This series introduces support for zoned block devices. It integrates
earlier submissions by Hannes Reinecke and Shaun Tancheff. Compared to the
previous series version, the code was significantly simplified by limiting
support to zoned devices satisfying the following conditions:
1) All zones of the device are the same size, with the exception of an
eventual last smaller runt zone.
2) For host-managed disks, reads must be unrestricted (read commands do not
fail due to zone or write pointer alignement constraints).
Zoned disks that do not satisfy these 2 conditions are ignored.
These 2 conditions allowed dropping the zone information cache implemented
in the previous version. This simplifies the code and also reduces the memory
consumption at run time. Support for zoned devices now only require one bit
per zone (less than 8KB in total). This bit field is used to write-lock
zones and prevent the concurrent execution of multiple write commands in
the same zone. This avoids write ordering problems at dispatch time, for
both the simple queue and scsi-mq settings.
The new operations introduced to suport zone manipulation was reduced to
only the two main ZBC/ZAC defined commands: REPORT ZONES (REQ_OP_ZONE_REPORT)
and RESET WRITE POINTER (REQ_OP_ZONE_RESET). This brings the total number of
operations defined to 8, which fits in the 3 bits (REQ_OP_BITS) reserved for
operation code in bio->bi_opf and req->cmd_flags.
Most of the ZBC specific code is kept out of sd.c and implemented in the
new file sd_zbc.c. Similarly, at the block layer, most of the zoned block
device code is implemented in the new blk-zoned.c.
For host-managed zoned block devices, the sequential write constraint of
write pointer zones is exposed to the user. Users of the disk (applications,
file systems or device mappers) must sequentially write to zones. This means
that for raw block device accesses from applications, buffered writes are
unreliable and direct I/Os must be used (or buffered writes with O_SYNC).
Access to zone manipulation operations is also provided to applications
through a set of new ioctls. This allows applications operating on raw
block devices (e.g. mkfs.xxx) to discover a device zone layout and
manipulate zone state.
v8:
* Fixed compile time warnings (unused variable and sd_printk format)
* For unsupported host-aware drives, the zone write lock bitmap is not
allocated, so check it before trying to use it
v7:
* Fixed problems with zone write locking:
- Wrong sdkp->zone_wlock bitmap allocation size
- Incorrect (reversed condition) test of lock state with test_and_set_bit
- Potential error in sd_setup_read_write_cmnd could leave a zone locked
without the locking write command being executed
v6:
* Rebased on Jens' for-4.9/block branch (v5 is based on next-20160928)
v5:
* Changed interface of sd_zbc_setup_read_write
v4:
* Fixed several typos and tabs/spaces
* Added description of zoned and chunk_sectors queue attributes in
Documentation/ABI/testing/sysfs-block
* Fixed sd_read_capacity call in sd.c and to avoid missing information on
the first pass of a disk scan
* Fixed scsi_disk zone related field to use logical block size unit instead
of 512B sector unit.
v3:
* Use kcalloc to allocate zone information array for ioctl
* Use kcalloc to allocate zone information array for ioctl
* Export GPL the functions blkdev_report_zones and blkdev_reset_zones
* Shuffled uapi definitions from patch 7 into patch 5
v2
* Removed zone information cache
* Limit support to drives that have unrestricted reads and a constant zone
size that is a power of two number of LBAs
* Introduce per zone write locking to avoid write reordering for both
blk-mq and simple queue cases
Damien Le Moal (1):
block: Add 'zoned' queue limit
Hannes Reinecke (4):
blk-sysfs: Add 'chunk_sectors' to sysfs attributes
block: update chunk_sectors in blk_stack_limits()
block: Implement support for zoned block devices
sd: Implement support for ZBC devices
Shaun Tancheff (2):
block: Define zoned block device operations
blk-zoned: implement ioctls
Documentation/ABI/testing/sysfs-block | 29 ++
block/Kconfig | 8 +
block/Makefile | 1 +
block/blk-core.c | 4 +
block/blk-settings.c | 5 +
block/blk-sysfs.c | 29 ++
block/blk-zoned.c | 350 ++++++++++++++++++
block/ioctl.c | 4 +
drivers/scsi/Makefile | 1 +
drivers/scsi/sd.c | 148 ++++++--
drivers/scsi/sd.h | 70 ++++
drivers/scsi/sd_zbc.c | 642 ++++++++++++++++++++++++++++++++++
include/linux/blk_types.h | 2 +
include/linux/blkdev.h | 99 ++++++
include/scsi/scsi_proto.h | 17 +
include/uapi/linux/Kbuild | 1 +
include/uapi/linux/blkzoned.h | 143 ++++++++
include/uapi/linux/fs.h | 4 +
18 files changed, 1522 insertions(+), 35 deletions(-)
create mode 100644 block/blk-zoned.c
create mode 100644 drivers/scsi/sd_zbc.c
create mode 100644 include/uapi/linux/blkzoned.h
--
2.7.4
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