The jbd2_alloc_handle() function is only called by new_handle(). So
this commit uses kmem_cache_zalloc() instead of
kmem_cache_alloc()/memset().
Signed-off-by: Zheng Liu <wenqing.lz@taobao.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
The following race is possible:
[kjournald2] other_task
jbd2_journal_commit_transaction()
j_state = T_FINISHED;
spin_unlock(&journal->j_list_lock);
->jbd2_journal_remove_checkpoint()
->jbd2_journal_free_transaction();
->kmem_cache_free(transaction)
->j_commit_callback(journal, transaction);
-> USE_AFTER_FREE
WARNING: at lib/list_debug.c:62 __list_del_entry+0x1c0/0x250()
Hardware name:
list_del corruption. prev->next should be ffff88019a4ec198, but was 6b6b6b6b6b6b6b6b
Modules linked in: cpufreq_ondemand acpi_cpufreq freq_table mperf coretemp kvm_intel kvm crc32c_intel ghash_clmulni_intel microcode sg xhci_hcd button sd_mod crc_t10dif aesni_intel ablk_helper cryptd lrw aes_x86_64 xts gf128mul ahci libahci pata_acpi ata_generic dm_mirror dm_region_hash dm_log dm_mod
Pid: 16400, comm: jbd2/dm-1-8 Tainted: G W 3.8.0-rc3+ #107
Call Trace:
[<ffffffff8106fb0d>] warn_slowpath_common+0xad/0xf0
[<ffffffff8106fc06>] warn_slowpath_fmt+0x46/0x50
[<ffffffff813637e9>] ? ext4_journal_commit_callback+0x99/0xc0
[<ffffffff8148cae0>] __list_del_entry+0x1c0/0x250
[<ffffffff813637bf>] ext4_journal_commit_callback+0x6f/0xc0
[<ffffffff813ca336>] jbd2_journal_commit_transaction+0x23a6/0x2570
[<ffffffff8108aa42>] ? try_to_del_timer_sync+0x82/0xa0
[<ffffffff8108b491>] ? del_timer_sync+0x91/0x1e0
[<ffffffff813d3ecf>] kjournald2+0x19f/0x6a0
[<ffffffff810ad630>] ? wake_up_bit+0x40/0x40
[<ffffffff813d3d30>] ? bit_spin_lock+0x80/0x80
[<ffffffff810ac6be>] kthread+0x10e/0x120
[<ffffffff810ac5b0>] ? __init_kthread_worker+0x70/0x70
[<ffffffff818ff6ac>] ret_from_fork+0x7c/0xb0
[<ffffffff810ac5b0>] ? __init_kthread_worker+0x70/0x70
In order to demonstrace this issue one should mount ext4 with mount -o
discard option on SSD disk. This makes callback longer and race
window becomes wider.
In order to fix this we should mark transaction as finished only after
callbacks have completed
Signed-off-by: Dmitry Monakhov <dmonakhov@openvz.org>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Cc: stable@vger.kernel.org
In the case where an inode has a very stale transaction id (tid) in
i_datasync_tid or i_sync_tid, it's possible that after a very large
(2**31) number of transactions, that the tid number space might wrap,
causing tid_geq()'s calculations to fail.
Commit deeeaf13 "jbd2: fix fsync() tid wraparound bug", later modified
by commit e7b04ac0 "jbd2: don't wake kjournald unnecessarily",
attempted to fix this problem, but it only avoided kjournald spinning
forever by fixing the logic in jbd2_log_start_commit().
Unfortunately, in the codepaths in fs/ext4/fsync.c and fs/ext4/inode.c
that might call jbd2_log_start_commit() with a stale tid, those
functions will subsequently call jbd2_log_wait_commit() with the same
stale tid, and then wait for a very long time. To fix this, we
replace the calls to jbd2_log_start_commit() and
jbd2_log_wait_commit() with a call to a new function,
jbd2_complete_transaction(), which will correctly handle stale tid's.
As a bonus, jbd2_complete_transaction() will avoid locking
j_state_lock for writing unless a commit needs to be started. This
should have a small (but probably not measurable) improvement for
ext4's scalability.
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Reported-by: Ben Hutchings <ben@decadent.org.uk>
Reported-by: George Barnett <gbarnett@atlassian.com>
Cc: stable@vger.kernel.org
There are multiple reasons to move away from debugfs. First of all,
we are only using it for a single parameter, and it is much more
complicated to set up (some 30 lines of code compared to 3), and one
more thing that might fail while loading the jbd2 module.
Secondly, as a module paramter it can be specified as a boot option if
jbd2 is built into the kernel, or as a parameter when the module is
loaded, and it can also be manipulated dynamically under
/sys/module/jbd2/parameters/jbd2_debug. So it is more flexible.
Ultimately we want to move away from using jbd_debug() towards
tracepoints, but for now this is still a useful simplification of the
code base.
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Handles which stay open a long time are problematic when it comes time
to close down a transaction so it can be committed. These tracepoints
will help us determine which ones are the problematic ones, and to
validate whether changes makes things better or worse.
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
This reverts commit 93737456d6.
The cow-snapshots effort is no longer active, so remove these extra
fields to shrink down the handle structure.
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Reviewed-by: Jan Kara <jack@suse.cz>
Track the delay between when we first request that the commit begin
and when it actually begins, so we can see how much of a gap exists.
In theory, this should just be the remaining scheduling quantuum of
the thread which requested the commit (assuming it was not a
synchronous operation which triggered the commit request) plus
scheduling overhead; however, it's possible that real time processes
might get in the way of letting the kjournald thread from executing.
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
We cannot wait for transaction commit in journal_unmap_buffer()
because we hold page lock which ranks below transaction start. We
solve the issue by bailing out of journal_unmap_buffer() and
jbd2_journal_invalidatepage() with -EBUSY. Caller is then responsible
for waiting for transaction commit to finish and try invalidation
again. Since the issue can happen only for page stradding i_size, it
is simple enough to manually call jbd2_journal_invalidatepage() for
such page from ext4_setattr(), check the return value and wait if
necessary.
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
The use of variable length arrays in structs (VLAIS) in the Linux Kernel code
precludes the use of compilers which don't implement VLAIS (for instance the
Clang compiler). Since ctx is always a 32-bit CRC, hard coding a size of 4
bytes accomplishes the same thing without the use of VLAIS. This is the same
technique already employed in fs/ext4/ext4.h
Signed-off-by: Mark Charlebois <charlebm@gmail.com>
Signed-off-by: Behan Webster <behanw@converseincode.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
ext4_handle_release_buffer() was intended to remove journal
write access from a buffer, but it doesn't actually do anything
at all other than add a BUFFER_TRACE point, but it's not reliably
used for that either. Remove all the associated dead code.
Signed-off-by: Eric Sandeen <sandeen@redhat.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Reviewed-by: Carlos Maiolino <cmaiolino@redhat.com>
After we transfer set the EXT4_ERROR_FS bit in the file system
superblock, it's not enough to call jbd2_journal_clear_err() to clear
the error indication from journal superblock --- we need to call
jbd2_journal_update_sb_errno() as well. Otherwise, when the root file
system is mounted read-only, the journal is replayed, and the error
indicator is transferred to the superblock --- but the s_errno field
in the jbd2 superblock is left set (since although we cleared it in
memory, we never flushed it out to disk).
This can end up confusing e2fsck. We should make e2fsck more robust
in this case, but the kernel shouldn't be leaving things in this
confused state, either.
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Cc: stable@kernel.org
Activate the metadata checksumming feature by adding it to ext4 and
jbd2's lists of supported features.
Signed-off-by: Darrick J. Wong <djwong@us.ibm.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Calculate and verify a checksum covering the journal superblock.
Signed-off-by: Darrick J. Wong <djwong@us.ibm.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Obtain a reference to the crc32c driver if needed for the v2 checksum.
Signed-off-by: Darrick J. Wong <djwong@us.ibm.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Define flags and allocate space in on-disk journal structures to support
checksumming of journal metadata.
Signed-off-by: Darrick J. Wong <djwong@us.ibm.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Normally, we have to issue a cache flush before we can update journal tail in
journal superblock, effectively wiping out old transactions from the journal.
So use the fact that during transaction commit we issue cache flush anyway and
opportunistically push journal tail as far as we can. Since update of journal
superblock is still costly (we have to use WRITE_FUA), we update log tail only
if we can free significant amount of space.
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
When we reach jbd2_cleanup_journal_tail(), there is no guarantee that
checkpointed buffers are on a stable storage - especially if buffers were
written out by jbd2_log_do_checkpoint(), they are likely to be only in disk's
caches. Thus when we update journal superblock effectively removing old
transaction from journal, this write of superblock can get to stable storage
before those checkpointed buffers which can result in filesystem corruption
after a crash. Thus we must unconditionally issue a cache flush before we
update journal superblock in these cases.
A similar problem can also occur if journal superblock is written only in
disk's caches, other transaction starts reusing space of the transaction
cleaned from the log and power failure happens. Subsequent journal replay would
still try to replay the old transaction but some of it's blocks may be already
overwritten by the new transaction. For this reason we must use WRITE_FUA when
updating log tail and we must first write new log tail to disk and update
in-memory information only after that.
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
There are three case of updating journal superblock. In the first case, we want
to mark journal as empty (setting s_sequence to 0), in the second case we want
to update log tail, in the third case we want to update s_errno. Split these
cases into separate functions. It makes the code slightly more straightforward
and later patches will make the distinction even more important.
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
There is normally only a handful of these active at any one time, but
putting them in a separate slab cache makes debugging memory
corruption problems easier. Manish Katiyar also wanted this make it
easier to test memory failure scenarios in the jbd2 layer.
Cc: Manish Katiyar <mkatiyar@gmail.com>
Signed-off-by: Yongqiang Yang <xiaoqiangnk@gmail.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Currently, we clear revoked flag only when a block is reused. However,
this can tigger a false journal error. Consider a situation when a block
is used as a meta block and is deleted(revoked) in ordered mode, then the
block is allocated as a data block to a file. At this moment, user changes
the file's journal mode from ordered to journaled and truncates the file.
The block will be considered re-revoked by journal because it has revoked
flag still pending from the last transaction and an assertion triggers.
We fix the problem by keeping the revoked status more uptodate - we clear
revoked flag when switching revoke tables to reflect there is no revoked
buffers in current transaction any more.
Signed-off-by: Yongqiang Yang <xiaoqiangnk@gmail.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
The state bits and the lock functions of jbd and jbd2 are
identical. Share them.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
This silences some Sparse warnings:
fs/jbd2/transaction.c:135:69: warning: incorrect type in argument 2 (different base types)
fs/jbd2/transaction.c:135:69: expected restricted gfp_t [usertype] flags
fs/jbd2/transaction.c:135:69: got int [signed] gfp_mask
Signed-off-by: Dan Carpenter <error27@gmail.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Using function calls in TP_printk causes perf heartburn, so print the
MAJOR/MINOR device numbers instead.
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
jbd2_journal_remove_journal_head() can oops when trying to access
journal_head returned by bh2jh(). This is caused for example by the
following race:
TASK1 TASK2
jbd2_journal_commit_transaction()
...
processing t_forget list
__jbd2_journal_refile_buffer(jh);
if (!jh->b_transaction) {
jbd_unlock_bh_state(bh);
jbd2_journal_try_to_free_buffers()
jbd2_journal_grab_journal_head(bh)
jbd_lock_bh_state(bh)
__journal_try_to_free_buffer()
jbd2_journal_put_journal_head(jh)
jbd2_journal_remove_journal_head(bh);
jbd2_journal_put_journal_head() in TASK2 sees that b_jcount == 0 and
buffer is not part of any transaction and thus frees journal_head
before TASK1 gets to doing so. Note that even buffer_head can be
released by try_to_free_buffers() after
jbd2_journal_put_journal_head() which adds even larger opportunity for
oops (but I didn't see this happen in reality).
Fix the problem by making transactions hold their own journal_head
reference (in b_jcount). That way we don't have to remove journal_head
explicitely via jbd2_journal_remove_journal_head() and instead just
remove journal_head when b_jcount drops to zero. The result of this is
that [__]jbd2_journal_refile_buffer(),
[__]jbd2_journal_unfile_buffer(), and
__jdb2_journal_remove_checkpoint() can free journal_head which needs
modification of a few callers. Also we have to be careful because once
journal_head is removed, buffer_head might be freed as well. So we
have to get our own buffer_head reference where it matters.
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Provide a function which returns whether a transaction with given tid
will send a flush to the filesystem device. The function will be used
by ext4 to detect whether fsync needs to send a separate flush or not.
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Zheng Liu
Dmitry Monakhov
Theodore Ts'o
Jan Kara
Behan Webster
Eric Sandeen
Darrick J. Wong
Yongqiang Yang
Thomas Gleixner
Dan Carpenter