Remove unused function getenv_or_die. All of our environment variable
parameters are optional or have default values.
Signed-off-by: Zygo Blaxell <bees@furryterror.org>
Get rid of unused template instantiation.
Drop the unused realtime signals from the ntoa table. If in the future
we really need to solve clang's issue with them, we'll address it then.
Signed-off-by: Zygo Blaxell <bees@furryterror.org>
A long time ago, when bees used dedicated threads to scan each subvol, the
calculation of the "dedup_unique_bytes" statistic was still wrong.
This stat can only be calculated when dedupe runs on extent data items
instead of extent reference items. Remove the stat variable until
that happens.
Signed-off-by: Zygo Blaxell <bees@furryterror.org>
There was a 4th tree mod log crash that showed up in testing. It can
be reproduced or eliminated by applying or reverting d2311e698578
("btrfs: relocation: Delay reloc tree deletion after merge_reloc_roots")
to a 5.4.x kernel before 5.4.54.
Unfortunately, the test can only run if several other patches that
fixed other bugs in d2311e698578 are applied or removed at the same time.
Commit d2311e698578 introduces a bug which destroys filesystems under test
long before tree mod log failures can be reproduced in testing. One of
those patches also fixes tree mod log issue #4. I do not know which one,
but since kernels after 5.1 cannot run without all of those patches, I do
not think it matters.
Tree mod issue #4 is the reason why the tree mod workaround is still
required on all kernels before 5.4. The issue still exists on older
LTS kernels, e.g. 4.9.
Signed-off-by: Zygo Blaxell <bees@furryterror.org>
Rewrite the text related to 'btrfs send' to clarify that the send
workaround is no longer necessary to avoid kernel crashes, but still
useful because send and dedupe still do not work at the same time.
Replace "many backref code changes" with a specific commit reference,
and improve the grammar of some issue descriptions.
Signed-off-by: Zygo Blaxell <bees@furryterror.org>
Apparently there's Github Flavored Markdown, and there's the markup
language that github uses, and they are distinct things.
Signed-off-by: Zygo Blaxell <bees@furryterror.org>
Present known kernel bugs in table form with issue descriptions,
fixed and broken kernel versions, and references to fixes.
Update kernel version recommendations to include information on kernel
versions up to 5.8.14.
Reduce emphasis on data corruption bugs which are 1) two or more
years old now, and 2) much less bad than the bugs in kernel 5.1.
Add deprecation warning for kernels before 4.15.
Signed-off-by: Zygo Blaxell <bees@furryterror.org>
Prefer to use cmark-gfm with extension 'table' so we can use tables in
locally-generated HTML files. If cmark-gfm is not installed then
fall back to some other Markdown implemeentation, but the tables will
be broken on every other implementation I have tried so far.
Also make the HTML output depend on the Makefile, since there may be
document translation options specified there (like '-e table' or an
entirely different Markdown implementation).
Signed-off-by: Zygo Blaxell <bees@furryterror.org>
uncaught_exception() had only the one valid use case, and it can be
reimplemented by literally calling current_exception() instead.
current_exception() has several valid use cases, so it is not likely
to be deprecated any time soon.
Signed-off-by: Zygo Blaxell <bees@furryterror.org>
We cannot use BeesContext::roots() until after
BeesContext::set_root_path() has been called.
Save up the parameter settings until then.
Signed-off-by: Zygo Blaxell <bees@furryterror.org>
"Storm of softlockups" starts with a simple BUG_ON, but after the
BUG_ON, all cores that are waiting on spinlocks get stuck.
The _first_ kernel call trace is required to identify the bug.
At least two such bugs have been identified.
Add some notes about the conflict between LOGICAL_INO and balance,
and the recently added bees workaround.
Update the gotchas page for balances to point to the kernel bugs page.
Remove "bees and the full balance will both work correctly" as that
statement is not true.
Signed-off-by: Zygo Blaxell <bees@furryterror.org>
This avoids some kernel bugs. One of them is fixed in 5.3.4 and later:
efad8a853a "Btrfs: fix use-after-free when using the tree modification log"
There are apparently others in current kernels, so for now just put bees
on pause until the balance is done.
At some point we may want to provide an option to disable this
workaround; however, running bees and balance at the same time makes
neither particularly fast, so maybe we'll just leave it this way.
Signed-off-by: Zygo Blaxell <bees@furryterror.org>
In version 2.30 glibc added it's own gettid() function. This resulted in
"error: call of overloaded ‘gettid()’ is ambiguous" because gettid()
now exists in both namespace crucible and std.
For now, use explicit references to namespace crucible. This continues
to work with new and old libc without having to test specific library
versions.
At some point, glibc gettid() will be deployed widely enough that we can
remove the crucible version entirely.
Signed-off-by: Zygo Blaxell <bees@furryterror.org>
Localize the hash function in bees to a single spot to make it easier
to change later (or at runtime).
Remove some code that was using a property of CRC as an optimization.
The optimization doesn't work for other hash functions, and running the
CRC function takes more CPU time than the optimization saved.
Signed-off-by: Zygo Blaxell <bees@furryterror.org>
CityHash64 appears to be the fastest available block hashing algorithm
that is good enough for dedupe. It takes much less CPU than the CRC64
function, and avoids hash-collision problems with file formats that use
CRC64 as an integrity check on 4K block boundaries.
Extracted from git://github.com/google/cityhash with the "CRC" hash
functions (which require Intel/AMD CPU support) removed. We don't
need those, and they introduce a new (if only theoretical) build-time
dependency.
Signed-off-by: Zygo Blaxell <bees@furryterror.org>
It is not possible to emulate extent-same by clone in a safe way.
EXTENT_SAME has been supported in btrfs since kernel 3.13, which
is much too old to contemplate running bees on.
Remove this dangerous and unused function.
Signed-off-by: Zygo Blaxell <bees@furryterror.org>
We are getting a lot of exceptions when an inline extent is too large for the
TREE_SEARCH_V2 buffer. This disrupts ExtentWalker's extent boundary
search when there is an inline extent at the beginning of a file:
# fiemap foo
Log 0x0..0x1000 Phy 0x0..0x1000 Flags FIEMAP_EXTENT_NOT_ALIGNED|FIEMAP_EXTENT_DATA_INLINE
Log 0x1000..0x2000 Phy 0x7307f9000..0x7307fa000 Flags 0
Log 0x2000..0x3000 Phy 0x731078000..0x731079000 Flags 0
Log 0x3000..0x5000 Phy 0x73127d000..0x73127f000 Flags FIEMAP_EXTENT_ENCODED
Log 0x5000..0x6000 Phy 0x73137a000..0x73137b000 Flags 0
Log 0x6000..0x7000 Phy 0x731683000..0x731684000 Flags 0
Log 0x7000..0x8000 Phy 0x73224f000..0x732250000 Flags 0
Log 0x8000..0x9000 Phy 0x7323c9000..0x7323ca000 Flags 0
Log 0x9000..0xb000 Phy 0x732425000..0x732427000 Flags FIEMAP_EXTENT_ENCODED
Log 0xb000..0xc000 Phy 0x732598000..0x732599000 Flags 0
Log 0xc000..0xd000 Phy 0x7325d5000..0x7325d6000 Flags FIEMAP_EXTENT_LAST
# fiewalk foo
exception type std::system_error: BTRFS_IOC_TREE_SEARCH_V2: /tmp/foo at fs.cc:844: Value too large for defined data type
Normally crawlers simply skip over inline extents, but ExtentWalker will
seek backward from the first non-inline extent to confirm that it has
an accurate starting block for the target extent. This fails when it
encounters the first inline extent.
strace reveals that buffer size is too small for the first extent,
as seen here:
ioctl(3, BTRFS_IOC_TREE_SEARCH_V2, {key={tree_id=258, min_objectid=78897856, max_objectid=UINT64_MAX, min_offset=0, max_offset=UINT64_MAX, min_transid=0, max_transid=UINT64_MAX, min_type=BTRFS_EXTENT_DATA_KEY, max_type=BTRFS_EXTENT_DATA_KEY, nr_items=16}, buf_size=1360} => {buf_size=1418}) = -1 EOVERFLOW (Value too large for defined data type)
Fix this by increasing the buffer size until it can handle the largest
possible object on the largest possible btrfs metadata page (65536 bytes).
BtrfsExtentWalker already has optimizations to minimize the allocation
cost, so we don't need any changes there.
Signed-off-by: Zygo Blaxell <bees@furryterror.org>
Some build environments (ARM? AARCH64?) do not have the fields
si_lower and si_upper in siginfo.
bees doesn't need them, so don't try to access them.
Signed-off-by: Zygo Blaxell <bees@furryterror.org>
Update the version ranges on the dependencies.
FIXME/TODO: start dropping early versions that don't work with current
code?
Signed-off-by: Zygo Blaxell <bees@furryterror.org>
flushoncommit or not-flushoncommit isn't really a bees matter--it's
a sysadmin's tradeoff between reliability and performance. bees does
not affect that tradeoff because all dedupe src extents are flushed, so
bees introduces no *new* data loss risks in the noflushoncommit
case--i.e. any data that you could lose while running bees, you'd also
lose when not running bees.
Note that the converse is not true: bees might trigger flushing on
data that would not normally have been flushed with noflushoncommit,
and improve data integrity after a crash as a side-effect of dedupe
operations. The risks of noflushoncommit might be reduced by running
bees. I don't have evidence based on experimental data to support that
conclusion, so I'll just leave this possibility as a rumor in a commit
log message.
lvmcache can be moved from the "bad" list to the "good" list now.
bcache remains in the "bad" list due to some non-data-losing failures
that only seem to happen with bcache.
Add a note about CPUs with strange endianness or page sizes, as nobody
seems to have tried those.
Remove "at great cost" from the btrfs send workaround. The cost is
the cost, there is no need to editorialize.
Signed-off-by: Zygo Blaxell <bees@furryterror.org>
The existence of information about known data corruption bugs should be
visible from the top-level page.
Signed-off-by: Zygo Blaxell <bees@furryterror.org>
* comprehensive list of kernels with bees-triggered corruption bug fixes
* deadlock between dedupe and rename is now fixed (in some places)
* compressed data corruption is now fixed (in more places)
* btrfs send fix for one bug is now merged in 5.2-rc1, another bug remains
* retired the bcache/lvmcache bug (can't reproduce those bugs any more,
although I *can* reproduce an interesting non-destructive bcache bug)
* new minor bug entries for two harmless kernel warnings
* new entry for storm-of-soft-lockups
Fixes: https://github.com/Zygo/bees/issues/107
Signed-off-by: Zygo Blaxell <bees@furryterror.org>
This is especially useful when dynamic load management allocates more
worker threads than active tasks, so the extra threads are effectively
invisible.
Signed-off-by: Zygo Blaxell <bees@furryterror.org>
This may help users understand some of the things that happen inside
bees...or it may just be horribly long and confusing.
Signed-off-by: Zygo Blaxell <bees@furryterror.org>
Enable much simpler Task management: each time a Task needs to be done
at least once in the future, simply invoke the run() method on the Task.
The Task will ensure that it only runs once, only appears in a queue
once, and will run again if a run request is made while the Task is
already running.
Make the queue policy a member of the Task rather than a method. This
enables Tasks to reschedule themselves, possibly on the appropriate queue
if we have more than one of those some day.
This happens to make Tasks more similar to Linux kernel workers.
This similarity is coincidental, but not undesirable.
Signed-off-by: Zygo Blaxell <bees@furryterror.org>
Introduce a mechanism to suppress exceptions which do not produce a
full stack trace for common known cases where a loop should be aborted.
Use this mechanism to suppress the infamous "FIXME" exception.
Reduce the log level to at most NOTICE, and in some cases DEBUG.
Signed-off-by: Zygo Blaxell <bees@furryterror.org>
libcrucible at one time in the distant past had to be a shared library
to force global C++ object initialization; however, this is no longer
required.
Make libcrucible static to solve various rpath and soname versioning
issues, especially when distros try (unwisely) to package the library
separately.
Signed-off-by: Zygo Blaxell <bees@furryterror.org>
We stopped supporting shared hash tables a long time ago. Remove comments
describing the behavior of shared hash tables.
Add an event counter for pushing a hash to the front when it is already at
the front.
Audited the code for a bug related to bucket handling that impairs space
efficiency when the bucket size is greater than 1. Didn't find one.
Signed-off-by: Zygo Blaxell <bees@furryterror.org>
Capture SIGINT and SIGTERM and shut down, preserving current completed
crawl and hash table state.
* Executing tasks are completed, queued tasks are paused.
* Crawl state is saved.
* The crawl master and crawl writeback threads are terminated.
* The task queue is flushed.
* Dirty hash table extents are flushed.
* Hash prefetch and writeback threads are terminated.
* Hash table is deallocated.
* FD caches and tmpfiles are destroyed.
* Assuming the above didn't crash or deadlock, bees exits.
The above order isn't the fastest, but it does roughly follow the
shared_ptr dependencies and avoids data races--especially those that
might lead to bees reporting an extent scanned when it was only queued
for future scanning that did not occur.
In case of a violation of expected shared_ptr dependency order,
exceptions in BeesContext child object accessor methods (i.e. roots(),
hash_table(), etc) prevent any further progress in threads that somehow
remain unexpectedly active.
Move some threads from main into BeesContext so they can be stopped
via BeesContext. The main thread now runs a loop waiting for signals.
A slow FD leak was discovered in TempFile handling. This has not been
fixed yet, but an implementation detail of the C++ runtime library makes
the leak so slow it may never be important enough to fix.
Signed-off-by: Zygo Blaxell <bees@furryterror.org>
We need to replace nanosleeps with condition variables so that we
can implement BeesContext::stop. Export the time calculation from
sleep_for() into a new method called sleep_time().
If the thread executing RateLimiter::sleep_for() is interrupted, it will
no longer be able to restart, as the sleep_time() method is destructive.
This calls for further refactoring of sleep_time() into destructive
and non-destructive parts; however, there are currently no users of
sleep_for() which rely on being able to restart after being interrupted
by a signal.
Signed-off-by: Zygo Blaxell <bees@furryterror.org>
Add a method to have TaskMaster discard any entries in its queue, terminate
all worker threads, and prevent any new Tasks from being queued.
Signed-off-by: Zygo Blaxell <bees@furryterror.org>
The deadlock seems to be fixed now (if there ever was one--there certainly
were deadlocks, but matching deadlocks to root causes is non-trivial
and a number of distinct deadlock cases have been fixed in recent years).
The benchmark data is inconclusive about whether it is better to fsync or
not to fsync. A paranoia option might be useful here.
Signed-off-by: Zygo Blaxell <bees@furryterror.org>
The crawl_master task had a simple atomic variable that was supposed
to prevent duplicate crawl_master tasks from ending up in the queue;
however, this had a race condition that could lead to m_task_running
being set with no crawl_master task running to clear it. This would in
turn prevent crawl_thread from scheduling any further crawl_master tasks,
and bees would eventually stop doing any more work.
A proper fix is to modify the Task class and its friends such that
Task::run() guarantees that 1) at most one instance of a Task is ever
scheduled or running at any time, and 2) if a Task is scheduled while
an instance of the Task is running, the scheduling is deferred until
after the current instance completes. This is part of a fairly large
planned change set, but it's not ready to push now.
So instead, unconditionally push a new crawl_master Task into the queue
on every poll, then silently and quickly exit if the queue is too full
or the supply of new extents is empty. Drop the scheduling-related
members of BeesRoots as they will not be needed when the proper fix lands.
Fixes: 4f0bc78a "crawl: don't block a Task waiting for new transids"
Signed-off-by: Zygo Blaxell <bees@furryterror.org>
If /bin/sh is bash, the 'type' builtin produces a list of filenames
that match the arguments to $PATH.
If /bin/sh is dash, we get errors like:
/bin/sh: 1: P:: not found
Hopefully having a build-dep on bash is not controversial.
Signed-off-by: Zygo Blaxell <bees@furryterror.org>
The two files are identical except README.md links to docs/* while
index.md links to *.
A sed script can do that transformation, so use sed to do it.
This does modify a file in git, but this is necessary to make all
the Github views work consistently.
Signed-off-by: Zygo Blaxell <bees@furryterror.org>
This sequence of log messages isn't clear:
crawl_master: WORKAROUND: Avoiding RO subvol 6094
crawl_master: WORKAROUND: RO root 6094
The first is from a cache miss, and appears wherever a root is opened
(dedupe or crawl). The second is skipping an entire subvol scan, and
only happens in crawl_master.
Elaborate on the second message a little.
Also use the term "root" consistently when referring to subvol tree IDs.
btrfs refers to these objects by (at least) three distinct names: tree,
subvol, and root. Using three different words for the same thing is worse
than using a single wrong word consistently to refer to the same concept.
Signed-off-by: Zygo Blaxell <bees@furryterror.org>
After weeks of testing I copied part of a change to main without copying
the rest of the change, leading to an immediate segfault on startup.
So here is the rest of the change: limit the number of
BeesContexts per process to 1. This change was discussed at
https://github.com/Zygo/bees/issues/54#issuecomment-360332529 but there
are more reasons to do it now: the candidates to replace the current
hash table format are less forgiving of sharing hash tables, and it may
even become necessary to have more than one hash table per BeesContext
instance (e.g. to keep datasum and nodatasum data separate).
Signed-off-by: Zygo Blaxell <bees@furryterror.org>
https://github.com/Zygo/bees/issues/91 describes problems encountered
when running bees on systems with many CPU cores.
Limit the computed number of threads (using --thread-factor or the
default) to a maximum of 8 (i.e. the number of logical cores in a modern
laptop). Users can override the limit by using --thread-count.
Signed-off-by: Zygo Blaxell <bees@furryterror.org>
options.md was a disorganized mess that markdown couldn't parse properly.
Break the options list down into sections by theme. Add the new
'--workaround-btrfs-send' option to the new 'Workarounds' section.
Clean up the rest of the text and fix some inconsistencies.
Signed-off-by: Zygo Blaxell <bees@furryterror.org>
Introduce --workaround options which trade performance or effectiveness to
avoid triggering kernel bugs.
The first such option is --workaround-btrfs-send, which avoids making any
modification to read-only subvols to avoid btrfs send bugs.
Clean up usage message: no tabs for formatting, split options into
sections by theme.
Make scan mode a non-static data member like all (most?) other options.
Signed-off-by: Zygo Blaxell <bees@furryterror.org>
The log message is quite CPU-intensive to generate, and some data sets
have enough hash collisions to throw off benchmarks.
Keep the event counter but drop the log message.
Signed-off-by: Zygo Blaxell <bees@furryterror.org>
Make sure the result set is empty before running the ioctl in case
something tries to consume the result without checking the error status.
Signed-off-by: Zygo Blaxell <bees@furryterror.org>
If we are not zero-filling containers then the overhead of allocating them
on each use is negligible. The effect that the thread_local containers
were having on RAM usage was very non-negligible.
Use dynamic containers (members or stack objects) for better control
of object lifetimes and much lower peak RAM usage. They're a tiny bit
faster, too.
Signed-off-by: Zygo Blaxell <bees@furryterror.org>
Automatically fall back to LOGICAL_INO if LOGICAL_INO_V2 fails and no
_V2 flags are used.
Add methods to set the flags argument with build portability to older
headers.
Use thread_local storage for the somewhat large buffers used by
LOGICAL_INO_V2 (and other users of BtrfsDataContainer like INO_PATHS).
Signed-off-by: Zygo Blaxell <bees@furryterror.org>
Better toxic extent detection means we can now handle extents with
many more references--easily hundreds of thousands.
Signed-off-by: Zygo Blaxell <bees@furryterror.org>
Faster and more reliable toxic extent detection means we can now be much
less paranoid about creating toxic extents.
The paranoia has significant impact on dedupe hit rates because every
extent that contains even one toxic hash is abandoned. The preloaded
toxic hashes were chosen because they occur more frequently than any
other block contents in typical filesystem data. The combination of these
resulted in as much as 30% of duplicate extents being left untouched.
Remove the preloaded toxic extent blacklist, and rely on the new
kernel-CPU-usage-based workaround instead.
Signed-off-by: Zygo Blaxell <bees@furryterror.org>
Leave AL16M defined in beesd to avoid breaking scripts based on
beesd.conf.sample which used this constant.
Use the absolute size in beesd.conf.sample to avoid any future problems.
Signed-off-by: Zygo Blaxell <bees@furryterror.org>
We detect toxic extents by measuring how long the LOGICAL_INO ioctl takes
to run. If it is above some threshold, we consider the extent toxic,
and blacklist it; otherwise, we process the extent normally.
The detector was using the execution time of the ioctl, which detects
toxic extents, but it also detects pauses of the bees process and
transaction commit latency due to load. This leads to a significant
number of false positives. The detection threshold was also very long,
burning a lot of kernel CPU before the detection was triggered.
Use the per-thread system CPU statistics to measure the kernel CPU usage
of the LOGICAL_INO call directly. This is much more reliable because it
is not confounded by other threads, and it's faster because we can set
the time threshold two orders of magnitude lower.
Also remove the lock and mutex added in "context: serialize LOGICAL_INO
calls" because we theoretically no longer need it (but leave the code
there with #if 0 in case we do need it in practice).
Signed-off-by: Zygo Blaxell <bees@furryterror.org>
ROOT_TREE contains the ROOT_ITEM for EXTENT_TREE. Every modification
(that we care about) to a btrfs must go through EXTENT_TREE, and must
modify the page in ROOT_TREE pointing to the root of EXTENT_TREE...
which makes that a very good source for the filesystem transid.
Remove the loop and the root lookups, and just look at one item for
max_transid.
Also note that every caller of transid_max_nocache() immediately
feeds the return value to m_transid_re.update(), so don't do that
inside transid_max_nocache().
Signed-off-by: Zygo Blaxell <bees@furryterror.org>
It turns out that we do need to scan all the subvols in order
to find transid_max.
Keep the bug fix though.
This reverts commit bf6ae80eee.
Signed-off-by: Zygo Blaxell <bees@furryterror.org>
BeesRoots::transid_max_nocache calls btrfs_get_root_transid() which
retrieves the transid of the root of the given Fd. Since the FS_TREE
(subvol 5) is the root of the subvol hierarchy, it will always have
the highest transid on the filesystem, and we do not need to look at
any others.
Also fix a bug where we pass BTRFS_FS_TREE_OBJECTID instead of the
file descriptor root_fd() to btrfs_get_root_transid(). If BEESHOME
is somewhere on the same btrfs filesystem, and there are no leaked FDs
at bees startup, then BTRFS_FS_TREE_OBJECTID (5) usually has the same
integer value as a valid file descriptor of some object on the filesystem
that has a regularly increasing transid value. If Fd 5 happens to be a
file in BEESHOME then bees itself drives the transid increments. This,
combined with the search of all subvol roots, hides the bug (unless Fd
5 gets closed somehow).
Signed-off-by: Zygo Blaxell <bees@furryterror.org>
BeesContext::home_fd() is supposed to open $BEESHOME once and cache
the Fd for later calls; however, instead it was reopening a new Fd each
time it was called, and _also_ holding that Fd in a BeesContext member.
Fds clean themselves up when they are forgotten, so it was not leaking
per se, but it certainly had more open Fds than it needed to.
Check to see if we have m_home_fd open, and return that if so.
Signed-off-by: Zygo Blaxell <bees@furryterror.org>
LOGICAL_INO can trip over the btrfs slow-backrefs bug, resulting in
some very long in-kernel runtimes. If too many threads are executing
LOGICAL_INO then there may be no cores left on the system to run other
tasks.
Toxic extent detection is done by a very rudimentary algorithm which
can be confused by unrelated sources of latency within btrfs (especially
commit latency). The algorithm can also be confused by other threads
executing the LOGICAL_INO ioctl.
These are two good reasons to prevent any two threads in a single bees
process instance from executing LOGICAL_INO at the same time, so let's
do that.
It is possible to limit the number of threads executing LOGICAL_INO with
the -c and -C options; however, this also limits the number of threads
which can perform any operation, while only LOGICAL_INO (*) has such a
profound effect on the rest of system operation.
Also make the status message clearer about exactly when LOGICAL_INO is
executed, as opposed to merely waiting to acquire a lock before executing
the ioctl.
(*) or maybe FILE_EXTENT_SAME. The problem function that keeps showing
up in kernel stack traces is find_parent_nodes, which is called by both
the LOGICAL_INO and FILE_EXTENT_SAME ioctls. We'll try this change
first and see if it prevents any recurrences of forced watchdog reboots;
if it does not, then we'll limit FILE_EXTENT_SAME the same way.
Signed-off-by: Zygo Blaxell <bees@furryterror.org>
The ordering function for BeesCrawlState did not consider
root 292 inode 0 min_transid 2345 max_transid 3456
to be larger than
root 292 inode 258 min_transid 2345 max_transid 2345
so when we attempted to update the end pointer for the crawl progress,
the new state was not considered newer than the old state because the
min_transid was equal, but the new crawl state's inode number was smaller.
Normally this is not a problem because subvol scans typically begin
and end in separate transactions (in part because we don't start a
subvol scan until at least two transactions are available); however,
the cleanup code for the aftermath of the recent transid_min() bug can
create crawlers with equal max_transid and min_transid records.
Fix this by ordering both transid fields before any others in the
crawl state.
Signed-off-by: Zygo Blaxell <bees@furryterror.org>
Due to an earlier bug some beescrawl.dat files will contain uint64_t
max as max_transid. This prevents any further scanning on the subvol
because there is no possibiity of having a real transid (or any other
uint64_t number) larger than uint64_t max.
If we detect a bad transid in beescrawl.dat, log a warning, then use
some more plausible value: either min_transid to repeat the previous
incremental crawl, or 0 to restart the subvol scan from the beginning.
Signed-off-by: Zygo Blaxell <bees@furryterror.org>
On a few test machines max_transid on subvols is getting set to
18446744073709551615 (aka uint64_t max).
Prevent transid_min() from ever returning this value.
Signed-off-by: Zygo Blaxell <bees@furryterror.org>
"saved" is used only during hash table correctness analysis, which is
normally not enabled at compile time, and requires source modification
to enable.
Remove the pointless copy and save a tiny bit of CPU.
Signed-off-by: Zygo Blaxell <bees@furryterror.org>
The 16MB hash table extent size did not serve any useful defragmentation
or compression purpose, and for very small filesystems (under 100GB),
16MB is much larger than necessary.
Signed-off-by: Zygo Blaxell <bees@furryterror.org>
systemd-coredumpctl collects core files for later analysis
with gdb. It's a convenient thing if the keys you use to encrypt
/var/lib/systemd/coredump are the same as the keys you use to encrypt
the filesystem where you're running bees.
Add it to the documentation just before the hand-rolled version.
Signed-off-by: Zygo Blaxell <bees@furryterror.org>
Standard crash backtrace collection, plus $BEESSTATUS for the high-level
overview of what bees is doing.
Signed-off-by: Zygo Blaxell <bees@furryterror.org>
Split the rather large README into smaller sections with a pitch and
a ToC at the top.
Move the sections into docs/ so that Github Pages can read them.
'make doc' produces a local HTML tree.
Update the kernel bugs and gotchas list.
Add some information that has been accumulating in Github comments.
Remove information about bugs in kernels earlier than 4.14.
Signed-off-by: Zygo Blaxell <bees@furryterror.org>
ExtentWalker doesn't gain significant benefits from caching, and the
extra SEARCH_V2 ioctls were blamed for a 33% kernel CPU overhead by perf.
Reduce the number of extents to 16 in lieu of fixing the caching.
This gives a significant speed boost on CPU-bound workloads compared
to the original 1024--almost 40% faster on a single SSD with a filesystem
consisting of raw VM images mounted with compress=zstd.
This also seems to reduce LOGICAL_INO overhead. Perhaps SEARCH_V2 and
LOGICAL_INO were trying to lock the same extents, and interfering with
each other?
Signed-off-by: Zygo Blaxell <bees@furryterror.org>
The -g option limits the number of worker threads when the target load
average is exceeded. On some systems the load normally runs high, and
continuous bees operation is required to avoid running out of disk space.
Add a -G/--thread-min option to force at least some threads to continue
running.
Signed-off-by: Zygo Blaxell <bees@furryterror.org>
The task queue may already be full of tasks when the crawl task is
executed. In this case simply reschedule the crawl task at the
end of the current queue.
Signed-off-by: Zygo Blaxell <bees@furryterror.org>
Add -g / --loadavg-target parameter to track system load and add or
remove bees worker threads dynamically to keep system load close to the
loadavg target. Thread count may vary from zero to the maximum
specified by -c or -C, and is adjusted every 5 seconds.
This is better than implementing a similar load average scheme from
outside of the process (though that is still possible) because the
in-process load tracker does not disrupt the performance timing feedback
mechanisms as a freezer cgroup or SIGSTOP would when controlling bees
from outside. The internal load average tracker can also adjust the
number of active threads while an external tracker can only choose from
the maximum or zero.
Also fix a bug where a Task could deadlock waiting for itself to exit
if it tries to insert a new Task after the number of worker threads has
been set to zero.
Also correct usage message for --scan-mode (values are 0..2) since
we are touching adjacent lines anyway.
Signed-off-by: Zygo Blaxell <bees@furryterror.org>
Other btrfs utils use readahead() not posix_fadvise().
There does not appear to be a performance or correctness difference
between the three (none, posix_fadvise, or readahead()).
Signed-off-by: Zygo Blaxell <bees@furryterror.org>
Log messages were already labelled with log levels, but there was no
way to filter by log level at run time.
Implement the filter inside the bees process so it can skip evaluation
of the BEESLOG* arguments if the log messages would not be emitted.
Fixes: https://github.com/Zygo/bees/issues/67
Signed-off-by: Zygo Blaxell <bees@furryterror.org>
When BEESLOGINFO is called multiple times it generates separate log
records that can be mixed up when multiple threads dedup.
Use a single BEESLOGINFO call for each dedup to prevent this.
Signed-off-by: Zygo Blaxell <bees@furryterror.org>
set() was broken and redundant. Calling hold() and discarding the
returned object has the correct effect.
Signed-off-by: Zygo Blaxell <bees@furryterror.org>
Also split "bad feature interactions" into "unknown" (which is what it
really was before) and "bad" (which includes some filesystem-destroying
problems).
Signed-off-by: Zygo Blaxell <bees@furryterror.org>
Linux kernel 4.14, while resistant to extent toxicity, is not immune to it.
Go back to the paranoid setting to avoid tying up filesystems in
ridiculously long kernel loops in find_parent_nodes.
Signed-off-by: Zygo Blaxell <bees@furryterror.org>
Zygo Blaxell