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Similar to what we've just done for the other btrees, create a function
to log corrupt bmbt records and call it whenever we encounter a bad
record in the ondisk btree.
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
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For every btree type except for the bmbt, refactor the code that
complains about bad records into a helper and make the ->query_range
helpers call it so that corruptions found via that avenue are logged.
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
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Fix all xfs_bmbt_disk_get_all callsites to call xfs_bmap_validate_extent
and bubble up corruption reports.
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
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Create a xfs_rmap_check_irec function to detect corruption in btree
records. Fix all xfs_rmap_btrec_to_irec callsites to call the new
helper and bubble up corruption reports.
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
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Currently, xfs_rmap_irec_offset_unpack returns only 0 or -EFSCORRUPTED.
Change this function to return the code address of a failed conversion
in preparation for the next patch, which standardizes localized record
checking and reporting code.
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
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Create a xfs_refcount_check_irec function to detect corruption in btree
records. Fix all xfs_refcount_btrec_to_irec callsites to call the new
helper and bubble up corruption reports.
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
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Create a xfs_inobt_check_irec function to detect corruption in btree
records. Fix all xfs_inobt_btrec_to_irec callsites to call the new
helper and bubble up corruption reports.
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
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Create a xfs_alloc_btrec_to_irec function to convert an ondisk record to
an incore record, and a xfs_alloc_check_irec function to detect
corruption. Replace all the open-coded logic with calls to the new
helpers and bubble up corruption reports.
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
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In the previous patch, we added jump labels to the intent drain code so
that regular filesystem operations need not pay the price of checking
for someone (scrub) waiting on intents to drain from some part of the
filesystem when that someone isn't running.
However, I observed that xfs/285 now spends a lot more time pushing the
AIL from the inode btree scrubber than it used to. This is because the
inobt scrubber will try push the AIL to try to get logged inode cores
written to the filesystem when it sees a weird discrepancy between the
ondisk inode and the inobt records. This AIL push is triggered when the
setup function sees TRY_HARDER is set; and the requisite EDEADLOCK
return is initiated when the discrepancy is seen.
The solution to this performance slow down is to use a different result
code (ECHRNG) for scrub code to signal that it needs to wait for
deferred intent work items to drain out of some part of the filesystem.
When this happens, set a new scrub state flag (XCHK_NEED_DRAIN) so that
setup functions will activate the jump label.
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
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To reduce the runtime overhead even further when online fsck isn't
running, use a static branch key to decide if we call wake_up on the
drain. For compilers that support jump labels, the call to wake_up is
replaced by a nop sled when nobody is waiting for intents to drain.
From my initial microbenchmarking, every transition of the static key
between the on and off states takes about 22000ns to complete; this is
paid entirely by the xfs_scrub process. When the static key is off
(which it should be when fsck isn't running), the nop sled adds an
overhead of approximately 0.36ns to runtime code.
For the few compilers that don't support jump labels, runtime code pays
the cost of calling wake_up on an empty waitqueue, which was observed to
be about 30ns. However, most architectures that have sufficient memory
and CPU capacity to run XFS also support jump labels, so this is not
much of a worry.
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
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It has been a longstanding convention that online scrub and repair
functions can return -EDEADLOCK to signal that they weren't able to
obtain some necessary resource. When this happens, the scrub framework
is supposed to release all resources attached to the scrub context, set
the TRY_HARDER flag in the scrub context flags, and try again. In this
context, individual scrub functions are supposed to take all the
resources they (incorrectly) speculated were not necessary.
We're about to make it so that the functions that lock and wait for a
filesystem AG can also return EDEADLOCK to signal that we need to try
again with the drain waiters enabled. Therefore, refactor
xfs_scrub_metadata to support this behavior for ->setup() functions.
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
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When a writer thread executes a chain of log intent items, the AG header
buffer locks will cycle during a transaction roll to get from one intent
item to the next in a chain. Although scrub takes all AG header buffer
locks, this isn't sufficient to guard against scrub checking an AG while
that writer thread is in the middle of finishing a chain because there's
no higher level locking primitive guarding allocation groups.
When there's a collision, cross-referencing between data structures
(e.g. rmapbt and refcountbt) yields false corruption events; if repair
is running, this results in incorrect repairs, which is catastrophic.
Fix this by adding to the perag structure the count of active intents
and make scrub wait until it has both AG header buffer locks and the
intent counter reaches zero.
One quirk of the drain code is that deferred bmap updates also bump and
drop the intent counter. A fundamental decision made during the design
phase of the reverse mapping feature is that updates to the rmapbt
records are always made by the same code that updates the primary
metadata. In other words, callers of bmapi functions expect that the
bmapi functions will queue deferred rmap updates.
Some parts of the reflink code queue deferred refcount (CUI) and bmap
(BUI) updates in the same head transaction, but the deferred work
manager completely finishes the CUI before the BUI work is started. As
a result, the CUI drops the intent count long before the deferred rmap
(RUI) update even has a chance to bump the intent count. The only way
to keep the intent count elevated between the CUI and RUI is for the BUI
to bump the counter until the RUI has been created.
A second quirk of the intent drain code is that deferred work items must
increment the intent counter as soon as the work item is added to the
transaction. When a BUI completes and queues an RUI, the RUI must
increment the counter before the BUI decrements it. The only way to
accomplish this is to require that the counter be bumped as soon as the
deferred work item is created in memory.
In the next patches we'll improve on this facility, but this patch
provides the basic functionality.
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
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Add a new tracepoint so that I can see exactly what and where we failed
the refcount check.
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
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There a few object constructor functions throughout XFS where a caller
provides an active perag reference and the constructor wants to give the
new object its own active reference. Replace the open-coded logic with
a common function to do this instead of open-coding atomic_inc logic.
This new function adds a few safeguards -- it checks that there's at
least one active reference to the perag structure passed in, and it
records the refcount bump in the ftrace information. This makes it much
easier to debug refcounting problems.
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
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Give the xfs_refcount_intent an active reference to the perag structure
data. This reference will be used to enable scrub intent draining
functionality in subsequent patches. Later, shrink will use these
active references to know if an AG is quiesced or not.
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
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Give the xfs_rmap_intent an active reference to the perag structure
data. This reference will be used to enable scrub intent draining
functionality in subsequent patches. Later, shrink will use these
active references to know if an AG is quiesced or not.
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
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Give the xfs_extfree_intent an active reference to the perag structure
data. This reference will be used to enable scrub intent draining
functionality in subsequent patches. Later, shrink will use these
active references to know if an AG is quiesced or not.
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
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Pass a reference to the per-AG structure to xfs_free_extent. Most
callers already have one, so we can eliminate unnecessary lookups. The
one exception to this is the EFI code, which the next patch will fix.
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
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Give the xfs_bmap_intent an active reference to the perag structure
data. This reference will be used to enable scrub intent draining
functionality in subsequent patches. Later, shrink will use these
active references to know if an AG is quiesced or not.
The reason why we take an active ref for a file mapping operation is
simple: we're committing to some sort of action involving space in an
AG, so we want to indicate our active interest in that AG.
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
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Variable names in this code module are inconsistent and confusing.
xfs_phys_extent describe physical mappings, so rename them "pmap".
xfs_refcount_intents describe refcount intents, so rename them "ri".
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
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Pass the incore refcount intent through the CUI logging code instead of
repeatedly boxing and unboxing parameters.
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
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Variable names in this code module are inconsistent and confusing.
xfs_map_extent describe file mappings, so rename them "map".
xfs_rmap_intents describe block mapping intents, so rename them "ri".
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
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Pass the incore rmap space mapping through the RUI logging code instead
of repeatedly boxing and unboxing parameters.
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
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Change the name of all pointers to xfs_extent_item structures to "xefi"
to make the name consistent and because the current selections ("new"
and "free") mean other things in C.
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
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Pass the incore xfs_extent_free_item through the EFI logging code
instead of repeatedly boxing and unboxing parameters.
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
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Variable names in this code module are inconsistent and confusing.
xfs_map_extent describe file mappings, so rename them "map".
xfs_bmap_intents describe block mapping intents, so rename them "bi".
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
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Instead of repeatedly boxing and unboxing the incore extent mapping
structure as it passes through the BUI code, pass the pointer directly
through.
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
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If we tried to repair something but the repair failed with -EDEADLOCK,
that means that the repair function couldn't grab some resource it
needed and wants us to try again. If we try again (with TRY_HARDER) but
still can't get all the resources we need, the repair fails and errors
remain on the filesystem.
Right now, repair returns the -EDEADLOCK to the caller as -EFSCORRUPTED,
which results in XFS_SCRUB_OFLAG_CORRUPT being passed out to userspace.
This is not correct because repair has not determined that anything is
corrupt. If the repair had been invoked on an object that could be
optimized but wasn't corrupt (OFLAG_PREEN), the inability to grab
resources will be reported to userspace as corrupt metadata, and users
will be unnecessarily alarmed that their suboptimal metadata turned into
a corruption.
Fix this by returning zero so that the results of the actual scrub will
be copied back out to userspace.
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
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-Wuninitialized complains about @target in xfsaild_push being
uninitialized in the case where the waitqueue is active but there is no
last item in the AIL to wait for. I /think/ it should never be the case
that the subsequent xfs_trans_ail_cursor_first returns a log item and
hence we'll never end up at XFS_LSN_CMP, but let's make this explicit.
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
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When -Wstringop-truncation is enabled, the compiler complains about
truncation of the null byte at the end of the xattr name prefix. This
is intentional, since we're concatenating the two strings together and
do _not_ want a null byte in the middle of the name.
We've already ensured that the name buffer is long enough to handle
prefix and name, and the prefix_len is supposed to be the length of the
prefix string without the null byte, so use memcpy here instead.
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
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Add the seventh and final chapter of the online fsck documentation,
where we talk about future functionality that can tie in with the
functionality provided by the online fsck patchset.
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
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Add the sixth chapter of the online fsck design documentation, where
we discuss the details of the data structures and algorithms used by the
driver program xfs_scrub.
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
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Directory tree repairs are the least complete part of online fsck, due
to the lack of directory parent pointers. However, even without that
feature, we can still make some corrections to the directory tree -- we
can salvage as many directory entries as we can from a damaged
directory, and we can reattach orphaned inodes to the lost+found, just
as xfs_repair does now.
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
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File-based metadata (such as xattrs and directories) can be extremely
large. To reduce the memory requirements and maximize code reuse, it is
very convenient to create a temporary file, use the regular dir/attr
code to store salvaged information, and then atomically swap the extents
between the file being repaired and the temporary file. Record the high
level concepts behind how temporary files and atomic content swapping
should work, and then present some case studies of what the actual
repair functions do.
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
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Certain parts of the online fsck code need to scan every file in the
entire filesystem. It is not acceptable to block the entire filesystem
while this happens, which means that we need to be clever in allowing
scans to coordinate with ongoing filesystem updates. We also need to
hook the filesystem so that regular updates propagate to the staging
records.
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
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Add to the fifth chapter of the online fsck design documentation, where
we discuss the details of the data structures and algorithms used by the
kernel to repair file metadata.
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
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Add a discussion of the btree bulk loading code, which makes it easy to
take an in-memory recordset and write it out to disk in an efficient
manner. This also enables atomic switchover from the old to the new
structure with minimal potential for leaking the old blocks.
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
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Add a discussion of pageable kernel memory, since online fsck needs
quite a bit more memory than most other parts of the filesystem to stage
records and other information.
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
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Writes to an XFS filesystem employ an eventual consistency update model
to break up complex multistep metadata updates into small chained
transactions. This is generally good for performance and scalability
because XFS doesn't need to prepare for enormous transactions, but it
also means that online fsck must be careful not to attempt a fsck action
unless it can be shown that there are no other threads processing a
transaction chain. This part of the design documentation covers the
thinking behind the consistency model and how scrub deals with it.
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
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Begin the fifth chapter of the online fsck design documentation, where
we discuss the details of the data structures and algorithms used by the
kernel to examine filesystem metadata and cross-reference it around the
filesystem.
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
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Start the fourth chapter of the online fsck design documentation, which
discusses the user interface and the background scrubbing service.
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
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Start the third chapter of the online fsck design documentation. This
covers the testing plan to make sure that both online and offline fsck
can detect arbitrary problems and correct them without making things
worse.
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
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Start the second chapter of the online fsck design documentation.
This covers the general theory underlying how online fsck works.
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
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Start the first chapter of the online fsck design documentation.
This covers the motivations for creating this in the first place.
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
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As of now only device names are printed out over __xfs_printk().
The device names are not persistent across reboots which in case
of searching for origin of corruption brings another task to properly
identify the devices. This patch add XFS UUID upon every mount/umount
event which will make the identification much easier.
Signed-off-by: Lukas Herbolt <lukas@herbolt.com>
[sandeen: rebase onto current upstream kernel]
Signed-off-by: Eric Sandeen <sandeen@redhat.com>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
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Clean up resources if resetting the dotdot entry doesn't succeed.
Observed through code inspection.
Fixes: 5838d0356bb3 ("xfs: reset child dir '..' entry when unlinking child")
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Andrey Albershteyn <aalbersh@redhat.com>
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CoW forks only exist in memory, which means that they can only ever have
an incore extent tree. Hence they must always be FMT_EXTENTS, so check
this when we're scrubbing them.
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
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Ensure that extents in an inode's CoW fork are not marked as shared in
the refcount btree.
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
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Teach scrub to flag quota files containing unwritten extents.
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
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Enhance the block map scrubber to check delayed allocation reservations.
Though there are no physical space allocations to check, we do need to
make sure that the range of file offsets being mapped are correct, and
to bump the lastoff cursor so that key order checking works correctly.
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
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