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![Lee Duncan](/assets/img/avatar_default.png)
The st tape driver recently added the MTWEOFI ioctl, which writes a tape filemark (EOF), like the MTWEOF ioctl, except that MTWEOFI returns immediately. This makes certain applications, like backup software, run much more quickly on buffered tape drives. Since legacy applications do not know about this new MTWEOFI ioctl, this patch adds a new ioctl option that tells the st driver to return immediately when writing an EOF (i.e. a filemark). This new flag is much like the existing flag that tells the st driver to perform writes (and certain other IOs) immediately, but this new flag only applies to writing EOFs. This new feature is controlled via the MTSETDRVBUFFER ioctl, using the newly-defined MT_ST_NOWAIT_EOF flag. Use of this new feature is displayed via the sysfs tape "options" attribute. The st documentation was updated to mention this new flag, as well as the problems that can occur from using it. Signed-off-by: Lee Duncan <lduncan@suse.com> Acked-by: Kai Makisara <kai.makisara@kolumbus.fi> Signed-off-by: James Bottomley <JBottomley@Parallels.com>
224 lines
6.1 KiB
C
224 lines
6.1 KiB
C
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#ifndef _ST_H
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#define _ST_H
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#include <linux/completion.h>
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#include <linux/mutex.h>
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#include <linux/kref.h>
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#include <scsi/scsi_cmnd.h>
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/* Descriptor for analyzed sense data */
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struct st_cmdstatus {
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int midlevel_result;
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struct scsi_sense_hdr sense_hdr;
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int have_sense;
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int residual;
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u64 uremainder64;
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u8 flags;
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u8 remainder_valid;
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u8 fixed_format;
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u8 deferred;
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};
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struct scsi_tape;
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/* scsi tape command */
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struct st_request {
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unsigned char cmd[MAX_COMMAND_SIZE];
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unsigned char sense[SCSI_SENSE_BUFFERSIZE];
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int result;
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struct scsi_tape *stp;
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struct completion *waiting;
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struct bio *bio;
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};
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/* The tape buffer descriptor. */
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struct st_buffer {
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unsigned char dma; /* DMA-able buffer */
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unsigned char do_dio; /* direct i/o set up? */
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unsigned char cleared; /* internal buffer cleared after open? */
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int buffer_size;
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int buffer_blocks;
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int buffer_bytes;
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int read_pointer;
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int writing;
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int syscall_result;
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struct st_request *last_SRpnt;
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struct st_cmdstatus cmdstat;
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struct page **reserved_pages;
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int reserved_page_order;
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struct page **mapped_pages;
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struct rq_map_data map_data;
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unsigned char *b_data;
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unsigned short use_sg; /* zero or max number of s/g segments for this adapter */
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unsigned short sg_segs; /* number of segments in s/g list */
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unsigned short frp_segs; /* number of buffer segments */
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};
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/* The tape mode definition */
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struct st_modedef {
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unsigned char defined;
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unsigned char sysv; /* SYS V semantics? */
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unsigned char do_async_writes;
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unsigned char do_buffer_writes;
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unsigned char do_read_ahead;
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unsigned char defaults_for_writes;
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unsigned char default_compression; /* 0 = don't touch, etc */
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short default_density; /* Forced density, -1 = no value */
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int default_blksize; /* Forced blocksize, -1 = no value */
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struct cdev *cdevs[2]; /* Auto-rewind and non-rewind devices */
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};
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/* Number of modes can be changed by changing ST_NBR_MODE_BITS. The maximum
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number of modes is 16 (ST_NBR_MODE_BITS 4) */
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#define ST_NBR_MODE_BITS 2
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#define ST_NBR_MODES (1 << ST_NBR_MODE_BITS)
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#define ST_MODE_SHIFT (7 - ST_NBR_MODE_BITS)
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#define ST_MODE_MASK ((ST_NBR_MODES - 1) << ST_MODE_SHIFT)
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#define ST_MAX_TAPES 128
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#define ST_MAX_TAPE_ENTRIES (ST_MAX_TAPES << (ST_NBR_MODE_BITS + 1))
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/* The status related to each partition */
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struct st_partstat {
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unsigned char rw;
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unsigned char eof;
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unsigned char at_sm;
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unsigned char last_block_valid;
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u32 last_block_visited;
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int drv_block; /* The block where the drive head is */
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int drv_file;
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};
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#define ST_NBR_PARTITIONS 4
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/* The tape drive descriptor */
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struct scsi_tape {
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struct scsi_driver *driver;
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struct scsi_device *device;
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struct mutex lock; /* For serialization */
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struct completion wait; /* For SCSI commands */
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struct st_buffer *buffer;
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/* Drive characteristics */
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unsigned char omit_blklims;
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unsigned char do_auto_lock;
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unsigned char can_bsr;
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unsigned char can_partitions;
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unsigned char two_fm;
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unsigned char fast_mteom;
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unsigned char immediate;
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unsigned char restr_dma;
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unsigned char scsi2_logical;
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unsigned char default_drvbuffer; /* 0xff = don't touch, value 3 bits */
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unsigned char cln_mode; /* 0 = none, otherwise sense byte nbr */
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unsigned char cln_sense_value;
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unsigned char cln_sense_mask;
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unsigned char use_pf; /* Set Page Format bit in all mode selects? */
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unsigned char try_dio; /* try direct i/o in general? */
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unsigned char try_dio_now; /* try direct i/o before next close? */
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unsigned char c_algo; /* compression algorithm */
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unsigned char pos_unknown; /* after reset position unknown */
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unsigned char sili; /* use SILI when reading in variable b mode */
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unsigned char immediate_filemark; /* write filemark immediately */
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int tape_type;
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int long_timeout; /* timeout for commands known to take long time */
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unsigned long max_pfn; /* the maximum page number reachable by the HBA */
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/* Mode characteristics */
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struct st_modedef modes[ST_NBR_MODES];
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int current_mode;
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/* Status variables */
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int partition;
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int new_partition;
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int nbr_partitions; /* zero until partition support enabled */
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struct st_partstat ps[ST_NBR_PARTITIONS];
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unsigned char dirty;
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unsigned char ready;
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unsigned char write_prot;
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unsigned char drv_write_prot;
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unsigned char in_use;
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unsigned char blksize_changed;
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unsigned char density_changed;
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unsigned char compression_changed;
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unsigned char drv_buffer;
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unsigned char density;
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unsigned char door_locked;
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unsigned char autorew_dev; /* auto-rewind device */
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unsigned char rew_at_close; /* rewind necessary at close */
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unsigned char inited;
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unsigned char cleaning_req; /* cleaning requested? */
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int block_size;
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int min_block;
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int max_block;
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int recover_count; /* From tape opening */
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int recover_reg; /* From last status call */
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#if DEBUG
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unsigned char write_pending;
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int nbr_finished;
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int nbr_waits;
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int nbr_requests;
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int nbr_dio;
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int nbr_pages;
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unsigned char last_cmnd[6];
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unsigned char last_sense[16];
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#endif
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struct gendisk *disk;
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struct kref kref;
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};
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/* Bit masks for use_pf */
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#define USE_PF 1
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#define PF_TESTED 2
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/* Values of eof */
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#define ST_NOEOF 0
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#define ST_FM_HIT 1
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#define ST_FM 2
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#define ST_EOM_OK 3
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#define ST_EOM_ERROR 4
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#define ST_EOD_1 5
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#define ST_EOD_2 6
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#define ST_EOD 7
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/* EOD hit while reading => ST_EOD_1 => return zero => ST_EOD_2 =>
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return zero => ST_EOD, return ENOSPC */
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/* When writing: ST_EOM_OK == early warning found, write OK
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ST_EOD_1 == allow trying new write after early warning
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ST_EOM_ERROR == early warning found, not able to write all */
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/* Values of rw */
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#define ST_IDLE 0
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#define ST_READING 1
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#define ST_WRITING 2
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/* Values of ready state */
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#define ST_READY 0
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#define ST_NOT_READY 1
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#define ST_NO_TAPE 2
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/* Values for door lock state */
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#define ST_UNLOCKED 0
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#define ST_LOCKED_EXPLICIT 1
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#define ST_LOCKED_AUTO 2
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#define ST_LOCK_FAILS 3
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/* Positioning SCSI-commands for Tandberg, etc. drives */
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#define QFA_REQUEST_BLOCK 0x02
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#define QFA_SEEK_BLOCK 0x0c
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/* Setting the binary options */
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#define ST_DONT_TOUCH 0
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#define ST_NO 1
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#define ST_YES 2
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#define EXTENDED_SENSE_START 18
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/* Masks for some conditions in the sense data */
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#define SENSE_FMK 0x80
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#define SENSE_EOM 0x40
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#define SENSE_ILI 0x20
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#endif
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