Use libblockdev for (un)mounting for btrfs operations

[vojtechtrefny]

This also fixes issue where failed temporary mount was silently ignored (because util.mount doesn't raise an exception) and the operation that requires the btrfs device to be mounted then failed with a hard to decipher error message.

Related: rhbz#2379800

Summary by Sourcery

Use libblockdev for performing temporary btrfs mount and unmount operations to ensure mount failures are handled explicitly and unmount errors are logged appropriately.

Bug Fixes:

• Raise a descriptive BTRFSError when a temporary btrfs mount fails instead of silently ignoring it

Enhancements:

• Switch to using libblockdev.fs.mount and unmount for temporary btrfs mounts
• Log errors when unmounting a temporarily mounted btrfs device fails and still clean up the mount directory

[sourcery-ai]

Reviewer's guide (collapsed on small PRs)

Reviewer's Guide

Switch temporary btrfs mount/unmount operations to use libblockdev’s APIs and improve error handling by raising a specific BTRFSError on mount failure and logging unmount failures before cleanup.

Class diagram for updated error handling in btrfs temporary mount

classDiagram
    class BtrfsDevice {
        _do_temp_mount(orig=False)
    }
    class blockdev {
        fs.mount(device, mountpoint, fstype, mountopts)
        fs.unmount(mountpoint)
        FSError
    }
    class errors {
        BTRFSError
    }
    BtrfsDevice --|> errors : raises BTRFSError
    BtrfsDevice --> blockdev : uses fs.mount, fs.unmount
    blockdev --|> errors : FSError used as cause

Loading

File-Level Changes

Change	Details	Files
Use libblockdev.fs.mount for temporary mounts with explicit BTRFSError on failure	Replaced util.mount call with blockdev.fs.mount Changed exception to catch blockdev.FSError Replaced silent mount failure with raising errors.BTRFSError containing device info	blivet/devices/btrfs.py
Use libblockdev.fs.unmount for cleanup with error logging	Replaced util.umount call with blockdev.fs.unmount Wrapped unmount in try/except to log failures Only remove temporary directory after successful unmount	blivet/devices/btrfs.py

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