mainlining shenanigans
5795eb4430
Emulate ZONE_APPEND for SCSI disks using a regular WRITE(16) command with a start LBA set to the target zone write pointer position. In order to always know the write pointer position of a sequential write zone, the write pointer of all zones is tracked using an array of 32bits zone write pointer offset attached to the scsi disk structure. Each entry of the array indicate a zone write pointer position relative to the zone start sector. The write pointer offsets are maintained in sync with the device as follows: 1) the write pointer offset of a zone is reset to 0 when a REQ_OP_ZONE_RESET command completes. 2) the write pointer offset of a zone is set to the zone size when a REQ_OP_ZONE_FINISH command completes. 3) the write pointer offset of a zone is incremented by the number of 512B sectors written when a write, write same or a zone append command completes. 4) the write pointer offset of all zones is reset to 0 when a REQ_OP_ZONE_RESET_ALL command completes. Since the block layer does not write lock zones for zone append commands, to ensure a sequential ordering of the regular write commands used for the emulation, the target zone of a zone append command is locked when the function sd_zbc_prepare_zone_append() is called from sd_setup_read_write_cmnd(). If the zone write lock cannot be obtained (e.g. a zone append is in-flight or a regular write has already locked the zone), the zone append command dispatching is delayed by returning BLK_STS_ZONE_RESOURCE. To avoid the need for write locking all zones for REQ_OP_ZONE_RESET_ALL requests, use a spinlock to protect accesses and modifications of the zone write pointer offsets. This spinlock is initialized from sd_probe() using the new function sd_zbc_init(). Co-developed-by: Damien Le Moal <Damien.LeMoal@wdc.com> Signed-off-by: Johannes Thumshirn <johannes.thumshirn@wdc.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com> Reviewed-by: Hannes Reinecke <hare@suse.de> Signed-off-by: Jens Axboe <axboe@kernel.dk> |
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| arch | ||
| block | ||
| certs | ||
| crypto | ||
| Documentation | ||
| drivers | ||
| fs | ||
| include | ||
| init | ||
| ipc | ||
| kernel | ||
| lib | ||
| LICENSES | ||
| mm | ||
| net | ||
| samples | ||
| scripts | ||
| security | ||
| sound | ||
| tools | ||
| usr | ||
| virt | ||
| .clang-format | ||
| .cocciconfig | ||
| .get_maintainer.ignore | ||
| .gitattributes | ||
| .gitignore | ||
| .mailmap | ||
| COPYING | ||
| CREDITS | ||
| Kbuild | ||
| Kconfig | ||
| MAINTAINERS | ||
| Makefile | ||
| README | ||
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.