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Revision 3e1a0699095803e53072699a4a1485af7744601d authored by Joe Thornber on 03 March 2014, 16:03:26 UTC, committed by Mike Snitzer on 05 March 2014, 20:26:58 UTC 
dm thin: fix out of data space handling
 
Ideally a thin pool would never run out of data space; the low water
mark would trigger userland to extend the pool before we completely run
out of space.  However, many small random IOs to unprovisioned space can
consume data space at an alarming rate.  Adjust your low water mark if
you're frequently seeing "out-of-data-space" mode.

Before this fix, if data space ran out the pool would be put in
PM_READ_ONLY mode which also aborted the pool's current metadata
transaction (data loss for any changes in the transaction).  This had a
side-effect of needlessly compromising data consistency.  And retry of
queued unserviceable bios, once the data pool was resized, could
initiate changes to potentially inconsistent pool metadata.

Now when the pool's data space is exhausted transition to a new pool
mode (PM_OUT_OF_DATA_SPACE) that allows metadata to be changed but data
may not be allocated.  This allows users to remove thin volumes or
discard data to recover data space.

The pool is no longer put in PM_READ_ONLY mode in response to the pool
running out of data space.  And PM_READ_ONLY mode no longer aborts the
pool's current metadata transaction.  Also, set_pool_mode() will now
notify userspace when the pool mode is changed.

Signed-off-by: Joe Thornber <ejt@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
1 parent 07f2b6e
Raw File
mac_scsi.h 
/*
 * Cumana Generic NCR5380 driver defines
 *
 * Copyright 1993, Drew Eckhardt
 *	Visionary Computing
 *	(Unix and Linux consulting and custom programming)
 *	drew@colorado.edu
 *      +1 (303) 440-4894
 *
 * ALPHA RELEASE 1.
 *
 * For more information, please consult
 *
 * NCR 5380 Family
 * SCSI Protocol Controller
 * Databook
 *
 * NCR Microelectronics
 * 1635 Aeroplaza Drive
 * Colorado Springs, CO 80916
 * 1+ (719) 578-3400
 * 1+ (800) 334-5454
 */

/*
 * $Log: cumana_NCR5380.h,v $
 */

#ifndef MAC_NCR5380_H
#define MAC_NCR5380_H

#define MACSCSI_PUBLIC_RELEASE 2

#ifndef ASM

#ifndef CMD_PER_LUN
#define CMD_PER_LUN 2
#endif

#ifndef CAN_QUEUE
#define CAN_QUEUE 16
#endif

#ifndef SG_TABLESIZE
#define SG_TABLESIZE SG_NONE
#endif

#ifndef USE_TAGGED_QUEUING
#define	USE_TAGGED_QUEUING 0
#endif

#include <scsi/scsicam.h>

#ifndef HOSTS_C

#define NCR5380_implementation_fields \
    int port, ctrl

#define NCR5380_local_declare() \
        struct Scsi_Host *_instance

#define NCR5380_setup(instance) \
        _instance = instance

#define NCR5380_read(reg) macscsi_read(_instance, reg)
#define NCR5380_write(reg, value) macscsi_write(_instance, reg, value)

#define NCR5380_pread 	macscsi_pread
#define NCR5380_pwrite 	macscsi_pwrite
	
#define NCR5380_intr macscsi_intr
#define NCR5380_queue_command macscsi_queue_command
#define NCR5380_abort macscsi_abort
#define NCR5380_bus_reset macscsi_bus_reset
#define NCR5380_show_info macscsi_show_info
#define NCR5380_write_info macscsi_write_info

#define BOARD_NORMAL	0
#define BOARD_NCR53C400	1

#endif /* ndef HOSTS_C */
#endif /* ndef ASM */
#endif /* MAC_NCR5380_H */
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