25 lines
1.0 KiB
ReStructuredText
25 lines
1.0 KiB
ReStructuredText
Custom ioctls
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=============
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Filesystems are usually extended by custom ioctls beyond the standard system
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call interface to let user applications access the advanced features. They're
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low level and the following list gives only an overview of the capabilities or
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a command if available:
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- reverse lookup, from file offset to inode, as command :command:`btrfs inspect-internal logical-resolve`
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- resolve inode number to list of names, as command :command:`btrfs inspect-internal inode-resolve`
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- tree search, given a key range and tree id, lookup and return all b-tree items
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found in that range, basically all metadata at your hand but you need to know
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what to do with them, the ioctl is privileged as it has full access to all
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filesystem metadata
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- informative, about devices, space allocation or the whole filesystem, many of
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which is also exported in :file:`/sys/fs/btrfs/`
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- query/set a subset of features on a mounted filesystem
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Programming documentaion of the ioctls is in the manual page
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:doc:`btrfs-ioctl`.
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