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tape: use LOCATE(16) SCSI command

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Turns out this works on LTO4 and newer.
This commit is contained in:
Dietmar Maurer 2021-05-06 10:51:59 +02:00
parent 25d78b1068
commit bbbf662d20
2 changed files with 27 additions and 24 deletions
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25
src/tape/drive/lto/mod.rs
View File

@ -215,31 +215,8 @@ impl LtoTapeHandle {
}
/// Position the tape after filemark count. Count 0 means BOT.
///
/// Note: we dont use LOCATE(10), because that needs LTO5
pub fn locate_file(&mut self, position: u64) -> Result<(), Error> {
if position == 0 {
return self.rewind();
}
let current_position = self.current_file_number()?;
if current_position == position {
// make sure we are immediated afer the filemark
self.sg_tape.space_filemarks(-1)?;
self.sg_tape.space_filemarks(1)?;
} else if current_position < position {
let diff = position - current_position;
self.sg_tape.space_filemarks(diff.try_into()?)?;
} else {
let diff = current_position - position + 1;
self.sg_tape.space_filemarks(-diff.try_into()?)?;
// move to EOT side of filemark
self.sg_tape.space_filemarks(1)?;
}
Ok(())
self.sg_tape.locate_file(position)
}
pub fn erase_media(&mut self, fast: bool) -> Result<(), Error> {

26
src/tape/drive/lto/sg_tape.rs
View File

@ -295,6 +295,32 @@ impl SgTape {
Ok(())
}
pub fn locate_file(&mut self, position: u64) -> Result<(), Error> {
if position == 0 {
return self.rewind();
}
let mut sg_raw = SgRaw::new(&mut self.file, 16)?;
sg_raw.set_timeout(Self::SCSI_TAPE_DEFAULT_TIMEOUT);
let mut cmd = Vec::new();
// Note: LOCATE(16) works for LTO4 or newer
cmd.extend(&[0x92, 0b000_01_000, 0, 0]); // LOCATE(16) filemarks
cmd.extend(&position.to_be_bytes());
cmd.extend(&[0, 0, 0, 0]);
sg_raw.do_command(&cmd)
.map_err(|err| format_err!("locate file {} failed - {}", position, err))?;
// move to other side of filemark
cmd.truncate(0);
cmd.extend(&[0x11, 0x01, 0, 0, 1, 0]); // SPACE(6) one filemarks
sg_raw.do_command(&cmd)
.map_err(|err| format_err!("locate file {} (space) failed - {}", position, err))?;
Ok(())
}
pub fn position(&mut self) -> Result<ReadPositionLongPage, Error> {
let expected_size = std::mem::size_of::<ReadPositionLongPage>();