NVM Express Zoned Namespace command set specification allows host software to communicate with a NVM subsystem using zones. ZNS defines a host-managed zoned block device model for NVMe devices. It divides the logical address space of a namespace into zones. Each zone provides a LBA range that shall be written sequentially. An explicit reset of zone is needed to write to the zone again. ZNS defines a per-zone capacity which can be equal or less than the zone-size. Zone-capacity is the number of usable blocks in the zone. This patchset implements support for ZNS devices with a zone-capacity that is less that the device zone-size. This patch checks if zone-capacity is less than zone-size, if it is, then any segment which starts after the zone-capacity is marked as not-free in the free segment bitmap at initial mount time. These segments are marked as permanently used so they are not allocated for writes and consequently not needed to be garbage collected. In case the zone-capacity is not aligned to default segment size(2MB), then a segment can start before the zone-capacity and span across zone-capacity boundary. Such spanning segments are also considered as usable segments. It tracks the usable blocks in a spanning segment, so that during writes and GC, usable blocks in spanning segment is calculated to ensure writes/reads do not cross the zone-capacity boundary. This patch is based on the git tree git://git.kernel.org/pub/scm/linux/kernel/git/jaegeuk/f2fs.git branch dev and requires the below patch in order to build. https://lore.kernel.org/linux-nvme/20200701063720.GA28954@xxxxxx/T/#m19e0197ae1837b7fe959b13fbc2a859b1f2abc1e The above patch has been merged to the nvme-5.9 branch in the git tree: git://git.infradead.org/nvme.git Aravind Ramesh (1): f2fs: support zone capacity less than zone size Documentation/filesystems/f2fs.rst | 15 +++ fs/f2fs/f2fs.h | 5 + fs/f2fs/gc.c | 25 +++-- fs/f2fs/gc.h | 44 +++++++- fs/f2fs/segment.c | 156 ++++++++++++++++++++++++++--- fs/f2fs/segment.h | 26 +++-- fs/f2fs/super.c | 41 ++++++-- 7 files changed, 275 insertions(+), 37 deletions(-) -- 2.19.1
