cgroup foreign inode handling has quite a bit of heuristics and
internal states which sometimes makes it difficult to understand
what's going on. Add tracepoints to improve visibility.
Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Implement cgroup_writeback_by_id() which initiates cgroup writeback
from bdi and memcg IDs. This will be used by memcg foreign inode
flushing.
v2: Use wb_get_lookup() instead of wb_get_create() to avoid creating
spurious wbs.
v3: Interpret 0 @nr as 1.25 * nr_dirty to implement best-effort
flushing while avoding possible livelocks.
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
wb_completion is used to track writeback completions. We want to use
it from memcg side for foreign inode flushes. This patch updates it
to remember the target waitq instead of assuming bdi->wb_waitq and
expose it outside of fs-writeback.c.
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
As inode wb switching may make sync(2) miss some inodes, they're
synchronized using wb_switch_rwsem so that no wb switching happens
while sync(2) is in progress. In addition to synchronizing the actual
switching, the rwsem is also used to prevent queueing new switch
attempts while sync(2) is in progress. This is to avoid queueing too
many instances while the rwsem is held by sync(2). Unfortunately,
this is too agressive and can block wb switching for a long time if
sync(2) is frequent.
The goal is avoiding expolding the number of scheduled switches, not
avoiding scheduling anything. Let's use wb_switch_rwsem only for
synchronizing the actual switching and sync(2) and use
isw_nr_in_flight instead for limiting the maximum number of scheduled
switches. The limit is set to 1024 which should be more than enough
while still avoiding extreme situations.
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
WB_FRN_TIME_CUT_DIV is used to tell the foreign inode detection logic
to ignore short writeback rounds to prevent getting confused by a
burst of short writebacks. The parameter is currently 2 meaning that
anything smaller than half of the running average writback duration
will be ignored.
This is unnecessarily aggressive. The detection logic uses 16 history
slots and is already reasonably protected against some short bursts
confusing it and the current parameter can lead to tens of seconds of
missed detection depending on the writeback pattern.
Let's change the parameter to 8, so that it only ignores writeback
with are smaller than 12.5% of the current running average.
v2: Add comment explaining what's going on with the foreign detection
parameters.
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Pull xfs fixes from Darrick Wong:
- Avoid leaking kernel stack contents to userspace
- Fix a potential null pointer dereference in the dabtree scrub code
* tag 'xfs-5.3-fixes-1' of git://git.kernel.org/pub/scm/fs/xfs/xfs-linux:
xfs: Fix possible null-pointer dereferences in xchk_da_btree_block_check_sibling()
xfs: fix stack contents leakage in the v1 inumber ioctls
Merge misc fixes from Andrew Morton:
"17 fixes"
* emailed patches from Andrew Morton <akpm@linux-foundation.org>:
drivers/acpi/scan.c: document why we don't need the device_hotplug_lock
memremap: move from kernel/ to mm/
lib/test_meminit.c: use GFP_ATOMIC in RCU critical section
asm-generic: fix -Wtype-limits compiler warnings
cgroup: kselftest: relax fs_spec checks
mm/memory_hotplug.c: remove unneeded return for void function
mm/migrate.c: initialize pud_entry in migrate_vma()
coredump: split pipe command whitespace before expanding template
page flags: prioritize kasan bits over last-cpuid
ubsan: build ubsan.c more conservatively
kasan: remove clang version check for KASAN_STACK
mm: compaction: avoid 100% CPU usage during compaction when a task is killed
mm: migrate: fix reference check race between __find_get_block() and migration
mm: vmscan: check if mem cgroup is disabled or not before calling memcg slab shrinker
ocfs2: remove set but not used variable 'last_hash'
Revert "kmemleak: allow to coexist with fault injection"
kernel/signal.c: fix a kernel-doc markup
Save the offsets of the start of each argument to avoid having to update
pointers to each argument after every corename krealloc and to avoid
having to duplicate the memory for the dump command.
Executable names containing spaces were previously being expanded from
%e or %E and then split in the middle of the filename. This is
incorrect behaviour since an argument list can represent arguments with
spaces.
The splitting could lead to extra arguments being passed to the core
dump handler that it might have interpreted as options or ignored
completely.
Core dump handlers that are not aware of this Linux kernel issue will be
using %e or %E without considering that it may be split and so they will
be vulnerable to processes with spaces in their names breaking their
argument list. If their internals are otherwise well written, such as
if they are written in shell but quote arguments, they will work better
after this change than before. If they are not well written, then there
is a slight chance of breakage depending on the details of the code but
they will already be fairly broken by the split filenames.
Core dump handlers that are aware of this Linux kernel issue will be
placing %e or %E as the last item in their core_pattern and then
aggregating all of the remaining arguments into one, separated by
spaces. Alternatively they will be obtaining the filename via other
methods. Both of these will be compatible with the new arrangement.
A side effect from this change is that unknown template types (for
example %z) result in an empty argument to the dump handler instead of
the argument being dropped. This is a desired change as:
It is easier for dump handlers to process empty arguments than dropped
ones, especially if they are written in shell or don't pass each
template item with a preceding command-line option in order to
differentiate between individual template types. Most core_patterns in
the wild do not use options so they can confuse different template types
(especially numeric ones) if an earlier one gets dropped in old kernels.
If the kernel introduces a new template type and a core_pattern uses it,
the core dump handler might not expect that the argument can be dropped
in old kernels.
For example, this can result in security issues when %d is dropped in
old kernels. This happened with the corekeeper package in Debian and
resulted in the interface between corekeeper and Linux having to be
rewritten to use command-line options to differentiate between template
types.
The core_pattern for most core dump handlers is written by the handler
author who would generally not insert unknown template types so this
change should be compatible with all the core dump handlers that exist.
Link: http://lkml.kernel.org/r/20190528051142.24939-1-pabs3@bonedaddy.net
Fixes: 74aadce986 ("core_pattern: allow passing of arguments to user mode helper when core_pattern is a pipe")
Signed-off-by: Paul Wise <pabs3@bonedaddy.net>
Reported-by: Jakub Wilk <jwilk@jwilk.net> [https://bugs.debian.org/924398]
Reported-by: Paul Wise <pabs3@bonedaddy.net> [https://lore.kernel.org/linux-fsdevel/c8b7ecb8508895bf4adb62a748e2ea2c71854597.camel@bonedaddy.net/]
Suggested-by: Jakub Wilk <jwilk@jwilk.net>
Acked-by: Neil Horman <nhorman@tuxdriver.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Fixes gcc '-Wunused-but-set-variable' warning:
fs/ocfs2/xattr.c: In function ocfs2_xattr_bucket_find:
fs/ocfs2/xattr.c:3828:6: warning: variable last_hash set but not used [-Wunused-but-set-variable]
It's never used and can be removed.
Link: http://lkml.kernel.org/r/20190716132110.34836-1-yuehaibing@huawei.com
Signed-off-by: YueHaibing <yuehaibing@huawei.com>
Acked-by: Joseph Qi <joseph.qi@linux.alibaba.com>
Cc: Mark Fasheh <mark@fasheh.com>
Cc: Joel Becker <jlbec@evilplan.org>
Cc: Junxiao Bi <junxiao.bi@oracle.com>
Cc: Changwei Ge <gechangwei@live.cn>
Cc: Gang He <ghe@suse.com>
Cc: Jun Piao <piaojun@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Merge tag 'for-linus-20190802' of git://git.kernel.dk/linux-block
Pull block fixes from Jens Axboe:
"Here's a small collection of fixes that should go into this series.
This contains:
- io_uring potential use-after-free fix (Jackie)
- loop regression fix (Jan)
- O_DIRECT fragmented bio regression fix (Damien)
- Mark Denis as the new floppy maintainer (Denis)
- ataflop switch fall-through annotation (Gustavo)
- libata zpodd overflow fix (Kees)
- libata ahci deferred probe fix (Miquel)
- nbd invalidation BUG_ON() fix (Munehisa)
- dasd endless loop fix (Stefan)"
* tag 'for-linus-20190802' of git://git.kernel.dk/linux-block:
s390/dasd: fix endless loop after read unit address configuration
block: Fix __blkdev_direct_IO() for bio fragments
MAINTAINERS: floppy: take over maintainership
nbd: replace kill_bdev() with __invalidate_device() again
ata: libahci: do not complain in case of deferred probe
io_uring: fix KASAN use after free in io_sq_wq_submit_work
loop: Fix mount(2) failure due to race with LOOP_SET_FD
libata: zpodd: Fix small read overflow in zpodd_get_mech_type()
ataflop: Mark expected switch fall-through
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Merge tag 'for-5.3-rc2-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux
Pull btrfs fixes from David Sterba:
- tiny race window during 2 transactions aborting at the same time can
accidentally lead to a commit
- regression fix, possible deadlock during fiemap
- fix for an old bug when incremental send can fail on a file that has
been deduplicated in a special way
* tag 'for-5.3-rc2-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux:
Btrfs: fix deadlock between fiemap and transaction commits
Btrfs: fix race leading to fs corruption after transaction abort
Btrfs: fix incremental send failure after deduplication
The recent fix to properly handle IOCB_NOWAIT for async O_DIRECT IO
(patch 6a43074e2f) introduced two problems with BIO fragment handling
for direct IOs:
1) The dio size processed is calculated by incrementing the ret variable
by the size of the bio fragment issued for the dio. However, this size
is obtained directly from bio->bi_iter.bi_size AFTER the bio submission
which may result in referencing the bi_size value after the bio
completed, resulting in an incorrect value use.
2) The ret variable is not incremented by the size of the last bio
fragment issued for the bio, leading to an invalid IO size being
returned to the user.
Fix both problem by using dio->size (which is incremented before the bio
submission) to update the value of ret after bio submissions, including
for the last bio fragment issued.
Fixes: 6a43074e2f ("block: properly handle IOCB_NOWAIT for async O_DIRECT IO")
Reported-by: Masato Suzuki <masato.suzuki@wdc.com>
Signed-off-by: Damien Le Moal <damien.lemoal@wdc.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
With the recent iomap write page reclaim deadlock fix, it turns out that the
GLF_DIRTY flag isn't always set when it needs to be anymore: previously, this
happened as a side effect of always adding the inode buffer head to the current
transaction with gfs2_trans_add_meta, but this isn't happening consistently
anymore. Fix by removing an additional unnecessary gfs2_trans_add_meta call
and by setting the GLF_DIRTY flag in gfs2_iomap_end.
(The GLF_DIRTY flag causes inode_go_sync to flush the transaction log when
syncing out the glock of that inode. When the flag isn't set, inode_go_sync
will skip inodes, including ones with an i_state of I_DIRTY_PAGES, which will
lead to cluster incoherency.)
In addition, in gfs2_iomap_page_done, if the metadata has changed, mark the
inode as I_DIRTY_DATASYNC to have the inode added to the current transaction:
we don't expect metadata to change here, but let's err on the safe side.
Fixes: d0a22a4b03 ("gfs2: Fix iomap write page reclaim deadlock");
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
In "consolidate the capability checks in sget_{fc,userns}())" the
wrong argument had been passed to mount_capable() by sget_fc().
That mistake had been further obscured later, when switching
mount_capable() to fs_context has moved the calculation of
bogus argument from sget_fc() to mount_capable() itself. It
should've been fc->user_ns all along.
Screwed-up-by: Al Viro <viro@zeniv.linux.org.uk>
Reported-by: Christian Brauner <christian@brauner.io>
Tested-by: Christian Brauner <christian@brauner.io>
Reviewed-by: David Howells <dhowells@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Pull dax fix from Dan Williams:
"Fix a botched manual patch update that got dropped between testing and
application"
* 'dax-fix-5.3-rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/nvdimm/nvdimm:
dax: Fix missed wakeup in put_unlocked_entry()
This set of patches adjust to follow recent setflags changes and fix two
regression introduced since 5.4-rc1.
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Merge tag 'f2fs-for-5.4-rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/jaegeuk/f2fs
Pull f2fs fixes from Jaegeuk Kim:
"This set of patches adjust to follow recent setflags changes and fix
two regressions"
* tag 'f2fs-for-5.4-rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/jaegeuk/f2fs:
f2fs: use EINVAL for superblock with invalid magic
f2fs: fix to read source block before invalidating it
f2fs: remove redundant check from f2fs_setflags_common()
f2fs: use generic checking function for FS_IOC_FSSETXATTR
f2fs: use generic checking and prep function for FS_IOC_SETFLAGS
Commit 33ec3e53e7 ("loop: Don't change loop device under exclusive
opener") made LOOP_SET_FD ioctl acquire exclusive block device reference
while it updates loop device binding. However this can make perfectly
valid mount(2) fail with EBUSY due to racing LOOP_SET_FD holding
temporarily the exclusive bdev reference in cases like this:
for i in {a..z}{a..z}; do
dd if=/dev/zero of=$i.image bs=1k count=0 seek=1024
mkfs.ext2 $i.image
mkdir mnt$i
done
echo "Run"
for i in {a..z}{a..z}; do
mount -o loop -t ext2 $i.image mnt$i &
done
Fix the problem by not getting full exclusive bdev reference in
LOOP_SET_FD but instead just mark the bdev as being claimed while we
update the binding information. This just blocks new exclusive openers
instead of failing them with EBUSY thus fixing the problem.
Fixes: 33ec3e53e7 ("loop: Don't change loop device under exclusive opener")
Cc: stable@vger.kernel.org
Tested-by: Kai-Heng Feng <kai.heng.feng@canonical.com>
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
In xchk_da_btree_block_check_sibling(), there is an if statement on
line 274 to check whether ds->state->altpath.blk[level].bp is NULL:
if (ds->state->altpath.blk[level].bp)
When ds->state->altpath.blk[level].bp is NULL, it is used on line 281:
xfs_trans_brelse(..., ds->state->altpath.blk[level].bp);
struct xfs_buf_log_item *bip = bp->b_log_item;
ASSERT(bp->b_transp == tp);
Thus, possible null-pointer dereferences may occur.
To fix these bugs, ds->state->altpath.blk[level].bp is checked before
being used.
These bugs are found by a static analysis tool STCheck written by us.
Signed-off-by: Jia-Ju Bai <baijiaju1990@gmail.com>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
The fiemap handler locks a file range that can have unflushed delalloc,
and after locking the range, it tries to attach to a running transaction.
If the running transaction started its commit, that is, it is in state
TRANS_STATE_COMMIT_START, and either the filesystem was mounted with the
flushoncommit option or the transaction is creating a snapshot for the
subvolume that contains the file that fiemap is operating on, we end up
deadlocking. This happens because fiemap is blocked on the transaction,
waiting for it to complete, and the transaction is waiting for the flushed
dealloc to complete, which requires locking the file range that the fiemap
task already locked. The following stack traces serve as an example of
when this deadlock happens:
(...)
[404571.515510] Workqueue: btrfs-endio-write btrfs_endio_write_helper [btrfs]
[404571.515956] Call Trace:
[404571.516360] ? __schedule+0x3ae/0x7b0
[404571.516730] schedule+0x3a/0xb0
[404571.517104] lock_extent_bits+0x1ec/0x2a0 [btrfs]
[404571.517465] ? remove_wait_queue+0x60/0x60
[404571.517832] btrfs_finish_ordered_io+0x292/0x800 [btrfs]
[404571.518202] normal_work_helper+0xea/0x530 [btrfs]
[404571.518566] process_one_work+0x21e/0x5c0
[404571.518990] worker_thread+0x4f/0x3b0
[404571.519413] ? process_one_work+0x5c0/0x5c0
[404571.519829] kthread+0x103/0x140
[404571.520191] ? kthread_create_worker_on_cpu+0x70/0x70
[404571.520565] ret_from_fork+0x3a/0x50
[404571.520915] kworker/u8:6 D 0 31651 2 0x80004000
[404571.521290] Workqueue: btrfs-flush_delalloc btrfs_flush_delalloc_helper [btrfs]
(...)
[404571.537000] fsstress D 0 13117 13115 0x00004000
[404571.537263] Call Trace:
[404571.537524] ? __schedule+0x3ae/0x7b0
[404571.537788] schedule+0x3a/0xb0
[404571.538066] wait_current_trans+0xc8/0x100 [btrfs]
[404571.538349] ? remove_wait_queue+0x60/0x60
[404571.538680] start_transaction+0x33c/0x500 [btrfs]
[404571.539076] btrfs_check_shared+0xa3/0x1f0 [btrfs]
[404571.539513] ? extent_fiemap+0x2ce/0x650 [btrfs]
[404571.539866] extent_fiemap+0x2ce/0x650 [btrfs]
[404571.540170] do_vfs_ioctl+0x526/0x6f0
[404571.540436] ksys_ioctl+0x70/0x80
[404571.540734] __x64_sys_ioctl+0x16/0x20
[404571.540997] do_syscall_64+0x60/0x1d0
[404571.541279] entry_SYSCALL_64_after_hwframe+0x49/0xbe
(...)
[404571.543729] btrfs D 0 14210 14208 0x00004000
[404571.544023] Call Trace:
[404571.544275] ? __schedule+0x3ae/0x7b0
[404571.544526] ? wait_for_completion+0x112/0x1a0
[404571.544795] schedule+0x3a/0xb0
[404571.545064] schedule_timeout+0x1ff/0x390
[404571.545351] ? lock_acquire+0xa6/0x190
[404571.545638] ? wait_for_completion+0x49/0x1a0
[404571.545890] ? wait_for_completion+0x112/0x1a0
[404571.546228] wait_for_completion+0x131/0x1a0
[404571.546503] ? wake_up_q+0x70/0x70
[404571.546775] btrfs_wait_ordered_extents+0x27c/0x400 [btrfs]
[404571.547159] btrfs_commit_transaction+0x3b0/0xae0 [btrfs]
[404571.547449] ? btrfs_mksubvol+0x4a4/0x640 [btrfs]
[404571.547703] ? remove_wait_queue+0x60/0x60
[404571.547969] btrfs_mksubvol+0x605/0x640 [btrfs]
[404571.548226] ? __sb_start_write+0xd4/0x1c0
[404571.548512] ? mnt_want_write_file+0x24/0x50
[404571.548789] btrfs_ioctl_snap_create_transid+0x169/0x1a0 [btrfs]
[404571.549048] btrfs_ioctl_snap_create_v2+0x11d/0x170 [btrfs]
[404571.549307] btrfs_ioctl+0x133f/0x3150 [btrfs]
[404571.549549] ? mem_cgroup_charge_statistics+0x4c/0xd0
[404571.549792] ? mem_cgroup_commit_charge+0x84/0x4b0
[404571.550064] ? __handle_mm_fault+0xe3e/0x11f0
[404571.550306] ? do_raw_spin_unlock+0x49/0xc0
[404571.550608] ? _raw_spin_unlock+0x24/0x30
[404571.550976] ? __handle_mm_fault+0xedf/0x11f0
[404571.551319] ? do_vfs_ioctl+0xa2/0x6f0
[404571.551659] ? btrfs_ioctl_get_supported_features+0x30/0x30 [btrfs]
[404571.552087] do_vfs_ioctl+0xa2/0x6f0
[404571.552355] ksys_ioctl+0x70/0x80
[404571.552621] __x64_sys_ioctl+0x16/0x20
[404571.552864] do_syscall_64+0x60/0x1d0
[404571.553104] entry_SYSCALL_64_after_hwframe+0x49/0xbe
(...)
If we were joining the transaction instead of attaching to it, we would
not risk a deadlock because a join only blocks if the transaction is in a
state greater then or equals to TRANS_STATE_COMMIT_DOING, and the delalloc
flush performed by a transaction is done before it reaches that state,
when it is in the state TRANS_STATE_COMMIT_START. However a transaction
join is intended for use cases where we do modify the filesystem, and
fiemap only needs to peek at delayed references from the current
transaction in order to determine if extents are shared, and, besides
that, when there is no current transaction or when it blocks to wait for
a current committing transaction to complete, it creates a new transaction
without reserving any space. Such unnecessary transactions, besides doing
unnecessary IO, can cause transaction aborts (-ENOSPC) and unnecessary
rotation of the precious backup roots.
So fix this by adding a new transaction join variant, named join_nostart,
which behaves like the regular join, but it does not create a transaction
when none currently exists or after waiting for a committing transaction
to complete.
Fixes: 03628cdbc6 ("Btrfs: do not start a transaction during fiemap")
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
When one transaction is finishing its commit, it is possible for another
transaction to start and enter its initial commit phase as well. If the
first ends up getting aborted, we have a small time window where the second
transaction commit does not notice that the previous transaction aborted
and ends up committing, writing a superblock that points to btrees that
reference extent buffers (nodes and leafs) that were not persisted to disk.
The consequence is that after mounting the filesystem again, we will be
unable to load some btree nodes/leafs, either because the content on disk
is either garbage (or just zeroes) or corresponds to the old content of a
previouly COWed or deleted node/leaf, resulting in the well known error
messages "parent transid verify failed on ...".
The following sequence diagram illustrates how this can happen.
CPU 1 CPU 2
<at transaction N>
btrfs_commit_transaction()
(...)
--> sets transaction state to
TRANS_STATE_UNBLOCKED
--> sets fs_info->running_transaction
to NULL
(...)
btrfs_start_transaction()
start_transaction()
wait_current_trans()
--> returns immediately
because
fs_info->running_transaction
is NULL
join_transaction()
--> creates transaction N + 1
--> sets
fs_info->running_transaction
to transaction N + 1
--> adds transaction N + 1 to
the fs_info->trans_list list
--> returns transaction handle
pointing to the new
transaction N + 1
(...)
btrfs_sync_file()
btrfs_start_transaction()
--> returns handle to
transaction N + 1
(...)
btrfs_write_and_wait_transaction()
--> writeback of some extent
buffer fails, returns an
error
btrfs_handle_fs_error()
--> sets BTRFS_FS_STATE_ERROR in
fs_info->fs_state
--> jumps to label "scrub_continue"
cleanup_transaction()
btrfs_abort_transaction(N)
--> sets BTRFS_FS_STATE_TRANS_ABORTED
flag in fs_info->fs_state
--> sets aborted field in the
transaction and transaction
handle structures, for
transaction N only
--> removes transaction from the
list fs_info->trans_list
btrfs_commit_transaction(N + 1)
--> transaction N + 1 was not
aborted, so it proceeds
(...)
--> sets the transaction's state
to TRANS_STATE_COMMIT_START
--> does not find the previous
transaction (N) in the
fs_info->trans_list, so it
doesn't know that transaction
was aborted, and the commit
of transaction N + 1 proceeds
(...)
--> sets transaction N + 1 state
to TRANS_STATE_UNBLOCKED
btrfs_write_and_wait_transaction()
--> succeeds writing all extent
buffers created in the
transaction N + 1
write_all_supers()
--> succeeds
--> we now have a superblock on
disk that points to trees
that refer to at least one
extent buffer that was
never persisted
So fix this by updating the transaction commit path to check if the flag
BTRFS_FS_STATE_TRANS_ABORTED is set on fs_info->fs_state if after setting
the transaction to the TRANS_STATE_COMMIT_START we do not find any previous
transaction in the fs_info->trans_list. If the flag is set, just fail the
transaction commit with -EROFS, as we do in other places. The exact error
code for the previous transaction abort was already logged and reported.
Fixes: 49b25e0540 ("btrfs: enhance transaction abort infrastructure")
CC: stable@vger.kernel.org # 4.4+
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
When doing an incremental send operation we can fail if we previously did
deduplication operations against a file that exists in both snapshots. In
that case we will fail the send operation with -EIO and print a message
to dmesg/syslog like the following:
BTRFS error (device sdc): Send: inconsistent snapshot, found updated \
extent for inode 257 without updated inode item, send root is 258, \
parent root is 257
This requires that we deduplicate to the same file in both snapshots for
the same amount of times on each snapshot. The issue happens because a
deduplication only updates the iversion of an inode and does not update
any other field of the inode, therefore if we deduplicate the file on
each snapshot for the same amount of time, the inode will have the same
iversion value (stored as the "sequence" field on the inode item) on both
snapshots, therefore it will be seen as unchanged between in the send
snapshot while there are new/updated/deleted extent items when comparing
to the parent snapshot. This makes the send operation return -EIO and
print an error message.
Example reproducer:
$ mkfs.btrfs -f /dev/sdb
$ mount /dev/sdb /mnt
# Create our first file. The first half of the file has several 64Kb
# extents while the second half as a single 512Kb extent.
$ xfs_io -f -s -c "pwrite -S 0xb8 -b 64K 0 512K" /mnt/foo
$ xfs_io -c "pwrite -S 0xb8 512K 512K" /mnt/foo
# Create the base snapshot and the parent send stream from it.
$ btrfs subvolume snapshot -r /mnt /mnt/mysnap1
$ btrfs send -f /tmp/1.snap /mnt/mysnap1
# Create our second file, that has exactly the same data as the first
# file.
$ xfs_io -f -c "pwrite -S 0xb8 0 1M" /mnt/bar
# Create the second snapshot, used for the incremental send, before
# doing the file deduplication.
$ btrfs subvolume snapshot -r /mnt /mnt/mysnap2
# Now before creating the incremental send stream:
#
# 1) Deduplicate into a subrange of file foo in snapshot mysnap1. This
# will drop several extent items and add a new one, also updating
# the inode's iversion (sequence field in inode item) by 1, but not
# any other field of the inode;
#
# 2) Deduplicate into a different subrange of file foo in snapshot
# mysnap2. This will replace an extent item with a new one, also
# updating the inode's iversion by 1 but not any other field of the
# inode.
#
# After these two deduplication operations, the inode items, for file
# foo, are identical in both snapshots, but we have different extent
# items for this inode in both snapshots. We want to check this doesn't
# cause send to fail with an error or produce an incorrect stream.
$ xfs_io -r -c "dedupe /mnt/bar 0 0 512K" /mnt/mysnap1/foo
$ xfs_io -r -c "dedupe /mnt/bar 512K 512K 512K" /mnt/mysnap2/foo
# Create the incremental send stream.
$ btrfs send -p /mnt/mysnap1 -f /tmp/2.snap /mnt/mysnap2
ERROR: send ioctl failed with -5: Input/output error
This issue started happening back in 2015 when deduplication was updated
to not update the inode's ctime and mtime and update only the iversion.
Back then we would hit a BUG_ON() in send, but later in 2016 send was
updated to return -EIO and print the error message instead of doing the
BUG_ON().
A test case for fstests follows soon.
Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=203933
Fixes: 1c919a5e13 ("btrfs: don't update mtime/ctime on deduped inodes")
CC: stable@vger.kernel.org # 4.4+
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
The condition checking whether put_unlocked_entry() needs to wake up
following waiter got broken by commit 23c84eb783 ("dax: Fix missed
wakeup with PMD faults"). We need to wake the waiter whenever the passed
entry is valid (i.e., non-NULL and not special conflict entry). This
could lead to processes never being woken up when waiting for entry
lock. Fix the condition.
Cc: <stable@vger.kernel.org>
Link: http://lore.kernel.org/r/20190729120228.GC17833@quack2.suse.cz
Fixes: 23c84eb783 ("dax: Fix missed wakeup with PMD faults")
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
The kernel mount_block_root() function expects -EACESS or -EINVAL for a
unmountable filesystem when trying to mount the root with different
filesystem types.
However, in 5.3-rc1 the behavior when F2FS code cannot find valid block
changed to return -EFSCORRUPTED(-EUCLEAN), and this error code makes
mount_block_root() fail when trying to probe F2FS.
When the magic number of the superblock mismatches, it has a high
probability that it's just not a F2FS. In this case return -EINVAL seems
to be a better result, and this return value can make mount_block_root()
probing work again.
Return -EINVAL when the superblock has magic mismatch, -EFSCORRUPTED in
other cases (the magic matches but the superblock cannot be recognized).
Fixes: 10f966bbf5 ("f2fs: use generic EFSBADCRC/EFSCORRUPTED")
Signed-off-by: Icenowy Zheng <icenowy@aosc.io>
Reviewed-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
Explicitly initialize the onstack structures to zero so we don't leak
kernel memory into userspace when converting the in-core inumbers
structure to the v1 inogrp ioctl structure. Add a comment about why we
have to use memset to ensure that the padding holes in the structures
are set to zero.
Fixes: 5f19c7fc68 ("xfs: introduce v5 inode group structure")
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Eric Sandeen <sandeen@redhat.com>
Here are some small SPDX fixes for 5.3-rc2 for things that came in
during the 5.3-rc1 merge window that we previously missed.
Only 3 small patches here:
- 2 uapi patches to resolve some SPDX tags that were not correct
- fix an invalid SPDX tag in the iomap Makefile file
All have been properly reviewed on the public mailing lists.
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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Merge tag 'spdx-5.3-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/spdx
Pull SPDX fixes from Greg KH:
"Here are some small SPDX fixes for 5.3-rc2 for things that came in
during the 5.3-rc1 merge window that we previously missed.
Only three small patches here:
- two uapi patches to resolve some SPDX tags that were not correct
- fix an invalid SPDX tag in the iomap Makefile file
All have been properly reviewed on the public mailing lists"
* tag 'spdx-5.3-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/spdx:
iomap: fix Invalid License ID
treewide: remove SPDX "WITH Linux-syscall-note" from kernel-space headers again
treewide: add "WITH Linux-syscall-note" to SPDX tag of uapi headers
Pull scheduler fixes from Thomas Gleixner:
"Two fixes for the fair scheduling class:
- Prevent freeing memory which is accessible by concurrent readers
- Make the RCU annotations for numa groups consistent"
* 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
sched/fair: Use RCU accessors consistently for ->numa_group
sched/fair: Don't free p->numa_faults with concurrent readers
Hi Linus,
Please, pull the following patches that mark switch cases where we are
expecting to fall through. These patches are part of the ongoing efforts
to enable -Wimplicit-fallthrough. Most of them have been baking in linux-next
for a whole development cycle.
Also, pull the Makefile patch that globally enables the
-Wimplicit-fallthrough option.
Finally, some missing-break fixes that have been tagged for -stable:
- drm/amdkfd: Fix missing break in switch statement
- drm/amdgpu/gfx10: Fix missing break in switch statement
Notice that with these changes, we completely get rid of all the
fall-through warnings in the kernel.
Thanks
Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
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Merge tag 'Wimplicit-fallthrough-5.3-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/gustavoars/linux
Pull Wimplicit-fallthrough enablement from Gustavo A. R. Silva:
"This marks switch cases where we are expecting to fall through, and
globally enables the -Wimplicit-fallthrough option in the main
Makefile.
Finally, some missing-break fixes that have been tagged for -stable:
- drm/amdkfd: Fix missing break in switch statement
- drm/amdgpu/gfx10: Fix missing break in switch statement
With these changes, we completely get rid of all the fall-through
warnings in the kernel"
* tag 'Wimplicit-fallthrough-5.3-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/gustavoars/linux:
Makefile: Globally enable fall-through warning
drm/i915: Mark expected switch fall-throughs
drm/amd/display: Mark expected switch fall-throughs
drm/amdkfd/kfd_mqd_manager_v10: Avoid fall-through warning
drm/amdgpu/gfx10: Fix missing break in switch statement
drm/amdkfd: Fix missing break in switch statement
perf/x86/intel: Mark expected switch fall-throughs
mtd: onenand_base: Mark expected switch fall-through
afs: fsclient: Mark expected switch fall-throughs
afs: yfsclient: Mark expected switch fall-throughs
can: mark expected switch fall-throughs
firewire: mark expected switch fall-throughs
f2fs_allocate_data_block() invalidates old block address and enable new block
address. Then, if we try to read old block by f2fs_submit_page_bio(), it will
give WARN due to reading invalid blocks.
Let's make the order sanely back.
Reviewed-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
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Merge tag 'for-5.3-rc1-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux
Pull btrfs fixes from David Sterba:
"Two regression fixes:
- hangs caused by a missing barrier in the locking code
- memory leaks of extent_state due to bad handling of a cached
pointer"
* tag 'for-5.3-rc1-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux:
btrfs: fix extent_state leak in btrfs_lock_and_flush_ordered_range
btrfs: Fix deadlock caused by missing memory barrier
Pull vfs umount_tree() leak fix from Al Viro:
"Fix braino introduced in 'switch the remnants of releasing the
mountpoint away from fs_pin'.
The most visible result is leaking struct mount when mounting btrfs,
making it impossible to shut down"
* 'fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
fix the struct mount leak in umount_tree()
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Merge tag 'for-linus-20190726' of git://git.kernel.dk/linux-block
Pull block fixes from Jens Axboe:
- Several io_uring fixes/improvements:
- Blocking fix for O_DIRECT (me)
- Latter page slowness for registered buffers (me)
- Fix poll hang under certain conditions (me)
- Defer sequence check fix for wrapped rings (Zhengyuan)
- Mismatch in async inc/dec accounting (Zhengyuan)
- Memory ordering issue that could cause stall (Zhengyuan)
- Track sequential defer in bytes, not pages (Zhengyuan)
- NVMe pull request from Christoph
- Set of hang fixes for wbt (Josef)
- Redundant error message kill for libahci (Ding)
- Remove unused blk_mq_sched_started_request() and related ops (Marcos)
- drbd dynamic alloc shash descriptor to reduce stack use (Arnd)
- blkcg ->pd_stat() non-debug print (Tejun)
- bcache memory leak fix (Wei)
- Comment fix (Akinobu)
- BFQ perf regression fix (Paolo)
* tag 'for-linus-20190726' of git://git.kernel.dk/linux-block: (24 commits)
io_uring: ensure ->list is initialized for poll commands
Revert "nvme-pci: don't create a read hctx mapping without read queues"
nvme: fix multipath crash when ANA is deactivated
nvme: fix memory leak caused by incorrect subsystem free
nvme: ignore subnqn for ADATA SX6000LNP
drbd: dynamically allocate shash descriptor
block: blk-mq: Remove blk_mq_sched_started_request and started_request
bcache: fix possible memory leak in bch_cached_dev_run()
io_uring: track io length in async_list based on bytes
io_uring: don't use iov_iter_advance() for fixed buffers
block: properly handle IOCB_NOWAIT for async O_DIRECT IO
blk-mq: allow REQ_NOWAIT to return an error inline
io_uring: add a memory barrier before atomic_read
rq-qos: use a mb for got_token
rq-qos: set ourself TASK_UNINTERRUPTIBLE after we schedule
rq-qos: don't reset has_sleepers on spurious wakeups
rq-qos: fix missed wake-ups in rq_qos_throttle
wait: add wq_has_single_sleeper helper
block, bfq: check also in-flight I/O in dispatch plugging
block: fix sysfs module parameters directory path in comment
...
We need to drop everything we remove from the tree, whether
mnt_has_parent() is true or not. Usually the bug manifests as a slow
memory leak (leaked struct mount for initramfs); it becomes much more
visible in mount_subtree() users, such as btrfs. There we leak
a struct mount for btrfs superblock being mounted, which prevents
fs shutdown on subsequent umount.
Fixes: 56cbb429d9 ("switch the remnants of releasing the mountpoint away from fs_pin")
Reported-by: Nikolay Borisov <nborisov@suse.com>
Tested-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
btrfs_lock_and_flush_ordered_range() loads given "*cached_state" into
cachedp, which, in general, is NULL. Then, lock_extent_bits() updates
"cachedp", but it never goes backs to the caller. Thus the caller still
see its "cached_state" to be NULL and never free the state allocated
under btrfs_lock_and_flush_ordered_range(). As a result, we will
see massive state leak with e.g. fstests btrfs/005. Fix this bug by
properly handling the pointers.
Fixes: bd80d94efb ("btrfs: Always use a cached extent_state in btrfs_lock_and_flush_ordered_range")
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: Naohiro Aota <naohiro.aota@wdc.com>
Signed-off-by: David Sterba <dsterba@suse.com>
In preparation to enabling -Wimplicit-fallthrough, mark switch
cases where we are expecting to fall through.
This patch fixes the following warnings:
Warning level 3 was used: -Wimplicit-fallthrough=3
fs/afs/fsclient.c: In function ‘afs_deliver_fs_fetch_acl’:
fs/afs/fsclient.c:2199:19: warning: this statement may fall through [-Wimplicit-fallthrough=]
call->unmarshall++;
~~~~~~~~~~~~~~~~^~
fs/afs/fsclient.c:2202:2: note: here
case 1:
^~~~
fs/afs/fsclient.c:2216:19: warning: this statement may fall through [-Wimplicit-fallthrough=]
call->unmarshall++;
~~~~~~~~~~~~~~~~^~
fs/afs/fsclient.c:2219:2: note: here
case 2:
^~~~
fs/afs/fsclient.c:2225:19: warning: this statement may fall through [-Wimplicit-fallthrough=]
call->unmarshall++;
~~~~~~~~~~~~~~~~^~
fs/afs/fsclient.c:2228:2: note: here
case 3:
^~~~
This patch is part of the ongoing efforts to enable
-Wimplicit-fallthrough.
Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
In preparation to enabling -Wimplicit-fallthrough, mark switch
cases where we are expecting to fall through.
This patch fixes the following warnings:
fs/afs/yfsclient.c: In function ‘yfs_deliver_fs_fetch_opaque_acl’:
fs/afs/yfsclient.c:1984:19: warning: this statement may fall through [-Wimplicit-fallthrough=]
call->unmarshall++;
~~~~~~~~~~~~~~~~^~
fs/afs/yfsclient.c:1987:2: note: here
case 1:
^~~~
fs/afs/yfsclient.c:2005:19: warning: this statement may fall through [-Wimplicit-fallthrough=]
call->unmarshall++;
~~~~~~~~~~~~~~~~^~
fs/afs/yfsclient.c:2008:2: note: here
case 2:
^~~~
fs/afs/yfsclient.c:2014:19: warning: this statement may fall through [-Wimplicit-fallthrough=]
call->unmarshall++;
~~~~~~~~~~~~~~~~^~
fs/afs/yfsclient.c:2017:2: note: here
case 3:
^~~~
fs/afs/yfsclient.c:2035:19: warning: this statement may fall through [-Wimplicit-fallthrough=]
call->unmarshall++;
~~~~~~~~~~~~~~~~^~
fs/afs/yfsclient.c:2038:2: note: here
case 4:
^~~~
fs/afs/yfsclient.c:2047:19: warning: this statement may fall through [-Wimplicit-fallthrough=]
call->unmarshall++;
~~~~~~~~~~~~~~~~^~
fs/afs/yfsclient.c:2050:2: note: here
case 5:
^~~~
Warning level 3 was used: -Wimplicit-fallthrough=3
Also, fix some commenting style issues.
This patch is part of the ongoing efforts to enable
-Wimplicit-fallthrough.
Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
Daniel reports that when testing an http server that uses io_uring
to poll for incoming connections, sometimes it hard crashes. This is
due to an uninitialized list member for the io_uring request. Normally
this doesn't trigger and none of the test cases caught it.
Reported-by: Daniel Kozak <kozzi11@gmail.com>
Tested-by: Daniel Kozak <kozzi11@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
The access() (and faccessat()) credentials change can cause an
unnecessary load on the RCU machinery because every access() call ends
up freeing the temporary access credential using RCU.
This isn't really noticeable on small machines, but if you have hundreds
of cores you can cause huge slowdowns due to RCU storms.
It's easy to avoid: the temporary access crededntials aren't actually
normally accessed using RCU at all, so we can avoid the whole issue by
just marking them as such.
* access-creds:
access: avoid the RCU grace period for the temporary subjective credentials
Commit 06297d8cef ("btrfs: switch extent_buffer blocking_writers from
atomic to int") changed the type of blocking_writers but forgot to
adjust relevant code in btrfs_tree_unlock by converting the
smp_mb__after_atomic to smp_mb. This opened up the possibility of a
deadlock due to re-ordering of setting blocking_writers and
checking/waking up the waiter. This particular lockup is explained in a
comment above waitqueue_active() function.
Fix it by converting the memory barrier to a full smp_mb, accounting
for the fact that blocking_writers is a simple integer.
Fixes: 06297d8cef ("btrfs: switch extent_buffer blocking_writers from atomic to int")
Tested-by: Johannes Thumshirn <jthumshirn@suse.com>
Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
When going through execve(), zero out the NUMA fault statistics instead of
freeing them.
During execve, the task is reachable through procfs and the scheduler. A
concurrent /proc/*/sched reader can read data from a freed ->numa_faults
allocation (confirmed by KASAN) and write it back to userspace.
I believe that it would also be possible for a use-after-free read to occur
through a race between a NUMA fault and execve(): task_numa_fault() can
lead to task_numa_compare(), which invokes task_weight() on the currently
running task of a different CPU.
Another way to fix this would be to make ->numa_faults RCU-managed or add
extra locking, but it seems easier to wipe the NUMA fault statistics on
execve.
Signed-off-by: Jann Horn <jannh@google.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Petr Mladek <pmladek@suse.com>
Cc: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Will Deacon <will@kernel.org>
Fixes: 82727018b0 ("sched/numa: Call task_numa_free() from do_execve()")
Link: https://lkml.kernel.org/r/20190716152047.14424-1-jannh@google.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
It turns out that 'access()' (and 'faccessat()') can cause a lot of RCU
work because it installs a temporary credential that gets allocated and
freed for each system call.
The allocation and freeing overhead is mostly benign, but because
credentials can be accessed under the RCU read lock, the freeing
involves a RCU grace period.
Which is not a huge deal normally, but if you have a lot of access()
calls, this causes a fair amount of seconday damage: instead of having a
nice alloc/free patterns that hits in hot per-CPU slab caches, you have
all those delayed free's, and on big machines with hundreds of cores,
the RCU overhead can end up being enormous.
But it turns out that all of this is entirely unnecessary. Exactly
because access() only installs the credential as the thread-local
subjective credential, the temporary cred pointer doesn't actually need
to be RCU free'd at all. Once we're done using it, we can just free it
synchronously and avoid all the RCU overhead.
So add a 'non_rcu' flag to 'struct cred', which can be set by users that
know they only use it in non-RCU context (there are other potential
users for this). We can make it a union with the rcu freeing list head
that we need for the RCU case, so this doesn't need any extra storage.
Note that this also makes 'get_current_cred()' clear the new non_rcu
flag, in case we have filesystems that take a long-term reference to the
cred and then expect the RCU delayed freeing afterwards. It's not
entirely clear that this is required, but it makes for clear semantics:
the subjective cred remains non-RCU as long as you only access it
synchronously using the thread-local accessors, but you _can_ use it as
a generic cred if you want to.
It is possible that we should just remove the whole RCU markings for
->cred entirely. Only ->real_cred is really supposed to be accessed
through RCU, and the long-term cred copies that nfs uses might want to
explicitly re-enable RCU freeing if required, rather than have
get_current_cred() do it implicitly.
But this is a "minimal semantic changes" change for the immediate
problem.
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Eric Dumazet <edumazet@google.com>
Acked-by: Paul E. McKenney <paulmck@linux.ibm.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Jan Glauber <jglauber@marvell.com>
Cc: Jiri Kosina <jikos@kernel.org>
Cc: Jayachandran Chandrasekharan Nair <jnair@marvell.com>
Cc: Greg KH <greg@kroah.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: David Howells <dhowells@redhat.com>
Cc: Miklos Szeredi <miklos@szeredi.hu>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Merge tag 'for-5.3-rc1-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux
Pull btrfs fixes from David Sterba:
- fixes for leaks caused by recently merged patches
- one build fix
- a fix to prevent mixing of incompatible features
* tag 'for-5.3-rc1-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux:
btrfs: don't leak extent_map in btrfs_get_io_geometry()
btrfs: free checksum hash on in close_ctree
btrfs: Fix build error while LIBCRC32C is module
btrfs: inode: Don't compress if NODATASUM or NODATACOW set
We are using PAGE_SIZE as the unit to determine if the total len in
async_list has exceeded max_pages, it's not fair for smaller io sizes.
For example, if we are doing 1k-size io streams, we will never exceed
max_pages since len >>= PAGE_SHIFT always gets zero. So use original
bytes to make it more accurate.
Signed-off-by: Zhengyuan Liu <liuzhengyuan@kylinos.cn>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Hrvoje reports that when a large fixed buffer is registered and IO is
being done to the latter pages of said buffer, the IO submission time
is much worse:
reading to the start of the buffer: 11238 ns
reading to the end of the buffer: 1039879 ns
In fact, it's worse by two orders of magnitude. The reason for that is
how io_uring figures out how to setup the iov_iter. We point the iter
at the first bvec, and then use iov_iter_advance() to fast-forward to
the offset within that buffer we need.
However, that is abysmally slow, as it entails iterating the bvecs
that we setup as part of buffer registration. There's really no need
to use this generic helper, as we know it's a BVEC type iterator, and
we also know that each bvec is PAGE_SIZE in size, apart from possibly
the first and last. Hence we can just use a shift on the offset to
find the right index, and then adjust the iov_iter appropriately.
After this fix, the timings are:
reading to the start of the buffer: 10135 ns
reading to the end of the buffer: 1377 ns
Or about an 755x improvement for the tail page.
Reported-by: Hrvoje Zeba <zeba.hrvoje@gmail.com>
Tested-by: Hrvoje Zeba <zeba.hrvoje@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
A caller is supposed to pass in REQ_NOWAIT if we can't block for any
given operation, but O_DIRECT for block devices just ignore this. Hence
we'll block for various resource shortages on the block layer side,
like having to wait for requests.
Use the new REQ_NOWAIT_INLINE to ask for this error to be returned
inline, so we can handle it appropriately and return -EAGAIN to the
caller.
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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Merge tag '5.3-smb3-fixes' of git://git.samba.org/sfrench/cifs-2.6
Pull cifs fixes from Steve French:
"Two fixes for stable, one that had dependency on earlier patch in this
merge window and can now go in, and a perf improvement in SMB3 open"
* tag '5.3-smb3-fixes' of git://git.samba.org/sfrench/cifs-2.6:
cifs: update internal module number
cifs: flush before set-info if we have writeable handles
smb3: optimize open to not send query file internal info
cifs: copy_file_range needs to strip setuid bits and update timestamps
CIFS: fix deadlock in cached root handling
Pull dcache and mountpoint updates from Al Viro:
"Saner handling of refcounts to mountpoints.
Transfer the counting reference from struct mount ->mnt_mountpoint
over to struct mountpoint ->m_dentry. That allows us to get rid of the
convoluted games with ordering of mount shutdowns.
The cost is in teaching shrink_dcache_{parent,for_umount} to cope with
mixed-filesystem shrink lists, which we'll also need for the Slab
Movable Objects patchset"
* 'work.dcache2' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
switch the remnants of releasing the mountpoint away from fs_pin
get rid of detach_mnt()
make struct mountpoint bear the dentry reference to mountpoint, not struct mount
Teach shrink_dcache_parent() to cope with mixed-filesystem shrink lists
fs/namespace.c: shift put_mountpoint() to callers of unhash_mnt()
__detach_mounts(): lookup_mountpoint() can't return ERR_PTR() anymore
nfs: dget_parent() never returns NULL
ceph: don't open-code the check for dead lockref
Tejun Heo