- Cache the RootFcb so that its cleanup can be handled separately
during dismounting.
- Force volume dismount at cleanup if the VCB_DISMOUNT_PENDING flag
is set.
- Actually dismount a volume if its VCB has been flagged as not good,
or if we force dismounting.
NOTE: In their *CheckForDismount() function, our 3rd-party FS drivers
as well as MS' fastfat, perform a comparison check of the current VCB's
VPB ReferenceCount with some sort of "dangling"/"residual" open count.
It seems to be related to the fact that the volume root directory as
well as auxiliary data stream(s) are still opened, and only these are
allowed to be opened at that moment. After analysis it appears that for
the ReactOS' fastfat, this number is equal to "3".
- On dismounting, cleanup and destroy the RootFcb, VolumeFcb and the
FATFileObject. Then cleanup the SpareVPB or the IoVPB members, and
finish by removing the dismounted volume from the VolumeListEntry
and cleaning up the notify synchronization object and the resources.
- During dismounting, and on shutdown, flush the volume before
resetting its dirty bit.
- On shutdown, after volume flushing, try to unmount it without forcing.
- Release the VCB resources only when we actually dismount the volume
in VfatCheckForDismount().
- Initialize first the notify list and the synchronization object,
before sending the FSRTL_VOLUME_MOUNT notification.
- If we failed at mounting a volume but its VCB's FATFileObject was
already initialized, first call CcUninitializeCacheMap() on it
before dereferencing it.
- Send FSRTL_VOLUME_LOCK, FSRTL_VOLUME_LOCK_FAILED and
FSRTL_VOLUME_UNLOCK notifications during volume locking (and failure)
and volume unlocking.
- Flush the volume before locking it, and clean its dirty bit if needed.
NOTE: In addition to checking for VCB_CLEAR_DIRTY, we also check for the
presence of the VCB_IS_DIRTY flag before cleaning up the dirty bit: this
allows us to not re-clean the bit if it has been previously cleaned.
This is needed for instance in this scenario:
- The volume is locked (it gets flushed and the dirty bit is possibly cleared);
- The volume then gets formatted with a completely different FS, that
possibly clears up the first sector (e.g. BTRFS ignores 1st sector);
- The volume is then dismounted: if we didn't check whether VCB_IS_DIRTY
was set prior to resetting it, we could attempt clearing it again! But
now that the volume's filesystem has been completely changed, we would
then try to modify the dirty bit on an erroneous position on disk!
That's why it should not be touched in this case during dismounting.
- The volume is unlocked (same comment as above), and later can be
detected as being BTRFS.
When we're about to close a file (ie, forget everything about it
and release any associated structure), actually delay it.
This allows keep data fresh in memory for faster reuse in case
it would be required. The effective closing will only happen after some time.
For specific operations, this will produce a real speed up in ReactOS.
For instance, with that patch, Winamp starts within seconds, instead of dozen
of minutes.
In most cases, it will bring ReactOS to performances it had before fixing
the huge leak in FastFAT (commit 94ead99) without leaking the whole FS.
For now, due to regressions, this is only activated for files and not
for directories. Once it gets fixed, it will be enabled for both.
CORE-14826
CORE-14917
This is a PoC of what it's possible to realize thanks to an
already existing hack in ntoskrnl :-).
With this extension, on the kdb:> prompt, you're able to type
in commands that will be handled by the FastFAT driver and not
by the kernel, allowing internal debug, not possible otherwise.
So far, three commands exist:
- ?fat.vols: lists all the mounted volumes by FastFAT
- ?fat.files: lists all the files on a specific volume (with their attributes)
- ?fat.setdbgfile: allows watching on specifics files lifetime
This is obviously only the begin and could be greatly improved.
For instance, this is what allowed to debug CORE-14557
