Near the beginning of the year, some long-lost work was carried out on the floppy disk drive of the Linux kernel, and half a year later, people discovered that the work earlier this year actually regressed the floppy disk handling of the Linux kernel. Now, Linux 5.15 is about to launch a fix.
Since the floppy disk driver was modified earlier this year, the driver has continued to function, but it has unintentionally changed some floppy disk handling code: the kernel with the O_NDELAY flag before will allow a floppy disk device to be opened even if there is no disk inserted Case.
The updated Linux kernel will generate an error if the floppy disk device is opened without the media/disk inserted. In addition, it also destroys the function of opening a write-protected floppy disk. If the release of Linux 5.14 goes well, the Linux 5.15 merge window is likely to open tonight, and the repair of the floppy disk drive in the queue should be added as a belated addition.
There is nothing worth paying attention to for these regression fixes, but the earlier patch around O_NDELAY in the floppy disk code is restored. The floppy disk patch earlier this year was originally merged during Linux 5.12, but it was also passed back to the previous stable version series, including Linux 5.10 LTS, so this new patch of 5.15 may eventually be passed back to the stable/LTS kernel. The floppy disk correction for Linux 5.15 can be found through this PR:
https://lore.kernel.org/lkml/ 388418f4-2b9a-6fed-836c-a004369dc7c0@linux.com/
In view of the fact that there are very few actual floppy disks used by kernel developers, the developer Denis Efremov is also working hard to add self-testing to the floppy disk drive to prevent this userspace damage from happening again in the future.
