Rebuild the reverse mapping btree from all primary metadata.  This first
patch establishes the bare mechanics of finding records and putting
together a new ondisk tree; more complex pieces are needed to make it
work properly.

Link: Documentation/filesystems/xfs-online-fsck-design.rst
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>

In the next patch, the rmap btree repair code will need to estimate the
size of the new ondisk rmapbt.  The size is a function of the number of
records that will be written to disk, and the size of the recordset is
the number of observations made while scanning the filesystem plus the
number of OWN_AG records that will be injected into the rmap btree.

OWN_AG rmap records track the free space btrees, the AGFL, and the new
rmap btree itself.  The repair tool uses a bitmap to record the space
used for all four structures, which is why we need a function to count
the number of set regions.

A reviewer requested that this be pulled into a separate patch with its
own justification, so here it is.
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>

Create a helper so that we can stop open-coding this decision
everywhere.
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>

As we've noted in various places, all current users of in-memory btrees
are online fsck.  Online fsck only stages a btree long enough to rebuild
an ondisk data structure, which means that the in-memory btree is
ephemeral.  Furthermore, if we encounter /any/ errors while updating an
in-memory btree, all we do is tear down all the staged data and return
an errno to userspace.  In-memory btrees need not be transactional, so
their buffers should not be committed to the ondisk log, nor should they
be checkpointed by the AIL.  That's just as well since the ephemeral
nature of the btree means that the buftarg and the buffers may disappear
quickly anyway.

Therefore, we need a way to launder the btree buffers that get attached
to the transaction by the generic btree code.  Because the buffers are
directly mapped to backing file pages, there's no need to bwrite them
back to the tmpfs file.  All we need to do is clean enough of the buffer
log item state so that the bli can be detached from the buffer, remove
the bli from the transaction's log item list, and reset the transaction
dirty state as if the laundered items had never been there.

For simplicity, create xfbtree transaction commit and cancel helpers
that launder the in-memory btree buffers for callers.  Once laundered,
call the write verifier on non-stale buffers to avoid integrity issues,
or punch a hole in the backing file for stale buffers.
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>

Adapt the generic btree cursor code to be able to create a btree whose
buffers come from a (presumably in-memory) buftarg with a header block
that's specific to in-memory btrees.  We'll connect this to other parts
of online scrub in the next patches.

Note that in-memory btrees always have a block size matching the system
memory page size for efficiency reasons.  There are also a few things we
need to do to finalize a btree update; that's covered in the next patch.
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>

This only has a single caller and thus might be a bit questionable,
but I think it really improves the readability of
xfs_btree_visit_block.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Darrick J. Wong <djwong@kernel.org>

Allow the buffer cache to target in-memory files by making it possible
to have a buftarg that maps pages from private shmem files.  As the
prevous patch alludes, the in-memory buftarg contains its own cache,
points to a shmem file, and does not point to a block_device.

The next few patches will make it possible to construct an xfs_btree in
pageable memory by using this buftarg.
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>

Currently, cached buffers are indexed by per-AG hashtables.  This works
great for the data device, but won't work for in-memory btrees.  To
handle that use case, buftargs will need to be able to index buffers
independently of other data structures.

We accomplish this by hoisting the rhashtable and its lock into a
separate xfs_buf_cache structure, make the buftarg point to the
_buf_cache structure, and rework various functions to use it.  This
will enable the in-memory buftarg to come up with its own _buf_cache.
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>

bt_logical_sectorsize and the associated mask is set based on the
constant logical block size in the block_device structure and thus
doesn't need to be updated in xfs_setsize_buftarg.  Move it into
xfs_alloc_buftarg so that it is only done once per buftarg.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Darrick J. Wong <djwong@kernel.org>

Open code the logic in the only caller, and improve the comment
explaining what is being done here.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Darrick J. Wong <djwong@kernel.org>

Switch the few remaining holdouts to the struct version.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Darrick J. Wong <djwong@kernel.org>

xfs_buf_rele is a bit confusing because it mixes up handling of normal
cached and the special uncached buffers without much explanation.
Split the handling into two different helpers, and use a clearly named
helper that checks the hash key to distinguish the two cases instead
of checking the pag pointer.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Darrick J. Wong <djwong@kernel.org>

Despite its name, xfs_btree_read_bufl doesn't contain any btree-related
functionaliy and isn't used by the btree code.  Move it to xfs_bmap.c,
hard code the refval and ops arguments and rename it to
xfs_bmap_read_buf.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Darrick J. Wong <djwong@kernel.org>

xfs_btree_reada_bufl just wraps xfs_btree_readahead and a agblock
to daddr conversion.  Just open code it's three callsites in the
two callers (One of which isn't even btree related).
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Darrick J. Wong <djwong@kernel.org>

xfs_btree_reada_bufl just wraps xfs_btree_readahead and a fsblock
to daddr conversion.  Just open code it's two callsites in the only
caller.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Darrick J. Wong <djwong@kernel.org>

This will allow sharing code with the in-memory block checking helper.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Darrick J. Wong <djwong@kernel.org>

All these helpers hardcode fsblocks or agblocks and not just the pointer
size.  Rename them so that the names are still fitting when we add the
long format in-memory blocks and adjust the checks when calling them to
check the btree types and not just pointer length.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Darrick J. Wong <djwong@kernel.org>

Add a __xfs_btree_check_block helper that can be called by the scrub code
to validate a btree block of any form, and move the duplicate error
handling code from xfs_btree_check_sblock and xfs_btree_check_lblock into
xfs_btree_check_block and thus remove these two helpers.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Darrick J. Wong <djwong@kernel.org>

Check that root blocks that sit in the inode fork and thus have a NULL
bp don't have siblings.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Darrick J. Wong <djwong@kernel.org>

crc is only used once, just use the xfs_has_crc check directly.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Darrick J. Wong <djwong@kernel.org>

Remove the local crc variable that is only used once and remove the bp
NULL checking as it can't ever be NULL for short form blocks.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Darrick J. Wong <djwong@kernel.org>

Merge xfs_btree_check_sptr and xfs_btree_check_lptr into a single
__xfs_btree_check_ptr that can be shared between xfs_btree_check_ptr
and the scrub code.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Darrick J. Wong <djwong@kernel.org>

xfs_bmap_btree_to_extents always passes a level of 1 to
xfs_btree_check_lptr, thus making the level check redundant.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Darrick J. Wong <djwong@kernel.org>

Stop using xfs_btree_check_lptr in xfs_btree_check_lblock_siblings,
as it only duplicates the xfs_verify_fsbno call in the other leg of
if / else besides adding a tautological level check.

With this the cur and level arguments can be removed as they are
now unused.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Darrick J. Wong <djwong@kernel.org>

Stop using xfs_btree_check_sptr in xfs_btree_check_sblock_siblings,
as it only duplicates the xfs_verify_agbno call in the other leg of
if / else besides adding a tautological level check.

With this the cur and level arguments can be removed as they are
now unused.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Darrick J. Wong <djwong@kernel.org>

The last checks for bc_btnum can be replaced with helpers that check
the btree ops.  This allows adding new btrees to XFS without having
to update a global enum.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
[djwong: complete the ops predicates]
Signed-off-by: Darrick J. Wong <djwong@kernel.org>

This is one of the last users of xfs_btnum_t and can only designate
either the inobt or finobt.  Replace it with a simple bool.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Darrick J. Wong <djwong@kernel.org>

Split xfs_inobt_init_cursor into separate routines for the inobt and
finobt to prepare for the removal of the xfs_btnum global enumeration
of btree types.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Darrick J. Wong <djwong@kernel.org>

Split the finobt version that never merges and uses a different cursor
out of xfs_inobt_insert_sprec to prepare for removing xfs_btnum_t.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Darrick J. Wong <djwong@kernel.org>

The which variable that holds a btree number is passed to two functions
that ignore it and used in a single check that can check the sm_type
as well.  Remove it to unclutter the code.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Darrick J. Wong <djwong@kernel.org>

xfs_inobt_count_blocks is only used for the finobt.  Hardcode the btnum
argument and rename the function to match that.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Darrick J. Wong <djwong@kernel.org>

This helper provides no real advantage over just open code the two
calls in it in the callers.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Darrick J. Wong <djwong@kernel.org>

Split xfs_allocbt_init_cursor into separate routines for the by-bno
and by-cnt btrees to prepare for the removal of the xfs_btnum global
enumeration of btree types.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Darrick J. Wong <djwong@kernel.org>

Change xchk_ag_btcur_init to allocate all cursors first and only then
check if we should delete them again because the btree is to damaged.

This allows reusing the sick_mask in struct xfs_btree_ops and simplifies
the code.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Darrick J. Wong <djwong@kernel.org>

Clean up xfs_btree_mark_sick by adding a sick_mask to the btree-ops
for all AG-root btrees.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Darrick J. Wong <djwong@kernel.org>

The btnum in struct xfs_btree_ops is often used for printing a symbolic
name for the btree.  Add a name field to the ops structure and use that
directly.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Darrick J. Wong <djwong@kernel.org>

Using arrays of largely unrelated fields that use the btree number
as index is not very robust.  Split the arrays into three separate
fields instead.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Darrick J. Wong <djwong@kernel.org>

Just open code the two calls in the callers.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Darrick J. Wong <djwong@kernel.org>

Make the levels initialization in xfs_bmbt_init_cursor conditional
and merge the two helpers.

This requires the fakeroot case to now pass a -1 whichfork directly
into xfs_bmbt_init_cursor, and some special casing for that, but
at least this scheme to deal with the fake btree root is handled and
documented in once place now.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
[djwong: tidy up a multline ternary]
Signed-off-by: Darrick J. Wong <djwong@kernel.org>

Don't open-code "-1" for whichfork when we're creating a staging btree
for a repair; let's define an actual symbol to make grepping and
understanding easier.
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>