25 Mar, 2020
1 commit
-
Zygo reported the following lockdep splat while testing the balance
patches======================================================
WARNING: possible circular locking dependency detected
5.6.0-c6f0579d496a+ #53 Not tainted
------------------------------------------------------
kswapd0/1133 is trying to acquire lock:
ffff888092f622c0 (&delayed_node->mutex){+.+.}, at: __btrfs_release_delayed_node+0x7c/0x5b0but task is already holding lock:
ffffffff8fc5f860 (fs_reclaim){+.+.}, at: __fs_reclaim_acquire+0x5/0x30which lock already depends on the new lock.
the existing dependency chain (in reverse order) is:
-> #1 (fs_reclaim){+.+.}:
fs_reclaim_acquire.part.91+0x29/0x30
fs_reclaim_acquire+0x19/0x20
kmem_cache_alloc_trace+0x32/0x740
add_block_entry+0x45/0x260
btrfs_ref_tree_mod+0x6e2/0x8b0
btrfs_alloc_tree_block+0x789/0x880
alloc_tree_block_no_bg_flush+0xc6/0xf0
__btrfs_cow_block+0x270/0x940
btrfs_cow_block+0x1ba/0x3a0
btrfs_search_slot+0x999/0x1030
btrfs_insert_empty_items+0x81/0xe0
btrfs_insert_delayed_items+0x128/0x7d0
__btrfs_run_delayed_items+0xf4/0x2a0
btrfs_run_delayed_items+0x13/0x20
btrfs_commit_transaction+0x5cc/0x1390
insert_balance_item.isra.39+0x6b2/0x6e0
btrfs_balance+0x72d/0x18d0
btrfs_ioctl_balance+0x3de/0x4c0
btrfs_ioctl+0x30ab/0x44a0
ksys_ioctl+0xa1/0xe0
__x64_sys_ioctl+0x43/0x50
do_syscall_64+0x77/0x2c0
entry_SYSCALL_64_after_hwframe+0x49/0xbe-> #0 (&delayed_node->mutex){+.+.}:
__lock_acquire+0x197e/0x2550
lock_acquire+0x103/0x220
__mutex_lock+0x13d/0xce0
mutex_lock_nested+0x1b/0x20
__btrfs_release_delayed_node+0x7c/0x5b0
btrfs_remove_delayed_node+0x49/0x50
btrfs_evict_inode+0x6fc/0x900
evict+0x19a/0x2c0
dispose_list+0xa0/0xe0
prune_icache_sb+0xbd/0xf0
super_cache_scan+0x1b5/0x250
do_shrink_slab+0x1f6/0x530
shrink_slab+0x32e/0x410
shrink_node+0x2a5/0xba0
balance_pgdat+0x4bd/0x8a0
kswapd+0x35a/0x800
kthread+0x1e9/0x210
ret_from_fork+0x3a/0x50other info that might help us debug this:
Possible unsafe locking scenario:
CPU0 CPU1
---- ----
lock(fs_reclaim);
lock(&delayed_node->mutex);
lock(fs_reclaim);
lock(&delayed_node->mutex);*** DEADLOCK ***
3 locks held by kswapd0/1133:
#0: ffffffff8fc5f860 (fs_reclaim){+.+.}, at: __fs_reclaim_acquire+0x5/0x30
#1: ffffffff8fc380d8 (shrinker_rwsem){++++}, at: shrink_slab+0x1e8/0x410
#2: ffff8881e0e6c0e8 (&type->s_umount_key#42){++++}, at: trylock_super+0x1b/0x70stack backtrace:
CPU: 2 PID: 1133 Comm: kswapd0 Not tainted 5.6.0-c6f0579d496a+ #53
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.12.0-1 04/01/2014
Call Trace:
dump_stack+0xc1/0x11a
print_circular_bug.isra.38.cold.57+0x145/0x14a
check_noncircular+0x2a9/0x2f0
? print_circular_bug.isra.38+0x130/0x130
? stack_trace_consume_entry+0x90/0x90
? save_trace+0x3cc/0x420
__lock_acquire+0x197e/0x2550
? btrfs_inode_clear_file_extent_range+0x9b/0xb0
? register_lock_class+0x960/0x960
lock_acquire+0x103/0x220
? __btrfs_release_delayed_node+0x7c/0x5b0
__mutex_lock+0x13d/0xce0
? __btrfs_release_delayed_node+0x7c/0x5b0
? __asan_loadN+0xf/0x20
? pvclock_clocksource_read+0xeb/0x190
? __btrfs_release_delayed_node+0x7c/0x5b0
? mutex_lock_io_nested+0xc20/0xc20
? __kasan_check_read+0x11/0x20
? check_chain_key+0x1e6/0x2e0
mutex_lock_nested+0x1b/0x20
? mutex_lock_nested+0x1b/0x20
__btrfs_release_delayed_node+0x7c/0x5b0
btrfs_remove_delayed_node+0x49/0x50
btrfs_evict_inode+0x6fc/0x900
? btrfs_setattr+0x840/0x840
? do_raw_spin_unlock+0xa8/0x140
evict+0x19a/0x2c0
dispose_list+0xa0/0xe0
prune_icache_sb+0xbd/0xf0
? invalidate_inodes+0x310/0x310
super_cache_scan+0x1b5/0x250
do_shrink_slab+0x1f6/0x530
shrink_slab+0x32e/0x410
? do_shrink_slab+0x530/0x530
? do_shrink_slab+0x530/0x530
? __kasan_check_read+0x11/0x20
? mem_cgroup_protected+0x13d/0x260
shrink_node+0x2a5/0xba0
balance_pgdat+0x4bd/0x8a0
? mem_cgroup_shrink_node+0x490/0x490
? _raw_spin_unlock_irq+0x27/0x40
? finish_task_switch+0xce/0x390
? rcu_read_lock_bh_held+0xb0/0xb0
kswapd+0x35a/0x800
? _raw_spin_unlock_irqrestore+0x4c/0x60
? balance_pgdat+0x8a0/0x8a0
? finish_wait+0x110/0x110
? __kasan_check_read+0x11/0x20
? __kthread_parkme+0xc6/0xe0
? balance_pgdat+0x8a0/0x8a0
kthread+0x1e9/0x210
? kthread_create_worker_on_cpu+0xc0/0xc0
ret_from_fork+0x3a/0x50This is because we hold that delayed node's mutex while doing tree
operations. Fix this by just wrapping the searches in nofs.CC: stable@vger.kernel.org # 4.4+
Signed-off-by: Josef Bacik
Reviewed-by: David Sterba
Signed-off-by: David Sterba
24 Mar, 2020
3 commits
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Currently the non-prefixed version is a simple wrapper used to hide
the 4th argument of the prefixed version. This doesn't bring much value
in practice and only makes the code harder to follow by adding another
level of indirection. Rectify this by removing the __ prefix and
have only one public function to release bytes from a block reservation.
No semantic changes.Signed-off-by: Nikolay Borisov
Reviewed-by: David Sterba
Signed-off-by: David Sterba -
The status of aborted transaction can change between calls and it needs
to be accessed by READ_ONCE. Add a helper that also wraps the unlikely
hint.Reviewed-by: Josef Bacik
Signed-off-by: David Sterba -
We want to use this everywhere we modify the file extent items
permanently. These include:1) Inserting new file extents for writes and prealloc extents.
2) Truncating inode items.
3) btrfs_cont_expand().
4) Insert inline extents.
5) Insert new extents from log replay.
6) Insert a new extent for clone, as it could be past i_size.
7) Hole punchingFor hole punching in particular it might seem it's not necessary because
anybody extending would use btrfs_cont_expand, however there is a corner
that still can give us trouble. Start with an empty file andfallocate KEEP_SIZE 1M-2M
We now have a 0 length file, and a hole file extent from 0-1M, and a
prealloc extent from 1M-2M. Nowpunch 1M-1.5M
Because this is past i_size we have
[HOLE EXTENT][ NOTHING ][PREALLOC]
[0 1M][1M 1.5M][1.5M 2M]with an i_size of 0. Now if we pwrite 0-1.5M we'll increas our i_size
to 1.5M, but our disk_i_size is still 0 until the ordered extent
completes.However if we now immediately truncate 2M on the file we'll just call
btrfs_cont_expand(inode, 1.5M, 2M), since our old i_size is 1.5M. If we
commit the transaction here and crash we'll expose the gap.To fix this we need to clear the file extent mapping for the range that
we punched but didn't insert a corresponding file extent for. This will
mean the truncate will only get an disk_i_size set to 1M if we crash
before the finish ordered io happens.I've written an xfstest to reproduce the problem and validate this fix.
Reviewed-by: Filipe Manana
Signed-off-by: Josef Bacik
Signed-off-by: David Sterba
18 Nov, 2019
3 commits
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We hit the following warning while running down a different problem
[ 6197.175850] ------------[ cut here ]------------
[ 6197.185082] refcount_t: underflow; use-after-free.
[ 6197.194704] WARNING: CPU: 47 PID: 966 at lib/refcount.c:190 refcount_sub_and_test_checked+0x53/0x60
[ 6197.521792] Call Trace:
[ 6197.526687] __btrfs_release_delayed_node+0x76/0x1c0
[ 6197.536615] btrfs_kill_all_delayed_nodes+0xec/0x130
[ 6197.546532] ? __btrfs_btree_balance_dirty+0x60/0x60
[ 6197.556482] btrfs_clean_one_deleted_snapshot+0x71/0xd0
[ 6197.566910] cleaner_kthread+0xfa/0x120
[ 6197.574573] kthread+0x111/0x130
[ 6197.581022] ? kthread_create_on_node+0x60/0x60
[ 6197.590086] ret_from_fork+0x1f/0x30
[ 6197.597228] ---[ end trace 424bb7ae00509f56 ]---This is because the free side drops the ref without the lock, and then
takes the lock if our refcount is 0. So you can have nodes on the tree
that have a refcount of 0. Fix this by zero'ing out that element in our
temporary array so we don't try to kill it again.CC: stable@vger.kernel.org # 4.14+
Reviewed-by: Nikolay Borisov
Signed-off-by: Josef Bacik
Reviewed-by: David Sterba
[ add comment ]
Signed-off-by: David Sterba -
The function belongs to the family of locking functions, so move it
there. The 'noinline' keyword is dropped as it's now an exported
function that does not need it.Reviewed-by: Josef Bacik
Signed-off-by: David Sterba -
Commit 9e0af2376434 ("Btrfs: fix task hang under heavy compressed
write") worked around the issue that a recycled work item could get a
false dependency on the original work item due to how the workqueue code
guarantees non-reentrancy. It did so by giving different work functions
to different types of work.However, the fixes in the previous few patches are more complete, as
they prevent a work item from being recycled at all (except for a tiny
window that the kernel workqueue code handles for us). This obsoletes
the previous fix, so we don't need the unique helpers for correctness.
The only other reason to keep them would be so they show up in stack
traces, but they always seem to be optimized to a tail call, so they
don't show up anyways. So, let's just get rid of the extra indirection.While we're here, rename normal_work_helper() to the more informative
btrfs_work_helper().Reviewed-by: Nikolay Borisov
Reviewed-by: Filipe Manana
Signed-off-by: Omar Sandoval
Reviewed-by: David Sterba
Signed-off-by: David Sterba
09 Sep, 2019
4 commits
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The file ctree.h serves as a header for everything and has become quite
bloated. Split some helpers that are generic and create a new file that
should be the catch-all for code that's not btrfs-specific.Reviewed-by: Johannes Thumshirn
Signed-off-by: David Sterba -
Historically we reserved worst case for every btree operation, and
generally speaking we want to do that in cases where it could be the
worst case. However for updating inodes we know the inode items are
already in the tree, so it will only be an update operation and never an
insert operation. This allows us to always reserve only the
metadata_size amount for inode updates rather than the
insert_metadata_size amount.Reviewed-by: Nikolay Borisov
Signed-off-by: Josef Bacik
Signed-off-by: David Sterba -
btrfs_calc_trunc_metadata_size differs from trans_metadata_size in that
it doesn't take into account any splitting at the levels, because
truncate will never split nodes. However truncate _and_ changing will
never split nodes, so rename btrfs_calc_trunc_metadata_size to
btrfs_calc_metadata_size. Also btrfs_calc_trans_metadata_size is purely
for inserting items, so rename this to btrfs_calc_insert_metadata_size.
Making these clearer will help when I start using them differently in
upcoming patches.Reviewed-by: Nikolay Borisov
Signed-off-by: Josef Bacik
Reviewed-by: David Sterba
Signed-off-by: David Sterba -
There is one report of fuzzed image which leads to BUG_ON() in
btrfs_delete_delayed_dir_index().Although that fuzzed image can already be addressed by enhanced
extent-tree error handler, it's still better to hunt down more BUG_ON().This patch will hunt down two BUG_ON()s in
btrfs_delete_delayed_dir_index():
- One for error from btrfs_delayed_item_reserve_metadata()
Instead of BUG_ON(), we output an error message and free the item.
And return the error.
All callers of this function handles the error by aborting current
trasaction.- One for possible EEXIST from __btrfs_add_delayed_deletion_item()
That function can return -EEXIST.
We already have a good enough error message for that, only need to
clean up the reserved metadata space and allocated item.To help above cleanup, also modifiy __btrfs_remove_delayed_item() called
in btrfs_release_delayed_item(), to skip unassociated item.Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=203253
Signed-off-by: Qu Wenruo
Reviewed-by: David Sterba
Signed-off-by: David Sterba
30 Apr, 2019
2 commits
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We can read fs_info from extent buffer and can drop it from the
parameters.Signed-off-by: David Sterba
-
Deduplicate the btrfs file type conversion implementation - file systems
that use the same file types as defined by POSIX do not need to define
their own versions and can use the common helper functions decared in
fs_types.h and implemented in fs_types.cCommon implementation can be found via commit:
bbe7449e2599 "fs: common implementation of file type"Reviewed-by: Jan Kara
Signed-off-by: Amir Goldstein
Signed-off-by: Phillip Potter
Reviewed-by: David Sterba
Signed-off-by: David Sterba
15 Oct, 2018
4 commits
-
Btrfs's btree locking has two modes, spinning mode and blocking mode,
while searching btree, locking is always acquired in spinning mode and
then converted to blocking mode if necessary, and in some hot paths we may
switch the locking back to spinning mode by btrfs_clear_path_blocking().When acquiring locks, both of reader and writer need to wait for blocking
readers and writers to complete before doing read_lock()/write_lock().The problem is that btrfs_clear_path_blocking() needs to switch nodes
in the path to blocking mode at first (by btrfs_set_path_blocking) to
make lockdep happy before doing its actual clearing blocking job.When switching to blocking mode from spinning mode, it consists of
step 1) bumping up blocking readers counter and
step 2) read_unlock()/write_unlock(),this has caused serious ping-pong effect if there're a great amount of
concurrent readers/writers, as waiters will be woken up and go to
sleep immediately.1) Killing this kind of ping-pong results in a big improvement in my 1600k
files creation script,MNT=/mnt/btrfs
mkfs.btrfs -f /dev/sdf
mount /dev/def $MNT
time fsmark -D 10000 -S0 -n 100000 -s 0 -L 1 -l /tmp/fs_log.txt \
-d $MNT/0 -d $MNT/1 \
-d $MNT/2 -d $MNT/3 \
-d $MNT/4 -d $MNT/5 \
-d $MNT/6 -d $MNT/7 \
-d $MNT/8 -d $MNT/9 \
-d $MNT/10 -d $MNT/11 \
-d $MNT/12 -d $MNT/13 \
-d $MNT/14 -d $MNT/15w/o patch:
real 2m27.307s
user 0m12.839s
sys 13m42.831sw/ patch:
real 1m2.273s
user 0m15.802s
sys 8m16.495s1.1) latency histogram from funclatency[1]
Overall with the patch, there're ~50% less write lock acquisition and
the 95% max latency that write lock takes also reduces to ~100ms from
>500ms.--------------------------------------------
w/o patch:
--------------------------------------------
Function = btrfs_tree_lock
msecs : count distribution
0 -> 1 : 2385222 |****************************************|
2 -> 3 : 37147 | |
4 -> 7 : 20452 | |
8 -> 15 : 13131 | |
16 -> 31 : 3877 | |
32 -> 63 : 3900 | |
64 -> 127 : 2612 | |
128 -> 255 : 974 | |
256 -> 511 : 165 | |
512 -> 1023 : 13 | |Function = btrfs_tree_read_lock
msecs : count distribution
0 -> 1 : 6743860 |****************************************|
2 -> 3 : 2146 | |
4 -> 7 : 190 | |
8 -> 15 : 38 | |
16 -> 31 : 4 | |--------------------------------------------
w/ patch:
--------------------------------------------
Function = btrfs_tree_lock
msecs : count distribution
0 -> 1 : 1318454 |****************************************|
2 -> 3 : 6800 | |
4 -> 7 : 3664 | |
8 -> 15 : 2145 | |
16 -> 31 : 809 | |
32 -> 63 : 219 | |
64 -> 127 : 10 | |Function = btrfs_tree_read_lock
msecs : count distribution
0 -> 1 : 6854317 |****************************************|
2 -> 3 : 2383 | |
4 -> 7 : 601 | |
8 -> 15 : 92 | |2) dbench also proves the improvement,
dbench -t 120 -D /mnt/btrfs 16w/o patch:
Throughput 158.363 MB/secw/ patch:
Throughput 449.52 MB/sec3) xfstests didn't show any additional failures.
One thing to note is that callers may set path->leave_spinning to have
all nodes in the path stay in spinning mode, which means callers are
ready to not sleep before releasing the path, but it won't cause
problems if they don't want to sleep in blocking mode.[1]: https://github.com/iovisor/bcc/blob/master/tools/funclatency.py
Signed-off-by: Liu Bo
Signed-off-by: David Sterba -
rb_first_cached() trades an extra pointer "leftmost" for doing the same job as
rb_first() but in O(1).Functions manipulating delayed_item need to get the first entry, this converts
it to use rb_first_cached().For more details about the optimization see patch "Btrfs: delayed-refs:
use rb_first_cached for href_root".Tested-by: Holger Hoffstätte
Signed-off-by: Liu Bo
Reviewed-by: David Sterba
Signed-off-by: David Sterba -
There are two members in struct btrfs_root which indicate root's
objectid: objectid and root_key.objectid.They are both set to the same value in __setup_root():
static void __setup_root(struct btrfs_root *root,
struct btrfs_fs_info *fs_info,
u64 objectid)
{
...
root->objectid = objectid;
...
root->root_key.objectid = objecitd;
...
}and not changed to other value after initialization.
grep in btrfs directory shows both are used in many places:
$ grep -rI "root->root_key.objectid" | wc -l
133
$ grep -rI "root->objectid" | wc -l
55
(4.17, inc. some noise)It is confusing to have two similar variable names and it seems
that there is no rule about which should be used in a certain case.Since ->root_key itself is needed for tree reloc tree, let's remove
'objecitd' member and unify code to use ->root_key.objectid in all places.Signed-off-by: Misono Tomohiro
Reviewed-by: Qu Wenruo
Reviewed-by: David Sterba
Signed-off-by: David Sterba -
Using true and false here is closer to the expected semantic than using
0 and 1. No functional change.Signed-off-by: Lu Fengqi
Reviewed-by: David Sterba
Signed-off-by: David Sterba
06 Aug, 2018
3 commits
-
It can be referenced from the passed transaction handle.
Signed-off-by: Lu Fengqi
Signed-off-by: David Sterba -
It can be referenced from the passed transaction handle.
Signed-off-by: Lu Fengqi
Signed-off-by: David Sterba -
Functions that get btrfs inode can simply reach the fs_info by
dereferencing the root and this looks a bit more straightforward
compared to the btrfs_sb(...) indirection.If the transaction handle is available and not NULL it's used instead.
Signed-off-by: David Sterba
29 May, 2018
1 commit
-
Use the wrappers and reduce the amount of low-level details about the
waitqueue management.Reviewed-by: Nikolay Borisov
Signed-off-by: David Sterba
18 Apr, 2018
1 commit
-
Commit 4f5427ccce5d ("btrfs: delayed-inode: Use new qgroup meta rsv for
delayed inode and item") merged into mainline was not latest version
submitted to the mail list in Dec 2017.Which lacks the following fixes:
1) Remove btrfs_qgroup_convert_reserved_meta() call in
btrfs_delayed_item_release_metadata()
2) Remove btrfs_qgroup_reserve_meta_prealloc() call in
btrfs_delayed_inode_reserve_metadata()Those fixes will resolve unexpected EDQUOT problems.
Fixes: 4f5427ccce5d ("btrfs: delayed-inode: Use new qgroup meta rsv for delayed inode and item")
Signed-off-by: Qu Wenruo
Signed-off-by: David Sterba
12 Apr, 2018
1 commit
-
Remove GPL boilerplate text (long, short, one-line) and keep the rest,
ie. personal, company or original source copyright statements. Add the
SPDX header.Signed-off-by: David Sterba
31 Mar, 2018
1 commit
-
Quite similar for delalloc, some modification to delayed-inode and
delayed-item reservation. Also needs extra parameter for release case
to distinguish normal release and error release.Signed-off-by: Qu Wenruo
Signed-off-by: David Sterba
26 Mar, 2018
3 commits
-
The __cold functions are placed to a special section, as they're
expected to be called rarely. This could help i-cache prefetches or help
compiler to decide which branches are more/less likely to be taken
without any other annotations needed.Though we can't add more __exit annotations, it's still possible to add
__cold (that's also added with __exit). That way the following function
categories are tagged:- printf wrappers, error messages
- exit helpersSigned-off-by: David Sterba
-
We already pass the transaction which has a reference to the fs_info,
so use that. No functional changes.Signed-off-by: Nikolay Borisov
Signed-off-by: David Sterba -
We already pass the transaction handle, which contains a refrence to
the fs_info so grab it from there. No functional changes.Signed-off-by: Nikolay Borisov
Signed-off-by: David Sterba
30 Jan, 2018
2 commits
-
Pull btrfs updates from David Sterba:
"Features or user visible changes:- fallocate: implement zero range mode
- avoid losing data raid profile when deleting a device
- tree item checker: more checks for directory items and xattrs
Notable fixes:
- raid56 recovery: don't use cached stripes, that could be
potentially changed and a later RMW or recovery would lead to
corruptions or failures- let raid56 try harder to rebuild damaged data, reading from all
stripes if necessary- fix scrub to repair raid56 in a similar way as in the case above
Other:
- cleanups: device freeing, removed some call indirections, redundant
bio_put/_get, unused parameters, refactorings and renames- RCU list traversal fixups
- simplify mount callchain, remove recursing back when mounting a
subvolume- plug for fsync, may improve bio merging on multiple devices
- compression heurisic: replace heap sort with radix sort, gains some
performance- add extent map selftests, buffered write vs dio"
* tag 'for-4.16-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux: (155 commits)
btrfs: drop devid as device_list_add() arg
btrfs: get device pointer from device_list_add()
btrfs: set the total_devices in device_list_add()
btrfs: move pr_info into device_list_add
btrfs: make btrfs_free_stale_devices() to match the path
btrfs: rename btrfs_free_stale_devices() arg to skip_dev
btrfs: make btrfs_free_stale_devices() argument optional
btrfs: make btrfs_free_stale_device() to iterate all stales
btrfs: no need to check for btrfs_fs_devices::seeding
btrfs: Use IS_ALIGNED in btrfs_truncate_block instead of opencoding it
Btrfs: noinline merge_extent_mapping
Btrfs: add WARN_ONCE to detect unexpected error from merge_extent_mapping
Btrfs: extent map selftest: dio write vs dio read
Btrfs: extent map selftest: buffered write vs dio read
Btrfs: add extent map selftests
Btrfs: move extent map specific code to extent_map.c
Btrfs: add helper for em merge logic
Btrfs: fix unexpected EEXIST from btrfs_get_extent
Btrfs: fix incorrect block_len in merge_extent_mapping
btrfs: Remove unused readahead spinlock
... -
Pull inode->i_version rework from Jeff Layton:
"This pile of patches is a rework of the inode->i_version field. We
have traditionally incremented that field on every inode data or
metadata change. Typically this increment needs to be logged on disk
even when nothing else has changed, which is rather expensive.It turns out though that none of the consumers of that field actually
require this behavior. The only real requirement for all of them is
that it be different iff the inode has changed since the last time the
field was checked.Given that, we can optimize away most of the i_version increments and
avoid dirtying inode metadata when the only change is to the i_version
and no one is querying it. Queries of the i_version field are rather
rare, so we can help write performance under many common workloads.This patch series converts existing accesses of the i_version field to
a new API, and then converts all of the in-kernel filesystems to use
it. The last patch in the series then converts the backend
implementation to a scheme that optimizes away a large portion of the
metadata updates when no one is looking at it.In my own testing this series significantly helps performance with
small I/O sizes. I also got this email for Christmas this year from
the kernel test robot (a 244% r/w bandwidth improvement with XFS over
DAX, with 4k writes):https://lkml.org/lkml/2017/12/25/8
A few of the earlier patches in this pile are also flowing to you via
other trees (mm, integrity, and nfsd trees in particular)".* tag 'iversion-v4.16-1' of git://git.kernel.org/pub/scm/linux/kernel/git/jlayton/linux: (22 commits)
fs: handle inode->i_version more efficiently
btrfs: only dirty the inode in btrfs_update_time if something was changed
xfs: avoid setting XFS_ILOG_CORE if i_version doesn't need incrementing
fs: only set S_VERSION when updating times if necessary
IMA: switch IMA over to new i_version API
xfs: convert to new i_version API
ufs: use new i_version API
ocfs2: convert to new i_version API
nfsd: convert to new i_version API
nfs: convert to new i_version API
ext4: convert to new i_version API
ext2: convert to new i_version API
exofs: switch to new i_version API
btrfs: convert to new i_version API
afs: convert to new i_version API
affs: convert to new i_version API
fat: convert to new i_version API
fs: don't take the i_lock in inode_inc_iversion
fs: new API for handling inode->i_version
ntfs: remove i_version handling
...
29 Jan, 2018
1 commit
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Signed-off-by: Jeff Layton
Acked-by: David Sterba
25 Jan, 2018
1 commit
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In fixing the readdir+pagefault deadlock I accidentally introduced a
stale entry regression in readdir. If we get close to full for the
temporary buffer, and then skip a few delayed deletions, and then try to
add another entry that won't fit, we will emit the entries we found and
retry. Unfortunately we delete entries from our del_list as we find
them, assuming we won't need them. However our pos will be with
whatever our last entry was, which could be before the delayed deletions
we skipped, so the next search will add the deleted entries back into
our readdir buffer. So instead don't delete entries we find in our
del_list so we can make sure we always find our delayed deletions. This
is a slight perf hit for readdir with lots of pending deletions, but
hopefully this isn't a common occurrence. If it is we can revist this
and optimize it.cc: stable@vger.kernel.org
Fixes: 23b5ec74943f ("btrfs: fix readdir deadlock with pagefault")
Signed-off-by: Josef Bacik
Signed-off-by: David Sterba
22 Jan, 2018
2 commits
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btrfs_balance_delayed_items is the sole caller of
btrfs_wq_run_delayed_node and already includes one of the checks whether
the delayed inodes should be run. On the other hand
btrfs_wq_run_delayed_node duplicates that check and performs an
additional one for wq congestion.Let's remove the duplicate check and move the congestion one in
btrfs_balance_delayed_items, leaving btrfs_wq_run_delayed_node to only
care about setting up the wq run. No functional changes.Signed-off-by: Nikolay Borisov
Reviewed-by: Qu Wenruo
Signed-off-by: David Sterba -
Currently btrfs_async_run_delayed_root's implementation uses 3 goto
labels to mimic the functionality of a simple do {} while loop. Refactor
the function to use a do {} while construct, making intention clear and
code easier to follow. No functional changes.Signed-off-by: Nikolay Borisov
Reviewed-by: Qu Wenruo
Signed-off-by: David Sterba
03 Jan, 2018
1 commit
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refcounts have a generic implementation and an asm optimized one. The
generic version has extra debugging to make sure that once a refcount
goes to zero, refcount_inc won't increase it.The btrfs delayed inode code wasn't expecting this, and we're tripping
over the warnings when the generic refcounts are used. We ended up with
this race:Process A Process B
btrfs_get_delayed_node()
spin_lock(root->inode_lock)
radix_tree_lookup()
__btrfs_release_delayed_node()
refcount_dec_and_test(&delayed_node->refs)
our refcount is now zero
refcount_add(2) inode_lock)
radix_tree_delete()With the generic refcounts, we actually warn again when process B above
tries to release his refcount because refcount_add() turned into a
no-op.We saw this in production on older kernels without the asm optimized
refcounts.The fix used here is to use refcount_inc_not_zero() to detect when the
object is in the middle of being freed and return NULL. This is almost
always the right answer anyway, since we usually end up pitching the
delayed_node if it didn't have fresh data in it.This also changes __btrfs_release_delayed_node() to remove the extra
check for zero refcounts before radix tree deletion.
btrfs_get_delayed_node() was the only path that was allowing refcounts
to go from zero to one.Fixes: 6de5f18e7b0da ("btrfs: fix refcount_t usage when deleting btrfs_delayed_node")
CC: # 4.12+
Signed-off-by: Chris Mason
Reviewed-by: Liu Bo
Signed-off-by: David Sterba
02 Nov, 2017
1 commit
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The way we handle delalloc metadata reservations has gotten
progressively more complicated over the years. There is so much cruft
and weirdness around keeping the reserved count and outstanding counters
consistent and handling the error cases that it's impossible to
understand.Fix this by making the delalloc block rsv per-inode. This way we can
calculate the actual size of the outstanding metadata reservations every
time we make a change, and then reserve the delta based on that amount.
This greatly simplifies the code everywhere, and makes the error
handling in btrfs_delalloc_reserve_metadata far less terrifying.Signed-off-by: Josef Bacik
Signed-off-by: David Sterba
18 Aug, 2017
1 commit
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Our dir_context->pos is supposed to hold the next position we're
supposed to look. If we successfully insert a delayed dir index we
could end up with a duplicate entry because we don't increase ctx->pos
after doing the dir_emit.Signed-off-by: Josef Bacik
Reviewed-by: Liu Bo
Signed-off-by: David Sterba
18 Apr, 2017
2 commits
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refcount_t type and corresponding API should be
used instead of atomic_t when the variable is used as
a reference counter. This allows to avoid accidental
refcounter overflows that might lead to use-after-free
situations.Signed-off-by: Elena Reshetova
Signed-off-by: Hans Liljestrand
Signed-off-by: Kees Cook
Signed-off-by: David Windsor
Signed-off-by: David Sterba -
refcount_t type and corresponding API should be
used instead of atomic_t when the variable is used as
a reference counter. This allows to avoid accidental
refcounter overflows that might lead to use-after-free
situations.Signed-off-by: Elena Reshetova
Signed-off-by: Hans Liljestrand
Signed-off-by: Kees Cook
Signed-off-by: David Windsor
Signed-off-by: David Sterba
28 Feb, 2017
1 commit
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Signed-off-by: Nikolay Borisov
Signed-off-by: David Sterba
14 Feb, 2017
1 commit
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This goes as a separate patch because fixing that inside the patches
caused too many many conflicts.Signed-off-by: David Sterba