3bb17a25bc
This is the actual mounting callback for the new mount API. Implement this using our current fill super as a guideline, making the appropriate adjustments for the new mount API. Our old mount operation had two fs_types, one to handle the actual opening, and the one that we called to handle the actual opening and then did the subvol lookup for returning the actual root dentry. This is mirrored here, but simply with different behaviors for ->get_tree. We use the existence of ->s_fs_info to tell which part we're in. The initial call allocates the fs_info, then call mount_fc() with a duplicated fc to do the actual open_ctree part. Then we take that vfsmount and use it to look up our subvolume that we're mounting and return that as our s_root. This idea was taken from Christians attempt to convert us to the new mount API [1]. In btrfs_get_tree_super() the mount device is scanned and opened in one go under uuid_mutex we expect that all related devices have been already scanned, either by mount or from the outside. A device forget can be called on some of the devices as the whole context is not protected but it's an unlikely event, though it's a minor behaviour change. References: https://lore.kernel.org/all/20230626-fs-btrfs-mount-api-v1-2-045e9735a00b@kernel.org/ Reviewed-by: Christian Brauner <brauner@kernel.org> Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com> Signed-off-by: Josef Bacik <josef@toxicpanda.com> Reviewed-by: David Sterba <dsterba@suse.com> [ add note about device scanning ] Signed-off-by: David Sterba <dsterba@suse.com>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.