- Stayed on non-system include for lfs_util.h for now
- Named internal functions "lfs_functionraw"
- Merged lfs_fs_traverseraw
- Added LFS_LOCK/UNLOCK macros
- Changed LFS_THREADSAFE from 1/0 to defined/undefined to
match LFS_READONLY
__VA_ARGS__ are frustrating in C. Even for their main purpose (printf),
they fall short in that they don't have a _portable_ way to have zero
arguments after the format string in a printf call.
Even if we detect compilers and use ##__VA_ARGS__ where available, GCC
emits a warning with -pedantic that is _impossible_ to explicitly
disable.
This commit contains the best solution we can think of. A bit of
indirection that adds a hidden "%s" % "" to the end of the format
string. This solution does not work everywhere as it has a runtime
cost, but it is hopefully ok for debug statements.
- Standardized littlefs debug statements to use hex prefixes and
brackets for printing pairs.
- Removed the entry behavior for readtree and made -t the default.
This is because 1. the CTZ skip-list parsing was broken, which is not
surprising, and 2. the entry parsing was more complicated than useful.
This functionality may be better implemented as a proper filesystem
read script, complete with directory tree dumping.
- Changed test.py's --gdb argument to take [init, main, assert],
this matches the names of the stages in C's startup.
- Added printing of tail to all mdir dumps in readtree/readmdir.
- Added a print for if any mdirs are corrupted in readtree.
- Added debug script side-effects to .gitignore.
Block device tracing has a lot of potential uses, of course debugging,
but it can also be used for profiling and externally tracking littlefs's
usage of the block device. However, block device tracing emits a massive
amount of output. So keeping block device tracing on by default limits
the usefulness of the filesystem tracing.
So, instead, I've moved the block device tracing into a separate
LFS_TESTBD_YES_TRACE define which switches on the LFS_TESTBD_TRACE
macro. Note that this means in order to get block device tracing, you
need to define both LFS_YES_TRACE and LFS_TESTBD_YES_TRACE. This is
needed as the LFS_TRACE definition is gated by LFS_YES_TRACE in
lfs_util.h.
These two features have been much requested by users, and have even had
several PRs proposed to fix these in several cases. Before this, these
error conditions usually were caught by internal asserts, however
asserts prevented users from implementing their own workarounds.
It's taken me a while to provide/accept a useful recovery mechanism
(returning LFS_ERR_CORRUPT instead of asserting) because my original thinking
was that these error conditions only occur due to bugs in the filesystem, and
these bugs should be fixed properly.
While I still think this is mostly true, the point has been made clear
that being able to recover from these conditions is definitely worth the
code cost. Hopefully this new behaviour helps the longevity of devices
even if the storage code fails.
Another, less important, reason I didn't want to accept fixes for these
situations was the lack of tests that prove the code's value. This has
been fixed with the new testing framework thanks to the additional of
"internal tests" which can call C static functions and really take
advantage of the internal information of the filesystem.
- Changed readmdir.py to print the metadata pair and revision count,
which is useful when debugging commit issues.
- Added truncated data view to readtree.py by default. This does mean
readtree.py must read all files on the filesystem to show the
truncated data, hopefully this does not end up being a problem.
- Made overall representation hopefully more readable, including moving
superblock under the root dir, userattrs under files, fixing a gstate
rendering issue.
- Added rendering of soft-tails as dotted-arrows, hopefully this isn't
too noisy.
- Fixed explode_asserts.py off-by-1 in #line mapping caused by a strip
call in the assert generation eating newlines. The script matches
line numbers between the original+modified files by emitting assert
statements that use the same number of lines. An off-by-1 here causes
the entire file to map lines incorrectly, which can be very annoying.
With the superblock expansion stuff, the test_format tests have grown
to test more advanced superblock-related features. This is fine but
deserves a rename so it's more clear.
Also fixed a typo that meant tests never ran with block cycles.
Byte-level writes are expensive and not suggested (caches >= 4 bytes
make much more sense), however there are many corner cases with
byte-level writes that can be easy to miss (power-loss leaving single
bytes written to disk).
Unfortunately, byte-level writes mixed with power-loss testing, the
Travis infrastructure, and Arm Thumb instruction set simulation
exceeds the 50-minute budget Travis allocates for jobs.
For now I'm disabling the byte-level tests under Qemu, with the hope that
performance improvements in littlefs will let us turn these tests back
on in the future.
- Added caching to Travis install dirs, because otherwise
pip3 install fails randomly
- Increased size of littlefs-fuse disk because test script has
a larger footprint now
- Skip a couple of reentrant tests under byte-level writes because
the tests just take too long and cause Travis to bail due to no
output for 10m
- Fixed various Valgrind errors
- Suppressed uninit checks for tests where LFS_BLOCK_ERASE_VALUE == -1.
In this case rambd goes uninitialized, which is fine for rambd's
purposes. Note I couldn't figure out how to limit this suppression
to only the malloc in rambd, this doesn't seem possible with Valgrind.
- Fixed memory leaks in exhaustion tests
- Fixed off-by-1 string null-terminator issue in paths tests
- Fixed lfs_file_sync issue caused by revealed by fixing memory leaks
in exhaustion tests. Getting ENOSPC during a file write puts the file
in a bad state where littlefs doesn't know how to write it out safely.
In this case, lfs_file_sync and lfs_file_close return 0 without
writing out state so that device-side resources can still be cleaned
up. To recover from ENOSPC, the file needs to be reopened and the
writes recreated. Not sure if there is a better way to handle this.
- Added some quality-of-life improvements to Valgrind testing
- Fit Valgrind messages into truncated output when not in verbose mode
- Turned on origin tracking
The core of littlefs's CI testing is the full test suite, `make test`, run
under a number of configurations:
- Processor architecture:
- x86 (native)
- Arm Thumb
- MIPS
- PowerPC
- Storage geometry:
- rs=16 ps=16 cs=64 bs=512 (default)
- rs=1 ps=1 cs=64 bs=4KiB (NOR flash)
- rs=512 ps=512 cs=512 bs=512 (eMMC)
- rs=4KiB ps=4KiB cs=4KiB bs=32KiB (NAND flash)
- Other corner cases:
- no intrinsics
- no inline
- byte-level read/writes
- single block-cycles
- odd block counts
- odd block sizes
The number of different configurations we need to test quickly exceeds the
50 minute time limit Travis has on jobs. Fortunately, we can split these
tests out into multiple jobs. This seems to be the intended course of
action for large CI "builds" in Travis, as this gives Travis a finer
grain of control over limiting builds.
Unfortunately, this created a couple issues:
1. The Travis configuration isn't actually that flexible. It allows a
single "matrix expansion" which can be generated from top-level lists
of different configurations. But it doesn't let you generate a matrix
from two seperate environment variable lists (for arch + geometry).
Without multiple matrix expansions, we're stuck writing out each test
permutation by hand.
On the bright-side, this was a good chance to really learn how YAML
anchors work. I'm torn because on one hand anchors add what feels
like unnecessary complexity to a config language, on the other hand,
they did help quite a bit in working around Travis's limitations.
2. Now that we have 47 jobs instead of 7, reporting a separate status
for each job stops making sense.
What I've opted for here is to use a special NAME variable to
deduplicate jobs, and used a few state-less rules to hopefully have
the reported status make sense most of the time.
- Overwrite "pending" statuses so that the last job to start owns the
most recent "pending" status
- Don't overwrite "failure" statuses unless the job number matches
our own (in the case of CI restarts)
- Don't write "success" statuses unless the job number matches our
own, this should delay a green check-mark until the last-to-start
job finishes
- Always overwrite non-failures with "failure" statuses
This does mean a temporary "success" may appear if the last job
terminates before earlier jobs. But this is the simpliest solution
I can think of without storing some complex state somewhere.
Note we can only report the size this way because it's cheap to
calculate in every job.
RAM-backed testing is faster than file-backed testing. This is why
test.py uses rambd by default.
So why add support for tmpfs-backed disks if we can already run tests in
RAM? For reentrant testing.
Under reentrant testing we simulate power-loss by forcefully exiting the
test program at specific times. To make this power-loss meaningful, we need to
persist the disk across these power-losses. However, it's interesting to
note this persistence doesn't need to be actually backed by the
filesystem.
It may be possible to rearchitecture the tests to simulate power-loss a
different way, by say, using coroutines or setjmp/longjmp to leave
behind ongoing filesystem operations without terminating the program
completely. But at this point, I think it's best to work with what we
have.
And simply putting the test disks into a tmpfs mount-point seems to
work just fine.
Note this does force serialization of the tests, which isn't required
otherwise. Currently they are only serialized due to limitations in
test.py. If a future change wants to perallelize the tests, it may need
to rework RAM-backed reentrant tests.
Moved .travis.yml over to use the new test framework. A part of this
involved testing all of the configurations ran on the old framework
and deciding which to carry over. The new framework duplicates some of
the cases tested by the configurations so some configurations could be
dropped.
The .travis.yml includes some extreme ones, such as no inline files,
relocations every cycle, no intrinsics, power-loss every byte, unaligned
block_count and lookahead, and odd read_sizes.
There were several configurations were some tests failed because of
limitations in the tests themselves, so many conditions were added
to make sure the configurations can run on as many tests as possible.
This is a bit of a strange case that can be caused by storage with
very large prog sizes, such as NAND flash. We only have 10 bits to store
the size of our padding, so when the prog_size gets larger than 1024
bytes, we have to use multiple padding tags to commit to the next
prog_size boundary.
This causes some complication for the new logic that checks CRCs in case
our block becomes "readonly" and contains existing commits that just happen
to match our new commit size.
Here we just check the CRC of the first commit. This isn't perfect but
does protect against pure "readonly" blocks.
These should probably have been cleaned up in each commit to allow
cherry-picking, but due to time I haven't been able to.
- Went with creating an mdir copy in lfs_dir_commit. This handles a
number of related cleanup issues in lfs_dir_compact and it does so
more robustly. As a plus we can use the copy to update dependencies
in the mlist.
- Eliminated code left by the ENOSPC file outlining
- Cleaned up TODOs and lingering comments
- Changed the reentrant many directory create/rename/remove test to use
a smaller set of directories because of space issues when
READ/PROG_SIZE=512
This was caused by the previous fix for allocations during
lfs_fs_deorphan in this branch. To catch half-orphans during block
allocations we needed to duplicate all metadata-pairs reported to
lfs_fs_traverse. Unfortunately this causes lfs_fs_size to report 2x the
number of metadata-pairs, which would undoubtably confuse users.
The fix here is inelegantly simple, just do a different traversale for
allocations and size measurements. It reuses the same code but touches
slightly different sets of blocks.
Unfortunately, this causes the public lfs_fs_traverse and lfs_fs_size
functions to split in how they report blocks. This is technically
allowed, since lfs_fs_traverse may report blocks multiple times due to
CoW behavior, however it's undesirable and I'm sure there will be some
confusion.
But I don't have a better solution, so from this point lfs_fs_traverse
will be reporting 2x metadata-blocks and shouldn't be used for finding
the number of available blocks on the filesystem.
This was an interesting issue found during a GitHub discussion with
rmollway and thrasher8390.
Blocks in the metadata-pair are relocated every "block_cycles", or, more
mathy, when rev % block_cycles == 0 as long as rev += 1 every block write.
But there's a problem, rev isn't += 1 every block write. There are two
blocks in a metadata-pair, so looking at it from each blocks
perspective, rev += 2 every block write.
This leads to a sort of aliasing issue, where, if block_cycles is
divisible by 2, one block in the metadata-pair is always relocated, and
the other block is _never_ relocated. Causing a complete failure of
block-level wear-leveling.
Fortunately, because of a previous workaround to avoid block_cycles = 1
(since this will cause the relocation algorithm to never terminate), the
actual math is rev % (block_cycles+1) == 0. This means the bug only
shows its head in the much less likely case where block_cycles is a
multiple of 2 plus 1, or, in more mathy terms, block_cycles = 2n+1 for
some n.
To workaround this we can bitwise or our block_cycles with 1 to force it
to never be a multiple of 2n.
(Maybe we should do this during initialization? But then block_cycles
would need to be mutable.)
---
There's a few unrelated changes mixed into this commit that shouldn't be
there since I added this as part of a branch of bug fixes I'm putting
together rather hastily, so unfortunately this is not easily cherry-pickable.
Added indention so there was a more clear separation between the tag
description and tag data.
Also took the best parts of readmdir.py and added it to readtree.py.
Initially I was thinking it was best for these to have completely
independent data representations, since you could always call readtree
to get more info, but this becomes tedius when needed to look at
low-level tag info across multiple directories on the filesystem.
This was initially added as protection against the case where a file
grew to no longer fit in a metadata-pair. While in most cases this
should be caught by the math in lfs_file_write, it doesn't handle a
problem that can happen if the files metadata is large enough that even
small inline files can't fit. This can happen if you combine a small
block size with large file names and many custom attributes.
But trying to outline on ENOSPC creates creates a lot of problems.
If we are actually low on space, this is one of the worst things we can
do. Inline files take up less space than CTZ skip-lists, but inline
files are rendered useless if we outline inline files as soon as we run
low on space.
On top of this, the outlining logic tries multiple mdir commits if it
gets ENOSPC, which can hide errors if ENOSPC is returned for other
reasons.
In a perfect world, we would be using a different error code for
no-room-in-metadata-pair, and no-blocks-on-disk.
For now I've removed the outlining logic and we will need to figure out
how to handle this situation more robustly.
