xfs: repair free space btrees

Rebuild the free space btrees from the gaps in the rmap btree. Refer to
the case study in Documentation/filesystems/xfs-online-fsck-design.rst
for more details.

Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>

xfs: remove trivial bnobt/inobt scrub helpers

Christoph Hellwig complained about awkward code in the next two repair
patches such as:

sc->sm->sm_type = XFS_SCRUB_TYPE_BNOBT;
error = xchk_bnobt(sc);

This is a little silly, so let's export the xchk_{,i}allocbt functions
to the dispatch table in scrub.c directly and get rid of the helpers.
Originally I had planned each btree gets its own separate entry point,
but since repair doesn't work that way, it no longer makes sense to
complicate the call chain that way.

Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>

xfs: flag free space btree records that could be merged

Complain if we encounter free space btree records that could be merged.

Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Dave Chinner <dchinner@redhat.com>

xfs: ensure that all metadata and data blocks are not cow staging extents

Make sure that all filesystem metadata blocks and file data blocks are
not also marked as CoW staging extents. The extra checking added here
was inspired by an actual VM host filesystem corruption incident due to
bugs in the CoW handling of 4.x kernels.

Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Dave Chinner <dchinner@redhat.com>

xfs: replace xfs_btree_has_record with a general keyspace scanner

The current implementation of xfs_btree_has_record returns true if it
finds /any/ record within the given range. Unfortunately, that's not
sufficient for scrub. We want to be able to tell if a range of keyspace
for a btree is devoid of records, is totally mapped to records, or is
somewhere in between. By forcing this to be a boolean, we conflated
sparseness and fullness, which caused scrub to return incorrect results.
Fix the API so that we can tell the caller which of those three is the
current state.

Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Dave Chinner <dchinner@redhat.com>

xfs: standardize ondisk to incore conversion for free space btrees

Create a xfs_alloc_btrec_to_irec function to convert an ondisk record to
an incore record, and a xfs_alloc_check_irec function to detect
corruption. Replace all the open-coded logic with calls to the new
helpers and bubble up corruption reports.

Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Dave Chinner <dchinner@redhat.com>

xfs: minimize overhead of drain wakeups by using jump labels

To reduce the runtime overhead even further when online fsck isn't
running, use a static branch key to decide if we call wake_up on the
drain. For compilers that support jump labels, the call to wake_up is
replaced by a nop sled when nobody is waiting for intents to drain.

From my initial microbenchmarking, every transition of the static key
between the on and off states takes about 22000ns to complete; this is
paid entirely by the xfs_scrub process. When the static key is off
(which it should be when fsck isn't running), the nop sled adds an
overhead of approximately 0.36ns to runtime code. The post-atomic
lockless waiter check adds about 0.03ns, which is basically free.

For the few compilers that don't support jump labels, runtime code pays
the cost of calling wake_up on an empty waitqueue, which was observed to
be about 30ns. However, most architectures that have sufficient memory
and CPU capacity to run XFS also support jump labels, so this is not
much of a worry.

Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Dave Chinner <dchinner@redhat.com>

xfs: update copyright years for scrub/ files

Update the copyright years in the scrub/ source code files. This isn't
required, but it's helpful to remind myself just how long it's taken to
develop this feature.

Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Dave Chinner <dchinner@redhat.com>

xfs: fix author and spdx headers on scrub/ files

Fix the spdx tags to match current practice, and update the author
contact information.

Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Dave Chinner <dchinner@redhat.com>

xfs: create a predicate to verify per-AG extents

Create a predicate function to verify that a given agbno/blockcount pair
fit entirely within a single allocation group and don't suffer
mathematical overflows. Refactor the existng open-coded logic; we're
going to add more calls to this function in the next patch.

Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Dave Chinner <dchinner@redhat.com>

xfs: Pre-calculate per-AG agbno geometry

There is a lot of overhead in functions like xfs_verify_agbno() that
repeatedly calculate the geometry limits of an AG. These can be
pre-calculated as they are static and the verification context has
a per-ag context it can quickly reference.

In the case of xfs_verify_agbno(), we now always have a perag
context handy, so we can store the AG length and the minimum valid
block in the AG in the perag. This means we don't have to calculate
it on every call and it can be inlined in callers if we move it
to xfs_ag.h.

Move xfs_ag_block_count() to xfs_ag.c because it's really a
per-ag function and not an XFS type function. We need a little
bit of rework that is specific to xfs_initialise_perag() to allow
growfs to calculate the new perag sizes before we've updated the
primary superblock during the grow (chicken/egg situation).

Note that we leave the original xfs_verify_agbno in place in
xfs_types.c as a static function as other callers in that file do
not have per-ag contexts so still need to go the long way. It's been
renamed to xfs_verify_agno_agbno() to indicate it takes both an agno
and an agbno to differentiate it from new function.

Future commits will make similar changes for other per-ag geometry
validation functions.

Further:

$ size --totals fs/xfs/built-in.a
text data bss dec hex filename
before 1483006 329588 572 1813166 1baaae (TOTALS)
after 1482185 329588 572 1812345 1ba779 (TOTALS)

This rework reduces the binary size by ~820 bytes, indicating
that much less work is being done to bounds check the agbno values
against on per-ag geometry information.

Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>

xfs: mark the record passed into xchk_btree functions as const

xchk_btree calls a user-supplied function to validate each btree record
that it finds. Those functions are not supposed to change the record
data, so mark the parameter const.

Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>

xfs: remove agno from btree cursor

Now that everything passes a perag, the agno is not needed anymore.
Convert all the users to use pag->pag_agno instead and remove the
agno from the cursor. This was largely done as an automated search
and replace.

Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Brian Foster <bfoster@redhat.com>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>

xfs: get rid of the ip parameter to xchk_setup_*

Now that the scrub context stores a pointer to the file that was used to
invoke the scrub call, the struct xfs_inode pointer that we passed to
all the setup functions is no longer necessary. This is only ever used
if the caller wants us to scrub the metadata of the open file.

Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Chandan Babu R <chandanrlinux@gmail.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>

xfs: convert btree cursor ag-private member name

bc_private.a -> bc_ag conversion via script:

`sed -i 's/bc_private\.a/bc_ag/g' fs/xfs/*[ch] fs/xfs/*/*[ch]`

And then revert the change to the bc_ag #define in
fs/xfs/libxfs/xfs_btree.h manually.

Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Brian Foster <bfoster@redhat.com>

xfs: removed unneeded variable

Returned value directly instead of using variable as it wasn't updated.

Signed-off-by: Aliasgar Surti <aliasgar.surti500@gmail.com>
Reviewed-by: Brian Foster <bfoster@redhat.com>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>

xfs: remove unused header files

There are many, many xfs header files which are included but
unneeded (or included twice) in the xfs code, so remove them.

nb: xfs_linux.h includes about 9 headers for everyone, so those
explicit includes get removed by this. I'm not sure what the
preference is, but if we wanted explicit includes everywhere,
a followup patch could remove those xfs_*.h includes from
xfs_linux.h and move them into the files that need them.
Or it could be left as-is.

Signed-off-by: Eric Sandeen <sandeen@redhat.com>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>

xfs: remove xfs_rmap_ag_owner and friends

Owner information for static fs metadata can be defined readonly at
build time because it never changes across filesystems. This enables us
to reduce stack usage (particularly in scrub) because we can use the
statically defined oinfo structures.

Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Brian Foster <bfoster@redhat.com>

xfs: remove duplicated include from alloc.c

Remove duplicated include xfs_alloc.h

Signed-off-by: YueHaibing <yuehaibing@huawei.com>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>

xfs: fix indentation and other whitespace problems in scrub/repair

Now that we've shortened everything, fix up all the indentation and
whitespace problems. There are no functional changes.

Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Brian Foster <bfoster@redhat.com>

xfs: shorten struct xfs_scrub_context to struct xfs_scrub

Shorten the name of the online fsck context structure. Whitespace
damage will be fixed by a subsequent patch. There are no functional
changes.

Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Brian Foster <bfoster@redhat.com>

xfs: shorten xfs_scrub_ prefix

Shorten all the metadata checking xfs_scrub_ prefixes to xchk_. After
this, the only xfs_scrub* symbols are the ones that pertain to both
scrub and repair. Whitespace damage will be fixed in a subsequent
patch. There are no functional changes.

Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Brian Foster <bfoster@redhat.com>

xfs: convert to SPDX license tags

Remove the verbose license text from XFS files and replace them
with SPDX tags. This does not change the license of any of the code,
merely refers to the common, up-to-date license files in LICENSES/

This change was mostly scripted. fs/xfs/Makefile and
fs/xfs/libxfs/xfs_fs.h were modified by hand, the rest were detected
and modified by the following command:

for f in `git grep -l "GNU General" fs/xfs/` ; do
echo $f
cat $f | awk -f hdr.awk > $f.new
mv -f $f.new $f
done

And the hdr.awk script that did the modification (including
detecting the difference between GPL-2.0 and GPL-2.0+ licenses)
is as follows:

$ cat hdr.awk
BEGIN {
hdr = 1.0
tag = "GPL-2.0"
str = ""
}

/^ \* This program is free software/ {
hdr = 2.0;
next
}

/any later version./ {
tag = "GPL-2.0+"
next
}

/^ \*\// {
if (hdr > 0.0) {
print "// SPDX-License-Identifier: " tag
print str
print $0
str=""
hdr = 0.0
next
}
print $0
next
}

/^ \* / {
if (hdr > 1.0)
next
if (hdr > 0.0) {
if (str != "")
str = str "\n"
str = str $0
next
}
print $0
next
}

/^ \*/ {
if (hdr > 0.0)
next
print $0
next
}

// {
if (hdr > 0.0) {
if (str != "")
str = str "\n"
str = str $0
next
}
print $0
}

END { }
$

Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>

xfs: skip scrub xref if corruption already noted

Don't bother looking for cross-referencing problems if the metadata is
already corrupt or we've already found a cross-referencing problem.
Since we added a helper function for flags testing, convert existing
users to use it.

Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Brian Foster <bfoster@redhat.com>

xfs: cross-reference refcount btree during scrub

During metadata btree scrub, we should cross-reference with the
reference counts.

Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Dave Chinner <dchinner@redhat.com>

xfs: cross-reference reverse-mapping btree

When scrubbing various btrees, we should cross-reference the records
with the reverse mapping btree and ensure that traversing the btree
finds the same number of blocks that the rmapbt thinks are owned by
that btree.

Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Dave Chinner <dchinner@redhat.com>

xfs: cross-reference inode btrees during scrub

Cross-reference the inode btrees with the other metadata when we
scrub the filesystem.

Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Dave Chinner <dchinner@redhat.com>

xfs: cross-reference bnobt records with cntbt

Scrub should make sure that each bnobt record has a corresponding
cntbt record.

Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Dave Chinner <dchinner@redhat.com>

xfs: cross-reference with the bnobt

When we're scrubbing various btrees, cross-reference the records with
the bnobt to ensure that we don't also think the space is free.

Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Dave Chinner <dchinner@redhat.com>

xfs: introduce scrubber cross-referencing stubs

Create some stubs that will be used to cross-reference metadata records.
The actual cross-referencing will be filled in by subsequent patches.

Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Dave Chinner <dchinner@redhat.com>

xfs: scrub free space btrees

Check the extent records free space btrees to ensure that the values
look sane.

Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Dave Chinner <dchinner@redhat.com>