Summary: Linux 4.4 has not been released

1. Prominent features

2. Drivers and architectures

All the driver and architecture-specific changes can be found in the [http://kernelnewbies.org/Linux_4.4-DriversArch Linux_4.4-DriversArch] page

Add Persistent Reservations support. It includes a user space interface for simplified Persistent Reservations which map to block devices that support these (only SCSI for now). Persistent Reservations allow restricting access to block devices to specific initiators in a shared storage setup [https://git.kernel.org/torvalds/c/bbd3e064362e5057cc4799ba2e4d68c7593e490b commit], [https://git.kernel.org/torvalds/c/924d55b06347d813b38c51e75ce1a6666c113933 commit], [https://git.kernel.org/torvalds/c/71cdb6978a80f9f6c51bef0622388c1414c2fe32 commit]
Add support for polling for specific IO to complete. This will be combined with request latency tracking later, so that the kernel can make qualified decisions about when to poll and when not to. For now, for benchmark purposes, a sysfs file (io_poll) is added to control whether polling is enabled or not [https://git.kernel.org/torvalds/c/05229beeddf7e75e2e616ddaad4b70e7fca9528d commit]
Export integrity data interval size in /sys/block/<disk>/integrity/protection_interval_bytes , so that apps can tell whether the interval is different from the device's logical block size [https://git.kernel.org/torvalds/c/4c241d08dbfcbdc7a949b91d72707a289d464954 commit]