In gfs2_ail1_flush, we're using I/O plugging to give the block layer a
better chance of merging I/O requests. If we're too aggressive here, we
can end up waiting on I/O to complete while still plugged. Fix that in
a way similar to writeback_sb_inodes, except that we can't use
blk_flush_plug because blk_flush_plug_list is not exported.
Signed-off-by: Bob Peterson <rpeterso@redhat.com>
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
In the log, revokes are stored as a revoke descriptor (struct
gfs2_log_descriptor), followed by zero or more additional revoke blocks
(struct gfs2_meta_header). On filesystems with a blocksize of 4k, the
revoke descriptor contains up to 503 revokes, and the metadata blocks
contain up to 509 revokes each. We've so far been reserving space for
revokes in transactions in block granularity, so a lot more space than
necessary was being allocated and then released again.
This patch switches to assigning revokes to transactions individually
instead. Initially, space for the revoke descriptor is reserved and
handed out to transactions. When more revokes than that are reserved,
additional revoke blocks are added. When the log is flushed, the space
for the additional revoke blocks is released, but we keep the space for
the revoke descriptor block allocated.
Transactions may still reserve more revokes than they will actually need
in the end, but now we won't overshoot the target as much, and by only
returning the space for excess revokes at log flush time, we further
reduce the amount of contention between processes.
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
The current log space allocation logic is hard to understand or extend.
The principle it that when the log is flushed, we may or may not have a
transaction active that has space allocated in the log. To deal with
that, we set aside a magical number of blocks to be used in case we
don't have an active transaction. It isn't clear that the pool will
always be big enough. In addition, we can't return unused log space at
the end of a transaction, so the number of blocks allocated must exactly
match the number of blocks used.
Simplify this as follows:
* When transactions are allocated or merged, always reserve enough
blocks to flush the transaction (err on the safe side).
* In gfs2_log_flush, return any allocated blocks that haven't been used.
* Maintain a pool of spare blocks big enough to do one log flush, as
before.
* In gfs2_log_flush, when we have no active transaction, allocate a
suitable number of blocks. For that, use the spare pool when
called from logd, and leave the pool alone otherwise. This means
that when the log is almost full, logd will still be able to do one
more log flush, which will result in more log space becoming
available.
This will make the log space allocator code easier to work with in
the future.
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
Keep the current value of the updated log tail in the super block as
sb_log_flush_tail instead of computing it on the fly. This avoids
unnecessary sd_ail_lock taking and cleans up the code.
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
Wake up log waiters in gfs2_log_release when log space has actually become
available. This is a much better place for the wakeup than gfs2_logd.
Check if enough log space is immeditely available before anything else. If
there isn't, use io_wait_event to wait instead of open-coding it.
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
Commit 588bff95c9 added gfs2_write_log_header() and started using it in
clean_journal(), with an additional call to log_flush_wait() at the end of
gfs2_write_log_header() which is unnecessary for clean_journal(). Move
that call out of gfs2_write_log_header() to restore the previous behavior.
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
Move the read locking of sd_log_flush_lock from gfs2_log_reserve to
gfs2_trans_begin, and its unlocking from gfs2_log_release to
gfs2_trans_end. Use gfs2_log_release in two places in which it was open
coded before.
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
This counter and the associated wait queue are only used so that
gfs2_make_fs_ro can efficiently wait for all pending log space
allocations to fail after setting the filesystem to read-only. This
comes at the cost of waking up that wait queue very frequently.
Instead, when gfs2_log_reserve fails because the filesystem has become
read-only, Wake up sd_log_waitq. In gfs2_make_fs_ro, set the file
system read-only and then wait until all the log space has been
released. Give up and report the problem after a while. With that,
sd_reserving_log and sd_reserving_log_wait can be removed.
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
Replace the TR_ALLOCED flag by its inverse, TR_ONSTACK: that way, the flag only
needs to be set in the exceptional case of on-stack transactions. Split off
__gfs2_trans_begin from gfs2_trans_begin and use it to replace the open-coded
version in gfs2_ail_empty_gl.
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
The recovery func can recover multiple journals, but they were all using
the same bio. This resulted in use-after-free related to sdp->sd_log_bio.
This patch moves the variable to the journal descriptor, jd, so that
every recovery can operate on its own bio. And hopefully we never run out.
Signed-off-by: Bob Peterson <rpeterso@redhat.com>
This reverts commit 428fd95d85.
Patch 428fd95d85b2 added a call to log_flush_wait to function
gfs2_log_flush. Then gfs2_log_flush calls log_write_header which submits
a write request with the REQ_PREFLUSH flag which also forces it to wait.
This patch removes the unnecessary call to log_flush_wait.
Signed-off-by: Bob Peterson <rpeterso@redhat.com>
Function gfs2_write_revokes doesn't actually write any revokes; instead, it
adds revokes to the system transaction during a flush.
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
The calc_reserved description claims that buf_limit is 502 (on 4k
filesystems), but it is actually 503. Fix / clarify the entire
description.
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
Patch b2a846dbef ("gfs2: Ignore journal log writes for jdata holes")
tried (unsuccessfully) to fix a case in which writes were done to jdata
blocks, the blocks are sent to the ail list, then a punch_hole or truncate
operation caused the blocks to be freed. In other words, the ail items
are for jdata holes. Before b2a846dbef, the jdata hole caused function
gfs2_block_map to return -EIO, which was eventually interpreted as an
IO error to the journal, and then withdraw.
This patch changes function gfs2_get_block_noalloc, which is only used
for jdata writes, so it returns -ENODATA rather than -EIO, and when
-ENODATA is returned to gfs2_ail1_start_one, the error is ignored.
We can safely ignore it because gfs2_ail1_start_one is only called
when the jdata pages have already been written and truncated, so the
ail1 content no longer applies.
Signed-off-by: Bob Peterson <rpeterso@redhat.com>
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
This patch is one baby step toward simplifying the journal management.
It simply changes function gfs2_ail1_empty_one from a void to an int and
makes it return a count of active items. This allows the caller to check
the return code rather than list_empty on the tr_ail1_list. This way
we can, in a later patch, combine transaction ail1 and ail2 lists.
Signed-off-by: Bob Peterson <rpeterso@redhat.com>
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
Before this patch, when blocks were freed, it called gfs2_meta_wipe to
take the metadata out of the pending journal blocks. It did this mostly
by calling another function called gfs2_remove_from_journal. This is
shortsighted because it does not do anything with jdata blocks which
may also be in the journal.
This patch expands the function so that it wipes out jdata blocks from
the journal as well, and it wipes it from the ail1 list if it hasn't
been written back yet. Since it now processes jdata blocks as well,
the function has been renamed from gfs2_meta_wipe to gfs2_journal_wipe.
New function gfs2_ail1_wipe wants a static view of the ail list, so it
locks the sd_ail_lock when removing items. To accomplish this, function
gfs2_remove_from_journal no longer locks the sd_ail_lock, and it's now
the caller's responsibility to do so.
I was going to make sd_ail_lock locking conditional, but the practice is
generally frowned upon. For details, see: https://lwn.net/Articles/109066/
Signed-off-by: Bob Peterson <rpeterso@redhat.com>
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
Function gfs2_write_revokes was incrementing and decrementing the number
of log blocks free, but there was never a log_blocks trace point for it.
Thus, the free blocks from a log_blocks trace would jump around
mysteriously.
This patch adds the missing trace points so the trace makes more sense.
Signed-off-by: Bob Peterson <rpeterso@redhat.com>
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
Commit ca399c96e9 changes gfs2_log_flush to not withdraw the
filesystem while holding the log flush lock, but it fails to check if
the filesystem needs to be withdrawn once the log flush lock has been
released. Likewise, commit f05b86db31 depends on gfs2_log_flush to
trigger for delayed withdraws. Add that and clean up the code flow
somewhat.
In gfs2_put_super, add a check for delayed withdraws that have been
missed to prevent these kinds of bugs in the future.
Fixes: ca399c96e9 ("gfs2: flesh out delayed withdraw for gfs2_log_flush")
Fixes: f05b86db31 ("gfs2: Prepare to withdraw as soon as an IO error occurs in log write")
Cc: stable@vger.kernel.org # v5.7+: 462582b99b607: gfs2: add some much needed cleanup for log flushes that fail
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
When a log flush fails due to io errors, it signals the failure but does
not clean up after itself very well. This is because buffers are added to
the transaction tr_buf and tr_databuf queue, but the io error causes
gfs2_log_flush to bypass the "after_commit" functions responsible for
dequeueing the bd elements. If the bd elements are added to the ail list
before the error, function ail_drain takes care of dequeueing them.
But if they haven't gotten that far, the elements are forgotten and
make the transactions unable to be freed.
This patch introduces new function trans_drain which drains the bd
elements from the transaction so they can be freed properly.
Signed-off-by: Bob Peterson <rpeterso@redhat.com>
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
The comment regarding journal flush thresholds is wrong. This patch fixes it.
Signed-off-by: Bob Peterson <rpeterso@redhat.com>
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
In several places, we used the GIF_ORDERED inode flag to determine
if an inode was on the ordered writes list. However, since we always
held the sd_ordered_lock spin_lock during the manipulation, we can
just as easily check list_empty(&ip->i_ordered) instead.
This allows us to keep more than one ordered writes list to make
journal writing improvements.
This patch eliminates GIF_ORDERED in favor of checking list_empty.
Signed-off-by: Bob Peterson <rpeterso@redhat.com>
Log flush operations (gfs2_log_flush()) can target a specific transaction.
But if the function encounters errors (e.g. io errors) and withdraws,
the transaction was only freed it if was queued to one of the ail lists.
If the withdraw occurred before the transaction was queued to the ail1
list, function ail_drain never freed it. The result was:
BUG gfs2_trans: Objects remaining in gfs2_trans on __kmem_cache_shutdown()
This patch makes log_flush() add the targeted transaction to the ail1
list so that function ail_drain() will find and free it properly.
Cc: stable@vger.kernel.org # v5.7+
Signed-off-by: Bob Peterson <rpeterso@redhat.com>
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
Before this patch, transactions could be merged into the system
transaction by function gfs2_merge_trans(), but the transaction ail
lists were never merged. Because the ail flushing mechanism can run
separately, bd elements can be attached to the transaction's buffer
list during the transaction (trans_add_meta, etc) but quickly moved
to its ail lists. Later, in function gfs2_trans_end, the transaction
can be freed (by gfs2_trans_end) while it still has bd elements
queued to its ail lists, which can cause it to either lose track of
the bd elements altogether (memory leak) or worse, reference the bd
elements after the parent transaction has been freed.
Although I've not seen any serious consequences, the problem becomes
apparent with the previous patch's addition of:
gfs2_assert_warn(sdp, list_empty(&tr->tr_ail1_list));
to function gfs2_trans_free().
This patch adds logic into gfs2_merge_trans() to move the merged
transaction's ail lists to the sdp transaction. This prevents the
use-after-free. To do this properly, we need to hold the ail lock,
so we pass sdp into the function instead of the transaction itself.
Signed-off-by: Bob Peterson <rpeterso@redhat.com>
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
This patch adds a new slab for gfs2 transactions. That allows us to
reduce kernel memory fragmentation, have better organization of data
for analysis of vmcore dumps. A new centralized function is added to
free the slab objects, and it exposes use-after-free by giving
warnings if a transaction is freed while it still has bd elements
attached to its buffers or ail lists. We make sure to initialize
those transaction ail lists so we can check their integrity when freeing.
At a later time, we should add a slab initialization function to
make it more efficient, but for this initial patch I wanted to
minimize the impact.
Signed-off-by: Bob Peterson <rpeterso@redhat.com>
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
Since transactions may be freed shortly after they're created, before
a log_flush occurs, we need to initialize their ail1 and ail2 lists
earlier. Before this patch, the ail1 list was initialized in gfs2_log_flush().
This moves the initialization to the point when the transaction is first
created.
Signed-off-by: Bob Peterson <rpeterso@redhat.com>
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
This adds checks for gfs2_log_flush being stuck, similarly to the check
in gfs2_ail1_flush. To faciliate this and make the strings easy to grep
we move the ail1 emptying to its own function, empty_ail1_list.
Signed-off-by: Bob Peterson <rpeterso@redhat.com>
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
This patch rearranges gfs2_add_revoke so that the extra glock
reference is added earlier on in the function to avoid races in which
the glock is freed before the new reference is taken.
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
Signed-off-by: Bob Peterson <rpeterso@redhat.com>
When the gfs2_logd daemon withdrew, the withdraw sequence called
into make_fs_ro() to make the file system read-only. That caused the
journal descriptors to be freed. However, those journal descriptors
were used by gfs2_logd's call to gfs2_ail_flush_reqd(). This caused
a use-after free and NULL pointer dereference.
This patch changes function gfs2_logd() so that it stops all logd
work until the thread is told to stop. Once a withdraw is done,
it only does an interruptible sleep.
Signed-off-by: Bob Peterson <rpeterso@redhat.com>
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
Ordinarily, function gfs2_ail1_start_one issues a write request
for one item on the ail1 list, then returns -EBUSY. This makes the
caller, gfs2_ail1_flush, loop around and start another. However,
it was not clearing the -EBUSY return code each time through the loop.
So on rare occasions, like when the wbc runs out of nr_to_write, it
remained set to -EBUSY, which triggered an error and withdraw.
This patch sets the return code to 0 each time through the restart
loop so this won't happen anymore.
Signed-off-by: Bob Peterson <rpeterso@redhat.com>
Before this patch, if the ail1 flush got stuck for some reason, there
were no clues as to why. This patch introduces a check for getting
stuck for more than a minute, and if it happens, it dumps the items
still remaining on the ail1 list.
Signed-off-by: Bob Peterson <rpeterso@redhat.com>
Replace open-coded versions of list_first_entry and list_last_entry with those
functions.
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
Signed-off-by: Bob Peterson <rpeterso@redhat.com>
Before this patch, if gfs2_ail1_flush gets an error from function
gfs2_ail1_start_one (which comes indirectly from generic_writepages)
the file system is withdrawn, but without any explanation why.
This patch adds an error message if gfs2_ail1_flush gets an error
from gfs2_ail1_start_one.
Signed-off-by: Bob Peterson <rpeterso@redhat.com>
Function gfs2_log_flush() had a few places where it tried to withdraw
from the file system when errors were encountered. The problem is,
it should delay those withdraws until the log flush lock is no longer
held.
This patch creates a new function just for delayed withdraws for
situations like this. If errors=panic was specified on mount, we
still want to do it the old fashioned way because the panic it does
not help to delay in that situation.
Signed-off-by: Bob Peterson <rpeterso@redhat.com>
Reviewed-by: Andreas Gruenbacher <agruenba@redhat.com>
Before this patch, gfs2_logd continually tried to flush its journal
log, after the file system is withdrawn. We don't want to write anything
to the journal, lest we add corruption. Best course of action is to
drain the ail1 into the ail2 list (via gfs2_ail1_empty) then drain the
ail2 list with a new function, ail2_drain.
Signed-off-by: Bob Peterson <rpeterso@redhat.com>
Reviewed-by: Andreas Gruenbacher <agruenba@redhat.com>
Before this patch, function gfs2_ail1_start_one would return any
errors it received from write_cache_pages (except -EBUSY) but it did
not withdraw. Since function gfs2_ail1_flush just checks for the bad
return code and loops, the loop might potentially never end.
This patch adds some logic to allow it to exit the loop and withdraw
properly when errors are received from write_cache_pages.
Signed-off-by: Bob Peterson <rpeterso@redhat.com>
Reviewed-by: Andreas Gruenbacher <agruenba@redhat.com>
Before this patch, if gfs2_ail_empty_gl saw there was nothing on
the ail list, it would return and not flush the log. The problem
is that there could still be a revoke for the rgrp sitting on the
sd_log_le_revoke list that's been recently taken off the ail list.
But that revoke still needs to be written, and the rgrp_go_inval
still needs to call log_flush_wait to ensure the revokes are all
properly written to the journal before we relinquish control of
the glock to another node. If we give the glock to another node
before we have this knowledge, the node might crash and its journal
replayed, in which case the missing revoke would allow the journal
replay to replay the rgrp over top of the rgrp we already gave to
another node, thus overwriting its changes and corrupting the
file system.
This patch makes gfs2_ail_empty_gl still call gfs2_log_flush rather
than returning.
Signed-off-by: Bob Peterson <rpeterso@redhat.com>
Reviewed-by: Andreas Gruenbacher <agruenba@redhat.com>
Before this patch, function gfs2_write_revokes would call
gfs2_ail1_empty, then traverse the sd_ail1_list looking for
transactions that had bds which were no longer queued to a glock.
And if it found some, it would try to issue revokes for them, up to
a predetermined maximum. There were two problems with how it did
this. First was the fact that gfs2_ail1_empty moves transactions
which have nothing remaining on the ail1 list from the sd_ail1_list
to the sd_ail2_list, thus making its traversal of sd_ail1_list
miss them completely, and therefore, never issue revokes for them.
Second was the fact that there were three traversals (or partial
traversals) of the sd_ail1_list, each of which took and then
released the sd_ail_lock lock: First inside gfs2_ail1_empty,
second to determine if there are any revokes to be issued, and
third to actually issue them. All this taking and releasing of the
sd_ail_lock meant other processes could modify the lists and the
conditions in which we're working.
This patch simplies the whole process by adding a new parameter
to function gfs2_ail1_empty, max_revokes. For normal calls, this
is passed in as 0, meaning we don't want to issue any revokes.
For function gfs2_write_revokes, we pass in the maximum number
of revokes we can, thus allowing gfs2_ail1_empty to add the
revokes where needed. This simplies the code, allows for a single
holding of the sd_ail_lock, and allows gfs2_ail1_empty to add
revokes for all the necessary bd items without missing any.
Signed-off-by: Bob Peterson <rpeterso@redhat.com>
Reviewed-by: Andreas Gruenbacher <agruenba@redhat.com>
Before this patch, gfs2 kept track of journal io errors in two
places sd_log_error and the SDF_AIL1_IO_ERROR flag in sd_flags.
This patch consolidates the two into sd_log_error so that it
reflects the first error encountered writing to the journal.
In future patches, we will take advantage of this by checking
this value rather than having to check both when reacting to
io errors.
In addition, this fixes a tight loop in unmount: If buffers
get on the ail1 list and an io error occurs elsewhere, the
ail1 list would never be cleared because they were always busy.
So unmount would hang, waiting for the ail1 list to empty.
Signed-off-by: Bob Peterson <rpeterso@redhat.com>
Reviewed-by: Andreas Gruenbacher <agruenba@redhat.com>
This patch fixes a bug in which function gfs2_log_flush can get into
an infinite loop when a gfs2 file system is withdrawn. The problem
is the infinite loop "for (;;)" in gfs2_log_flush which would never
finish because the io error and subsequent withdraw prevented the
items from being taken off the ail list.
This patch tries to clean up the mess by allowing withdraw situations
to move not-in-flight buffer_heads to the ail2 list, where they will
be dealt with later.
Signed-off-by: Bob Peterson <rpeterso@redhat.com>
Reviewed-by: Andreas Gruenbacher <agruenba@redhat.com>
File system withdraws can be delayed when inconsistencies are
discovered when we cannot withdraw immediately, for example, when
critical spin_locks are held. But delaying the withdraw can cause
gfs2 to ignore the error and keep running for a short period of time.
For example, an rgrp glock may be dequeued and demoted while there
are still buffers that haven't been properly revoked, due to io
errors writing to the journal.
This patch introduces a new concept of a pending withdraw, which
means an inconsistency has been discovered and we need to withdraw
at the earliest possible opportunity. In these cases, we aren't
quite withdrawn yet, but we still need to not dequeue glocks and
other critical things. If we dequeue the glocks and the withdraw
results in our journal being replayed, the replay could overwrite
data that's been modified by a different node that acquired the
glock in the meantime.
Signed-off-by: Bob Peterson <rpeterso@redhat.com>
Reviewed-by: Andreas Gruenbacher <agruenba@redhat.com>
Split gfs2_lm_withdraw into a function that prints an error message and a
function that withdraws the filesystem.
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
Signed-off-by: Bob Peterson <rpeterso@redhat.com>
This reverts commit e955537e32.
Before patch e955537e32, tr_num_revoke tracked the number of revokes
added to the transaction, and tr_num_revoke_rm tracked how many
revokes were removed. But since revokes are queued off the sdp
(superblock) pointer, some transactions could remove more revokes
than they added. (e.g. revokes added by a different process).
Commit e955537e32 eliminated transaction variable tr_num_revoke_rm,
but in order to do so, it changed the accounting to always use
tr_num_revoke for its math. Since you can remove more revokes than
you add, tr_num_revoke could now become a negative value.
This negative value broke the assert in function gfs2_trans_end:
if (gfs2_assert_withdraw(sdp, (nbuf <=3D tr->tr_blocks) &&
(tr->tr_num_revoke <=3D tr->tr_revokes)))
One way to fix this is to simply remove the tr_num_revoke clause
from the assert and allow the value to become negative. Andreas
didn't like that idea, so instead, we decided to revert e955537e32.
Signed-off-by: Bob Peterson <rpeterso@redhat.com>
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
Every caller of function gfs2_struct2blk specified sizeof(u64).
This patch eliminates the unnecessary parameter and replaces the
size calculation with a new superblock variable that is computed
to be the maximum number of block pointers we can fit inside a
log descriptor, as is done for pointers per dinode and indirect
block.
Signed-off-by: Bob Peterson <rpeterso@redhat.com>
Reviewed-by: Andrew Price <anprice@redhat.com>
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
Bob Peterson