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An early performance analysis of the atomic file update code revealed an
astonishingly large number of deferred work items accumulating when
userspace requested an atomic update of two very fragmented files. The
cause of this was traced to a subtle ordering bug in the inner loop of
xfs_defer_finish_noroll.
If the ->finish_item method of a deferred operation queues new deferred
operations, those new deferred ops are appended to the tail of the
pending work list. To illustrate, say that a caller creates a
transaction t0 with four deferred operations D0-D3. The first thing
defer ops does is roll the transaction to t1, leaving us with:
t1: D0(t0), D1(t0), D2(t0), D3(t0)
Let's say that finishing each of D0-D3 will create two new deferred ops.
After finish D0 and roll, we'll have the following chain:
t2: D1(t0), D2(t0), D3(t0), d4(t1), d5(t1)
d4 and d5 were logged to t1. Notice that while we're about to start
work on D1, we haven't actually completed all the work implied by D0
being finished. So far we've been careful (or lucky) to structure the
dfops callers such that D1 doesn't depend on d4 or d5 being finished,
but this is a potential logic bomb.
There's a second problem lurking. Let's see what happens as we finish
D1-D3:
t3: D2(t0), D3(t0), d4(t1), d5(t1), d6(t2), d7(t2)
t4: D3(t0), d4(t1), d5(t1), d6(t2), d7(t2), d8(t3), d9(t3)
t5: d4(t1), d5(t1), d6(t2), d7(t2), d8(t3), d9(t3), d10(t4), d11(t4)
Let's say that d4-d11 are simple work items that don't queue any other
operations, which means that we can complete each d4 and roll to t6:
t6: d5(t1), d6(t2), d7(t2), d8(t3), d9(t3), d10(t4), d11(t4)
t7: d6(t2), d7(t2), d8(t3), d9(t3), d10(t4), d11(t4)
...
t11: d10(t4), d11(t4)
t12: d11(t4)
<done>
When we try to roll to transaction #12, we're holding defer op d11,
which we logged way back in t4. This means that the tail of the log is
pinned at t4. If the log is very small or there are a lot of other
threads updating metadata, this means that we might have wrapped the log
and cannot get roll to t11 because there isn't enough space left before
we'd run into t4.
Let's shift back to the original failure. I mentioned before that I
discovered this flaw while developing the atomic file update code. In
that scenario, we have a defer op (D0) that finds a range of file blocks
to remap, creates a handful of new defer ops to do that, and then asks
to be continued with however much work remains.
So, D0 is the original swapext deferred op. The first thing defer ops
does is rolls to t1:
t1: D0(t0)
We try to finish D0, logging d1 and d2 in the process, but can't get all
the work done. We log a done item and a new intent item for the work
that D0 still has to do, and roll to t2:
t2: D0'(t1), d1(t1), d2(t1)
We roll and try to finish D0', but still can't get all the work done, so
we log a done item and a new intent item for it, requeue D0 a second
time, and roll to t3:
t3: D0''(t2), d1(t1), d2(t1), d3(t2), d4(t2)
If it takes 48 more rolls to complete D0, then we'll finally dispense
with D0 in t50:
t50: D<fifty primes>(t49), d1(t1), ..., d102(t50)
We then try to roll again to get a chain like this:
t51: d1(t1), d2(t1), ..., d101(t50), d102(t50)
...
t152: d102(t50)
<done>
Notice that in rolling to transaction #51, we're holding on to a log
intent item for d1 that was logged in transaction #1. This means that
the tail of the log is pinned at t1. If the log is very small or there
are a lot of other threads updating metadata, this means that we might
have wrapped the log and cannot roll to t51 because there isn't enough
space left before we'd run into t1. This is of course problem #2 again.
But notice the third problem with this scenario: we have 102 defer ops
tied to this transaction! Each of these items are backed by pinned
kernel memory, which means that we risk OOM if the chains get too long.
Yikes. Problem #1 is a subtle logic bomb that could hit someone in the
future; problem #2 applies (rarely) to the current upstream, and problem
#3 applies to work under development.
This is not how incremental deferred operations were supposed to work.
The dfops design of logging in the same transaction an intent-done item
and a new intent item for the work remaining was to make it so that we
only have to juggle enough deferred work items to finish that one small
piece of work. Deferred log item recovery will find that first
unfinished work item and restart it, no matter how many other intent
items might follow it in the log. Therefore, it's ok to put the new
intents at the start of the dfops chain.
For the first example, the chains look like this:
t2: d4(t1), d5(t1), D1(t0), D2(t0), D3(t0)
t3: d5(t1), D1(t0), D2(t0), D3(t0)
...
t9: d9(t7), D3(t0)
t10: D3(t0)
t11: d10(t10), d11(t10)
t12: d11(t10)
For the second example, the chains look like this:
t1: D0(t0)
t2: d1(t1), d2(t1), D0'(t1)
t3: d2(t1), D0'(t1)
t4: D0'(t1)
t5: d1(t4), d2(t4), D0''(t4)
...
t148: D0<50 primes>(t147)
t149: d101(t148), d102(t148)
t150: d102(t148)
<done>
This actually sucks more for pinning the log tail (we try to roll to t10
while holding an intent item that was logged in t1) but we've solved
problem #1. We've also reduced the maximum chain length from:
sum(all the new items) + nr_original_items
to:
max(new items that each original item creates) + nr_original_items
This solves problem #3 by sharply reducing the number of defer ops that
can be attached to a transaction at any given time. The change makes
the problem of log tail pinning worse, but is improvement we need to
solve problem #2. Actually solving #2, however, is left to the next
patch.
Note that a subsequent analysis of some hard-to-trigger reflink and COW
livelocks on extremely fragmented filesystems (or systems running a lot
of IO threads) showed the same symptoms -- uncomfortably large numbers
of incore deferred work items and occasional stalls in the transaction
grant code while waiting for log reservations. I think this patch and
the next one will also solve these problems.
As originally written, the code used list_splice_tail_init instead of
list_splice_init, so change that, and leave a short comment explaining
our actions.
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
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In xfs_bui_item_recover, there exists a use-after-free bug with regards
to the inode that is involved in the bmap replay operation. If the
mapping operation does not complete, we call xfs_bmap_unmap_extent to
create a deferred op to finish the unmapping work, and we retain a
pointer to the incore inode.
Unfortunately, the very next thing we do is commit the transaction and
drop the inode. If reclaim tears down the inode before we try to finish
the defer ops, we dereference garbage and blow up. Therefore, create a
way to join inodes to the defer ops freezer so that we can maintain the
xfs_inode reference until we're done with the inode.
Note: This imposes the requirement that there be enough memory to keep
every incore inode in memory throughout recovery.
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
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In most places in XFS, we have a specific order in which we gather
resources: grab the inode, allocate a transaction, then lock the inode.
xfs_bui_item_recover doesn't do it in that order, so fix it to be more
consistent. This also makes the error bailout code a bit less weird.
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
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The bmap intent item checking code in xfs_bui_item_recover is spread all
over the function. We should check the recovered log item at the top
before we allocate any resources or do anything else, so do that.
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
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When xfs_defer_capture extracts the deferred ops and transaction state
from a transaction, it should absorb the remaining block reservation so
that when we continue the dfops chain, we still have those blocks to
use.
This adds the requirement that every log intent item recovery function
must be careful to reserve enough blocks to handle both itself and all
defer ops that it can queue. On the other hand, this enables us to do
away with the handwaving block estimation nonsense that was going on in
xlog_finish_defer_ops.
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
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When we replay unfinished intent items that have been recovered from the
log, it's possible that the replay will cause the creation of more
deferred work items. As outlined in commit 509955823cc9c ("xfs: log
recovery should replay deferred ops in order"), later work items have an
implicit ordering dependency on earlier work items. Therefore, recovery
must replay the items (both recovered and created) in the same order
that they would have been during normal operation.
For log recovery, we enforce this ordering by using an empty transaction
to collect deferred ops that get created in the process of recovering a
log intent item to prevent them from being committed before the rest of
the recovered intent items. After we finish committing all the
recovered log items, we allocate a transaction with an enormous block
reservation, splice our huge list of created deferred ops into that
transaction, and commit it, thereby finishing all those ops.
This is /really/ hokey -- it's the one place in XFS where we allow
nested transactions; the splicing of the defer ops list is is inelegant
and has to be done twice per recovery function; and the broken way we
handle inode pointers and block reservations cause subtle use-after-free
and allocator problems that will be fixed by this patch and the two
patches after it.
Therefore, replace the hokey empty transaction with a structure designed
to capture each chain of deferred ops that are created as part of
recovering a single unfinished log intent. Finally, refactor the loop
that replays those chains to do so using one transaction per chain.
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
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Move the double-inode locking helpers to xfs_inode.c since they're not
specific to reflink.
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Brian Foster <bfoster@redhat.com>
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Refactor the two functions that we use to lock and unlock two inodes to
block userspace from initiating IO against a file, whether via system
calls or mmap activity.
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Brian Foster <bfoster@redhat.com>
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Fix the return value of xfs_reflink_remap_prep so that its return value
conventions match the rest of xfs.
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Brian Foster <bfoster@redhat.com>
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If the source and destination map are identical, we can skip the remap
step to save some time.
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
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When logging quota block count updates during a reflink operation, we
only log the /delta/ of the block count changes to the dquot. Since we
now know ahead of time the extent type of both dmap and smap (and that
they have the same length), we know that we only need to reserve quota
blocks for dmap's blockcount if we're mapping it into a hole.
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
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Now that we've reworked xfs_reflink_remap_extent to remap only one
extent per transaction, we actually know if the extent being removed is
an allocated mapping. This means that we now know ahead of time if
we're going to be touching the data fork.
Since we only need blocks for a bmbt split if we're going to update the
data fork, we only need to get quota reservation if we know we're going
to touch the data fork.
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
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The existing reflink remapping loop has some structural problems that
need addressing:
The biggest problem is that we create one transaction for each extent in
the source file without accounting for the number of mappings there are
for the same range in the destination file. In other words, we don't
know the number of remap operations that will be necessary and we
therefore cannot guess the block reservation required. On highly
fragmented filesystems (e.g. ones with active dedupe) we guess wrong,
run out of block reservation, and fail.
The second problem is that we don't actually use the bmap intents to
their full potential -- instead of calling bunmapi directly and having
to deal with its backwards operation, we could call the deferred ops
xfs_bmap_unmap_extent and xfs_refcount_decrease_extent instead. This
makes the frontend loop much simpler.
Solve all of these problems by refactoring the remapping loops so that
we only perform one remapping operation per transaction, and each
operation only tries to remap a single extent from source to dest.
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
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The name of this predicate is a little misleading -- it decides if the
extent mapping is allocated and written. Change the name to be more
direct, as we're going to add a new predicate in the next patch.
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
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Quota reservations are supposed to account for the blocks that might be
allocated due to a bmap btree split. Reflink doesn't do this, so fix
this to make the quota accounting more accurate before we start
rearranging things.
Fixes: 862bb360ef56 ("xfs: reflink extents from one file to another")
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
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The data fork scrubber calls filemap_write_and_wait to flush dirty pages
and delalloc reservations out to disk prior to checking the data fork's
extent mappings. Unfortunately, this means that scrub can consume the
EIO/ENOSPC errors that would otherwise have stayed around in the address
space until (we hope) the writer application calls fsync to persist data
and collect errors. The end result is that programs that wrote to a
file might never see the error code and proceed as if nothing were
wrong.
xfs_scrub is not in a position to notify file writers about the
writeback failure, and it's only here to check metadata, not file
contents. Therefore, if writeback fails, we should stuff the error code
back into the address space so that an fsync by the writer application
can pick that up.
Fixes: 99d9d8d05da2 ("xfs: scrub inode block mappings")
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
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git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace
Pull tracing fixes from Steven Rostedt:
- Have recordmcount work with > 64K sections (to support LTO)
- kprobe RCU fixes
- Correct a kprobe critical section with missing mutex
- Remove redundant arch_disarm_kprobe() call
- Fix lockup when kretprobe triggers within kprobe_flush_task()
- Fix memory leak in fetch_op_data operations
- Fix sleep in atomic in ftrace trace array sample code
- Free up memory on failure in sample trace array code
- Fix incorrect reporting of function_graph fields in format file
- Fix quote within quote parsing in bootconfig
- Fix return value of bootconfig tool
- Add testcases for bootconfig tool
- Fix maybe uninitialized warning in ftrace pid file code
- Remove unused variable in tracing_iter_reset()
- Fix some typos
* tag 'trace-v5.8-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace:
ftrace: Fix maybe-uninitialized compiler warning
tools/bootconfig: Add testcase for show-command and quotes test
tools/bootconfig: Fix to return 0 if succeeded to show the bootconfig
tools/bootconfig: Fix to use correct quotes for value
proc/bootconfig: Fix to use correct quotes for value
tracing: Remove unused event variable in tracing_iter_reset
tracing/probe: Fix memleak in fetch_op_data operations
trace: Fix typo in allocate_ftrace_ops()'s comment
tracing: Make ftrace packed events have align of 1
sample-trace-array: Remove trace_array 'sample-instance'
sample-trace-array: Fix sleeping function called from invalid context
kretprobe: Prevent triggering kretprobe from within kprobe_flush_task
kprobes: Remove redundant arch_disarm_kprobe() call
kprobes: Fix to protect kick_kprobe_optimizer() by kprobe_mutex
kprobes: Use non RCU traversal APIs on kprobe_tables if possible
kprobes: Suppress the suspicious RCU warning on kprobes
recordmcount: support >64k sections
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The fileserver probe timer, net->fs_probe_timer, isn't cancelled when
the kafs module is being removed and so the count it holds on
net->servers_outstanding doesn't get dropped..
This causes rmmod to wait forever. The hung process shows a stack like:
afs_purge_servers+0x1b5/0x23c [kafs]
afs_net_exit+0x44/0x6e [kafs]
ops_exit_list+0x72/0x93
unregister_pernet_operations+0x14c/0x1ba
unregister_pernet_subsys+0x1d/0x2a
afs_exit+0x29/0x6f [kafs]
__do_sys_delete_module.isra.0+0x1a2/0x24b
do_syscall_64+0x51/0x95
entry_SYSCALL_64_after_hwframe+0x44/0xa9
Fix this by:
(1) Attempting to cancel the probe timer and, if successful, drop the
count that the timer was holding.
(2) Make the timer function just drop the count and not schedule the
prober if the afs portion of net namespace is being destroyed.
Also, whilst we're at it, make the following changes:
(3) Initialise net->servers_outstanding to 1 and decrement it before
waiting on it so that it doesn't generate wake up events by being
decremented to 0 until we're cleaning up.
(4) Switch the atomic_dec() on ->servers_outstanding for ->fs_timer in
afs_purge_servers() to use the helper function for that.
Fixes: f6cbb368bcb0 ("afs: Actively poll fileservers to maintain NAT or firewall openings")
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Fix afs_do_lookup()'s fallback case for when FS.InlineBulkStatus isn't
supported by the server.
In the fallback, it calls FS.FetchStatus for the specific vnode it's
meant to be looking up. Commit b6489a49f7b7 broke this by renaming one
of the two identically-named afs_fetch_status_operation descriptors to
something else so that one of them could be made non-static. The site
that used the renamed one, however, wasn't renamed and didn't produce
any warning because the other was declared in a header.
Fix this by making afs_do_lookup() use the renamed variant.
Note that there are two variants of the success method because one is
called from ->lookup() where we may or may not have an inode, but can't
call iget until after we've talked to the server - whereas the other is
called from within iget where we have an inode, but it may or may not be
initialised.
The latter variant expects there to be an inode, but because it's being
called from there former case, there might not be - resulting in an oops
like the following:
BUG: kernel NULL pointer dereference, address: 00000000000000b0
...
RIP: 0010:afs_fetch_status_success+0x27/0x7e
...
Call Trace:
afs_wait_for_operation+0xda/0x234
afs_do_lookup+0x2fe/0x3c1
afs_lookup+0x3c5/0x4bd
__lookup_slow+0xcd/0x10f
walk_component+0xa2/0x10c
path_lookupat.isra.0+0x80/0x110
filename_lookup+0x81/0x104
vfs_statx+0x76/0x109
__do_sys_newlstat+0x39/0x6b
do_syscall_64+0x4c/0x78
entry_SYSCALL_64_after_hwframe+0x44/0xa9
Fixes: b6489a49f7b7 ("afs: Fix silly rename")
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Pull io_uring fixes from Jens Axboe:
- Catch a case where io_sq_thread() didn't do proper mm acquire
- Ensure poll completions are reaped on shutdown
- Async cancelation and run fixes (Pavel)
- io-poll race fixes (Xiaoguang)
- Request cleanup race fix (Xiaoguang)
* tag 'io_uring-5.8-2020-06-19' of git://git.kernel.dk/linux-block:
io_uring: fix possible race condition against REQ_F_NEED_CLEANUP
io_uring: reap poll completions while waiting for refs to drop on exit
io_uring: acquire 'mm' for task_work for SQPOLL
io_uring: add memory barrier to synchronize io_kiocb's result and iopoll_completed
io_uring: don't fail links for EAGAIN error in IOPOLL mode
io_uring: cancel by ->task not pid
io_uring: lazy get task
io_uring: batch cancel in io_uring_cancel_files()
io_uring: cancel all task's requests on exit
io-wq: add an option to cancel all matched reqs
io-wq: reorder cancellation pending -> running
io_uring: fix lazy work init
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Pull block fixes from Jens Axboe:
- Use import_uuid() where appropriate (Andy)
- bcache fixes (Coly, Mauricio, Zhiqiang)
- blktrace sparse warnings fix (Jan)
- blktrace concurrent setup fix (Luis)
- blkdev_get use-after-free fix (Jason)
- Ensure all blk-mq maps are updated (Weiping)
- Loop invalidate bdev fix (Zheng)
* tag 'block-5.8-2020-06-19' of git://git.kernel.dk/linux-block:
block: make function 'kill_bdev' static
loop: replace kill_bdev with invalidate_bdev
partitions/ldm: Replace uuid_copy() with import_uuid() where it makes sense
block: update hctx map when use multiple maps
blktrace: Avoid sparse warnings when assigning q->blk_trace
blktrace: break out of blktrace setup on concurrent calls
block: Fix use-after-free in blkdev_get()
trace/events/block.h: drop kernel-doc for dropped function parameter
blk-mq: Remove redundant 'return' statement
bcache: pr_info() format clean up in bcache_device_init()
bcache: use delayed kworker fo asynchronous devices registration
bcache: check and adjust logical block size for backing devices
bcache: fix potential deadlock problem in btree_gc_coalesce
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Merge non-faulting memory access cleanups from Christoph Hellwig:
"Andrew and I decided to drop the patches implementing your suggested
rename of the probe_kernel_* and probe_user_* helpers from -mm as
there were way to many conflicts.
After -rc1 might be a good time for this as all the conflicts are
resolved now"
This also adds a type safety checking patch on top of the renaming
series to make the subtle behavioral difference between 'get_user()' and
'get_kernel_nofault()' less potentially dangerous and surprising.
* emailed patches from Christoph Hellwig <hch@lst.de>:
maccess: make get_kernel_nofault() check for minimal type compatibility
maccess: rename probe_kernel_address to get_kernel_nofault
maccess: rename probe_user_{read,write} to copy_{from,to}_user_nofault
maccess: rename probe_kernel_{read,write} to copy_{from,to}_kernel_nofault
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kill_bdev does not have any external user, so make it static.
Signed-off-by: Zheng Bin <zhengbin13@huawei.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Bart Van Assche <bvanassche@acm.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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In io_read() or io_write(), when io request is submitted successfully,
it'll go through the below sequence:
kfree(iovec);
req->flags &= ~REQ_F_NEED_CLEANUP;
return ret;
But clearing REQ_F_NEED_CLEANUP might be unsafe. The io request may
already have been completed, and then io_complete_rw_iopoll()
and io_complete_rw() will be called, both of which will also modify
req->flags if needed. This causes a race condition, with concurrent
non-atomic modification of req->flags.
To eliminate this race, in io_read() or io_write(), if io request is
submitted successfully, we don't remove REQ_F_NEED_CLEANUP flag. If
REQ_F_NEED_CLEANUP is set, we'll leave __io_req_aux_free() to the
iovec cleanup work correspondingly.
Cc: stable@vger.kernel.org
Signed-off-by: Xiaoguang Wang <xiaoguang.wang@linux.alibaba.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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If we're doing polled IO and end up having requests being submitted
async, then completions can come in while we're waiting for refs to
drop. We need to reap these manually, as nobody else will be looking
for them.
Break the wait into 1/20th of a second time waits, and check for done
poll completions if we time out. Otherwise we can have done poll
completions sitting in ctx->poll_list, which needs us to reap them but
we're just waiting for them.
Cc: stable@vger.kernel.org
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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If we're unlucky with timing, we could be running task_work after
having dropped the memory context in the sq thread. Since dropping
the context requires a runnable task state, we cannot reliably drop
it as part of our check-for-work loop in io_sq_thread(). Instead,
abstract out the mm acquire for the sq thread into a helper, and call
it from the async task work handler.
Cc: stable@vger.kernel.org # v5.7
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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iopoll_completed
In io_complete_rw_iopoll(), stores to io_kiocb's result and iopoll
completed are two independent store operations, to ensure that once
iopoll_completed is ture and then req->result must been perceived by
the cpu executing io_do_iopoll(), proper memory barrier should be used.
And in io_do_iopoll(), we check whether req->result is EAGAIN, if it is,
we'll need to issue this io request using io-wq again. In order to just
issue a single smp_rmb() on the completion side, move the re-submit work
to io_iopoll_complete().
Cc: stable@vger.kernel.org
Signed-off-by: Xiaoguang Wang <xiaoguang.wang@linux.alibaba.com>
[axboe: don't set ->iopoll_completed for -EAGAIN retry]
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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In IOPOLL mode, for EAGAIN error, we'll try to submit io request
again using io-wq, so don't fail rest of links if this io request
has links.
Cc: stable@vger.kernel.org
Signed-off-by: Xiaoguang Wang <xiaoguang.wang@linux.alibaba.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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Better describe what these functions do.
Suggested-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
|
|
Fix /proc/bootconfig to select double or single quotes
corrctly according to the value.
If a bootconfig value includes a double quote character,
we must use single-quotes to quote that value.
This modifies if() condition and blocks for avoiding
double-quote in value check in 2 places. Anyway, since
xbc_array_for_each_value() can handle the array which
has a single node correctly.
Thus,
if (vnode && xbc_node_is_array(vnode)) {
xbc_array_for_each_value(vnode) /* vnode->next != NULL */
...
} else {
snprintf(val); /* val is an empty string if !vnode */
}
is equivalent to
if (vnode) {
xbc_array_for_each_value(vnode) /* vnode->next can be NULL */
...
} else {
snprintf(""); /* value is always empty */
}
Link: http://lkml.kernel.org/r/159230244786.65555.3763894451251622488.stgit@devnote2
Cc: stable@vger.kernel.org
Fixes: c1a3c36017d4 ("proc: bootconfig: Add /proc/bootconfig to show boot config list")
Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
|
|
git://git.kernel.org/pub/scm/linux/kernel/git/dhowells/linux-fs
Pull AFS fixes from David Howells:
"I've managed to get xfstests kind of working with afs. Here are a set
of patches that fix most of the bugs found.
There are a number of primary issues:
- Incorrect handling of mtime and non-handling of ctime. It might be
argued, that the latter isn't a bug since the AFS protocol doesn't
support ctime, but I should probably still update it locally.
- Shared-write mmap, truncate and writeback bugs. This includes not
changing i_size under the callback lock, overwriting local i_size
with the reply from the server after a partial writeback, not
limiting the writeback from an mmapped page to EOF.
- Checks for an abort code indicating that the primary vnode in an
operation was deleted by a third-party are done in the wrong place.
- Silly rename bugs. This includes an incomplete conversion to the
new operation handling, duplicate nlink handling, nlink changing
not being done inside the callback lock and insufficient handling
of third-party conflicting directory changes.
And some secondary ones:
- The UAEOVERFLOW abort code should map to EOVERFLOW not EREMOTEIO.
- Remove a couple of unused or incompletely used bits.
- Remove a couple of redundant success checks.
These seem to fix all the data-corruption bugs found by
./check -afs -g quick
along with the obvious silly rename bugs and time bugs.
There are still some test failures, but they seem to fall into two
classes: firstly, the authentication/security model is different to
the standard UNIX model and permission is arbitrated by the server and
cached locally; and secondly, there are a number of features that AFS
does not support (such as mknod). But in these cases, the tests
themselves need to be adapted or skipped.
Using the in-kernel afs client with xfstests also found a bug in the
AuriStor AFS server that has been fixed for a future release"
* tag 'afs-fixes-20200616' of git://git.kernel.org/pub/scm/linux/kernel/git/dhowells/linux-fs:
afs: Fix silly rename
afs: afs_vnode_commit_status() doesn't need to check the RPC error
afs: Fix use of afs_check_for_remote_deletion()
afs: Remove afs_operation::abort_code
afs: Fix yfs_fs_fetch_status() to honour vnode selector
afs: Remove yfs_fs_fetch_file_status() as it's not used
afs: Fix the mapping of the UAEOVERFLOW abort code
afs: Fix truncation issues and mmap writeback size
afs: Concoct ctimes
afs: Fix EOF corruption
afs: afs_write_end() should change i_size under the right lock
afs: Fix non-setting of mtime when writing into mmap
|
|
git://git.kernel.org/pub/scm/linux/kernel/git/gustavoars/linux
Pull flexible-array member conversions from Gustavo A. R. Silva:
"Replace zero-length arrays with flexible-array members.
Notice that all of these patches have been baking in linux-next for
two development cycles now.
There is a regular need in the kernel to provide a way to declare
having a dynamically sized set of trailing elements in a structure.
Kernel code should always use “flexible array members”[1] for these
cases. The older style of one-element or zero-length arrays should no
longer be used[2].
C99 introduced “flexible array members”, which lacks a numeric size
for the array declaration entirely:
struct something {
size_t count;
struct foo items[];
};
This is the way the kernel expects dynamically sized trailing elements
to be declared. It allows the compiler to generate errors when the
flexible array does not occur last in the structure, which helps to
prevent some kind of undefined behavior[3] bugs from being
inadvertently introduced to the codebase.
It also allows the compiler to correctly analyze array sizes (via
sizeof(), CONFIG_FORTIFY_SOURCE, and CONFIG_UBSAN_BOUNDS). For
instance, there is no mechanism that warns us that the following
application of the sizeof() operator to a zero-length array always
results in zero:
struct something {
size_t count;
struct foo items[0];
};
struct something *instance;
instance = kmalloc(struct_size(instance, items, count), GFP_KERNEL);
instance->count = count;
size = sizeof(instance->items) * instance->count;
memcpy(instance->items, source, size);
At the last line of code above, size turns out to be zero, when one
might have thought it represents the total size in bytes of the
dynamic memory recently allocated for the trailing array items. Here
are a couple examples of this issue[4][5].
Instead, flexible array members have incomplete type, and so the
sizeof() operator may not be applied[6], so any misuse of such
operators will be immediately noticed at build time.
The cleanest and least error-prone way to implement this is through
the use of a flexible array member:
struct something {
size_t count;
struct foo items[];
};
struct something *instance;
instance = kmalloc(struct_size(instance, items, count), GFP_KERNEL);
instance->count = count;
size = sizeof(instance->items[0]) * instance->count;
memcpy(instance->items, source, size);
instead"
[1] https://en.wikipedia.org/wiki/Flexible_array_member
[2] https://github.com/KSPP/linux/issues/21
[3] commit 76497732932f ("cxgb3/l2t: Fix undefined behaviour")
[4] commit f2cd32a443da ("rndis_wlan: Remove logically dead code")
[5] commit ab91c2a89f86 ("tpm: eventlog: Replace zero-length array with flexible-array member")
[6] https://gcc.gnu.org/onlinedocs/gcc/Zero-Length.html
* tag 'flex-array-conversions-5.8-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/gustavoars/linux: (41 commits)
w1: Replace zero-length array with flexible-array
tracing/probe: Replace zero-length array with flexible-array
soc: ti: Replace zero-length array with flexible-array
tifm: Replace zero-length array with flexible-array
dmaengine: tegra-apb: Replace zero-length array with flexible-array
stm class: Replace zero-length array with flexible-array
Squashfs: Replace zero-length array with flexible-array
ASoC: SOF: Replace zero-length array with flexible-array
ima: Replace zero-length array with flexible-array
sctp: Replace zero-length array with flexible-array
phy: samsung: Replace zero-length array with flexible-array
RxRPC: Replace zero-length array with flexible-array
rapidio: Replace zero-length array with flexible-array
media: pwc: Replace zero-length array with flexible-array
firmware: pcdp: Replace zero-length array with flexible-array
oprofile: Replace zero-length array with flexible-array
block: Replace zero-length array with flexible-array
tools/testing/nvdimm: Replace zero-length array with flexible-array
libata: Replace zero-length array with flexible-array
kprobes: Replace zero-length array with flexible-array
...
|
|
Fix AFS's silly rename by the following means:
(1) Set the destination directory in afs_do_silly_rename() so as to avoid
misbehaviour and indicate that the directory data version will
increment by 1 so as to avoid warnings about unexpected changes in the
DV. Also indicate that the ctime should be updated to avoid xfstest
grumbling.
(2) Note when the server indicates that a directory changed more than we
expected (AFS_OPERATION_DIR_CONFLICT), indicating a conflict with a
third party change, checking on successful completion of unlink and
rename.
The problem is that the FS.RemoveFile RPC op doesn't report the status
of the unlinked file, though YFS.RemoveFile2 does. This can be
mitigated by the assumption that if the directory DV cranked by
exactly 1, we can be sure we removed one link from the file; further,
ordinarily in AFS, files cannot be hardlinked across directories, so
if we reduce nlink to 0, the file is deleted.
However, if the directory DV jumps by more than 1, we cannot know if a
third party intervened by adding or removing a link on the file we
just removed a link from.
The same also goes for any vnode that is at the destination of the
FS.Rename RPC op.
(3) Make afs_vnode_commit_status() apply the nlink drop inside the cb_lock
section along with the other attribute updates if ->op_unlinked is set
on the descriptor for the appropriate vnode.
(4) Issue a follow up status fetch to the unlinked file in the event of a
third party conflict that makes it impossible for us to know if we
actually deleted the file or not.
(5) Provide a flag, AFS_VNODE_SILLY_DELETED, to make afs_getattr() lie to
the user about the nlink of a silly deleted file so that it appears as
0, not 1.
Found with the generic/035 and generic/084 xfstests.
Fixes: e49c7b2f6de7 ("afs: Build an abstraction around an "operation" concept")
Reported-by: Marc Dionne <marc.dionne@auristor.com>
Signed-off-by: David Howells <dhowells@redhat.com>
|
|
In blkdev_get() we call __blkdev_get() to do some internal jobs and if
there is some errors in __blkdev_get(), the bdput() is called which
means we have released the refcount of the bdev (actually the refcount of
the bdev inode). This means we cannot access bdev after that point. But
acctually bdev is still accessed in blkdev_get() after calling
__blkdev_get(). This results in use-after-free if the refcount is the
last one we released in __blkdev_get(). Let's take a look at the
following scenerio:
CPU0 CPU1 CPU2
blkdev_open blkdev_open Remove disk
bd_acquire
blkdev_get
__blkdev_get del_gendisk
bdev_unhash_inode
bd_acquire bdev_get_gendisk
bd_forget failed because of unhashed
bdput
bdput (the last one)
bdev_evict_inode
access bdev => use after free
[ 459.350216] BUG: KASAN: use-after-free in __lock_acquire+0x24c1/0x31b0
[ 459.351190] Read of size 8 at addr ffff88806c815a80 by task syz-executor.0/20132
[ 459.352347]
[ 459.352594] CPU: 0 PID: 20132 Comm: syz-executor.0 Not tainted 4.19.90 #2
[ 459.353628] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.10.2-1ubuntu1 04/01/2014
[ 459.354947] Call Trace:
[ 459.355337] dump_stack+0x111/0x19e
[ 459.355879] ? __lock_acquire+0x24c1/0x31b0
[ 459.356523] print_address_description+0x60/0x223
[ 459.357248] ? __lock_acquire+0x24c1/0x31b0
[ 459.357887] kasan_report.cold+0xae/0x2d8
[ 459.358503] __lock_acquire+0x24c1/0x31b0
[ 459.359120] ? _raw_spin_unlock_irq+0x24/0x40
[ 459.359784] ? lockdep_hardirqs_on+0x37b/0x580
[ 459.360465] ? _raw_spin_unlock_irq+0x24/0x40
[ 459.361123] ? finish_task_switch+0x125/0x600
[ 459.361812] ? finish_task_switch+0xee/0x600
[ 459.362471] ? mark_held_locks+0xf0/0xf0
[ 459.363108] ? __schedule+0x96f/0x21d0
[ 459.363716] lock_acquire+0x111/0x320
[ 459.364285] ? blkdev_get+0xce/0xbe0
[ 459.364846] ? blkdev_get+0xce/0xbe0
[ 459.365390] __mutex_lock+0xf9/0x12a0
[ 459.365948] ? blkdev_get+0xce/0xbe0
[ 459.366493] ? bdev_evict_inode+0x1f0/0x1f0
[ 459.367130] ? blkdev_get+0xce/0xbe0
[ 459.367678] ? destroy_inode+0xbc/0x110
[ 459.368261] ? mutex_trylock+0x1a0/0x1a0
[ 459.368867] ? __blkdev_get+0x3e6/0x1280
[ 459.369463] ? bdev_disk_changed+0x1d0/0x1d0
[ 459.370114] ? blkdev_get+0xce/0xbe0
[ 459.370656] blkdev_get+0xce/0xbe0
[ 459.371178] ? find_held_lock+0x2c/0x110
[ 459.371774] ? __blkdev_get+0x1280/0x1280
[ 459.372383] ? lock_downgrade+0x680/0x680
[ 459.373002] ? lock_acquire+0x111/0x320
[ 459.373587] ? bd_acquire+0x21/0x2c0
[ 459.374134] ? do_raw_spin_unlock+0x4f/0x250
[ 459.374780] blkdev_open+0x202/0x290
[ 459.375325] do_dentry_open+0x49e/0x1050
[ 459.375924] ? blkdev_get_by_dev+0x70/0x70
[ 459.376543] ? __x64_sys_fchdir+0x1f0/0x1f0
[ 459.377192] ? inode_permission+0xbe/0x3a0
[ 459.377818] path_openat+0x148c/0x3f50
[ 459.378392] ? kmem_cache_alloc+0xd5/0x280
[ 459.379016] ? entry_SYSCALL_64_after_hwframe+0x49/0xbe
[ 459.379802] ? path_lookupat.isra.0+0x900/0x900
[ 459.380489] ? __lock_is_held+0xad/0x140
[ 459.381093] do_filp_open+0x1a1/0x280
[ 459.381654] ? may_open_dev+0xf0/0xf0
[ 459.382214] ? find_held_lock+0x2c/0x110
[ 459.382816] ? lock_downgrade+0x680/0x680
[ 459.383425] ? __lock_is_held+0xad/0x140
[ 459.384024] ? do_raw_spin_unlock+0x4f/0x250
[ 459.384668] ? _raw_spin_unlock+0x1f/0x30
[ 459.385280] ? __alloc_fd+0x448/0x560
[ 459.385841] do_sys_open+0x3c3/0x500
[ 459.386386] ? filp_open+0x70/0x70
[ 459.386911] ? trace_hardirqs_on_thunk+0x1a/0x1c
[ 459.387610] ? trace_hardirqs_off_caller+0x55/0x1c0
[ 459.388342] ? do_syscall_64+0x1a/0x520
[ 459.388930] do_syscall_64+0xc3/0x520
[ 459.389490] entry_SYSCALL_64_after_hwframe+0x49/0xbe
[ 459.390248] RIP: 0033:0x416211
[ 459.390720] Code: 75 14 b8 02 00 00 00 0f 05 48 3d 01 f0 ff ff 0f 83
04 19 00 00 c3 48 83 ec 08 e8 0a fa ff ff 48 89 04 24 b8 02 00 00 00 0f
05 <48> 8b 3c 24 48 89 c2 e8 53 fa ff ff 48 89 d0 48 83 c4 08 48 3d
01
[ 459.393483] RSP: 002b:00007fe45dfe9a60 EFLAGS: 00000293 ORIG_RAX: 0000000000000002
[ 459.394610] RAX: ffffffffffffffda RBX: 00007fe45dfea6d4 RCX: 0000000000416211
[ 459.395678] RDX: 00007fe45dfe9b0a RSI: 0000000000000002 RDI: 00007fe45dfe9b00
[ 459.396758] RBP: 000000000076bf20 R08: 0000000000000000 R09: 000000000000000a
[ 459.397930] R10: 0000000000000075 R11: 0000000000000293 R12: 00000000ffffffff
[ 459.399022] R13: 0000000000000bd9 R14: 00000000004cdb80 R15: 000000000076bf2c
[ 459.400168]
[ 459.400430] Allocated by task 20132:
[ 459.401038] kasan_kmalloc+0xbf/0xe0
[ 459.401652] kmem_cache_alloc+0xd5/0x280
[ 459.402330] bdev_alloc_inode+0x18/0x40
[ 459.402970] alloc_inode+0x5f/0x180
[ 459.403510] iget5_locked+0x57/0xd0
[ 459.404095] bdget+0x94/0x4e0
[ 459.404607] bd_acquire+0xfa/0x2c0
[ 459.405113] blkdev_open+0x110/0x290
[ 459.405702] do_dentry_open+0x49e/0x1050
[ 459.406340] path_openat+0x148c/0x3f50
[ 459.406926] do_filp_open+0x1a1/0x280
[ 459.407471] do_sys_open+0x3c3/0x500
[ 459.408010] do_syscall_64+0xc3/0x520
[ 459.408572] entry_SYSCALL_64_after_hwframe+0x49/0xbe
[ 459.409415]
[ 459.409679] Freed by task 1262:
[ 459.410212] __kasan_slab_free+0x129/0x170
[ 459.410919] kmem_cache_free+0xb2/0x2a0
[ 459.411564] rcu_process_callbacks+0xbb2/0x2320
[ 459.412318] __do_softirq+0x225/0x8ac
Fix this by delaying bdput() to the end of blkdev_get() which means we
have finished accessing bdev.
Fixes: 77ea887e433a ("implement in-kernel gendisk events handling")
Reported-by: Hulk Robot <hulkci@huawei.com>
Signed-off-by: Jason Yan <yanaijie@huawei.com>
Tested-by: Sedat Dilek <sedat.dilek@gmail.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Dan Carpenter <dan.carpenter@oracle.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Ming Lei <ming.lei@redhat.com>
Cc: Jan Kara <jack@suse.cz>
Cc: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
|
|
afs_vnode_commit_status() is only ever called if op->error is 0, so remove
the op->error checks from the function.
Fixes: e49c7b2f6de7 ("afs: Build an abstraction around an "operation" concept")
Signed-off-by: David Howells <dhowells@redhat.com>
|
|
afs_check_for_remote_deletion() checks to see if error ENOENT is returned
by the server in response to an operation and, if so, marks the primary
vnode as having been deleted as the FID is no longer valid.
However, it's being called from the operation success functions, where no
abort has happened - and if an inline abort is recorded, it's handled by
afs_vnode_commit_status().
Fix this by actually calling the operation aborted method if provided and
having that point to afs_check_for_remote_deletion().
Fixes: e49c7b2f6de7 ("afs: Build an abstraction around an "operation" concept")
Signed-off-by: David Howells <dhowells@redhat.com>
|
|
Remove afs_operation::abort_code as it's read but never set. Use
ac.abort_code instead.
Signed-off-by: David Howells <dhowells@redhat.com>
|
|
Fix yfs_fs_fetch_status() to honour the vnode selector in
op->fetch_status.which as does afs_fs_fetch_status() that allows
afs_do_lookup() to use this as an alternative to the InlineBulkStatus RPC
call if not implemented by the server.
This doesn't matter in the current code as YFS servers always implement
InlineBulkStatus, but a subsequent will call it on YFS servers too in some
circumstances.
Fixes: e49c7b2f6de7 ("afs: Build an abstraction around an "operation" concept")
Signed-off-by: David Howells <dhowells@redhat.com>
|
|
Remove yfs_fs_fetch_file_status() as it's no longer used.
Signed-off-by: David Howells <dhowells@redhat.com>
|
|
There is a regular need in the kernel to provide a way to declare having a
dynamically sized set of trailing elements in a structure. Kernel code should
always use “flexible array members”[1] for these cases. The older style of
one-element or zero-length arrays should no longer be used[2].
[1] https://en.wikipedia.org/wiki/Flexible_array_member
[2] https://github.com/KSPP/linux/issues/21
Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>
|
|
There is a regular need in the kernel to provide a way to declare having a
dynamically sized set of trailing elements in a structure. Kernel code should
always use “flexible array members”[1] for these cases. The older style of
one-element or zero-length arrays should no longer be used[2].
[1] https://en.wikipedia.org/wiki/Flexible_array_member
[2] https://github.com/KSPP/linux/issues/21
Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>
|
|
There is a regular need in the kernel to provide a way to declare having a
dynamically sized set of trailing elements in a structure. Kernel code should
always use “flexible array members”[1] for these cases. The older style of
one-element or zero-length arrays should no longer be used[2].
[1] https://en.wikipedia.org/wiki/Flexible_array_member
[2] https://github.com/KSPP/linux/issues/21
Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>
|
|
git://git.kernel.org/pub/scm/linux/kernel/git/tytso/ext4
Pull more ext4 updates from Ted Ts'o:
"This is the second round of ext4 commits for 5.8 merge window [1].
It includes the per-inode DAX support, which was dependant on the DAX
infrastructure which came in via the XFS tree, and a number of
regression and bug fixes; most notably the "BUG: using
smp_processor_id() in preemptible code in ext4_mb_new_blocks" reported
by syzkaller"
[1] The pull request actually came in 15 minutes after I had tagged the
rc1 release. Tssk, tssk, late.. - Linus
* tag 'ext4-for-linus-5.8-rc1-2' of git://git.kernel.org/pub/scm/linux/kernel/git/tytso/ext4:
ext4, jbd2: ensure panic by fix a race between jbd2 abort and ext4 error handlers
ext4: support xattr gnu.* namespace for the Hurd
ext4: mballoc: Use this_cpu_read instead of this_cpu_ptr
ext4: avoid utf8_strncasecmp() with unstable name
ext4: stop overwrite the errcode in ext4_setup_super
ext4: fix partial cluster initialization when splitting extent
ext4: avoid race conditions when remounting with options that change dax
Documentation/dax: Update DAX enablement for ext4
fs/ext4: Introduce DAX inode flag
fs/ext4: Remove jflag variable
fs/ext4: Make DAX mount option a tri-state
fs/ext4: Only change S_DAX on inode load
fs/ext4: Update ext4_should_use_dax()
fs/ext4: Change EXT4_MOUNT_DAX to EXT4_MOUNT_DAX_ALWAYS
fs/ext4: Disallow verity if inode is DAX
fs/ext4: Narrow scope of DAX check in setflags
|
|
For an exiting process it tries to cancel all its inflight requests. Use
req->task to match such instead of work.pid. We always have req->task
set, and it will be valid because we're matching only current exiting
task.
Also, remove work.pid and everything related, it's useless now.
Reported-by: Eric W. Biederman <ebiederm@xmission.com>
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
|
|
There will be multiple places where req->task is used, so refcount-pin
it lazily with introduced *io_{get,put}_req_task(). We need to always
have valid ->task for cancellation reasons, but don't care about pinning
it in some cases. That's why it sets req->task in io_req_init() and
implements get/put laziness with a flag.
This also removes using @current from polling io_arm_poll_handler(),
etc., but doesn't change observable behaviour.
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
|
|
Instead of waiting for each request one by one, first try to cancel all
of them in a batched manner, and then go over inflight_list/etc to reap
leftovers.
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
|
|
If a process is going away, io_uring_flush() will cancel only 1
request with a matching pid. Cancel all of them
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
|
|
This adds support for cancelling all io-wq works matching a predicate.
It isn't used yet, so no change in observable behaviour.
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
|
|
Go all over all pending lists and cancel works there, and only then
try to match running requests. No functional changes here, just a
preparation for bulk cancellation.
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
|
|
Abort code UAEOVERFLOW is returned when we try and set a time that's out of
range, but it's currently mapped to EREMOTEIO by the default case.
Fix UAEOVERFLOW to map instead to EOVERFLOW.
Found with the generic/258 xfstest. Note that the test is wrong as it
assumes that the filesystem will support a pre-UNIX-epoch date.
Fixes: 1eda8bab70ca ("afs: Add support for the UAE error table")
Signed-off-by: David Howells <dhowells@redhat.com>
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