL(get_tree_bdev); + static int test_bdev_super(struct super_block *s, void *data) { return (void *)s->s_bdev == data; diff --git a/include/linux/fs_context.h b/include/linux/fs_context.h index aad5e68d58e2..84a5eaa09f19 100644 --- a/include/linux/fs_context.h +++ b/include/linux/fs_context.h @@ -88,6 +88,7 @@ struct fs_context { struct mutex uapi_mutex; /* Userspace access mutex */ struct file_system_type *fs_type; void *fs_private; /* The filesystem's context */ + void *sget_key; struct dentry *root; /* The root and superblock */ struct user_namespace *user_ns; /* The user namespace for this mount */ struct net *net_ns; /* The network namespace for this mount */ @@ -159,6 +160,10 @@ extern int get_tree_keyed(struct fs_context *fc, struct fs_context *fc), void *key); +extern int get_tree_bdev(struct fs_context *fc, + int (*fill_super)(struct super_block *sb, + struct fs_context *fc)); + extern const struct file_operations fscontext_fops; /* |