Struct FileDevice 

pub struct FileDevice { /* private fields */ }

File-backed device — used for disk images and /dev/diskN.

Implementations

impl FileDevice

pub fn open(path: &str) -> Result<Self>

Open read-only. Matches pre-existing behaviour.

pub fn open_path(path: &Path) -> Result<Self>

Open read-only by a path that need not be UTF-8: a device or image name is bytes on Unix, and a lossy rendering of it can name another file.

pub fn open_rw(path: &str) -> Result<Self>

Open read-write. Prefer this when the caller needs to journal-replay or apply Phase 4 mutations. Falls back to an error if the path is not writable.

pub fn open_path_rw(path: &Path) -> Result<Self>

Open read-write by a path that need not be UTF-8; see FileDevice::open_path.

pub fn open_best_effort(path: &str) -> Result<Self>

Open read-write if possible; otherwise fall back to read-only. Useful for the mount path so read-only images on e.g. a locked volume still mount, just without replay.

Trait Implementations

impl BlockDevice for FileDevice

fn read_at(&self, offset: u64, buf: &mut [u8]) -> Result<()>

Read exactly buf.len() bytes starting at offset (bytes from start of device).

fn size_bytes(&self) -> u64

Total device size in bytes (for bounds-checking).

fn write_at(&self, offset: u64, buf: &[u8]) -> Result<()>

Write exactly buf.len() bytes at offset. Default: returns an error for read-only devices. Writable devices override this.

fn flush(&self) -> Result<()>

Flush any pending writes to stable storage. Default: no-op for read-only devices; writable devices should implement fsync semantics.

fn is_writable(&self) -> bool

Reports whether write_at is likely to succeed. Used by the mount path to decide whether journal replay is possible.

fn populate_cache(&self, _block: u64, _bytes: Vec<u8>)

Buffer-cache hook: stash bytes for block so a subsequent read_at returns those bytes instead of reading from physical storage. Used by a read-only mount’s journal replay to make committed metadata visible to readers without writing it back to the data area on disk.

fn unpin_all(&self)

Buffer-cache hook: tell the device the journal has been checkpointed, so any blocks pinned via populate_cache are now consistent with disk and can be evicted under normal LRU pressure. No-op for un-cached devices.

fn invalidate_cache(&self) -> Result<()>

Discard clean read-cache entries. Pinned journal metadata must be checkpointed and unpinned first; cached implementations reject otherwise. This does not flush writes and requires exclusive filesystem ownership.

impl BlockDevice for FileDevice

fn write_at(&self, offset: u64, buf: &[u8]) -> Result<()>

Write exactly buf.len() bytes at offset. Default: returns Error::ReadOnly.

fn flush(&self) -> Result<()>

Flush pending writes to stable storage. No-op by default.

fn is_writable(&self) -> bool

Whether write_at is likely to succeed. Mount paths use this to decide whether to attempt journal replay or stay strict-read-only.

fn set_len(&self, _new_len: u64) -> Result<(), Error>

Set the device’s length to new_len. Default: returns Error::ReadOnly.

fn can_grow(&self) -> bool

Whether set_len is likely to succeed. Default: false.

impl BlockRead for FileDevice

fn read_at(&self, offset: u64, buf: &mut [u8]) -> Result<()>

Read exactly buf.len() bytes starting at offset (bytes from the start of the device).

fn size_bytes(&self) -> u64

Total device size in bytes. Used for bounds checks.