journal_file_move_to_object() can skip the second
journal_file_move_to() call if the first one already mapped a
sufficiently large area.
Now that mmap_cache_get() returns the size of the mapped area
when asked, ask for the size and only perform the second call if
the required size exceeds the mapped size instead of the object
header size.
This results in a nice performance boost in my testing, even with
a corpus of many small logs burning much CPU time elsewhere:
Before:
# time ./journalctl -b -1 --no-pager > /dev/null
real 0m16.330s
user 0m16.281s
sys 0m0.046s
# time ./journalctl -b -1 --no-pager > /dev/null
real 0m16.409s
user 0m16.358s
sys 0m0.048s
# time ./journalctl -b -1 --no-pager > /dev/null
real 0m16.625s
user 0m16.558s
sys 0m0.061s
After:
# time ./journalctl -b -1 --no-pager > /dev/null
real 0m15.311s
user 0m15.257s
sys 0m0.046s
# time ./journalctl -b -1 --no-pager > /dev/null
real 0m15.201s
user 0m15.135s
sys 0m0.062s
# time ./journalctl -b -1 --no-pager > /dev/null
real 0m15.170s
user 0m15.113s
sys 0m0.053s
If requested, return the actual mapping size to the caller in
addition to the address.
journal_file_move_to_object() often performs two successive
mmap_cache_get() calls via journal_file_move_to(); one to get the
object header, then another to get the entire object when it's
larger than the header's size.
If mmap_cache_get() returned the actual mapping's size, it's
probable that the second mmap_cache_get() could be skipped when
the established mapping already encompassed the desired size.
This way we have a MMapFileDescriptor reference external to the cache,
and can supply the handle directly to mmap_cache_get(), eliminating
hashmap lookups entirely from the hot path.
When some error occurs during the initialization of JournalFile,
the JournalFile can be left without hash tables created. When later
trying to append an entry to that file, the assertion in
journal_file_link_data() fails, and journald crashes.
This patch fix this issue by checking *_hash_table_size in
journal_file_verify_header().
It is possible to overflow uint64_t while validating the header of
a journal file. To prevent this, the addition itself is checked to
be within the limits of UINT64_MAX first.
To keep this readable, I have introduced two stack variables which
hold the converted values during validation.
76ec966f0e changed the code from ESHUTDOWN to ERFKILL, but missed one
spot in bus-common-errors.c. Fix that.
The code in transaction.c was checking for ERFKILL, but I'm not sure if this
mismatch had any effect, i.e. if there were any code paths in which the wrong
code actually made difference.
Also add comments when ESHUTDOWN is used in the journal code, so it's easy to
distinguish those cases when grepping. Standarize on the same capitalization.
(There's also a bunch of uses in sd-bus.c, but that's clearly different.)
* logind: trivial simplification
free_and_strdup() handles NULL arg, so make use of that.
* boot: fix two typos
* pid1: rewrite check in ignore_proc() to not check condition twice
It's harmless, but it seems nicer to evaluate a condition just a single time.
* core/execute: reformat exec_context_named_iofds() for legibility
* core/execute.c: check asprintf return value in the usual fashion
This is unlikely to fail, but we cannot rely on asprintf return value
on failure, so let's just be correct here.
CID #1368227.
* core/timer: use (void)
CID #1368234.
* journal-file: check asprintf return value in the usual fashion
This is unlikely to fail, but we cannot rely on asprintf return value
on failure, so let's just be correct here.
CID #1368236.
* shared/cgroup-show: use (void)
CID #1368243.
* cryptsetup: do not return uninitialized value on error
CID #1368416.
gcc 7 adds -Wimplicit-fallthrough=3 to -Wextra. There are a few ways
we could deal with that. After we take into account the need to stay compatible
with older versions of the compiler (and other compilers), I don't think adding
__attribute__((fallthrough)), even as a macro, is worth the trouble. It sticks
out too much, a comment is just as good. But gcc has some very specific
requiremnts how the comment should look. Adjust it the specific form that it
likes. I don't think the extra stuff we had in those comments was adding much
value.
(Note: the documentation seems to be wrong, and seems to describe a different
pattern from the one that is actually used. I guess either the docs or the code
will have to change before gcc 7 is finalized.)
https://bugzilla.redhat.com/show_bug.cgi?id=1416201
$ journalctl -b
Journal file /var/log/journal/ad18f69b80264b52bb3b766240742383/system@0005467d92e23784-a6571c8b69d09124.journal~ uses an unsupported feature, ignoring file.
Use SYSTEMD_LOG_LEVEL=debug journalctl --file=/var/log/journal/ad18f69b80264b52bb3b766240742383/system@0005467d92e23784-a6571c8b69d09124.journal~ to see the details.
-- No entries --
$ journalctl --file=/var/log/journal/ad18f69b80264b52bb3b766240742383/system@0005467d92e23784-a6571c8b69d09124.journal~
Journal file /var/log/journal/ad18f69b80264b52bb3b766240742383/system@0005467d92e23784-a6571c8b69d09124.journal~ uses incompatible flag lz4-compressed disabled at compilation time.
Failed to open journal file /var/log/journal/ad18f69b80264b52bb3b766240742383/system@0005467d92e23784-a6571c8b69d09124.journal~: Protocol not supported
mmap cache statistics: 0 hit, 1 miss
Failed to open files: Protocol not supported
Never permit that we write to journal files that have newer timestamps than our
local wallclock has. If we'd accept that, then the entries in the file might
end up not being ordered strictly.
Let's refuse this with ETXTBSY, and then immediately rotate to use a new file,
so that each file remains strictly ordered also be wallclock internally.
When iterating through partially synced journal files we need to be prepared
for hitting with invalid entries (specifically: non-initialized). Instead of
generated an error and giving up, let's simply try to preceed with the next one
that is valid (and debug log about this).
This reworks the logic introduced with caeab8f626
to iteration in both directions, and tries to look for valid entries located
after the invalid one. It also extends the behaviour to both iterating through
the global entry array and per-data object entry arrays.
Fixes: #4088
Let's make dissecting of borked journal files more expressive: if we encounter
an object whose first 8 bytes are all zeroes, then let's assume the object was
simply never initialized, and say so.
Previously, this would be detected as "overly short object", which is true too
in a away, but it's a lot more helpful printing different debug options for the
case where the size is not initialized at all and where the size is initialized
to some bogus value.
No function behaviour change, only a different log messages for both cases.
Let's make it easier to figure out when we see an invalid journal file, why we
consider it invalid, and add some minimal debug logging for it.
This log output is normally not seen (after all, this all is library code),
unless debug logging is exlicitly turned on.
Since commit 5996c7c295 (v190 !), the
calculation of the HMAC is broken because the hash for a data object
including a field is done in the wrong order: the field object is
hashed before the data object is.
However during verification, the hash is done in the opposite order as
objects are scanned sequentially.
The only code path which makes a journal durable is via
journal_file_set_offline().
When we perform a rotate the journal's header->state is being set to
STATE_ARCHIVED prior to journal_file_set_offline() being called.
In journal_file_set_offline(), we short-circuit the entire offline when
f->header->state != STATE_ONLINE.
This all results in none of the journal_file_set_offline() fsync() calls
being reached when rotate archives a journal, so archived journals are
never explicitly made durable.
What we do now is instead of setting the f->header->state to
STATE_ARCHIVED directly in journal_file_rotate() prior to
journal_file_close(), we set an archive flag in f->archive for the
journal_file_set_offline() machinery to honor by committing
STATE_ARCHIVED instead of STATE_OFFLINE when set.
Prior to this, rotated journals were never getting fsync() explicitly
performed on them, since journal_file_set_offline() short-circuited.
Obviously this is undesirable, and depends entirely on the underlying
filesystem as to how much durability was achieved when simply closing
the file.
Note that this problem existed prior to the recent asynchronous fsync
changes, but those changes do facilitate our performing this durable
offline on rotate without blocking, regardless of the underlying
filesystem sync-on-close semantics.
Previously, when we used a bisection table for seeking through a corrupted
file, and the end of the bisection table was corrupted we'd most likely fail
the entire seek operation. Improve the situation: if we encounter invalid
entries in a bisection table, linearly go backwards until we find a working
entry again.
When we linearly iterate through a corrupted journal file, and we encounter a
read error, don't consider this fatal, but merely as EOF condition (and log
about it).
Early in journal_file_set_offline() f->header->state is tested to see if
it's != STATE_ONLINE, and since there's no need to do anything if the
journal isn't online, the function simply returned here.
Since moving part of the offlining process to a separate thread, there
are two problems here:
1. We can't simply check f->header->state, because if there is an
offline thread active it may modify f->header->state.
2. Even if the journal is deemed offline, the thread responsible may
still need joining, so a bare return may leak the thread's resources
like its stack.
To address #1, the helper journal_file_is_offlining() is called prior to
accessing f->header->state.
If journal_file_is_offlining() returns true, f->header->state isn't even
checked, because an offlining journal is obviously online, and we'll
just continue with the normal set offline code path.
If journal_file_is_offlining() returns false, then it's safe to check
f->header->state, because the offline_state is beyond the point of
modifying f->header->state, and there's a memory barrier in the helper.
If we find f->header->state is != STATE_ONLINE, then we call the
idempotent journal_file_set_offline_thread_join() on the way out of the
function, to join a potential lingering offline thread.
Show the various timestamps in hexadecimal too. This is useful for matching the
timestamps included in cursor strings (which are encoded in hex, too), with the
references in the journal header.
Also, expose this via the "journalctl --file=-" syntax for STDIN. This feature
remains undocumented though, as it is probably not too useful in real-life as
this still requires fds that support mmaping and seeking, i.e. does not work
for pipes, for which reading from STDIN is most commonly used.
Throughout the tree there's spurious use of spaces separating ++ and --
operators from their respective operands. Make ++ and -- operator
consistent with the majority of existing uses; discard the spaces.
When we rotate journals, we must set offline and close the current one,
but don't generally need to wait for this to complete.
Instead, we'll initiate an asynchronous offline via
journal_file_set_offline(oldfile, false), and add the file to a
per-server set of deferred closes to be closed later when they
won't block.
There's one complication however; journal_file_open() via
journal_file_verify_header() assumes that any writable journal in the
online state is the product of an unclean shutdown or other form of
corruption.
Thus there's a need for journal_file_open() to be aware of deferred
closes and synchronize with their completion when opening preexisting
journals for writing. To facilitate this the deferred closes set is
supplied to the journal_file_open() function where the deferred closes
may be closed synchronously before verifying the header in such
circumstances.
This adds a wait flag to journal_file_set_offline(), when false the offline is
performed asynchronously in a separate thread.
When wait is true, if an asynchronous offline is already in-progress it is
restarted and waited for. Otherwise the offline is performed synchronously
without the use of a thread.
journal_file_set_online() cancels or waits for the asynchronous offline to
complete if in-flight, depending on where in the offline process the thread
happens to be. If the thread is in the fsync() phase, it is cancelled and
waiting is unnecessary. Otherwise, the thread is joined before proceeding.
A new offline_state member is added to JournalFile which is used via
atomic operations for communicating between the offline thread and the
journal_file_set_{offline,online}() functions.
ISO/IEC 9899:1999 §7.21.1/2 says:
Where an argument declared as size_t n specifies the length of the array
for a function, n can have the value zero on a call to that
function. Unless explicitly stated otherwise in the description of a
particular function in this subclause, pointer arguments on such a call
shall still have valid values, as described in 7.1.4.
In base64_append_width memcpy was called as memcpy(x, NULL, 0). GCC 4.9
started making use of this and assumes This worked fine under -O0, but
does something strange under -O3.
This patch fixes a bug in base64_append_width(), fixes a possible bug in
journal_file_append_entry_internal(), and makes use of the new function
to simplify the code in other places.