vfs abstractions and tarfs #1037

As it is currently declared, the xattr_handler structs are const but the array containing their pointers is not. This patch makes it so that fs modules can place them in .rodata, which makes it harder for accidental/malicious modifications at runtime. Signed-off-by: Wedson Almeida Filho <walmeida@microsoft.com>

This allows modules to be initialised in-place in pinned memory, which enables the usage of pinned types (e.g., mutexes, spinlocks, driver registrations, etc.) in modules without any extra allocations. Drivers that don't need this may continue to implement `Module` without any changes. Signed-off-by: Wedson Almeida Filho <walmeida@microsoft.com>

This is a modified version of rust_minimal that is initialised in-place. Signed-off-by: Wedson Almeida Filho <walmeida@microsoft.com>

This is the Rust version of the macro with the same name in C. It produces a raw pointer to an outer type from a pointer to an inner field. Signed-off-by: Wedson Almeida Filho <walmeida@microsoft.com>

We'll need it, for example, when calling `register_filesystem` to initialise a file system registration. Signed-off-by: Wedson Almeida Filho <walmeida@microsoft.com>

It only contains the bare minimum to implement inode timestamps. Signed-off-by: Wedson Almeida Filho <walmeida@microsoft.com>

It allows us to read/write data in little-endian format. Compared to just using the correctly-sized integer type, it has the advantage of forcing users to convert to and from little endian format (which will be no-ops in little-endian architectures). Signed-off-by: Wedson Almeida Filho <walmeida@microsoft.com>

If a type `T` implements this trait, it's possible to safely get a shared reference to a `T` from a byte slice. This commit also provides a macro that allows the automatic derivation of `FromBytes` for simple structs whose fields all implement `FromBytes` as well. Signed-off-by: Wedson Almeida Filho <walmeida@microsoft.com>

This is just the basics of `kmem_cache` to be used in file systems for inodes. All dead-code annotations will be removed in the next commit. Signed-off-by: Wedson Almeida Filho <walmeida@microsoft.com>

The `allocator_api` feature is needed by drivers that allocate memory. Signed-off-by: Wedson Almeida Filho <walmeida@microsoft.com>

Allow basic registration and unregistration of Rust file system types. Unregistration happens automatically when a registration variable is dropped (e.g., when it goes out of scope). File systems registered this way are visible in `/proc/filesystems` but cannot be mounted yet because `init_fs_context` fails. Signed-off-by: Wedson Almeida Filho <walmeida@microsoft.com>

Simplify the declaration of modules that only expose a file system type. They can now do it using the `module_fs` macro. Signed-off-by: Wedson Almeida Filho <walmeida@microsoft.com>

Introduce a basic sample that for now only registers the file system and doesn't really provide any functionality beyond having it listed in `/proc/filesystems`. New functionality will be added to the sample in subsequent patches as their abstractions are introduced. Signed-off-by: Wedson Almeida Filho <walmeida@microsoft.com>

Allow Rust file systems to initialise superblocks, which allows them to be mounted (though they are still empty). Some scaffolding code is added to create an empty directory as the root. It is replaced by proper inode creation in a subsequent patch in this series. Signed-off-by: Wedson Almeida Filho <walmeida@microsoft.com>

Allow Rust file systems to handle typed and ref-counted inodes. This is in preparation for creating new inodes (for example, to create the root inode of a new superblock), which comes in the next patch in the series. Signed-off-by: Wedson Almeida Filho <walmeida@microsoft.com>

Allow Rust file systems to specify their root directory. Also allow them to create (and do cache lookups of) directory inodes. (More types of inodes are added in subsequent patches in the series.) The `NewINode` type ensures that a new inode is properly initialised before it is marked so. It also facilitates error paths by automatically marking inodes as failed if they're not properly initialised. Signed-off-by: Wedson Almeida Filho <walmeida@microsoft.com>

Allow Rust file systems to report the contents of their directory inodes. The reported entries cannot be opened yet. Signed-off-by: Wedson Almeida Filho <walmeida@microsoft.com>

Allow Rust file systems to create inodes that are children of a directory inode when they're looked up by name. Signed-off-by: Wedson Almeida Filho <walmeida@microsoft.com>

Allow Rust file systems to handle ref-counted folios. Provide the minimum needed to implement `read_folio` (part of `struct address_space_operations`) in read-only file systems and to read uncached blocks. Signed-off-by: Wedson Almeida Filho <walmeida@microsoft.com>

Allow Rust file systems to create regular file inodes backed by the page cache. The contents of such files are read into folios via `read_folio`. Signed-off-by: Wedson Almeida Filho <walmeida@microsoft.com>

Allow Rust file systems to expose xattrs associated with inodes. `overlayfs` uses an xattr to indicate that a directory is opaque (i.e., that lower layers should not be looked up). The planned file systems need to support opaque directories, so they must be able to implement this. Signed-off-by: Wedson Almeida Filho <walmeida@microsoft.com>

Allow Rust file systems to expose their stats. `overlayfs` requires that this be implemented by all file systems that are part of an overlay. The planned file systems need to be overlayed with overlayfs, so they must be able to implement this. Signed-off-by: Wedson Almeida Filho <walmeida@microsoft.com>

Allow Rust file system modules to create inodes that are symlinks, pipes, sockets, char devices and block devices (in addition to the already-supported directories and regular files). Signed-off-by: Wedson Almeida Filho <walmeida@microsoft.com>

Allow Rust file systems to associate [typed] data to super blocks when they're created. Since we only have a pointer-sized field in which to store the state, it must implement the `ForeignOwnable` trait. Signed-off-by: Wedson Almeida Filho <walmeida@microsoft.com>

Introduce the abstractions that will be used by modules to handle buffer heads, which will be used to access cached blocks from block devices. All dead-code annotations are removed in the next commit in the series. Signed-off-by: Wedson Almeida Filho <walmeida@microsoft.com>

Allow Rust file systems that are backed by block devices (in addition to in-memory ones). Signed-off-by: Wedson Almeida Filho <walmeida@microsoft.com>

Allow Rust file systems to attach extra [typed] data to each inode. If no data is needed, use the regular inode kmem_cache, otherwise we create a new one. Signed-off-by: Wedson Almeida Filho <walmeida@microsoft.com>

Allow Rust file system modules to use these constants if needed. Signed-off-by: Wedson Almeida Filho <walmeida@microsoft.com>

It is a file system based on tar files and an index appended to them (to facilitate finding fs entries without having to traverse the whole tar file). Signed-off-by: Wedson Almeida Filho <walmeida@microsoft.com>

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vfs abstractions and tarfs #1037

vfs abstractions and tarfs #1037

Commits on Oct 18, 2023

vfs abstractions and tarfs #1037

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vfs abstractions and tarfs #1037

Commits on Oct 18, 2023