Bit-spinlocks are problematic on PREEMPT_RT if functions which might sleep
on RT, e.g. spin_lock(), alloc/free(), are invoked inside the lock held
region because bit spinlocks disable preemption even on RT.
A first attempt was to replace state lock with a spinlock placed in struct
buffer_head and make the locking conditional on PREEMPT_RT and
DEBUG_BIT_SPINLOCKS.
Jan pointed out that there is a 4 byte hole in struct journal_head where a
regular spinlock fits in and he would not object to convert the state lock
to a spinlock unconditionally.
Aside of solving the RT problem, this also gains lockdep coverage for the
journal head state lock (bit-spinlocks are not covered by lockdep as it's
hard to fit a lockdep map into a single bit).
The trivial change would have been to convert the jbd_*lock_bh_state()
inlines, but that comes with the downside that these functions take a
buffer head pointer which needs to be converted to a journal head pointer
which adds another level of indirection.
As almost all functions which use this lock have a journal head pointer
readily available, it makes more sense to remove the lock helper inlines
and write out spin_*lock() at all call sites.
Fixup all locking comments as well.
Suggested-by: Jan Kara <jack@suse.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Jan Kara <jack@suse.cz>
Cc: "Theodore Ts'o" <tytso@mit.edu>
Cc: Mark Fasheh <mark@fasheh.com>
Cc: Joseph Qi <joseph.qi@linux.alibaba.com>
Cc: Joel Becker <jlbec@evilplan.org>
Cc: Jan Kara <jack@suse.com>
Cc: linux-ext4@vger.kernel.org
Link: https://lore.kernel.org/r/20190809124233.13277-7-jack@suse.cz
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Many source files in the tree are missing licensing information, which
makes it harder for compliance tools to determine the correct license.
By default all files without license information are under the default
license of the kernel, which is GPL version 2.
Update the files which contain no license information with the 'GPL-2.0'
SPDX license identifier. The SPDX identifier is a legally binding
shorthand, which can be used instead of the full boiler plate text.
This patch is based on work done by Thomas Gleixner and Kate Stewart and
Philippe Ombredanne.
How this work was done:
Patches were generated and checked against linux-4.14-rc6 for a subset of
the use cases:
- file had no licensing information it it.
- file was a */uapi/* one with no licensing information in it,
- file was a */uapi/* one with existing licensing information,
Further patches will be generated in subsequent months to fix up cases
where non-standard license headers were used, and references to license
had to be inferred by heuristics based on keywords.
The analysis to determine which SPDX License Identifier to be applied to
a file was done in a spreadsheet of side by side results from of the
output of two independent scanners (ScanCode & Windriver) producing SPDX
tag:value files created by Philippe Ombredanne. Philippe prepared the
base worksheet, and did an initial spot review of a few 1000 files.
The 4.13 kernel was the starting point of the analysis with 60,537 files
assessed. Kate Stewart did a file by file comparison of the scanner
results in the spreadsheet to determine which SPDX license identifier(s)
to be applied to the file. She confirmed any determination that was not
immediately clear with lawyers working with the Linux Foundation.
Criteria used to select files for SPDX license identifier tagging was:
- Files considered eligible had to be source code files.
- Make and config files were included as candidates if they contained >5
lines of source
- File already had some variant of a license header in it (even if <5
lines).
All documentation files were explicitly excluded.
The following heuristics were used to determine which SPDX license
identifiers to apply.
- when both scanners couldn't find any license traces, file was
considered to have no license information in it, and the top level
COPYING file license applied.
For non */uapi/* files that summary was:
SPDX license identifier # files
---------------------------------------------------|-------
GPL-2.0 11139
and resulted in the first patch in this series.
If that file was a */uapi/* path one, it was "GPL-2.0 WITH
Linux-syscall-note" otherwise it was "GPL-2.0". Results of that was:
SPDX license identifier # files
---------------------------------------------------|-------
GPL-2.0 WITH Linux-syscall-note 930
and resulted in the second patch in this series.
- if a file had some form of licensing information in it, and was one
of the */uapi/* ones, it was denoted with the Linux-syscall-note if
any GPL family license was found in the file or had no licensing in
it (per prior point). Results summary:
SPDX license identifier # files
---------------------------------------------------|------
GPL-2.0 WITH Linux-syscall-note 270
GPL-2.0+ WITH Linux-syscall-note 169
((GPL-2.0 WITH Linux-syscall-note) OR BSD-2-Clause) 21
((GPL-2.0 WITH Linux-syscall-note) OR BSD-3-Clause) 17
LGPL-2.1+ WITH Linux-syscall-note 15
GPL-1.0+ WITH Linux-syscall-note 14
((GPL-2.0+ WITH Linux-syscall-note) OR BSD-3-Clause) 5
LGPL-2.0+ WITH Linux-syscall-note 4
LGPL-2.1 WITH Linux-syscall-note 3
((GPL-2.0 WITH Linux-syscall-note) OR MIT) 3
((GPL-2.0 WITH Linux-syscall-note) AND MIT) 1
and that resulted in the third patch in this series.
- when the two scanners agreed on the detected license(s), that became
the concluded license(s).
- when there was disagreement between the two scanners (one detected a
license but the other didn't, or they both detected different
licenses) a manual inspection of the file occurred.
- In most cases a manual inspection of the information in the file
resulted in a clear resolution of the license that should apply (and
which scanner probably needed to revisit its heuristics).
- When it was not immediately clear, the license identifier was
confirmed with lawyers working with the Linux Foundation.
- If there was any question as to the appropriate license identifier,
the file was flagged for further research and to be revisited later
in time.
In total, over 70 hours of logged manual review was done on the
spreadsheet to determine the SPDX license identifiers to apply to the
source files by Kate, Philippe, Thomas and, in some cases, confirmation
by lawyers working with the Linux Foundation.
Kate also obtained a third independent scan of the 4.13 code base from
FOSSology, and compared selected files where the other two scanners
disagreed against that SPDX file, to see if there was new insights. The
Windriver scanner is based on an older version of FOSSology in part, so
they are related.
Thomas did random spot checks in about 500 files from the spreadsheets
for the uapi headers and agreed with SPDX license identifier in the
files he inspected. For the non-uapi files Thomas did random spot checks
in about 15000 files.
In initial set of patches against 4.14-rc6, 3 files were found to have
copy/paste license identifier errors, and have been fixed to reflect the
correct identifier.
Additionally Philippe spent 10 hours this week doing a detailed manual
inspection and review of the 12,461 patched files from the initial patch
version early this week with:
- a full scancode scan run, collecting the matched texts, detected
license ids and scores
- reviewing anything where there was a license detected (about 500+
files) to ensure that the applied SPDX license was correct
- reviewing anything where there was no detection but the patch license
was not GPL-2.0 WITH Linux-syscall-note to ensure that the applied
SPDX license was correct
This produced a worksheet with 20 files needing minor correction. This
worksheet was then exported into 3 different .csv files for the
different types of files to be modified.
These .csv files were then reviewed by Greg. Thomas wrote a script to
parse the csv files and add the proper SPDX tag to the file, in the
format that the file expected. This script was further refined by Greg
based on the output to detect more types of files automatically and to
distinguish between header and source .c files (which need different
comment types.) Finally Greg ran the script using the .csv files to
generate the patches.
Reviewed-by: Kate Stewart <kstewart@linuxfoundation.org>
Reviewed-by: Philippe Ombredanne <pombredanne@nexb.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Commit ae4647fb (jbd2: reduce journal_head size) introduced a
regression where we occasionally hit panic in
jbd2_journal_put_journal_head() because of wrong b_jcount. The bug is
caused by gcc making 64-bit access to 32-bit bitfield and thus
clobbering b_jcount.
At least for now, those 8 bytes saved in struct journal_head are not
worth the trouble with gcc bitfield handling so revert that part of
the patch.
Reported-by: EUNBONG SONG <eunb.song@samsung.com>
Reported-by: Tony Luck <tony.luck@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Remove unused t_cow_tid field (ext4 copy-on-write support doesn't seem
to be happening) and change b_modified and b_jlist to bitfields thus
saving 8 bytes in the structure.
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Reviewed-by: Zheng Liu <wenqing.lz@taobao.com>
All accesses to checkpointing entries in journal_head are protected
by j_list_lock. Thus __jbd2_journal_remove_checkpoint() doesn't really
need bh_state lock.
Also the only part of journal head that the rest of checkpointing code
needs to check is jh->b_transaction which is safe to read under
j_list_lock.
So we can safely remove bh_state lock from all of checkpointing code which
makes it considerably prettier.
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
In the definition of struct journal_head, the comment for
the field "unsigned b_cow_tid" says the field tracks the
last transaction id in which this buffer has been cowed.
In the header part of file journal-head.h, it defines
typedef unsigned int tid_t;
We should use type tid_t to define transaction id fields.
Change the field "b_cow_tid" of struct journal_head from
type unsigned to tid_t.
Signed-off-by: Wang Sheng-Hui <shhuiw@gmail.com>
Acked-by: Amir Goldstein <amir73il@users.sf.net>
Signed-off-by: Jan Kara <jack@suse.cz>
The b_cow_tid field will be used by the ext4 snapshots code to store
the transaction id when the buffer was last cowed.
Merging this patch to mainline will allow users to test ext4 snapshots
as a standalone module, without the need to patch and install a
development kernel.
On 64bit machines this field uses fills in a padding "hole" and does
not increase the size of the struct. On a 32bit machine this patch
increases the size of the struct from 60 to 64 bytes.
Signed-off-by: Amir Goldstein <amir73il@users.sf.net>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Filesystems often to do compute intensive operation on some
metadata. If this operation is repeated many times, it can be very
expensive. It would be much nicer if the operation could be performed
once before a buffer goes to disk.
This adds triggers to jbd2 buffer heads. Just before writing a metadata
buffer to the journal, jbd2 will optionally call a commit trigger associated
with the buffer. If the journal is aborted, an abort trigger will be
called on any dirty buffers as they are dropped from pending
transactions.
ocfs2 will use this feature.
Initially I tried to come up with a more generic trigger that could be
used for non-buffer-related events like transaction completion. It
doesn't tie nicely, because the information a buffer trigger needs
(specific to a journal_head) isn't the same as what a transaction
trigger needs (specific to a tranaction_t or perhaps journal_t). So I
implemented a buffer set, with the understanding that
journal/transaction wide triggers should be implemented separately.
There is only one trigger set allowed per buffer. I can't think of any
reason to attach more than one set. Contrast this with a journal or
transaction in which multiple places may want to watch the entire
transaction separately.
The trigger sets are considered static allocation from the jbd2
perspective. ocfs2 will just have one trigger set per block type,
setting the same set on every bh of the same type.
Signed-off-by: Joel Becker <joel.becker@oracle.com>
Cc: "Theodore Ts'o" <tytso@mit.edu>
Cc: <linux-ext4@vger.kernel.org>
Signed-off-by: Mark Fasheh <mfasheh@suse.com>
People can use the real name an an index into MAINTAINERS to find the
current email address.
Signed-off-by: Francois Cami <francois.cami@free.fr>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Initial git repository build. I'm not bothering with the full history,
even though we have it. We can create a separate "historical" git
archive of that later if we want to, and in the meantime it's about
3.2GB when imported into git - space that would just make the early
git days unnecessarily complicated, when we don't have a lot of good
infrastructure for it.
Let it rip!
Thomas Gleixner