bch2_trans_begin() is now required for transaction restarts.
Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com>

These paths weren't updated for btree_path and snapshots - a couple of
minor fixes.
Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com>

 - check for getting to the end of the btree in bch2_path_verify_locks
   and __btree_path_traverse_all(), this fixes an infinite loop in
   __btree_path_traverse_all().
 - relax requirement in bch2_btree_node_upgrade() that we must want an
   intent lock, this fixes bugs with paths that point to interior nodes
   (nonzero level).
 - bch2_btree_node_update_key(): fix it to upgrade the path to an intent
   lock, if necessary
Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com>

Btree node iterators want the interior btree_path to point to the same
pos as the returned btree node - this fixes a regression from the
introduction of btree_path, where rewriting/updating keys of btree nodes
(e.g. in bch2_dev_metadata_drop()) via btree node iterators.
Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com>

It was missing a lockrestart_do(), to call bch2_trans_begin() and also
handle transaction restarts.
Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com>

Factor out a little helper.
Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com>

We return 1 to indicate kthread_should_stop() returned true - we
shouldn't be printing an error.
Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com>

We were getting spurious "multiple types of data in same bucket" errors
in fsck, because the check was running for (cached) stale pointers -
oops.
Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com>

We were incorrectly using bch2_inode_write(), which gets the snapshot ID
from the iterator, with a BTREE_ITER_ALL_SNAPSHOTS iterator -
fortunately caught by an assertion in the update path.
Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com>

This will cause the compat code to be run that creates entries in the
subvolumes and snapshots btrees.
Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com>

We can end up in a strange situation where a btree_path points to a node
being freed even after pointers to it should have been replaced by
pointers to the new node - if the btree node has been reused since the
pointer to it was created.
Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com>

This is the final patch in the patch series implementing snapshots.
This patch implements two new ioctls that work like creation and
deletion of directories, but fancier.

 - BCH_IOCTL_SUBVOLUME_CREATE, for creating new subvolumes and snaphots
 - BCH_IOCTL_SUBVOLUME_DESTROY, for deleting subvolumes and snapshots
Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com>

Now that all the existing code has been converted for snapshots, this
patch changes the code for initializing a btree iterator to require a
snapshot to be specified, and also change bkey_invalid() to allow for
non U32_MAX snapshot IDs.
Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com>

This finishes updating the unit & perf tests for snapshots - btrees that
use snapshots now always require the snapshot field of the start
position to be a valid snapshot ID.
Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com>

The data move path operates on existing extents, and not within a
subvolume as the regular IO paths do. It needs to change because it may
cause existing extents to be split, and when splitting an existing
extent in an ancestor snapshot we need to make sure the new split has
the same visibility in child snapshots as the existing extent.
Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com>

This patch adds KEY_TYPE_whiteout, a new type of whiteout for snapshots,
when we're deleting and the key being deleted is in an ancestor
snapshot - and updates the transaction update/commit path to use it.
Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com>

This plumbs around the subvolume ID as was done previously for other
filesystem code, but now for the IO paths - the control flow in the IO
paths is trickier so the changes in this patch are more involved.
Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com>

This updates the fsck algorithms to handle snapshots - meaning there
will be multiple versions of the same key (extents, inodes, dirents,
xattrs) in different snapshots, and we have to carefully consider which
keys are visible in which snapshot.
Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com>

To implement snapshots, we need every filesystem btree operation (every
btree operation without a subvolume) to start by looking up the
subvolume and getting the current snapshot ID, with
bch2_subvolume_get_snapshot() - then, that snapshot ID is used for doing
btree lookups in BTREE_ITER_FILTER_SNAPSHOTS mode.

This patch adds those bch2_subvolume_get_snapshot() calls, and also
switches to passing around a subvol_inum instead of just an inode
number.
Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com>

For snapshots, we need to implement btree lookups that return the first
key that's an ancestor of the snapshot ID the lookup is being done in -
and filter out keys in unrelated snapshots. This patch adds the btree
iterator flag BTREE_ITER_FILTER_SNAPSHOTS which does that filtering.
Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com>

Filesystem operations generally operate within a subvolume: at the start
of every btree transaction we'll be looking up (and locking) the
subvolume to get the current snapshot ID, which we then use for our
other btree lookups in BTREE_ITER_FILTER_SNAPSHOTS mode.

But inodes don't record what subvolume they're in - they can't, because
if they did we'd have to update every single inode within a subvolume
when taking a snapshot in order to keep that field up to date. So it
needs to be tracked in memory, based on how we got to that inode.

Hence this patch adds a subvolume field to ei_inode_info, and switches
to iget5() so we can index by it in the inode hash table.
Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com>

On existing filesystems, we have a single global lost+found. Introducing
subvolumes means we need to introduce per subvolume lost+found
directories, because inodes are added to lost+found by their inode
number, and inode numbers are now only unique within a subvolume.

This patch adds support to fsck for per subvolume lost+found.
Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com>

Dirents currently always point to inodes. Subvolumes add a new type of
dirent, with d_type DT_SUBVOL, that instead points to an entry in the
subvolumes btree, and the subvolume has a pointer to the root inode.

This patch adds bch2_dirent_read_target() to get the inode (and
potentially subvolume) a dirent points to, and changes existing code to
use that instead of reading from d_inum directly.
Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com>

This patch adds subvolume.c - support for the subvolumes and snapshots
btrees and related data types and on disk data structures. The next
patches will start hooking up this new code to existing code.
Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com>

Existing quota support breaks badly with snapshots. We're not deleting
the code because some of it will be needed when we reimplement quotas
along the lines of btrfs subvolume quotas.
Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com>

Figured out the bug we were chasing, and it had nothing to do with
locking btree iterators/paths out of order.

This reverts commit ff08733dd298c969aec7c7828095458f73fd5374.
Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com>

This patch checks b->hash_val before attempting to lock the node in the
btree, which makes it more equivalent to the "lookup in hash table"
path - and potentially avoids an unnecessary transaction restart if
btree_node_mem_ptr(k) no longer points to the node we want.
Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com>

This was causing an assertion to pop in fsck, in one of the repair
paths.
Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com>

gcc couldn't always deduce that written wasn't used uninitialized
Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com>

No reason not to be using it here...
Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com>

Instead of unconditionally upgrading read locks to intent locks in
do_bch2_trans_commit(), this patch changes the path that takes write
locks to first trylock, and then if trylock fails check if we have a
conflicting read lock, and restart the transaction if necessary.
Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com>

This is a new approach to avoiding the self deadlock we'd get if we
tried to take a write lock on a node while holding a read lock - we
simply upgrade the readers to intent.
Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com>

We need to take all needed intent locks when relocking an iterator:
bch2_btree_path_traverse() had a special cased, faster version of this,
but it really should be in up_until_good_node() so that set_pos() can
use it too.
Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com>

This patch significantly reduces the number of btree lookups required in
the extent update path.
Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com>

Also add another small helper, btree_path_clone().
Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com>

We'd like performance increasing options to be on by default.
Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com>

Since btree_path is now internally refcounted, we don't need to clone an
iterator before calling bch2_trans_update() if we'll be mutating it.
Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com>

Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com>

These haven't turned out to be useful
Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com>

New rule is: if a btree path holds any locks it should be holding
precisely the locks wanted (accoringing to path->level and
path->locks_want).
Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com>