The idea here was that we'd expand the size of the struct and
valid_bytes would tell the kernel which fields were present in
userspace's struct. That doesn't combine well with the ioctl convention
of having the size of the type baked into the ioctl number. We'll
remove this to make the world less surprising. If we expand the
interface we'd add additional ioctls and types.
Signed-off-by: Zach Brown <zab@versity.com>
Returning ENOSPC is challenging because we have clients working on
allocators which are a fraction of the whole and we use COW transactions
so we need to be able to allocate to free. This adds support for
returning ENOSPC to client posix allocators as free space gets low.
For metadata, we reserve a number of free blocks for making progress
with client and server transactions which can free space. The server
sets the low flag in a client's allocator if we start to dip into
reserved blocks. In the client we add an argument to entering a
transaction which indicates if we're allocating new space (as opposed to
just modifying existing data or freeing). When an allocating
transaction runs low and the server low flag is set then we return
ENOSPC.
Adding an argument to transaciton holders and having it return ENOSPC
gave us the opportunity to clean it up and make it a little clearer.
More work is done outside the wait_event function and it now
specifically waits for a transaction to cycle when it forces a commit
rather than spinning until the transaction worker acquires the lock and
stops it.
For data the same pattern applies except there are no reserved blocks
and we don't COW data so it's a simple case of returning the hard ENOSPC
when the data allocator flag is set.
The server needs to consider the reserved count when refilling the
client's meta_avail allocator and when swapping between the two
meta_avail and meta_free allocators.
We add the reserved metadata block count to statfs_more so that df can
subtract it from the free meta blocks and make it clear when enospc is
going to be returned for metadata allocations.
We increase the minimum device size in mkfs so that small testing
devices provide sufficient reserved blocks.
And finally we add a little test that makes sure we can fill both
metadata and data to ENOSPC and then recover by deleting what we filled.
Signed-off-by: Zach Brown <zab@versity.com>
Make it static and then use it both for argp_parse as well as
cmd_register_argp.
Split commands into five groups, to help understanding of their
usefulness.
Mention that each command has its own help text, and that we are being
fancy to keep the user from having to give fs path.
Signed-off-by: Andy Grover <agrover@versity.com>
Not initializing wid[] can cause incorrect output.
Also, we only need 6 columns if we reference the array from 0.
Signed-off-by: Andy Grover <agrover@versity.com>
It was too tricky to pick out the difference between metadata and data
usage in the previous format. This makes it much more clear which
values are for either metadata or data.
Signed-off-by: Zach Brown <zab@versity.com>
Add the df command which uses the new alloc_detail ioctl to show df for
the metadata and data devices separately.
Signed-off-by: Zach Brown <zab@versity.com>
