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In doing an investigation into AIL push stalls, I was looking at the
log force code to see if an async CIL push could be done instead.
This lead me to xfs_log_force_lsn() and looking at how it works.
xfs_log_force_lsn() is only called from inode synchronisation
contexts such as fsync(), and it takes the ip->i_itemp->ili_last_lsn
value as the LSN to sync the log to. This gets passed to
xlog_cil_force_lsn() via xfs_log_force_lsn() to flush the CIL to the
journal, and then used by xfs_log_force_lsn() to flush the iclogs to
the journal.
The problem is that ip->i_itemp->ili_last_lsn does not store a
log sequence number. What it stores is passed to it from the
->iop_committing method, which is called by xfs_log_commit_cil().
The value this passes to the iop_committing method is the CIL
context sequence number that the item was committed to.
As it turns out, xlog_cil_force_lsn() converts the sequence to an
actual commit LSN for the related context and returns that to
xfs_log_force_lsn(). xfs_log_force_lsn() overwrites it's "lsn"
variable that contained a sequence with an actual LSN and then uses
that to sync the iclogs.
This caused me some confusion for a while, even though I originally
wrote all this code a decade ago. ->iop_committing is only used by
a couple of log item types, and only inode items use the sequence
number it is passed.
Let's clean up the API, CIL structures and inode log item to call it
a sequence number, and make it clear that the high level code is
using CIL sequence numbers and not on-disk LSNs for integrity
synchronisation purposes.
Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Brian Foster <bfoster@redhat.com>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Allison Henderson <allison.henderson@oracle.com>
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
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A hang with tasks stuck on the CIL hard throttle was reported and
largely diagnosed by Donald Buczek, who discovered that it was a
result of the CIL context space usage decrementing in committed
transactions once the hard throttle limit had been hit and processes
were already blocked. This resulted in the CIL push not waking up
those waiters because the CIL context was no longer over the hard
throttle limit.
The surprising aspect of this was the CIL space usage going
backwards regularly enough to trigger this situation. Assumptions
had been made in design that the relogging process would only
increase the size of the objects in the CIL, and so that space would
only increase.
This change and commit message fixes the issue and documents the
result of an audit of the triggers that can cause the CIL space to
go backwards, how large the backwards steps tend to be, the
frequency in which they occur, and what the impact on the CIL
accounting code is.
Even though the CIL ctx->space_used can go backwards, it will only
do so if the log item is already logged to the CIL and contains a
space reservation for it's entire logged state. This is tracked by
the shadow buffer state on the log item. If the item is not
previously logged in the CIL it has no shadow buffer nor log vector,
and hence the entire size of the logged item copied to the log
vector is accounted to the CIL space usage. i.e. it will always go
up in this case.
If the item has a log vector (i.e. already in the CIL) and the size
decreases, then the existing log vector will be overwritten and the
space usage will go down. This is the only condition where the space
usage reduces, and it can only occur when an item is already tracked
in the CIL. Hence we are safe from CIL space usage underruns as a
result of log items decreasing in size when they are relogged.
Typically this reduction in CIL usage occurs from metadata blocks
being free, such as when a btree block merge occurs or a directory
enter/xattr entry is removed and the da-tree is reduced in size.
This generally results in a reduction in size of around a single
block in the CIL, but also tends to increase the number of log
vectors because the parent and sibling nodes in the tree needs to be
updated when a btree block is removed. If a multi-level merge
occurs, then we see reduction in size of 2+ blocks, but again the
log vector count goes up.
The other vector is inode fork size changes, which only log the
current size of the fork and ignore the previously logged size when
the fork is relogged. Hence if we are removing items from the inode
fork (dir/xattr removal in shortform, extent record removal in
extent form, etc) the relogged size of the inode for can decrease.
No other log items can decrease in size either because they are a
fixed size (e.g. dquots) or they cannot be relogged (e.g. relogging
an intent actually creates a new intent log item and doesn't relog
the old item at all.) Hence the only two vectors for CIL context
size reduction are relogging inode forks and marking buffers active
in the CIL as stale.
Long story short: the majority of the code does the right thing and
handles the reduction in log item size correctly, and only the CIL
hard throttle implementation is problematic and needs fixing. This
patch makes that fix, as well as adds comments in the log item code
that result in items shrinking in size when they are relogged as a
clear reminder that this can and does happen frequently.
The throttle fix is based upon the change Donald proposed, though it
goes further to ensure that once the throttle is activated, it
captures all tasks until the CIL push issues a wakeup, regardless of
whether the CIL space used has gone back under the throttle
threshold.
This ensures that we prevent tasks reducing the CIL slightly under
the throttle threshold and then making more changes that push it
well over the throttle limit. This is acheived by checking if the
throttle wait queue is already active as a condition of throttling.
Hence once we start throttling, we continue to apply the throttle
until the CIL context push wakes everything on the wait queue.
We can use waitqueue_active() for the waitqueue manipulations and
checks as they are all done under the ctx->xc_push_lock. Hence the
waitqueue has external serialisation and we can safely peek inside
the wait queue without holding the internal waitqueue locks.
Many thanks to Donald for his diagnostic and analysis work to
isolate the cause of this hang.
Reported-and-tested-by: Donald Buczek <buczek@molgen.mpg.de>
Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Brian Foster <bfoster@redhat.com>
Reviewed-by: Chandan Babu R <chandanrlinux@gmail.com>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Allison Henderson <allison.henderson@oracle.com>
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
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Currently every journal IO is issued as REQ_PREFLUSH | REQ_FUA to
guarantee the ordering requirements the journal has w.r.t. metadata
writeback. THe two ordering constraints are:
1. we cannot overwrite metadata in the journal until we guarantee
that the dirty metadata has been written back in place and is
stable.
2. we cannot write back dirty metadata until it has been written to
the journal and guaranteed to be stable (and hence recoverable) in
the journal.
The ordering guarantees of #1 are provided by REQ_PREFLUSH. This
causes the journal IO to issue a cache flush and wait for it to
complete before issuing the write IO to the journal. Hence all
completed metadata IO is guaranteed to be stable before the journal
overwrites the old metadata.
The ordering guarantees of #2 are provided by the REQ_FUA, which
ensures the journal writes do not complete until they are on stable
storage. Hence by the time the last journal IO in a checkpoint
completes, we know that the entire checkpoint is on stable storage
and we can unpin the dirty metadata and allow it to be written back.
This is the mechanism by which ordering was first implemented in XFS
way back in 2002 by commit 95d97c36e5155075ba2eb22b17562cfcc53fcf96
("Add support for drive write cache flushing") in the xfs-archive
tree.
A lot has changed since then, most notably we now use delayed
logging to checkpoint the filesystem to the journal rather than
write each individual transaction to the journal. Cache flushes on
journal IO are necessary when individual transactions are wholly
contained within a single iclog. However, CIL checkpoints are single
transactions that typically span hundreds to thousands of individual
journal writes, and so the requirements for device cache flushing
have changed.
That is, the ordering rules I state above apply to ordering of
atomic transactions recorded in the journal, not to the journal IO
itself. Hence we need to ensure metadata is stable before we start
writing a new transaction to the journal (guarantee #1), and we need
to ensure the entire transaction is stable in the journal before we
start metadata writeback (guarantee #2).
Hence we only need a REQ_PREFLUSH on the journal IO that starts a
new journal transaction to provide #1, and it is not on any other
journal IO done within the context of that journal transaction.
The CIL checkpoint already issues a cache flush before it starts
writing to the log, so we no longer need the iclog IO to issue a
REQ_REFLUSH for us. Hence if XLOG_START_TRANS is passed
to xlog_write(), we no longer need to mark the first iclog in
the log write with REQ_PREFLUSH for this case. As an added bonus,
this ordering mechanism works for both internal and external logs,
meaning we can remove the explicit data device cache flushes from
the iclog write code when using external logs.
Given the new ordering semantics of commit records for the CIL, we
need iclogs containing commit records to issue a REQ_PREFLUSH. We
also require unmount records to do this. Hence for both
XLOG_COMMIT_TRANS and XLOG_UNMOUNT_TRANS xlog_write() calls we need
to mark the first iclog being written with REQ_PREFLUSH.
For both commit records and unmount records, we also want them
immediately on stable storage, so we want to also mark the iclogs
that contain these records to be marked REQ_FUA. That means if a
record is split across multiple iclogs, they are all marked REQ_FUA
and not just the last one so that when the transaction is completed
all the parts of the record are on stable storage.
And for external logs, unmount records need a pre-write data device
cache flush similar to the CIL checkpoint cache pre-flush as the
internal iclog write code does not do this implicitly anymore.
As an optimisation, when the commit record lands in the same iclog
as the journal transaction starts, we don't need to wait for
anything and can simply use REQ_FUA to provide guarantee #2. This
means that for fsync() heavy workloads, the cache flush behaviour is
completely unchanged and there is no degradation in performance as a
result of optimise the multi-IO transaction case.
The most notable sign that there is less IO latency on my test
machine (nvme SSDs) is that the "noiclogs" rate has dropped
substantially. This metric indicates that the CIL push is blocking
in xlog_get_iclog_space() waiting for iclog IO completion to occur.
With 8 iclogs of 256kB, the rate is appoximately 1 noiclog event to
every 4 iclog writes. IOWs, every 4th call to xlog_get_iclog_space()
is blocking waiting for log IO. With the changes in this patch, this
drops to 1 noiclog event for every 100 iclog writes. Hence it is
clear that log IO is completing much faster than it was previously,
but it is also clear that for large iclog sizes, this isn't the
performance limiting factor on this hardware.
With smaller iclogs (32kB), however, there is a substantial
difference. With the cache flush modifications, the journal is now
running at over 4000 write IOPS, and the journal throughput is
largely identical to the 256kB iclogs and the noiclog event rate
stays low at about 1:50 iclog writes. The existing code tops out at
about 2500 IOPS as the number of cache flushes dominate performance
and latency. The noiclog event rate is about 1:4, and the
performance variance is quite large as the journal throughput can
fall to less than half the peak sustained rate when the cache flush
rate prevents metadata writeback from keeping up and the log runs
out of space and throttles reservations.
As a result:
logbsize fsmark create rate rm -rf
before 32kb 152851+/-5.3e+04 5m28s
patched 32kb 221533+/-1.1e+04 5m24s
before 256kb 220239+/-6.2e+03 4m58s
patched 256kb 228286+/-9.2e+03 5m06s
The rm -rf times are included because I ran them, but the
differences are largely noise. This workload is largely metadata
read IO latency bound and the changes to the journal cache flushing
doesn't really make any noticable difference to behaviour apart from
a reduction in noiclog events from background CIL pushing.
Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Chandan Babu R <chandanrlinux@gmail.com>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Allison Henderson <allison.henderson@oracle.com>
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
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The CIL push is the only call to xlog_write that sets this variable
to true. The other callers don't need a start rec, and they tell
xlog_write what to do by passing the type of ophdr they need written
in the flags field. The need_start_rec parameter essentially tells
xlog_write to to write an extra ophdr with a XLOG_START_TRANS type,
so get rid of the variable to do this and pass XLOG_START_TRANS as
the flag value into xlog_write() from the CIL push.
$ size fs/xfs/xfs_log.o*
text data bss dec hex filename
27595 560 8 28163 6e03 fs/xfs/xfs_log.o.orig
27454 560 8 28022 6d76 fs/xfs/xfs_log.o.patched
Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Chandan Babu R <chandanrlinux@gmail.com>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Allison Henderson <allison.henderson@oracle.com>
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
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Currently every journal IO is issued as REQ_PREFLUSH | REQ_FUA to
guarantee the ordering requirements the journal has w.r.t. metadata
writeback. THe two ordering constraints are:
1. we cannot overwrite metadata in the journal until we guarantee
that the dirty metadata has been written back in place and is
stable.
2. we cannot write back dirty metadata until it has been written to
the journal and guaranteed to be stable (and hence recoverable) in
the journal.
These rules apply to the atomic transactions recorded in the
journal, not to the journal IO itself. Hence we need to ensure
metadata is stable before we start writing a new transaction to the
journal (guarantee #1), and we need to ensure the entire transaction
is stable in the journal before we start metadata writeback
(guarantee #2).
The ordering guarantees of #1 are currently provided by REQ_PREFLUSH
being added to every iclog IO. This causes the journal IO to issue a
cache flush and wait for it to complete before issuing the write IO
to the journal. Hence all completed metadata IO is guaranteed to be
stable before the journal overwrites the old metadata.
However, for long running CIL checkpoints that might do a thousand
journal IOs, we don't need every single one of these iclog IOs to
issue a cache flush - the cache flush done before the first iclog is
submitted is sufficient to cover the entire range in the log that
the checkpoint will overwrite because the CIL space reservation
guarantees the tail of the log (completed metadata) is already
beyond the range of the checkpoint write.
Hence we only need a full cache flush between closing off the CIL
checkpoint context (i.e. when the push switches it out) and issuing
the first journal IO. Rather than plumbing this through to the
journal IO, we can start this cache flush the moment the CIL context
is owned exclusively by the push worker. The cache flush can be in
progress while we process the CIL ready for writing, hence
reducing the latency of the initial iclog write. This is especially
true for large checkpoints, where we might have to process hundreds
of thousands of log vectors before we issue the first iclog write.
In these cases, it is likely the cache flush has already been
completed by the time we have built the CIL log vector chain.
Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Chandan Babu R <chandanrlinux@gmail.com>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Brian Foster <bfoster@redhat.com>
Reviewed-by: Allison Henderson <allison.henderson@oracle.com>
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
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The new checkpoint cache flush mechanism requires us to issue an
unconditional cache flush before we start a new checkpoint. We don't
want to block for this if we can help it, and we have a fair chunk
of CPU work to do between starting the checkpoint and issuing the
first journal IO.
Hence it makes sense to amortise the latency cost of the cache flush
by issuing it asynchronously and then waiting for it only when we
need to issue the first IO in the transaction.
To do this, we need async cache flush primitives to submit the cache
flush bio and to wait on it. The block layer has no such primitives
for filesystems, so roll our own for the moment.
Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Brian Foster <bfoster@redhat.com>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Allison Henderson <allison.henderson@oracle.com>
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
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It's a one line wrapper around blkdev_issue_flush(). Just replace it
with direct calls to blkdev_issue_flush().
Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Chandan Babu R <chandanrlinux@gmail.com>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Brian Foster <bfoster@redhat.com>
Reviewed-by: Allison Henderson <allison.henderson@oracle.com>
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
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To allow for iclog IO device cache flush behaviour to be optimised,
we first need to separate out the commit record iclog IO from the
rest of the checkpoint so we can wait for the checkpoint IO to
complete before we issue the commit record.
This separation is only necessary if the commit record is being
written into a different iclog to the start of the checkpoint as the
upcoming cache flushing changes requires completion ordering against
the other iclogs submitted by the checkpoint.
If the entire checkpoint and commit is in the one iclog, then they
are both covered by the one set of cache flush primitives on the
iclog and hence there is no need to separate them for ordering.
Otherwise, we need to wait for all the previous iclogs to complete
so they are ordered correctly and made stable by the REQ_PREFLUSH
that the commit record iclog IO issues. This guarantees that if a
reader sees the commit record in the journal, they will also see the
entire checkpoint that commit record closes off.
This also provides the guarantee that when the commit record IO
completes, we can safely unpin all the log items in the checkpoint
so they can be written back because the entire checkpoint is stable
in the journal.
Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Chandan Babu R <chandanrlinux@gmail.com>
Reviewed-by: Brian Foster <bfoster@redhat.com>
Reviewed-by: Allison Henderson <allison.henderson@oracle.com>
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
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On 32-bit (e.g. m68k):
ERROR: modpost: "__udivdi3" [fs/xfs/xfs.ko] undefined!
Fix this by using a uint32_t intermediate, like before.
Reported-by: noreply@ellerman.id.au
Fixes: 7660a5b48fbef958 ("xfs: log stripe roundoff is a property of the log")
Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
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We don't need to look at the xfs_mount and superblock every time we
need to do an iclog roundoff calculation. The property is fixed for
the life of the log, so store the roundoff in the log at mount time
and use that everywhere.
On a debug build:
$ size fs/xfs/xfs_log.o.*
text data bss dec hex filename
27360 560 8 27928 6d18 fs/xfs/xfs_log.o.orig
27219 560 8 27787 6c8b fs/xfs/xfs_log.o.patched
Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Chandan Babu R <chandanrlinux@gmail.com>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Allison Henderson <allison.henderson@oracle.com>
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'error' will be initialized, so clean up the redundant initialization.
Cc: "Darrick J. Wong" <djwong@kernel.org>
Signed-off-by: Shaokun Zhang <zhangshaokun@hisilicon.com>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
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Dan Carpenter's static checker reported:
The patch 7b13c5155182: "xfs: use perag for ialloc btree cursors"
from Jun 2, 2021, leads to the following Smatch complaint:
fs/xfs/libxfs/xfs_ialloc.c:2403 xfs_imap()
error: we previously assumed 'pag' could be null (see line 2294)
And it's right. Fix it.
Fixes: 7b13c5155182 ("xfs: use perag for ialloc btree cursors")
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Allison Henderson <allison.henderson@oracle.com>
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https://github.com/allisonhenderson/xfs_work into xfs-5.14-merge4
xfs: Delay Ready Attributes
Hi all,
This set is a subset of a larger series for Dealyed Attributes. Which is a
subset of a yet larger series for parent pointers. Delayed attributes allow
attribute operations (set and remove) to be logged and committed in the same
way that other delayed operations do. This allows more complex operations (like
parent pointers) to be broken up into multiple smaller transactions. To do
this, the existing attr operations must be modified to operate as a delayed
operation. This means that they cannot roll, commit, or finish transactions.
Instead, they return -EAGAIN to allow the calling function to handle the
transaction. In this series, we focus on only the delayed attribute portion.
We will introduce parent pointers in a later set.
The set as a whole is a bit much to digest at once, so I usually send out the
smaller sub series to reduce reviewer burn out. But the entire extended series
is visible through the included github links.
Updates since v19: Added Darricks fix for the remote block accounting as well as
some minor nits about the default assert in xfs_attr_set_iter. Spent quite
a bit of time testing this cycle to weed out any more unexpected bugs. No new
test failures were observed with the addition of this set.
xfs: Fix default ASSERT in xfs_attr_set_iter
Replaced the assert with ASSERT(0);
xfs: Add delay ready attr remove routines
Added Darricks fix for remote block accounting
This series can be viewed on github here:
https://github.com/allisonhenderson/xfs_work/tree/delay_ready_attrs_v20
As well as the extended delayed attribute and parent pointer series:
https://github.com/allisonhenderson/xfs_work/tree/delay_ready_attrs_v20_extended
And the test cases:
https://github.com/allisonhenderson/xfs_work/tree/pptr_xfstestsv3
In order to run the test cases, you will need have the corresponding xfsprogs
changes as well. Which can be found here:
https://github.com/allisonhenderson/xfs_work/tree/delay_ready_attrs_xfsprogs_v20
https://github.com/allisonhenderson/xfs_work/tree/delay_ready_attrs_xfsprogs_v20_extended
To run the xfs attributes tests run:
check -g attr
To run as delayed attributes run:
export MOUNT_OPTIONS="-o delattr"
check -g attr
To run parent pointer tests:
check -g parent
I've also made the corresponding updates to the user space side as well, and ported anything
they need to seat correctly.
Questions, comment and feedback appreciated!
Thanks all!
Allison
* tag 'xfs-delay-ready-attrs-v20.1' of https://github.com/allisonhenderson/xfs_work:
xfs: Make attr name schemes consistent
xfs: Fix default ASSERT in xfs_attr_set_iter
xfs: Clean up xfs_attr_node_addname_clear_incomplete
xfs: Remove xfs_attr_rmtval_set
xfs: Add delay ready attr set routines
xfs: Add delay ready attr remove routines
xfs: Hoist node transaction handling
xfs: Hoist xfs_attr_leaf_addname
xfs: Hoist xfs_attr_node_addname
xfs: Add helper xfs_attr_node_addname_find_attr
xfs: Separate xfs_attr_node_addname and xfs_attr_node_addname_clear_incomplete
xfs: Refactor xfs_attr_set_shortform
xfs: Add xfs_attr_node_remove_name
xfs: Reverse apply 72b97ea40d
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This patch renames the following functions to make the nameing scheme more consistent:
xfs_attr_shortform_remove -> xfs_attr_sf_removename
xfs_attr_node_remove_name -> xfs_attr_node_removename
xfs_attr_set_fmt -> xfs_attr_sf_addname
Suggested-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Allison Henderson <allison.henderson@oracle.com>
Reviewed-by: Chandan Babu R <chandanrlinux@gmail.com>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
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This ASSERT checks for the state value of RM_SHRINK in the set path
which should never happen. Change to ASSERT(0);
Suggested-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Allison Henderson <allison.henderson@oracle.com>
Reviewed-by: Chandan Babu R <chandanrlinux@gmail.com>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
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https://git.kernel.org/pub/scm/linux/kernel/git/djwong/xfs-linux into xfs-5.14-merge2
xfs: rename struct xfs_eofblocks
In the old days, struct xfs_eofblocks was an optional parameter to the
speculative post-EOF allocation garbage collector to narrow the scope of
a scan to files fitting specific criteria. Nowadays it is used for all
other kinds of inode cache walks (reclaim, quotaoff, inactivation), so
the name is no longer fitting. Change the flag namespace and rename the
structure to something more appropriate for what it does.
v2: separate the inode cache walk flag namespace from eofblocks
* tag 'rename-eofblocks-5.14_2021-06-08' of https://git.kernel.org/pub/scm/linux/kernel/git/djwong/xfs-linux:
xfs: rename struct xfs_eofblocks to xfs_icwalk
xfs: change the prefix of XFS_EOF_FLAGS_* to XFS_ICWALK_FLAG_
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https://git.kernel.org/pub/scm/linux/kernel/git/djwong/xfs-linux into xfs-5.14-merge2
xfs: preserve inode health reports for longer
This is a quick series to make sure that inode sickness reports stick
around in memory for some amount of time.
v2: rebase to 5.13-rc4
v3: require explicit request to reclaim sick inodes, drop weird icache
miss interaction with DONTCACHE
* tag 'fix-inode-health-reports-5.14_2021-06-08' of https://git.kernel.org/pub/scm/linux/kernel/git/djwong/xfs-linux:
xfs: selectively keep sick inodes in memory
xfs: drop IDONTCACHE on inodes when we mark them sick
xfs: only reset incore inode health state flags when reclaiming an inode
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The xfs_eofblocks structure is no longer well-named -- nowadays it
provides optional filtering criteria to any walk of the incore inode
cache. Only one of the cache walk goals has anything to do with
clearing of speculative post-EOF preallocations, so change the name to
be more appropriate.
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
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It's important that the filesystem retain its memory of sick inodes for
a little while after problems are found so that reports can be collected
about what was wrong. Don't let inode reclamation free sick inodes
unless we're unmounting or the fs already went down.
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Carlos Maiolino <cmaiolino@redhat.com>
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In preparation for renaming struct xfs_eofblocks to struct xfs_icwalk,
change the prefix of the existing XFS_EOF_FLAGS_* flags to
XFS_ICWALK_FLAG_ and convert all the existing users. This adds a degree
of interface separation between the ioctl definitions and the incore
parameters. Since FLAGS_UNION is only used in xfs_icache.c, move it
there as a private flag.
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Carlos Maiolino <cmaiolino@redhat.com>
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When we decide to mark an inode sick, clear the DONTCACHE flag so that
the incore inode will be kept around until memory pressure forces it out
of memory. This increases the chances that the sick status will be
caught by someone compiling a health report later on.
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Carlos Maiolino <cmaiolino@redhat.com>
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While running some fuzz tests on inode metadata, I noticed that the
filesystem health report (as provided by xfs_spaceman) failed to report
the file corruption even when spaceman was run immediately after running
xfs_scrub to detect the corruption. That isn't the intended behavior;
one ought to be able to run scrub to detect errors in the ondisk
metadata and be able to access to those reports for some time after the
scrub.
After running the same sequence through an instrumented kernel, I
discovered the reason why -- scrub igets the file, scans it, marks it
sick, and ireleases the inode. When the VFS lets go of the incore
inode, it moves to RECLAIMABLE state. If spaceman igets the incore
inode before it moves to RECLAIM state, iget reinitializes the VFS
state, clears the sick and checked masks, and hands back the inode. At
this point, the caller has the exact same incore inode, but with all the
health state erased.
In other words, we're erasing the incore inode's health state flags when
we've decided NOT to sever the link between the incore inode and the
ondisk inode. This is wrong, so we need to remove the lines that zero
the fields from xfs_iget_cache_hit.
As a precaution, we add the same lines into xfs_reclaim_inode just after
we sever the link between incore and ondisk inode. Strictly speaking
this isn't necessary because once an inode has gone through reclaim it
must go through xfs_inode_alloc (which also zeroes the state) and
xfs_iget is careful to check for mismatches between the inode it pulls
out of the radix tree and the one it wants.
Fixes: 6772c1f11206 ("xfs: track metadata health status")
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Brian Foster <bfoster@redhat.com>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Carlos Maiolino <cmaiolino@redhat.com>
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https://git.kernel.org/pub/scm/linux/kernel/git/djwong/xfs-linux into xfs-5.14-merge2
xfs: clean up incore inode walk functions
This ambitious series aims to cleans up redundant inode walk code in
xfs_icache.c, hide implementation details of the quotaoff dquot release
code, and eliminates indirect function calls from incore inode walks.
The first thing it does is to move all the code that quotaoff calls to
release dquots from all incore inodes into xfs_icache.c. Next, it
separates the goal of an inode walk from the actual radix tree tags that
may or may not be involved and drops the kludgy XFS_ICI_NO_TAG thing.
Finally, we split the speculative preallocation (blockgc) and quotaoff
dquot release code paths into separate functions so that we can keep the
implementations cohesive.
Christoph suggested last cycle that we 'simply' change quotaoff not to
allow deactivating quota entirely, but as these cleanups are to enable
one major change in behavior (deferred inode inactivation) I do not want
to add a second behavior change (quotaoff) as a dependency.
To be blunt: Additional cleanups are not in scope for this series.
Next, I made two observations about incore inode radix tree walks --
since there's a 1:1 mapping between the walk goal and the per-inode
processing function passed in, we can use the goal to make a direct call
to the processing function. Furthermore, the only caller to supply a
nonzero iter_flags argument is quotaoff, and there's only one INEW flag.
From that observation, I concluded that it's quite possible to remove
two parameters from the xfs_inode_walk* function signatures -- the
iter_flags, and the execute function pointer. The middle of the series
moves the INEW functionality into the one piece (quotaoff) that wants
it, and removes the indirect calls.
The final observation is that the inode reclaim walk loop is now almost
the same as xfs_inode_walk, so it's silly to maintain two copies. Merge
the reclaim loop code into xfs_inode_walk.
Lastly, refactor the per-ag radix tagging functions since there's
duplicated code that can be consolidated.
This series is a prerequisite for the next two patchsets, since deferred
inode inactivation will add another inode radix tree tag and iterator
function to xfs_inode_walk.
v2: walk the vfs inode list when running quotaoff instead of the radix
tree, then rework the (now completely internal) inode walk function
to take the tag as the main parameter.
v3: merge the reclaim loop into xfs_inode_walk, then consolidate the
radix tree tagging functions
v4: rebase to 5.13-rc4
v5: combine with the quotaoff patchset, reorder functions to minimize
forward declarations, split inode walk goals from radix tree tags
to reduce conceptual confusion
v6: start moving the inode cache code towards the xfs_icwalk prefix
* tag 'inode-walk-cleanups-5.14_2021-06-03' of https://git.kernel.org/pub/scm/linux/kernel/git/djwong/xfs-linux:
xfs: refactor per-AG inode tagging functions
xfs: merge xfs_reclaim_inodes_ag into xfs_inode_walk_ag
xfs: pass struct xfs_eofblocks to the inode scan callback
xfs: fix radix tree tag signs
xfs: make the icwalk processing functions clean up the grab state
xfs: clean up inode state flag tests in xfs_blockgc_igrab
xfs: remove indirect calls from xfs_inode_walk{,_ag}
xfs: remove iter_flags parameter from xfs_inode_walk_*
xfs: move xfs_inew_wait call into xfs_dqrele_inode
xfs: separate the dqrele_all inode grab logic from xfs_inode_walk_ag_grab
xfs: pass the goal of the incore inode walk to xfs_inode_walk()
xfs: rename xfs_inode_walk functions to xfs_icwalk
xfs: move the inode walk functions further down
xfs: detach inode dquots at the end of inactivation
xfs: move the quotaoff dqrele inode walk into xfs_icache.c
[djwong: added variable names to function declarations while fixing
merge conflicts]
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
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https://git.kernel.org/pub/scm/linux/kernel/git/djwong/xfs-linux into xfs-5.14-merge2
xfs: assorted fixes for 5.14, part 1
This branch contains the first round of various small fixes for 5.14.
* tag 'assorted-fixes-5.14-1_2021-06-03' of https://git.kernel.org/pub/scm/linux/kernel/git/djwong/xfs-linux:
xfs: don't take a spinlock unconditionally in the DIO fastpath
xfs: mark xfs_bmap_set_attrforkoff static
xfs: Remove redundant assignment to busy
xfs: sort variable alphabetically to avoid repeated declaration
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https://git.kernel.org/pub/scm/linux/kernel/git/djwong/xfs-linux into xfs-5.14-merge2
xfs: various unit conversions
Crafting the realtime file extent size hint fixes revealed various
opportunities to clean up unit conversions, so now that gets its own
series.
* tag 'unit-conversion-cleanups-5.14_2021-06-03' of https://git.kernel.org/pub/scm/linux/kernel/git/djwong/xfs-linux:
xfs: remove unnecessary shifts
xfs: clean up open-coded fs block unit conversions
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From: Dave Chinner <dchinner@redhat.com>
Stephen Rothwell reported this compiler warning from linux-next:
fs/xfs/libxfs/xfs_ialloc.c: In function 'xfs_difree_finobt':
fs/xfs/libxfs/xfs_ialloc.c:2032:20: warning: unused variable 'agi' [-Wunused-variable]
2032 | struct xfs_agi *agi = agbp->b_addr;
Which is fallout from agno -> perag conversions that were done in
this function. xfs_check_agi_freecount() is the only user of "agi"
in xfs_difree_finobt() now, and it only uses the agi to get the
current free inode count. We hold that in the perag structure, so
there's not need to directly reference the raw AGI to get this
information.
The btree cursor being passed to xfs_check_agi_freecount() has a
reference to the perag being operated on, so use that directly in
xfs_check_agi_freecount() rather than passing an AGI.
Fixes: 7b13c5155182 ("xfs: use perag for ialloc btree cursors")
Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Carlos Maiolino <cmaiolino@redhat.com>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
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git://git.kernel.org/pub/scm/linux/kernel/git/dgc/linux-xfs into xfs-5.14-merge2
xfs: initial agnumber -> perag conversions for shrink
If we want to use active references to the perag to be able to gate
shrink removing AGs and hence perags safely, we've got a fair bit of
work to do actually use perags in all the places we need to.
There's a lot of code that iterates ag numbers and then
looks up perags from that, often multiple times for the same perag
in the one operation. If we want to use reference counted perags for
access control, then we need to convert all these uses to perag
iterators, not agno iterators.
[Patches 1-4]
The first step of this is consolidating all the perag management -
init, free, get, put, etc into a common location. THis is spread all
over the place right now, so move it all into libxfs/xfs_ag.[ch].
This does expose kernel only bits of the perag to libxfs and hence
userspace, so the structures and code is rearranged to minimise the
number of ifdefs that need to be added to the userspace codebase.
The perag iterator in xfs_icache.c is promoted to a first class API
and expanded to the needs of the code as required.
[Patches 5-10]
These are the first basic perag iterator conversions and changes to
pass the perag down the stack from those iterators where
appropriate. A lot of this is obvious, simple changes, though in
some places we stop passing the perag down the stack because the
code enters into an as yet unconverted subsystem that still uses raw
AGs.
[Patches 11-16]
These replace the agno passed in the btree cursor for per-ag btree
operations with a perag that is passed to the cursor init function.
The cursor takes it's own reference to the perag, and the reference
is dropped when the cursor is deleted. Hence we get reference
coverage for the entire time the cursor is active, even if the code
that initialised the cursor drops it's reference before the cursor
or any of it's children (duplicates) have been deleted.
The first patch adds the perag infrastructure for the cursor, the
next four patches convert a btree cursor at a time, and the last
removes the agno from the cursor once it is unused.
[Patches 17-21]
These patches are a demonstration of the simplifications and
cleanups that come from plumbing the perag through interfaces that
select and then operate on a specific AG. In this case the inode
allocation algorithm does up to three walks across all AGs before it
either allocates an inode or fails. Two of these walks are purely
just to select the AG, and even then it doesn't guarantee inode
allocation success so there's a third walk if the selected AG
allocation fails.
These patches collapse the selection and allocation into a single
loop, simplifies the error handling because xfs_dir_ialloc() always
returns ENOSPC if no AG was selected for inode allocation or we fail
to allocate an inode in any AG, gets rid of xfs_dir_ialloc()
wrapper, converts inode allocation to run entirely from a single
perag instance, and then factors xfs_dialloc() into a much, much
simpler loop which is easy to understand.
Hence we end up with the same inode allocation logic, but it only
needs two complete iterations at worst, makes AG selection and
allocation atomic w.r.t. shrink and chops out out over 100 lines of
code from this hot code path.
[Patch 22]
Converts the unlink path to pass perags through it.
There's more conversion work to be done, but this patchset gets
through a large chunk of it in one hit. Most of the iterators are
converted, so once this is solidified we can move on to converting
these to active references for being able to free perags while the
fs is still active.
* tag 'xfs-perag-conv-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/dgc/linux-xfs: (23 commits)
xfs: remove xfs_perag_t
xfs: use perag through unlink processing
xfs: clean up and simplify xfs_dialloc()
xfs: inode allocation can use a single perag instance
xfs: get rid of xfs_dir_ialloc()
xfs: collapse AG selection for inode allocation
xfs: simplify xfs_dialloc_select_ag() return values
xfs: remove agno from btree cursor
xfs: use perag for ialloc btree cursors
xfs: convert allocbt cursors to use perags
xfs: convert refcount btree cursor to use perags
xfs: convert rmap btree cursor to using a perag
xfs: add a perag to the btree cursor
xfs: pass perags around in fsmap data dev functions
xfs: push perags through the ag reservation callouts
xfs: pass perags through to the busy extent code
xfs: convert secondary superblock walk to use perags
xfs: convert xfs_iwalk to use perag references
xfs: convert raw ag walks to use for_each_perag
xfs: make for_each_perag... a first class citizen
...
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git://git.kernel.org/pub/scm/linux/kernel/git/dgc/linux-xfs into xfs-5.14-merge2
xfs: buffer cache bulk page allocation
This patchset makes use of the new bulk page allocation interface to
reduce the overhead of allocating large numbers of pages in a
loop.
The first two patches are refactoring buffer memory allocation and
converting the uncached buffer path to use the same page allocation
path, followed by converting the page allocation path to use bulk
allocation.
The rest of the patches are then consolidation of the page
allocation and freeing code to simplify the code and remove a chunk
of unnecessary abstraction. This is largely based on a series of
changes made by Christoph Hellwig.
* tag 'xfs-buf-bulk-alloc-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/dgc/linux-xfs:
xfs: merge xfs_buf_allocate_memory
xfs: cleanup error handling in xfs_buf_get_map
xfs: get rid of xb_to_gfp()
xfs: simplify the b_page_count calculation
xfs: remove ->b_offset handling for page backed buffers
xfs: move page freeing into _xfs_buf_free_pages()
xfs: merge _xfs_buf_get_pages()
xfs: use alloc_pages_bulk_array() for buffers
xfs: use xfs_buf_alloc_pages for uncached buffers
xfs: split up xfs_buf_allocate_memory
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It only has one caller and is now a simple function, so merge it
into the caller.
Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
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Use a single goto label for freeing the buffer and returning an
error.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Dave Chinner <dchinner@redhat.com>
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Only used in one place, so just open code the logic in the macro.
Based on a patch from Christoph Hellwig.
Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
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Ever since we stopped using the Linux page cache to back XFS buffers
there is no need to take the start sector into account for
calculating the number of pages in a buffer, as the data always
start from the beginning of the buffer.
Signed-off-by: Christoph Hellwig <hch@lst.de>
[dgc: modified to suit this series]
Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
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->b_offset can only be non-zero for _XBF_KMEM backed buffers, so
remove all code dealing with it for page backed buffers.
Signed-off-by: Christoph Hellwig <hch@lst.de>
[dgc: modified to fit this patchset]
Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
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In preparation for adding another incore inode tree tag, refactor the
code that sets and clears tags from the per-AG inode tree and the tree
of per-AG structures, and remove the open-coded versions used by the
blockgc code.
Note: For reclaim, we now rely on the radix tree tags instead of the
reclaimable inode count more heavily than we used to. The conversion
should be fine, but the logic isn't 100% identical.
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
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Merge these two inode walk loops together, since they're pretty similar
now.
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
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Pass a pointer to the actual eofb structure around the inode scanner
functions instead of a void pointer, now that none of the functions is
used as a callback.
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
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Radix tree tags are supposed to be unsigned ints, so fix the callers.
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
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Soon we're going to be adding two new callers to the incore inode walk
code: reclaim of incore inodes, and (later) inactivation of inodes.
Both states operate on inodes that no longer have any VFS state, so we
need to move the xfs_irele calls into the processing functions.
In other words, icwalk processing functions are responsible for cleaning
up whatever state changes are made by the corresponding icwalk igrab
function that picked the inode for processing.
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
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Clean up the definition of which inode states are not eligible for
speculative preallocation garbage collecting by creating a private
#define. The deferred inactivation patchset will add two new entries to
the set of flags-to-ignore, so we want the definition not to end up a
cluttered mess.
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
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It turns out that there is a 1:1 mapping between the execute and goal
parameters that are passed to xfs_inode_walk_ag:
xfs_blockgc_scan_inode <=> XFS_ICWALK_BLOCKGC
xfs_dqrele_inode <=> XFS_ICWALK_DQRELE
Because of this exact correspondence, we don't need the execute function
pointer and can replace it with a direct call.
For the price of a forward static declaration, we can eliminate the
indirect function call. This likely has a negligible impact on
performance (since the execute function runs transactions), but it also
simplifies the function signature.
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
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The sole iter_flags is XFS_INODE_WALK_INEW_WAIT, and there are no users.
Remove the flag, and the parameter, and all the code that used it.
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
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Move the INEW wait into xfs_dqrele_inode so that we can drop the
iter_flags parameter in the next patch.
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
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Disentangle the dqrele_all inode grab code from the "generic" inode walk
grabbing code, and and use the opportunity to document why the dqrele
grab function does what it does. Since xfs_inode_walk_ag_grab is now
only used for blockgc, rename it to reflect that.
Ultimately, there will be four reasons to perform a walk of incore
inodes: quotaoff dquote releasing (dqrele), garbage collection of
speculative preallocations (blockgc), reclamation of incore inodes
(reclaim), and deferred inactivation (inodegc). Each of these four have
their own slightly different criteria for deciding if they want to
handle an inode, so it makes more sense to have four cohesive igrab
functions than one confusing parameteric grab function like we do now.
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
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As part of removing the indirect calls and radix tag implementation
details from the incore inode walk loop, create an enum to represent the
goal of the inode iteration. More immediately, this separate removes
the need for the "ICI_NOTAG" define which makes little sense.
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
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Shorten the prefix so that all the incore inode cache walk code has
"xfs_icwalk" in the name somewhere.
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
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Move the inode walk functions further down in the file to limit the
forward declarations to the two walk functions as we add new code that
uses the inode walks. We'll clean them out later (i.e. after the
deferred inode inactivation series).
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
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Once we're done with inactivating an inode, we're finished updating
metadata for that inode. This means that we can detach the dquots at
the end and not have to wait for reclaim to do it for us.
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
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The only external caller of xfs_inode_walk* happens in quotaoff, when we
want to walk all the incore inodes to detach the dquots. Move this code
to xfs_icache.c so that we can hide xfs_inode_walk as the starting step
in more cleanups of inode walks.
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
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Because this happens at high thread counts on high IOPS devices
doing mixed read/write AIO-DIO to a single file at about a million
iops:
64.09% 0.21% [kernel] [k] io_submit_one
- 63.87% io_submit_one
- 44.33% aio_write
- 42.70% xfs_file_write_iter
- 41.32% xfs_file_dio_write_aligned
- 25.51% xfs_file_write_checks
- 21.60% _raw_spin_lock
- 21.59% do_raw_spin_lock
- 19.70% __pv_queued_spin_lock_slowpath
This also happens of the IO completion IO path:
22.89% 0.69% [kernel] [k] xfs_dio_write_end_io
- 22.49% xfs_dio_write_end_io
- 21.79% _raw_spin_lock
- 20.97% do_raw_spin_lock
- 20.10% __pv_queued_spin_lock_slowpath
IOWs, fio is burning ~14 whole CPUs on this spin lock.
So, do an unlocked check against inode size first, then if we are
at/beyond EOF, take the spinlock and recheck. This makes the
spinlock disappear from the overwrite fastpath.
I'd like to report that fixing this makes things go faster. It
doesn't - it just exposes the the XFS_ILOCK as the next severe
contention point doing extent mapping lookups, and that now burns
all the 14 CPUs this spinlock was burning.
Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Carlos Maiolino <cmaiolino@redhat.com>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
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xfs_bmap_set_attrforkoff is only used inside of xfs_bmap.c, so mark it
static.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
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