Summary:
Previously we would simply report the raw pointer address to the kernel and
rely on it to return that same number to us as the file handle, and make sure
that it told us to shut down the handle when it was closed.
This meant that we had no real idea about which files were still open.
For our future live upgrade plans we need to be able to know this so that we
can transfer the appropriate information to our replacement process.
To facilitate this this diff implements a FileHandleMap class that will assign
file handle numbers and keep track of the instances. The number assignment
strategy is the same as it used to be in the common case: we take the address
of the newly created instance and use that 64-bit number as the file handle
number. However, in the future when we transfer the mapping to a new process,
we may experience a collision when subsequently opening a file handle. To deal
with that, we have a bounded number of attempts to assign a random file handle
number.
We don't yet offer a means to iterate the map, but it would be trivial to
expose such an accessor when we're ready to use it.
Since we now keep track of these things via shared_ptr this changes the
appropriate portions of the fuse interface from unique_ptr to shared_ptr.
Reviewed By: simpkins
Differential Revision: D3602364
fbshipit-source-id: dd996339c2838225a2caeee9da16ef99a06c1e2b
Summary:
This enables O_EXCL to function by allowing the create routine to
move its folly::File instance down in to the underlying FileData instance.
Previously we would close and then re-open the file; this would discard
any of the natural gating for the open call that is performed by the kernel
for the underlying filesystem in the overlay.
Reviewed By: bolinfest
Differential Revision: D3513758
fbshipit-source-id: 85967a3b7affa1b1df46842be8ba21c8fbb843a6
Summary:
setattr is a bit of a multi-purpose interface; depending on the flag
values, this is responsible for:
* ftruncate(2)
* fchmod(2)
* fchown(2)
* futimens(2)
In order to apply any of these things, we have to materialize the file. In
the future we may want to allow setting the utimes without materializing the file.
We don't allow chown to actually chown anything. We may want to relax that in
the future, but at the moment we will return an error if an attempt is made to
change the ownership of a file.
Reviewed By: bolinfest
Differential Revision: D3511011
fbshipit-source-id: 858d2c07686fcbe2dcdb60a07527f739a9726be3
Summary:
This fixes inode number handling problems in TreeInode and TreeEntryFileInode.
Previosly these classes each had an ino_ member variable, despite deriving from
InodeBase which has its own (private) ino_ member.
TreeEntryFileInode never actually initialized its own local ino_ variable.
This was causing problems for many applications which use inode numbers to
cache file data. TreeEntryFileInode returned garbage data in the inode field,
resulting in incorrect cache collisions.
This fixes the inode handling, and also fixes the stat data returned by
FileData. It now sets the uid, gid, and inode fields correctly. It 0s out
several other fields rather than leaving them uninitialized.
Reviewed By: bolinfest
Differential Revision: D3455126
fbshipit-source-id: 631276b01676733f96035bc153219ef84406dcc9
Summary:
This avoids translation from string->Hash in the common case
where the file is unmodified and its hash is read directly from
the store rather than computed from the overlay.
I'm guessing I should use `unique_ptr` as the return value throughout?
Reviewed By: simpkins
Differential Revision: D3355773
fbshipit-source-id: 50dff879a78b3d6ff49f86b856866ca28808c4f7
Summary:
We still have naked pointers at the handoff to the kernel, but now
have a cleaner implementation at the level that we're going to be working at
day to day.
I also renamed `FileHandle::release` to `FileHandle::releasefile` so that it
isn't visually ambiguous with `std::unique_ptr::release` in the
`Dispatcher.cpp` code: `fh.release()` vs `fh->release()` look similar but are
dramatically different in behavior.
Reviewed By: bolinfest
Differential Revision: D3309455
fbshipit-source-id: f8cf055bcd51121048a20f0202988cf0aef1f085
Summary:
Another step towards making TreeEntryFileInode overlay aware, this diff implements:
- stat
- readlink (although it is not possible to create symlinks yet)
- open
Reviewed By: bolinfest
Differential Revision: D3255158
fbshipit-source-id: 3f90b624e629ef279d6cc32e1d82787ee24796eb
Summary:
This allows us to share the same state between multiple open files and
also helps to reduce the size of inode instances that are otherwise inactive;
when there are no outstanding references to the data, we can drop it and forget
it.
Reviewed By: bolinfest
Differential Revision: D3301198
fbshipit-source-id: f0b3fc73a666ec2033c7a22e9eb587d3212cf966
