with NFS.
We are moving responsibility for creating the vnode_pager object into
the filesystems which own the vnode, and this is one of the places
we have to cover.
We call vnode_create_vobject() directly because we own the vnode.
If we can get the size easily, pass it as an argument to save the
call to VOP_GETATTR() in vnode_create_vobject()
and KASSERT coverage.
After this check there is only one "nasty" cast in this code but there
is a KASSERT to protect against the wrong argument structure behind
that cast.
Un-inlining the meat of VOP_FOO() saves 35kB of text segment on a typical
kernel with no change in performance.
We also now run the checking and tracing on VOP's which have been layered
by nullfs, umapfs, deadfs or unionfs.
Add new (non-inline) VOP_FOO_AP() functions which take a "struct
foo_args" argument and does everything the VOP_FOO() macros
used to do with checks and debugging code.
Add KASSERT to VOP_FOO_AP() check for argument type being
correct.
Slim down VOP_FOO() inline functions to just stuff arguments
into the struct foo_args and call VOP_FOO_AP().
Put function pointer to VOP_FOO_AP() into vop_foo_desc structure
and make VCALL() use it instead of the current offsetoff() hack.
Retire vcall() which implemented the offsetoff()
Make deadfs and unionfs use VOP_FOO_AP() calls instead of
VCALL(), we know which specific call we want already.
Remove unneeded arguments to VCALL() in nullfs and umapfs bypass
functions.
Remove unused vdesc_offset and VOFFSET().
Generally improve style/readability of the generated code.
I'm not sure why a credential was added to these in the first place, it is
not used anywhere and it doesn't make much sense:
The credentials for syncing a file (ability to write to the
file) should be checked at the system call level.
Credentials for syncing one or more filesystems ("none")
should be checked at the system call level as well.
If the filesystem implementation needs a particular credential
to carry out the syncing it would logically have to the
cached mount credential, or a credential cached along with
any delayed write data.
Discussed with: rwatson
After disscussing things I have decided to take the easy and
consistent 90% solution instead of aiming for the very involved 99%
solution.
If we allow forceful unmounts of DEVFS we need to decide how to handle
the devices which are in use through this filesystem at the time.
We cannot just readopt the open devices in the main /dev instance since
that would open us to security issues.
For the majority of the devices, this is relatively straightforward
as we can just pretend they got revoke(2)'ed.
Some devices get tricky: /dev/console and /dev/tty for instance
does a sort of recursive open of the real console device. Other devices
may be mmap'ed (kill the processes ?).
And then there are disk devices which are mounted.
The correct thing here would be to recursively unmount the filesystems
mounte from devices from our DEVFS instance (forcefully) and if
this succeeds, complete the forcefully unmount of DEVFS. But if
one of the forceful unmounts fail we cannot complete the forceful
unmount of DEVFS, but we are likely to already have severed a lot
of stuff in the process of trying.
Event attempting this would be a lot of code for a very far out
corner-case which most people would never see or get in touch with.
It's just not worth it.
methods:
Read can see O_NONBLOCK and O_DIRECT.
Write can see O_NONBLOCK, O_DIRECT and O_FSYNC.
In addition O_DIRECT is shadowed as IO_DIRECT for now for backwards
compatibility.
fcntl.h.
This is in preparation for making the flags passed to device drivers be
consistently from fcntl.h for all entrypoints.
Today open, close and ioctl uses fcntl.h flags, while read and write
uses vnode.h flags.
split the conversion of the remaining three filesystems out from the root
mounting changes, so in one go:
cd9660:
Convert to nmount.
Add omount compat shims.
Remove dedicated rootfs mounting code.
Use vfs_mountedfrom()
Rely on vfs_mount.c calling VFS_STATFS()
nfs(client):
Convert to nmount (the simple way, mount_nfs(8) is still necessary).
Add omount compat shims.
Drop COMPAT_PRELITE2 mount arg compatibility.
ffs:
Convert to nmount.
Add omount compat shims.
Remove dedicated rootfs mounting code.
Use vfs_mountedfrom()
Rely on vfs_mount.c calling VFS_STATFS()
Remove vfs_omount() method, all filesystems are now converted.
Remove MNTK_WANTRDWR, handling RO/RW conversions is a filesystem
task, and they all do it now.
Change rootmounting to use DEVFS trampoline:
vfs_mount.c:
Mount devfs on /. Devfs needs no 'from' so this is clean.
symlink /dev to /. This makes it possible to lookup /dev/foo.
Mount "real" root filesystem on /.
Surgically move the devfs mountpoint from under the real root
filesystem onto /dev in the real root filesystem.
Remove now unnecessary getdiskbyname().
kern_init.c:
Don't do devfs mounting and rootvnode assignment here, it was
already handled by vfs_mount.c.
Remove now unused bdevvp(), addaliasu() and addalias(). Put the
few necessary lines in devfs where they belong. This eliminates the
second-last source of bogo vnodes, leaving only the lemming-syncer.
Remove rootdev variable, it doesn't give meaning in a global context and
was not trustworth anyway. Correct information is provided by
statfs(/).
