Old StorageDevice::read_sectors() read each sector separately if the
underlying disk had a disk cache. This patch allows multiple sectors to
be read even if the disk cache exists and contains some of the sectors.
Only sectors that could not be found from the disk cache are actually
read from the disk. This optimization is not done for writing, which
still will write each sector separately, if disk cache has no memory to
store new sectors. It would feel kind of unnecessary optimization as you
have greater problems if disk cache cannot allocate a single page.
Signal handling code was way too complex. Now everything is
simplified and there is no need for ThreadBlockers.
Only complication that this patch includes is that blocking syscalls
have to manually be made interruptable by signal. There might be some
clever solution to combat this is make this happen automatically.
I have used two weeks in locating a bug in my ext2 implementation
while the bug was actually in disk write. If you called write_sectors
on disk it would write the first sector_size bytes repeatedly to all
asked sectors and this corrupted the disk...
We now have DevFileSystem which is derived from RamFileSystem. All
devices are RamInodes. We don't have separate DeviceManager anymore.
To iterate over devices, you can loop througn every inode in devfs.
We don't store the error message anymore in BAN::Error.
Instead we store a error code that can be mapped into a string.
This allows BAN::Error to only take 4 bytes instead of 128.
We should also make some kernel initialization just panic instead
of returning errors since they are required for succesfull boot
anyway.
This is a big commit that was kinda hard to split to smaller ones.
Essentially we now look at all the mass storage devices from PCI
and initialize (P)ATA devices. This doesn't provide any more functionality
but better abstractions and everything doesn't have to be on its old
default port that might be different for modern computers.
Bananymous
Bananymous