OSDN Git Service
Naohiro Aota [Tue, 10 Nov 2020 11:26:07 +0000 (20:26 +0900)]
btrfs: get zone information of zoned block devices
If a zoned block device is found, get its zone information (number of
zones and zone size). To avoid costly run-time zone report
commands to test the device zones type during block allocation, attach
the seq_zones bitmap to the device structure to indicate if a zone is
sequential or accept random writes. Also it attaches the empty_zones
bitmap to indicate if a zone is empty or not.
This patch also introduces the helper function btrfs_dev_is_sequential()
to test if the zone storing a block is a sequential write required zone
and btrfs_dev_is_empty_zone() to test if the zone is a empty zone.
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: Anand Jain <anand.jain@oracle.com>
Signed-off-by: Damien Le Moal <damien.lemoal@wdc.com>
Signed-off-by: Naohiro Aota <naohiro.aota@wdc.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Naohiro Aota [Tue, 10 Nov 2020 11:26:06 +0000 (20:26 +0900)]
btrfs: introduce ZONED feature flag
This patch introduces the ZONED incompat flag. The flag indicates that
the volume management will satisfy the constraints imposed by
host-managed zoned block devices (aligned chunk allocation, append-only
updates, reset zone after filled).
As the zoned support will happen incrementally due to enhancing some
core infrastructure like super block writes, tree-log, raid support, the
feature will appear in sysfs only on debug builds. It will be enabled
once the support is feature complete and applications can reliably check
whether zoned support is present or not.
Reviewed-by: Anand Jain <anand.jain@oracle.com>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: Damien Le Moal <damien.lemoal@wdc.com>
Signed-off-by: Naohiro Aota <naohiro.aota@wdc.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Nikolay Borisov [Tue, 24 Nov 2020 14:49:25 +0000 (16:49 +0200)]
btrfs: return bool from btrfs_should_end_transaction
Results in slightly smaller code.
add/remove: 0/0 grow/shrink: 0/1 up/down: 0/-11 (-11)
Function old new delta
btrfs_should_end_transaction 96 85 -11
Total: Before=20070, After=20059, chg -0.05%
Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Nikolay Borisov [Tue, 24 Nov 2020 14:49:08 +0000 (16:49 +0200)]
btrfs: return bool from should_end_transaction
Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Nikolay Borisov [Tue, 24 Nov 2020 15:49:32 +0000 (17:49 +0200)]
btrfs: remove err variable from do_relocation
It simply gets assigned to 'ret' in case of errors. The flow of the
while loop is not changed by this commit since the few call sites
that 'goto next' will simply break from the loop.
Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Nikolay Borisov [Tue, 24 Nov 2020 15:49:31 +0000 (17:49 +0200)]
btrfs: eliminate err variable from merge_reloc_root
In most cases when an error is returned from a function 'ret' is simply
assigned to 'err'. There is only one case where walk_up_reloc_tree can
return a positive value - in this case the code breaks from the loop and
ret is going to get its return value from btrfs_cow_block - either 0 or
negative. This retains the old logic of how 'err' used to be set at
this call site.
Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Nikolay Borisov [Tue, 24 Nov 2020 15:49:30 +0000 (17:49 +0200)]
btrfs: remove err variable from btrfs_delete_subvolume
Use only a single 'ret' to control whether we should abort the
transaction or not. That's fine, because if we abort a transaction then
btrfs_end_transaction will return the same value as passed to
btrfs_abort_transaction. No semantic changes.
Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Filipe Manana [Wed, 18 Nov 2020 11:00:17 +0000 (11:00 +0000)]
btrfs: unlock path before checking if extent is shared during nocow writeback
When we are attempting to start writeback for an existing extent in NOCOW
mode, at run_delalloc_nocow(), we must check if the extent is shared, and
if it is, fallback to a COW write. However we do such check while still
holding a read lock on the leaf that contains the file extent item, and
that check, the call to btrfs_cross_ref_exist(), can take some time
because:
1) It needs to do a search on the extent tree, which obviously takes some
time, specially if delayed references are being run at the moment, as
we can block when trying to lock currently write locked btree nodes;
2) It needs to check the delayed references for any existing reference
for our data extent, this requires acquiring the delayed references'
spinlock and maybe block on the mutex of a delayed reference head in the
case where there is a delayed reference for our data extent, in the
worst case it makes us release the path on the extent tree and retry
the whole process again (going back to step 1).
There are other operations we do while holding the leaf locked that can
take some significant time as well (specially all together):
* btrfs_extent_readonly() - to check if the block group containing the
extent is currently in RO mode. This requires taking a spinlock and
searching for the block group in a rbtree that can be big on large
filesystems;
* csum_exist_in_range() - to search if there are any checksums in the
csum tree for the extent. Like before, this can take some time if we are
in a filesystem that has both COW and NOCOW files, in which case the
csum tree is not empty;
* btrfs_inc_nocow_writers() - increment the number of nocow writers in the
block group that contains the data extent. Needs to acquire a spinlock
and search for the block group in a rbtree that can be big on large
filesystems.
So just unlock the leaf (release the path) before doing all those checks,
since we do not need it anymore. In case we can not do a NOCOW write for
the extent, due to any of those checks failing, and the writeback range
goes beyond that extents' length, we will do another btree search for the
next file extent item.
The following script that calls dbench was used to measure the impact of
this change on a VM with 8 CPUs, 16Gb of ram, using a raw NVMe device
directly (no intermediary filesystem on the host) and using a non-debug
kernel (default configuration on Debian):
$ cat test-dbench.sh
#!/bin/bash
DEV=/dev/sdk
MNT=/mnt/sdk
MOUNT_OPTIONS="-o ssd -o nodatacow"
MKFS_OPTIONS="-m single -d single"
mkfs.btrfs -f $MKFS_OPTIONS $DEV
mount $MOUNT_OPTIONS $DEV $MNT
dbench -D $MNT -t 300 64
umount $MNT
Before this change:
Operation Count AvgLat MaxLat
----------------------------------------
NTCreateX
9326331 0.317 399.957
Close
6851198 0.002 6.402
Rename 394894 2.621 402.819
Unlink
1883131 0.931 398.082
Deltree 256 19.160 303.580
Mkdir 128 0.003 0.016
Qpathinfo
8452314 0.068 116.133
Qfileinfo
1481921 0.001 5.081
Qfsinfo
1549963 0.002 4.444
Sfileinfo 759679 0.084 17.079
Find
3268168 0.396 118.196
WriteX
4653310 0.056 110.993
ReadX
14618818 0.005 23.314
LockX 30364 0.003 0.497
UnlockX 30364 0.002 1.720
Flush 653619 16.954 569.299
Throughput 966.651 MB/sec 64 clients 64 procs max_latency=569.377 ms
After this change:
Operation Count AvgLat MaxLat
----------------------------------------
NTCreateX
9710433 0.302 232.449
Close
7132948 0.002 11.496
Rename 411144 2.452 131.805
Unlink
1960961 0.893 230.383
Deltree 256 14.858 198.646
Mkdir 128 0.002 0.005
Qpathinfo
8800890 0.066 111.588
Qfileinfo
1542556 0.001 3.852
Qfsinfo
1613835 0.002 5.483
Sfileinfo 790871 0.081 19.492
Find
3402743 0.386 120.185
WriteX
4842918 0.054 179.312
ReadX
15220407 0.005 32.435
LockX 31612 0.003 1.533
UnlockX 31612 0.002 1.047
Flush 680567 16.320 463.323
Throughput 1016.59 MB/sec 64 clients 64 procs max_latency=463.327 ms
+5.0% throughput, -20.5% max latency
Also, the following test using fio was run:
$ cat test-fio.sh
#!/bin/bash
DEV=/dev/sdk
MNT=/mnt/sdk
MOUNT_OPTIONS="-o ssd -o nodatacow"
MKFS_OPTIONS="-d single -m single"
if [ $# -ne 4 ]; then
echo "Use $0 NUM_JOBS FILE_SIZE FSYNC_FREQ BLOCK_SIZE"
exit 1
fi
NUM_JOBS=$1
FILE_SIZE=$2
FSYNC_FREQ=$3
BLOCK_SIZE=$4
cat <<EOF > /tmp/fio-job.ini
[writers]
rw=randwrite
fsync=$FSYNC_FREQ
fallocate=none
group_reporting=1
direct=0
bs=$BLOCK_SIZE
ioengine=sync
size=$FILE_SIZE
directory=$MNT
numjobs=$NUM_JOBS
EOF
echo
echo "Using fio config:"
echo
cat /tmp/fio-job.ini
echo
echo "mount options: $MOUNT_OPTIONS"
echo
mkfs.btrfs -f $MKFS_OPTIONS $DEV > /dev/null
mount $MOUNT_OPTIONS $DEV $MNT
echo "Creating nodatacow files before fio runs..."
for ((i = 0; i < $NUM_JOBS; i++)); do
xfs_io -f -c "pwrite -b 128M 0 $FILE_SIZE" "$MNT/writers.$i.0"
done
sync
fio /tmp/fio-job.ini
umount $MNT
Before this change:
$ ./test-fio.sh 16 512M 2 4K
(...)
WRITE: bw=28.3MiB/s (29.6MB/s), 28.3MiB/s-28.3MiB/s (29.6MB/s-29.6MB/s), io=8192MiB (8590MB), run=289800-289800msec
After this change:
$ ./test-fio.sh 16 512M 2 4K
(...)
WRITE: bw=31.2MiB/s (32.7MB/s), 31.2MiB/s-31.2MiB/s (32.7MB/s-32.7MB/s), io=8192MiB (8590MB), run=262845-262845msec
+9.7% throughput, -9.8% runtime
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
David Sterba [Wed, 4 Nov 2020 15:12:45 +0000 (16:12 +0100)]
btrfs: tree-checker: annotate all error branches as unlikely
The tree checker is called many times as it verifies metadata at
read/write time. The checks follow a simple pattern:
if (error_condition) {
report_error();
return -EUCLEAN;
}
All the error reporting functions are annotated as __cold that is
supposed to hint the compiler to move the statement block out of the hot
path. This does not seem to happen that often.
As the error condition is expected to be false almost always, we can
annotate it with 'unlikely' as this satisfies one of the few use cases
for the annotation. The expected outcome is a stronger hint to compiler
to reorder the checks
test
jump to exit
test
jump to exit
...
which can be observed in asm of eg. check_dir_item,
btrfs_check_chunk_valid, check_root_item or check_leaf.
There's a measurable run time improvement reported by Josef, the testing
workload went from 655 MiB/s to 677 MiB/s, which is about +3%.
There should be no functional changes but some of the conditions have
been rewritten to produce more readable result, some lines are longer
than 80, for the sake of readability.
Signed-off-by: David Sterba <dsterba@suse.com>
David Sterba [Fri, 13 Nov 2020 16:58:03 +0000 (17:58 +0100)]
btrfs: remove stub device info from messages when we have no fs_info
Without a NULL fs_info the helpers will print something like
BTRFS error (device <unknown>): ...
This can happen in contexts where fs_info is not available at all or
it's potentially unsafe due to object lifetime. The <unknown> stub does
not bring much information and with the prefix makes the message
unnecessarily longer.
Remove it for the NULL fs_info case.
BTRFS error: ...
Callers can add the device information to the message itself if needed.
Reviewed-by: Anand Jain <anand.jain@oracle.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Qu Wenruo [Fri, 13 Nov 2020 12:51:49 +0000 (20:51 +0800)]
btrfs: use detach_page_private() in alloc_extent_buffer()
In alloc_extent_buffer(), after we got a page from btree inode, we check
if that page has private pointer attached.
If attached, we check if the existing extent buffer has proper refs.
If not (the eb is being freed), we will detach that private eb pointer.
The point here is, we are detaching that eb pointer by calling:
- ClearPagePrivate()
- put_page()
The put_page() here is especially confusing, as it's decreasing the ref
from attach_page_private(). Without knowing that, it looks like the
put_page() is for the find_or_create_page() call, confusing the reader.
Since we're always modifying page private with attach_page_private() and
detach_page_private(), the only open-coded detach_page_private() here is
really confusing.
Fix it by calling detach_page_private().
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Qu Wenruo [Fri, 13 Nov 2020 12:51:41 +0000 (20:51 +0800)]
btrfs: use nodesize to determine if we need readahead in btrfs_lookup_bio_sums
In btrfs_lookup_bio_sums() if the bio is pretty large, we want to
start readahead in the csum tree.
However the threshold is an immediate number, (PAGE_SIZE * 8), from the
initial btrfs merge.
The meaning of the value is pretty hard to guess, especially when the
immediate number is from the times when 4K sectorsize was the default
and only CRC32C was supported.
For the most common btrfs setup, CRC32 csum and 4K sectorsize,
it means just 32K read would kick readahead, while the csum itself is
only 32 bytes in size.
Now let's be more reasonable by taking both csum size and node size into
consideration.
If the csum size for the bio is larger than one leaf, then we kick the
readahead. This means for current default btrfs, the threshold will be
16M.
This change should not change performance observably, thus this is
mostly a readability enhancement.
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Qu Wenruo [Fri, 13 Nov 2020 12:51:39 +0000 (20:51 +0800)]
btrfs: only clear EXTENT_LOCK bit in extent_invalidatepage
extent_invalidatepage() will try to clear all possible bits since it's
calling clear_extent_bit() with delete == 1.
This is currently fine, since for btree io tree, it only utilizes
EXTENT_LOCK bit. But this could be a problem for later subpage support,
which will utilize extra io tree bit to represent additional info.
This patch will just convert that clear_extent_bit() to
unlock_extent_cached().
For current code since only EXTENT_LOCKED bit is utilized, this doesn't
change the behavior, but provides a much cleaner basis for incoming
subpage support.
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Qu Wenruo [Thu, 12 Nov 2020 08:47:57 +0000 (16:47 +0800)]
btrfs: remove unused parameter phy_offset from btrfs_validate_metadata_buffer
Parameter @phy_offset is the offset against the bio->bi_iter.bi_sector.
@phy_offset is mostly for data io to lookup the csum in btrfs_io_bio.
But for metadata, it's completely useless as metadata stores their own
csum in its header, so we can remove it.
Note: parameters @start and @end, they are not utilized at all for
current sectorsize == PAGE_SIZE case, as we can grab eb directly from
page.
But those two parameters are very important for later subpage support,
thus @start/@len are not touched here.
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Qu Wenruo [Fri, 13 Nov 2020 12:51:44 +0000 (20:51 +0800)]
btrfs: scrub: remove the anonymous structure from scrub_page
That anonymous structure serve no special purpose, just replace it with
regular members.
Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Qu Wenruo [Fri, 13 Nov 2020 12:51:40 +0000 (20:51 +0800)]
btrfs: use fixed width int type for extent_state::state
Currently the type is unsigned int which could change its width
depending on the architecture. We need up to 32 bits so make it
explicit.
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Qu Wenruo [Fri, 13 Nov 2020 12:51:29 +0000 (20:51 +0800)]
btrfs: introduce helper to handle page status update in end_bio_extent_readpage()
Introduce a new helper to handle update page status in
end_bio_extent_readpage(). This will be later used for subpage support
where the page status update can be more complex than now.
Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Qu Wenruo [Fri, 13 Nov 2020 12:51:28 +0000 (20:51 +0800)]
btrfs: add structure to keep track of extent range in end_bio_extent_readpage
In end_bio_extent_readpage() we had a strange dance around
extent_start/extent_len.
Hidden behind the strange dance is, it's just calling
endio_readpage_release_extent() on each bvec range.
Here is an example to explain the original work flow:
Bio is for inode 257, containing 2 pages, for range [1M, 1M+8K)
end_bio_extent_extent_readpage() entered
|- extent_start = 0;
|- extent_end = 0;
|- bio_for_each_segment_all() {
| |- /* Got the 1st bvec */
| |- start = SZ_1M;
| |- end = SZ_1M + SZ_4K - 1;
| |- update = 1;
| |- if (extent_len == 0) {
| | |- extent_start = start; /* SZ_1M */
| | |- extent_len = end + 1 - start; /* SZ_1M */
| | }
| |
| |- /* Got the 2nd bvec */
| |- start = SZ_1M + 4K;
| |- end = SZ_1M + 4K - 1;
| |- update = 1;
| |- if (extent_start + extent_len == start) {
| | |- extent_len += end + 1 - start; /* SZ_8K */
| | }
| } /* All bio vec iterated */
|
|- if (extent_len) {
|- endio_readpage_release_extent(tree, extent_start, extent_len,
update);
/* extent_start == SZ_1M, extent_len == SZ_8K, uptodate = 1 */
As the above flow shows, the existing code in end_bio_extent_readpage()
is accumulates extent_start/extent_len, and when the contiguous range
stops, calls endio_readpage_release_extent() for the range.
However current behavior has something not really considered:
- The inode can change
For bio, its pages don't need to have contiguous page_offset.
This means, even pages from different inodes can be packed into one
bio.
- bvec cross page boundary
There is a feature called multi-page bvec, where bvec->bv_len can go
beyond bvec->bv_page boundary.
- Poor readability
This patch will address the problem:
- Introduce a proper structure, processed_extent, to record processed
extent range
- Integrate inode/start/end/uptodate check into
endio_readpage_release_extent()
- Add more comment on each step.
This should greatly improve the readability, now in
end_bio_extent_readpage() there are only two
endio_readpage_release_extent() calls.
- Add inode check for contiguity
Now we also ensure the inode is the same one before checking if the
range is contiguous.
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Qu Wenruo [Fri, 13 Nov 2020 12:51:27 +0000 (20:51 +0800)]
btrfs: tests: remove invalid extent-io test
In extent-io-test, there are two invalid tests:
- Invalid nodesize for test_eb_bitmaps()
Instead of the sectorsize and nodesize combination passed in, we're
always using hand-crafted nodesize, e.g:
len = (sectorsize < BTRFS_MAX_METADATA_BLOCKSIZE)
? sectorsize * 4 : sectorsize;
In above case, if we have 32K page size, then we will get a length of
128K, which is beyond max node size, and obviously invalid.
The common page size goes up to 64K so we haven't hit that
- Invalid extent buffer bytenr
For 64K page size, the only combination we're going to test is
sectorsize = nodesize = 64K.
However, in that case we will try to test an eb which bytenr is not
sectorsize aligned:
/* Do it over again with an extent buffer which isn't page-aligned. */
eb = __alloc_dummy_extent_buffer(fs_info, nodesize / 2, len);
Sector alignment is a hard requirement for any sector size.
The only exception is superblock. But anything else should follow
sector size alignment.
This is definitely an invalid test case.
This patch will fix both problems by:
- Honor the sectorsize/nodesize combination
Now we won't bother to hand-craft the length and use it as nodesize.
- Use sectorsize as the 2nd run extent buffer start
This would test the case where extent buffer is aligned to sectorsize
but not always aligned to nodesize.
Please note that, later subpage related cleanup will reduce
extent_buffer::pages[] to exactly what we need, making the sector
unaligned extent buffer operations cause problems.
Since only extent_io self tests utilize this, this patch is required for
all later cleanup/refactoring.
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Tom Rix [Sun, 1 Nov 2020 15:30:08 +0000 (07:30 -0800)]
btrfs: sysfs: remove unneeded semicolon
A semicolon is not needed after a switch statement.
Signed-off-by: Tom Rix <trix@redhat.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Nikolay Borisov [Fri, 13 Nov 2020 07:29:40 +0000 (09:29 +0200)]
btrfs: simplify return values in setup_nodes_for_search
The function is needlessly convoluted. Fix that by:
* removing redundant sret variable definition in both if arms
* replace the again/done labels with direct return statements, the
function is short enough and doesn't do anything special upon exit
* remove BUG_ON on split_node returning a positive number - it can't
happen as split_node returns either 0 or a negative error code.
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Nikolay Borisov [Thu, 12 Nov 2020 11:24:02 +0000 (13:24 +0200)]
btrfs: remove useless return value statement in split_node
At the point when we set 'ret = 0' it's guaranteed that the function is
going to return 0 so directly return 0. No functional changes.
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Filipe Manana [Fri, 13 Nov 2020 11:24:17 +0000 (11:24 +0000)]
btrfs: remove unnecessary attempt to drop extent maps after adding inline extent
At inode.c:cow_file_range_inline(), after we insert the inline extent
in the fs/subvolume btree, we call btrfs_drop_extent_cache() to drop
all extent maps in the file range, however that is not necessary because
we have already done it in the call to btrfs_drop_extents(), which calls
btrfs_drop_extent_cache() for us, and since at this point we have the file
range locked in the inode's iotree (we are in the writeback path), we know
no other task can come in and read stale file extent items or find none
and therefore create either stale extent maps or an extent map that
represents a hole.
So just remove that unnecessary call to btrfs_drop_extent_cache(), as it's
doing nothing and only wasting time. This call has been around since 2008,
introduced in commit
c8b978188c9a ("Btrfs: Add zlib compression support"),
but even back then it seems it was not necessary, since we had the range
locked in the inode's iotree and the call to btrfs_drop_extents() already
used to always call btrfs_drop_extent_cache().
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>
Filipe Manana [Fri, 13 Nov 2020 11:23:30 +0000 (11:23 +0000)]
btrfs: stop incrementing log batch when joining log transaction
When joining a log transaction we acquire the root's log mutex, then
increment the root's log batch and log writers counters while holding
the mutex. However we don't need to increment the log batch there,
because we are holding the mutex and incremented the log writers counter
as well, so any other task trying to sync log will wait for the current
task to finish its logging and still achieve the desired log batching.
Since the log batch counter is an atomic counter and is incremented twice
at the very beginning of the fsync callback (btrfs_sync_file()), once
before flushing delalloc and once again after waiting for writeback to
complete, eliminating its increment when joining the log transaction
may provide some performance gains in case we have multiple concurrent
tasks doing fsyncs against different files in the same subvolume, as it
reduces contention on the atomic (locking the cacheline and bouncing it).
When testing fio with 32 jobs, on a 8 cores VM, doing fsyncs against
different files of the same subvolume, on top of a zram device, I could
consistently see gains (higher throughput) between 1% to 2%, which is a
very low value and possibly hard to be observed with a real device (I
couldn't observe consistent gains with my low/mid end NVMe device).
So this change is mostly motivated to just simplify the logic, as updating
the log batch counter is only relevant when an fsync starts and while not
holding the root's log mutex.
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>
Filipe Manana [Fri, 13 Nov 2020 11:21:49 +0000 (11:21 +0000)]
btrfs: skip unnecessary searches for xattrs when logging an inode
Every time we log an inode we lookup in the fs/subvol tree for xattrs and
if we have any, log them into the log tree. However it is very common to
have inodes without any xattrs, so doing the search wastes times, but more
importantly it adds contention on the fs/subvol tree locks, either making
the logging code block and wait for tree locks or making the logging code
making other concurrent operations block and wait.
The most typical use cases where xattrs are used are when capabilities or
ACLs are defined for an inode, or when SELinux is enabled.
This change makes the logging code detect when an inode does not have
xattrs and skip the xattrs search the next time the inode is logged,
unless the inode is evicted and loaded again or a xattr is added to the
inode. Therefore skipping the search for xattrs on inodes that don't ever
have xattrs and are fsynced with some frequency.
The following script that calls dbench was used to measure the impact of
this change on a VM with 8 CPUs, 16Gb of ram, using a raw NVMe device
directly (no intermediary filesystem on the host) and using a non-debug
kernel (default configuration on Debian distributions):
$ cat test.sh
#!/bin/bash
DEV=/dev/sdk
MNT=/mnt/sdk
MOUNT_OPTIONS="-o ssd"
mkfs.btrfs -f -m single -d single $DEV
mount $MOUNT_OPTIONS $DEV $MNT
dbench -D $MNT -t 200 40
umount $MNT
The results before this change:
Operation Count AvgLat MaxLat
----------------------------------------
NTCreateX
5761605 0.172 312.057
Close
4232452 0.002 10.927
Rename 243937 1.406 277.344
Unlink
1163456 0.631 298.402
Deltree 160 11.581 221.107
Mkdir 80 0.003 0.005
Qpathinfo
5221410 0.065 122.309
Qfileinfo 915432 0.001 3.333
Qfsinfo 957555 0.003 3.992
Sfileinfo 469244 0.023 20.494
Find
2018865 0.448 123.659
WriteX
2874851 0.049 118.529
ReadX
9030579 0.004 21.654
LockX 18754 0.003 4.423
UnlockX 18754 0.002 0.331
Flush 403792 10.944 359.494
Throughput 908.444 MB/sec 40 clients 40 procs max_latency=359.500 ms
The results after this change:
Operation Count AvgLat MaxLat
----------------------------------------
NTCreateX
6442521 0.159 230.693
Close
4732357 0.002 10.972
Rename 272809 1.293 227.398
Unlink
1301059 0.563 218.500
Deltree 160 7.796 54.887
Mkdir 80 0.008 0.478
Qpathinfo
5839452 0.047 124.330
Qfileinfo
1023199 0.001 4.996
Qfsinfo
1070760 0.003 5.709
Sfileinfo 524790 0.033 21.765
Find
2257658 0.314 125.611
WriteX
3211520 0.040 232.135
ReadX
10098969 0.004 25.340
LockX 20974 0.003 1.569
UnlockX 20974 0.002 3.475
Flush 451553 10.287 331.037
Throughput 1011.77 MB/sec 40 clients 40 procs max_latency=331.045 ms
+10.8% throughput, -8.2% max latency
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>
Nikolay Borisov [Thu, 5 Nov 2020 09:08:00 +0000 (11:08 +0200)]
btrfs: merge __set_extent_bit and set_extent_bit
There are only 2 direct calls to set_extent_bit outside of extent-io -
in btrfs_find_new_delalloc_bytes and btrfs_truncate_block, the rest are
thin wrappers around __set_extent_bit. This adds unnecessary indirection
and just makes it more annoying when looking at the various extent bit
manipulation functions. This patch renames __set_extent_bit to
set_extent_bit effectively removing a level of indirection. No
functional changes.
Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
[ reformat and remove __must_check ]
Signed-off-by: David Sterba <dsterba@suse.com>
Nikolay Borisov [Mon, 2 Nov 2020 14:49:06 +0000 (16:49 +0200)]
btrfs: make btrfs_update_inode_fallback take btrfs_inode
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Nikolay Borisov [Mon, 2 Nov 2020 14:49:04 +0000 (16:49 +0200)]
btrfs: make btrfs_cont_expand take btrfs_inode
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Nikolay Borisov [Mon, 2 Nov 2020 14:49:03 +0000 (16:49 +0200)]
btrfs: make btrfs_truncate_block take btrfs_inode
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Nikolay Borisov [Mon, 2 Nov 2020 14:49:02 +0000 (16:49 +0200)]
btrfs: make btrfs_insert_replace_extent take btrfs_inode
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Nikolay Borisov [Mon, 2 Nov 2020 14:49:01 +0000 (16:49 +0200)]
btrfs: make find_first_non_hole take btrfs_inode
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Nikolay Borisov [Mon, 2 Nov 2020 14:49:00 +0000 (16:49 +0200)]
btrfs: make maybe_insert_hole take btrfs_inode
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Nikolay Borisov [Mon, 2 Nov 2020 14:48:59 +0000 (16:48 +0200)]
btrfs: make btrfs_update_inode take btrfs_inode
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Nikolay Borisov [Mon, 2 Nov 2020 14:48:58 +0000 (16:48 +0200)]
btrfs: make btrfs_update_inode_item take btrfs_inode
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Nikolay Borisov [Mon, 2 Nov 2020 14:48:57 +0000 (16:48 +0200)]
btrfs: make btrfs_delayed_update_inode take btrfs_inode
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Nikolay Borisov [Mon, 2 Nov 2020 14:48:56 +0000 (16:48 +0200)]
btrfs: make btrfs_finish_ordered_io btrfs_inode-centric
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Nikolay Borisov [Mon, 2 Nov 2020 14:48:55 +0000 (16:48 +0200)]
btrfs: make btrfs_truncate_inode_items take btrfs_inode
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Nikolay Borisov [Mon, 2 Nov 2020 14:48:54 +0000 (16:48 +0200)]
btrfs: make insert_prealloc_file_extent take btrfs_inode
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Nikolay Borisov [Mon, 2 Nov 2020 14:48:53 +0000 (16:48 +0200)]
btrfs: make btrfs_inode_safe_disk_i_size_write take btrfs_inode
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Josef Bacik [Fri, 6 Nov 2020 21:27:36 +0000 (16:27 -0500)]
btrfs: remove extent_buffer::recursed
It is unused everywhere now, it can be removed.
Reviewed-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Josef Bacik [Fri, 6 Nov 2020 21:27:35 +0000 (16:27 -0500)]
btrfs: remove the recurse parameter from __btrfs_tree_read_lock
It is completely unused now, remove it.
Reviewed-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Josef Bacik [Fri, 6 Nov 2020 21:27:34 +0000 (16:27 -0500)]
btrfs: use btrfs_tree_read_lock in btrfs_search_slot
We no longer use recursion, so
__btrfs_tree_read_lock(BTRFS_NESTING_NORMAL) == btrfs_tree_read_lock.
Replace this call with the simple helper.
Reviewed-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Josef Bacik [Fri, 6 Nov 2020 21:27:33 +0000 (16:27 -0500)]
btrfs: merge back btrfs_read_lock_root_node helpers
We no longer have recursive locking and there's no need for separate
helpers that allowed the transition to rwsem with minimal code changes.
Reviewed-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Josef Bacik [Fri, 6 Nov 2020 21:27:32 +0000 (16:27 -0500)]
btrfs: locking: remove the recursion handling code
Now that we're no longer using recursion, rip out all of the supporting
code. Follow up patches will clean up the callers of these functions.
The extent_buffer::lock_owner is still retained as it allows safety
checks in btrfs_init_new_buffer for the case that the free space cache
is corrupted and we try to allocate a block that we are currently using
and have locked in the path.
Reviewed-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Josef Bacik [Fri, 6 Nov 2020 21:27:31 +0000 (16:27 -0500)]
btrfs: remove btrfs_path::recurse
With my async free space cache loading patches ("btrfs: load free space
cache asynchronously") we no longer have a user of path->recurse and can
remove it.
Reviewed-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Josef Bacik [Fri, 6 Nov 2020 21:27:30 +0000 (16:27 -0500)]
btrfs: unlock to current level in btrfs_next_old_leaf
Filipe reported the following lockdep splat
======================================================
WARNING: possible circular locking dependency detected
5.10.0-rc2-btrfs-next-71 #1 Not tainted
------------------------------------------------------
find/324157 is trying to acquire lock:
ffff8ebc48d293a0 (btrfs-tree-01#2/3){++++}-{3:3}, at: __btrfs_tree_read_lock+0x32/0x1a0 [btrfs]
but task is already holding lock:
ffff8eb9932c5088 (btrfs-tree-00){++++}-{3:3}, at: __btrfs_tree_read_lock+0x32/0x1a0 [btrfs]
which lock already depends on the new lock.
the existing dependency chain (in reverse order) is:
-> #1 (btrfs-tree-00){++++}-{3:3}:
lock_acquire+0xd8/0x490
down_write_nested+0x44/0x120
__btrfs_tree_lock+0x27/0x120 [btrfs]
btrfs_search_slot+0x2a3/0xc50 [btrfs]
btrfs_insert_empty_items+0x58/0xa0 [btrfs]
insert_with_overflow+0x44/0x110 [btrfs]
btrfs_insert_xattr_item+0xb8/0x1d0 [btrfs]
btrfs_setxattr+0xd6/0x4c0 [btrfs]
btrfs_setxattr_trans+0x68/0x100 [btrfs]
__vfs_setxattr+0x66/0x80
__vfs_setxattr_noperm+0x70/0x200
vfs_setxattr+0x6b/0x120
setxattr+0x125/0x240
path_setxattr+0xba/0xd0
__x64_sys_setxattr+0x27/0x30
do_syscall_64+0x33/0x80
entry_SYSCALL_64_after_hwframe+0x44/0xa9
-> #0 (btrfs-tree-01#2/3){++++}-{3:3}:
check_prev_add+0x91/0xc60
__lock_acquire+0x1689/0x3130
lock_acquire+0xd8/0x490
down_read_nested+0x45/0x220
__btrfs_tree_read_lock+0x32/0x1a0 [btrfs]
btrfs_next_old_leaf+0x27d/0x580 [btrfs]
btrfs_real_readdir+0x1e3/0x4b0 [btrfs]
iterate_dir+0x170/0x1c0
__x64_sys_getdents64+0x83/0x140
do_syscall_64+0x33/0x80
entry_SYSCALL_64_after_hwframe+0x44/0xa9
other info that might help us debug this:
Possible unsafe locking scenario:
CPU0 CPU1
---- ----
lock(btrfs-tree-00);
lock(btrfs-tree-01#2/3);
lock(btrfs-tree-00);
lock(btrfs-tree-01#2/3);
*** DEADLOCK ***
5 locks held by find/324157:
#0:
ffff8ebc502c6e00 (&f->f_pos_lock){+.+.}-{3:3}, at: __fdget_pos+0x4d/0x60
#1:
ffff8eb97f689980 (&type->i_mutex_dir_key#10){++++}-{3:3}, at: iterate_dir+0x52/0x1c0
#2:
ffff8ebaec00ca58 (btrfs-tree-02#2){++++}-{3:3}, at: __btrfs_tree_read_lock+0x32/0x1a0 [btrfs]
#3:
ffff8eb98f986f78 (btrfs-tree-01#2){++++}-{3:3}, at: __btrfs_tree_read_lock+0x32/0x1a0 [btrfs]
#4:
ffff8eb9932c5088 (btrfs-tree-00){++++}-{3:3}, at: __btrfs_tree_read_lock+0x32/0x1a0 [btrfs]
stack backtrace:
CPU: 2 PID: 324157 Comm: find Not tainted 5.10.0-rc2-btrfs-next-71 #1
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS
rel-1.13.0-0-gf21b5a4aeb02-prebuilt.qemu.org 04/01/2014
Call Trace:
dump_stack+0x8d/0xb5
check_noncircular+0xff/0x110
? mark_lock.part.0+0x468/0xe90
check_prev_add+0x91/0xc60
__lock_acquire+0x1689/0x3130
? kvm_clock_read+0x14/0x30
? kvm_sched_clock_read+0x5/0x10
lock_acquire+0xd8/0x490
? __btrfs_tree_read_lock+0x32/0x1a0 [btrfs]
down_read_nested+0x45/0x220
? __btrfs_tree_read_lock+0x32/0x1a0 [btrfs]
__btrfs_tree_read_lock+0x32/0x1a0 [btrfs]
btrfs_next_old_leaf+0x27d/0x580 [btrfs]
btrfs_real_readdir+0x1e3/0x4b0 [btrfs]
iterate_dir+0x170/0x1c0
__x64_sys_getdents64+0x83/0x140
? filldir+0x1d0/0x1d0
do_syscall_64+0x33/0x80
entry_SYSCALL_64_after_hwframe+0x44/0xa9
This happens because btrfs_next_old_leaf searches down to our current
key, and then walks up the path until we can move to the next slot, and
then reads back down the path so we get the next leaf.
However it doesn't unlock any lower levels until it replaces them with
the new extent buffer. This is technically fine, but of course causes
lockdep to complain, because we could be holding locks on lower levels
while locking upper levels.
Fix this by dropping all nodes below the level that we use as our new
starting point before we start reading back down the path. This also
allows us to drop the nested/recursive locking magic, because we're no
longer locking two nodes at the same level anymore.
Reported-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Josef Bacik [Fri, 6 Nov 2020 21:27:29 +0000 (16:27 -0500)]
btrfs: cleanup the locking in btrfs_next_old_leaf
We are carrying around this next_rw_lock from when we would do spinning
vs blocking read locks. Now that we have the rwsem locking we can
simply use the read lock flag unconditionally and the read lock helpers.
Reviewed-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Anand Jain [Tue, 3 Nov 2020 05:49:43 +0000 (13:49 +0800)]
btrfs: remove unused argument seed from btrfs_find_device
Commit
343694eee8d8 ("btrfs: switch seed device to list api"), missed to
check if the parameter seed is true in the function btrfs_find_device().
This tells it whether to traverse the seed device list or not.
After this commit, the argument is unused and can be removed.
In device_list_add() it's not necessary because fs_devices always points
to the device's fs_devices. So with the devid+uuid matching, it will
find the right device and return, thus not needing to traverse seed
devices.
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Anand Jain <anand.jain@oracle.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Anand Jain [Tue, 3 Nov 2020 05:49:42 +0000 (13:49 +0800)]
btrfs: drop never met disk total bytes check in verify_one_dev_extent
Drop the condition in verify_one_dev_extent,
btrfs_device::disk_total_bytes is set even for a seed device. The
comment is wrong, the size is properly set when cloning the device.
Commit
1b3922a8bc74 ("btrfs: Use real device structure to verify
dev extent") introduced it but it's unclear why the total_disk_bytes
was 0.
Theoretically, all devices (including missing and seed) marked with the
BTRFS_DEV_STATE_IN_FS_METADATA flag gets the total_disk_bytes updated at
fill_device_from_item():
open_ctree()
btrfs_read_chunk_tree()
read_one_dev()
open_seed_device()
fill_device_from_item()
Even if verify_one_dev_extent() reports total_disk_bytes == 0, then its
a bug to be fixed somewhere else and not in verify_one_dev_extent() as
it's just a messenger. It is never expected that a total_disk_bytes
shall be zero.
The function fill_device_from_item() does the job of reading it from the
item and updating btrfs_device::disk_total_bytes. So both the missing
device and the seed devices do have their disk_total_bytes updated.
btrfs_find_device can also return a device from fs_info->seed_list
because it searches it as well.
Furthermore, while removing the device if there is a power loss, we
could have a device with its total_bytes = 0, that's still valid.
Instead, introduce a check against maximum block device size in
read_one_dev().
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: Anand Jain <anand.jain@oracle.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Anand Jain [Fri, 6 Nov 2020 08:06:33 +0000 (16:06 +0800)]
btrfs: drop unused argument step from btrfs_free_extra_devids
Commit
cf89af146b7e ("btrfs: dev-replace: fail mount if we don't have
replace item with target device") dropped the multi stage operation of
btrfs_free_extra_devids() that does not need to check replace target
anymore and we can remove the 'step' argument.
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Anand Jain <anand.jain@oracle.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Filipe Manana [Wed, 4 Nov 2020 11:07:34 +0000 (11:07 +0000)]
btrfs: update the number of bytes used by an inode atomically
There are several occasions where we do not update the inode's number of
used bytes atomically, resulting in a concurrent stat(2) syscall to report
a value of used blocks that does not correspond to a valid value, that is,
a value that does not match neither what we had before the operation nor
what we get after the operation completes.
In extreme cases it can result in stat(2) reporting zero used blocks, which
can cause problems for some userspace tools where they can consider a file
with a non-zero size and zero used blocks as completely sparse and skip
reading data, as reported/discussed a long time ago in some threads like
the following:
https://lists.gnu.org/archive/html/bug-tar/2016-07/msg00001.html
The cases where this can happen are the following:
-> Case 1
If we do a write (buffered or direct IO) against a file region for which
there is already an allocated extent (or multiple extents), then we have a
short time window where we can report a number of used blocks to stat(2)
that does not take into account the file region being overwritten. This
short time window happens when completing the ordered extent(s).
This happens because when we drop the extents in the write range we
decrement the inode's number of bytes and later on when we insert the new
extent(s) we increment the number of bytes in the inode, resulting in a
short time window where a stat(2) syscall can get an incorrect number of
used blocks.
If we do writes that overwrite an entire file, then we have a short time
window where we report 0 used blocks to stat(2).
Example reproducer:
$ cat reproducer-1.sh
#!/bin/bash
MNT=/mnt/sdi
DEV=/dev/sdi
stat_loop()
{
trap "wait; exit" SIGTERM
local filepath=$1
local expected=$2
local got
while :; do
got=$(stat -c %b $filepath)
if [ $got -ne $expected ]; then
echo -n "ERROR: unexpected used blocks"
echo " (got: $got expected: $expected)"
fi
done
}
mkfs.btrfs -f $DEV > /dev/null
# mkfs.xfs -f $DEV > /dev/null
# mkfs.ext4 -F $DEV > /dev/null
# mkfs.f2fs -f $DEV > /dev/null
# mkfs.reiserfs -f $DEV > /dev/null
mount $DEV $MNT
xfs_io -f -s -c "pwrite -b 64K 0 64K" $MNT/foobar >/dev/null
expected=$(stat -c %b $MNT/foobar)
# Create a process to keep calling stat(2) on the file and see if the
# reported number of blocks used (disk space used) changes, it should
# not because we are not increasing the file size nor punching holes.
stat_loop $MNT/foobar $expected &
loop_pid=$!
for ((i = 0; i < 50000; i++)); do
xfs_io -s -c "pwrite -b 64K 0 64K" $MNT/foobar >/dev/null
done
kill $loop_pid &> /dev/null
wait
umount $DEV
$ ./reproducer-1.sh
ERROR: unexpected used blocks (got: 0 expected: 128)
ERROR: unexpected used blocks (got: 0 expected: 128)
(...)
Note that since this is a short time window where the race can happen, the
reproducer may not be able to always trigger the bug in one run, or it may
trigger it multiple times.
-> Case 2
If we do a buffered write against a file region that does not have any
allocated extents, like a hole or beyond EOF, then during ordered extent
completion we have a short time window where a concurrent stat(2) syscall
can report a number of used blocks that does not correspond to the value
before or after the write operation, a value that is actually larger than
the value after the write completes.
This happens because once we start a buffered write into an unallocated
file range we increment the inode's 'new_delalloc_bytes', to make sure
any stat(2) call gets a correct used blocks value before delalloc is
flushed and completes. However at ordered extent completion, after we
inserted the new extent, we increment the inode's number of bytes used
with the size of the new extent, and only later, when clearing the range
in the inode's iotree, we decrement the inode's 'new_delalloc_bytes'
counter with the size of the extent. So this results in a short time
window where a concurrent stat(2) syscall can report a number of used
blocks that accounts for the new extent twice.
Example reproducer:
$ cat reproducer-2.sh
#!/bin/bash
MNT=/mnt/sdi
DEV=/dev/sdi
stat_loop()
{
trap "wait; exit" SIGTERM
local filepath=$1
local expected=$2
local got
while :; do
got=$(stat -c %b $filepath)
if [ $got -ne $expected ]; then
echo -n "ERROR: unexpected used blocks"
echo " (got: $got expected: $expected)"
fi
done
}
mkfs.btrfs -f $DEV > /dev/null
# mkfs.xfs -f $DEV > /dev/null
# mkfs.ext4 -F $DEV > /dev/null
# mkfs.f2fs -f $DEV > /dev/null
# mkfs.reiserfs -f $DEV > /dev/null
mount $DEV $MNT
touch $MNT/foobar
write_size=$((64 * 1024))
for ((i = 0; i < 16384; i++)); do
offset=$(($i * $write_size))
xfs_io -c "pwrite -S 0xab $offset $write_size" $MNT/foobar >/dev/null
blocks_used=$(stat -c %b $MNT/foobar)
# Fsync the file to trigger writeback and keep calling stat(2) on it
# to see if the number of blocks used changes.
stat_loop $MNT/foobar $blocks_used &
loop_pid=$!
xfs_io -c "fsync" $MNT/foobar
kill $loop_pid &> /dev/null
wait $loop_pid
done
umount $DEV
$ ./reproducer-2.sh
ERROR: unexpected used blocks (got: 265472 expected: 265344)
ERROR: unexpected used blocks (got: 284032 expected: 283904)
(...)
Note that since this is a short time window where the race can happen, the
reproducer may not be able to always trigger the bug in one run, or it may
trigger it multiple times.
-> Case 3
Another case where such problems happen is during other operations that
replace extents in a file range with other extents. Those operations are
extent cloning, deduplication and fallocate's zero range operation.
The cause of the problem is similar to the first case. When we drop the
extents from a range, we decrement the inode's number of bytes, and later
on, after inserting the new extents we increment it. Since this is not
done atomically, a concurrent stat(2) call can see and return a number of
used blocks that is smaller than it should be, does not match the number
of used blocks before or after the clone/deduplication/zero operation.
Like for the first case, when doing a clone, deduplication or zero range
operation against an entire file, we end up having a time window where we
can report 0 used blocks to a stat(2) call.
Example reproducer:
$ cat reproducer-3.sh
#!/bin/bash
MNT=/mnt/sdi
DEV=/dev/sdi
mkfs.btrfs -f $DEV > /dev/null
# mkfs.xfs -f -m reflink=1 $DEV > /dev/null
mount $DEV $MNT
extent_size=$((64 * 1024))
num_extents=16384
file_size=$(($extent_size * $num_extents))
# File foo has many small extents.
xfs_io -f -s -c "pwrite -S 0xab -b $extent_size 0 $file_size" $MNT/foo \
> /dev/null
# File bar has much less extents and has exactly the same data as foo.
xfs_io -f -c "pwrite -S 0xab 0 $file_size" $MNT/bar > /dev/null
expected=$(stat -c %b $MNT/foo)
# Now deduplicate bar into foo. While the deduplication is in progres,
# the number of used blocks/file size reported by stat should not change
xfs_io -c "dedupe $MNT/bar 0 0 $file_size" $MNT/foo > /dev/null &
dedupe_pid=$!
while [ -n "$(ps -p $dedupe_pid -o pid=)" ]; do
used=$(stat -c %b $MNT/foo)
if [ $used -ne $expected ]; then
echo "Unexpected blocks used: $used (expected: $expected)"
fi
done
umount $DEV
$ ./reproducer-3.sh
Unexpected blocks used:
2076800 (expected:
2097152)
Unexpected blocks used:
2097024 (expected:
2097152)
Unexpected blocks used:
2079872 (expected:
2097152)
(...)
Note that since this is a short time window where the race can happen, the
reproducer may not be able to always trigger the bug in one run, or it may
trigger it multiple times.
So fix this by:
1) Making btrfs_drop_extents() not decrement the VFS inode's number of
bytes, and instead return the number of bytes;
2) Making any code that drops extents and adds new extents update the
inode's number of bytes atomically, while holding the btrfs inode's
spinlock, which is also used by the stat(2) callback to get the inode's
number of bytes;
3) For ranges in the inode's iotree that are marked as 'delalloc new',
corresponding to previously unallocated ranges, increment the inode's
number of bytes when clearing the 'delalloc new' bit from the range,
in the same critical section that decrements the inode's
'new_delalloc_bytes' counter, delimited by the btrfs inode's spinlock.
An alternative would be to have btrfs_getattr() wait for any IO (ordered
extents in progress) and locking the whole range (0 to (u64)-1) while it
it computes the number of blocks used. But that would mean blocking
stat(2), which is a very used syscall and expected to be fast, waiting
for writes, clone/dedupe, fallocate, page reads, fiemap, etc.
CC: stable@vger.kernel.org # 5.4+
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>
Filipe Manana [Wed, 4 Nov 2020 11:07:33 +0000 (11:07 +0000)]
btrfs: fix race when defragmenting leads to unnecessary IO
When defragmenting we skip ranges that have holes or inline extents, so that
we don't do unnecessary IO and waste space. We do this check when calling
should_defrag_range() at btrfs_defrag_file(). However we do it without
holding the inode's lock. The reason we do it like this is to avoid
blocking other tasks for too long, that possibly want to operate on other
file ranges, since after the call to should_defrag_range() and before
locking the inode, we trigger a synchronous page cache readahead. However
before we were able to lock the inode, some other task might have punched
a hole in our range, or we may now have an inline extent there, in which
case we should not set the range for defrag anymore since that would cause
unnecessary IO and make us waste space (i.e. allocating extents to contain
zeros for a hole).
So after we locked the inode and the range in the iotree, check again if
we have holes or an inline extent, and if we do, just skip the range.
I hit this while testing my next patch that fixes races when updating an
inode's number of bytes (subject "btrfs: update the number of bytes used
by an inode atomically"), and it depends on this change in order to work
correctly. Alternatively I could rework that other patch to detect holes
and flag their range with the 'new delalloc' bit, but this itself fixes
an efficiency problem due a race that from a functional point of view is
not harmful (it could be triggered with btrfs/062 from fstests).
CC: stable@vger.kernel.org # 5.4+
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Filipe Manana [Wed, 4 Nov 2020 11:07:32 +0000 (11:07 +0000)]
btrfs: refactor btrfs_drop_extents() to make it easier to extend
There are many arguments for __btrfs_drop_extents() and its wrapper
btrfs_drop_extents(), which makes it hard to add more arguments to it and
requires changing every caller. I have added a couple myself back in 2014
commit
1acae57b161e ("Btrfs: faster file extent item replace operations")
and therefore know firsthand that it is a bit cumbersome to add additional
arguments to these functions.
Since I will need to add more arguments in a subsequent bug fix, this
change is preparatory work and adds a data structure that holds all the
arguments, for both input and output, that are passed to this function,
with some comments in the structure's definition mentioning what each
field is and how it relates to other fields.
Callers of this function need only to zero out the content of the
structure and setup only the fields they need. This also removes the
need to have both __btrfs_drop_extents() and btrfs_drop_extents(), so
now we have a single function named btrfs_drop_extents() that takes a
pointer to this new data structure (struct btrfs_drop_extents_args).
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>
Josef Bacik [Thu, 5 Nov 2020 15:45:21 +0000 (10:45 -0500)]
btrfs: set the lockdep class for extent buffers on creation
Both Filipe and Fedora QA recently hit the following lockdep splat:
WARNING: possible recursive locking detected
5.10.0-0.rc1.20201028gited8780e3f2ec.57.fc34.x86_64 #1 Not tainted
--------------------------------------------
rsync/2610 is trying to acquire lock:
ffff89617ed48f20 (&eb->lock){++++}-{2:2}, at: btrfs_tree_read_lock_atomic+0x34/0x140
but task is already holding lock:
ffff8961757b1130 (&eb->lock){++++}-{2:2}, at: btrfs_tree_read_lock_atomic+0x34/0x140
other info that might help us debug this:
Possible unsafe locking scenario:
CPU0
----
lock(&eb->lock);
lock(&eb->lock);
*** DEADLOCK ***
May be due to missing lock nesting notation
2 locks held by rsync/2610:
#0:
ffff896107212b90 (&type->i_mutex_dir_key#10){++++}-{3:3}, at: walk_component+0x10c/0x190
#1:
ffff8961757b1130 (&eb->lock){++++}-{2:2}, at: btrfs_tree_read_lock_atomic+0x34/0x140
stack backtrace:
CPU: 1 PID: 2610 Comm: rsync Not tainted 5.10.0-0.rc1.20201028gited8780e3f2ec.57.fc34.x86_64 #1
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 0.0.0 02/06/2015
Call Trace:
dump_stack+0x8b/0xb0
__lock_acquire.cold+0x12d/0x2a4
? kvm_sched_clock_read+0x14/0x30
? sched_clock+0x5/0x10
lock_acquire+0xc8/0x400
? btrfs_tree_read_lock_atomic+0x34/0x140
? read_block_for_search.isra.0+0xdd/0x320
_raw_read_lock+0x3d/0xa0
? btrfs_tree_read_lock_atomic+0x34/0x140
btrfs_tree_read_lock_atomic+0x34/0x140
btrfs_search_slot+0x616/0x9a0
btrfs_lookup_dir_item+0x6c/0xb0
btrfs_lookup_dentry+0xa8/0x520
? lockdep_init_map_waits+0x4c/0x210
btrfs_lookup+0xe/0x30
__lookup_slow+0x10f/0x1e0
walk_component+0x11b/0x190
path_lookupat+0x72/0x1c0
filename_lookup+0x97/0x180
? strncpy_from_user+0x96/0x1e0
? getname_flags.part.0+0x45/0x1a0
vfs_statx+0x64/0x100
? lockdep_hardirqs_on_prepare+0xff/0x180
? _raw_spin_unlock_irqrestore+0x41/0x50
__do_sys_newlstat+0x26/0x40
? lockdep_hardirqs_on_prepare+0xff/0x180
? syscall_enter_from_user_mode+0x27/0x80
? syscall_enter_from_user_mode+0x27/0x80
do_syscall_64+0x33/0x40
entry_SYSCALL_64_after_hwframe+0x44/0xa9
I have also seen a report of lockdep complaining about the lock class
that was looked up being the same as the lock class on the lock we were
using, but I can't find the report.
These are problems that occur because we do not have the lockdep class
set on the extent buffer until _after_ we read the eb in properly. This
is problematic for concurrent readers, because we will create the extent
buffer, lock it, and then attempt to read the extent buffer.
If a second thread comes in and tries to do a search down the same path
they'll get the above lockdep splat because the class isn't set properly
on the extent buffer.
There was a good reason for this, we generally didn't know the real
owner of the eb until we read it, specifically in refcounted roots.
However now all refcounted roots have the same class name, so we no
longer need to worry about this. For non-refcounted trees we know
which root we're on based on the parent.
Fix this by setting the lockdep class on the eb at creation time instead
of read time. This will fix the splat and the weirdness where the class
changes in the middle of locking the block.
Reviewed-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Josef Bacik [Thu, 5 Nov 2020 15:45:20 +0000 (10:45 -0500)]
btrfs: pass the owner_root and level to alloc_extent_buffer
Now that we've plumbed all of the callers to have the owner root and the
level, plumb it down into alloc_extent_buffer().
Reviewed-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Josef Bacik [Thu, 5 Nov 2020 15:45:19 +0000 (10:45 -0500)]
btrfs: pass the root owner and level around for readahead
The readahead infrastructure does raw reads of extent buffers, but we're
going to need to know their owner and level in order to set the lockdep
key properly, so plumb in the infrastructure that we'll need to have
this information when we start allocating extent buffers.
Reviewed-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Josef Bacik [Thu, 5 Nov 2020 15:45:18 +0000 (10:45 -0500)]
btrfs: pass root owner to read_tree_block
In order to properly set the lockdep class of a newly allocated block we
need to know the owner of the block. For non-refcounted trees this is
straightforward, we always know in advance what tree we're reading from.
For refcounted trees we don't necessarily know, however all refcounted
trees share the same lockdep class name, tree-<level>.
Fix all the callers of read_tree_block() to pass in the root objectid
we're using. In places like relocation and backref we could probably
unconditionally use 0, but just in case use the root when we have it,
otherwise use 0 in the cases we don't have the root as it's going to be
a refcounted tree anyway.
This is a preparation patch for further changes.
Reviewed-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Josef Bacik [Thu, 5 Nov 2020 15:45:17 +0000 (10:45 -0500)]
btrfs: use btrfs_read_node_slot in btrfs_qgroup_trace_subtree
We're open-coding btrfs_read_node_slot() here, replace with the helper.
Reviewed-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Josef Bacik [Thu, 5 Nov 2020 15:45:16 +0000 (10:45 -0500)]
btrfs: use btrfs_read_node_slot in qgroup_trace_new_subtree_blocks
We're open-coding btrfs_read_node_slot() here, replace with the helper.
Reviewed-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Josef Bacik [Thu, 5 Nov 2020 15:45:15 +0000 (10:45 -0500)]
btrfs: use btrfs_read_node_slot in qgroup_trace_extent_swap
We're open-coding btrfs_read_node_slot() here, replace with the helper.
Reviewed-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Josef Bacik [Thu, 5 Nov 2020 15:45:14 +0000 (10:45 -0500)]
btrfs: use btrfs_read_node_slot in walk_down_tree
We're open-coding btrfs_read_node_slot() here, replace with the helper.
Reviewed-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Josef Bacik [Thu, 5 Nov 2020 15:45:13 +0000 (10:45 -0500)]
btrfs: use btrfs_read_node_slot in replace_path
We're open-coding btrfs_read_node_slot() here, replace with the helper.
Reviewed-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Josef Bacik [Thu, 5 Nov 2020 15:45:12 +0000 (10:45 -0500)]
btrfs: use btrfs_read_node_slot in do_relocation
We're open coding btrfs_read_node_slot in do_relocation, replace this
with the proper helper.
Reviewed-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Josef Bacik [Thu, 5 Nov 2020 15:45:11 +0000 (10:45 -0500)]
btrfs: use btrfs_read_node_slot in walk_down_reloc_tree
We do not need to call read_tree_block() here, simply use the
btrfs_read_node_slot helper.
Reviewed-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Josef Bacik [Thu, 5 Nov 2020 15:45:10 +0000 (10:45 -0500)]
btrfs: use btrfs_read_node_slot in btrfs_realloc_node
We have this open-coded nightmare in btrfs_realloc_node that does
the same thing that the normal read path does, which is to see if we
have the eb in memory already, and if not read it, and verify the eb is
uptodate. Delete this open coding and simply use btrfs_read_node_slot.
Reviewed-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Josef Bacik [Thu, 5 Nov 2020 15:45:09 +0000 (10:45 -0500)]
btrfs: cleanup extent buffer readahead
We're going to pass around more information when we allocate extent
buffers, in order to make that cleaner how we do readahead. Most of the
callers have the parent node that we're getting our blockptr from, with
the sole exception of relocation which simply has the bytenr it wants to
read.
Add a helper that takes the current arguments that we need (bytenr and
gen), and add another helper for simply reading the slot out of a node.
In followup patches the helper that takes all the extra arguments will
be expanded, and the simpler helper won't need to have it's arguments
adjusted.
Reviewed-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Josef Bacik [Thu, 5 Nov 2020 15:45:08 +0000 (10:45 -0500)]
btrfs: remove lockdep classes for the fs tree
We have this weird problem where our lockdep class is set after we
read a tree block, which can race with concurrent readers and result in
erroneous lockdep errors. We want to set the lockdep class at
allocation time if possible, but in certain cases we may not have the
actual root owner, such as with relocation or any backref lookups. This
is only really a problem for reference counted trees, because all other
trees have their root reference set in their extent reference. Remove
the fs tree specific lock class. We need to still keep the reloc tree
one, it's still reference counted, because replace_path will lock the
reloc tree and the destination tree, and if they're both set to
tree-<level> we'll have issues.
Reviewed-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Pavel Begunkov [Wed, 4 Nov 2020 09:45:54 +0000 (09:45 +0000)]
btrfs: discard: reschedule work after sysfs param update
After sysfs updates discard's iops_limit or kbps_limit it also needs to
adjust current timer through rescheduling, otherwise the discard work
may wait for a long time for the previous timer to expire or bumped by
someone else.
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Pavel Begunkov [Wed, 4 Nov 2020 09:45:53 +0000 (09:45 +0000)]
btrfs: don't miss async discards after scheduled work override
If btrfs_discard_schedule_work() is called with override=true, it sets
delay anew regardless how much time is left until the timer should have
fired. If delays are long (that can happen, for example, with low
kbps_limit), they might get constantly overridden without having a
chance to run the discard work.
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Pavel Begunkov [Wed, 4 Nov 2020 09:45:52 +0000 (09:45 +0000)]
btrfs: discard: store async discard delay as ns not as jiffies
Most delay calculations are done in ns or ms, so store
discard_ctl->delay in ms and convert the final delay to jiffies only at
the end.
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Pavel Begunkov [Wed, 4 Nov 2020 09:45:51 +0000 (09:45 +0000)]
btrfs: discard: speed up async discard up to iops_limit
Instead of using iops_limit only for cutting off extremes, calculate the
discard delay directly from it, so it closely follows iops_limit and
doesn't under-discard even though quotas are not saturated.
The iops limit could be hit more often in some cases and could increase
the discard rate.
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Qu Wenruo [Tue, 3 Nov 2020 13:31:04 +0000 (21:31 +0800)]
btrfs: scrub: refactor scrub_find_csum()
Function scrub_find_csum() is to locate the csum for bytenr @logical
from sctx->csum_list.
However it lacks a lot of comments to explain things like how the
csum_list is organized and why we need to drop csum range which is
before us.
Refactor the function by:
- Add more comments explaining the behavior
- Add comment explaining why we need to drop the csum range
- Put the csum copy in the main loop
This is mostly for the incoming patches to make scrub_find_csum() able
to find multiple checksums.
Signed-off-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Qu Wenruo [Tue, 3 Nov 2020 13:31:02 +0000 (21:31 +0800)]
btrfs: scrub: remove the force parameter from scrub_pages
The @force parameter for scrub_pages() is to indicate whether we want to
force bio submission. Currently it's only used for the super block,
and it can be easily determined by the @flags, so we can remove the
parameter.
Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Qu Wenruo [Tue, 3 Nov 2020 13:31:01 +0000 (21:31 +0800)]
btrfs: scrub: distinguish scrub page from regular page
There are several call sites where we declare something like
"struct scrub_page *page".
This is confusing as we also use regular page in this code,
rename it to 'spage' where applicable.
Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Qu Wenruo [Tue, 3 Nov 2020 13:30:49 +0000 (21:30 +0800)]
btrfs: pass bvec to csum_dirty_buffer instead of page
Currently csum_dirty_buffer() uses page to grab extent buffer, but that
only works for sector size == PAGE_SIZE case.
For subpage we need page + page_offset to grab extent buffer.
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Qu Wenruo [Tue, 3 Nov 2020 13:30:48 +0000 (21:30 +0800)]
btrfs: extract extent buffer verification from btrfs_validate_metadata_buffer()
Currently btrfs_validate_metadata_buffer() only needs to handle one
extent buffer as currently one page maps to at most one extent buffer.
For incoming subpage support, we need to extend the support where one
page could contain multiple extent buffers.
Split the function so we can call validate_extent_buffer on extent
buffers independently.
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Qu Wenruo [Tue, 3 Nov 2020 13:30:47 +0000 (21:30 +0800)]
btrfs: make csum_tree_block() handle node smaller than page
For subpage size support, metadata blocks of nodesize are smaller than
one page and this needs to be handled when calculating the checksum.
The checksummed start and length need to be adjusted but only for the
first page:
- start is simply offset in the page
- length is nodesize (subpage) or PAGE_SIZE for all other cases
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: Goldwyn Rodrigues <rgoldwyn@suse.com>
Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Qu Wenruo [Tue, 3 Nov 2020 13:30:46 +0000 (21:30 +0800)]
btrfs: grab fs_info from extent_buffer in btrfs_mark_buffer_dirty
Since commit
f28491e0a6c4 ("Btrfs: move the extent buffer radix tree into
the fs_info"), fs_info can be grabbed from extent_buffer directly.
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Qu Wenruo [Wed, 21 Oct 2020 06:25:05 +0000 (14:25 +0800)]
btrfs: make buffer_radix take sector size units
For subpage sector size support, one page can contain multiple tree
blocks. The entries cannot be based on page size and index must be
derived from the sectorsize. No change for page size == sector size.
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Qu Wenruo [Wed, 21 Oct 2020 06:25:02 +0000 (14:25 +0800)]
btrfs: assert page mapping lock in attach_extent_buffer_page
When calling attach_extent_buffer_page(), either we're attaching
anonymous pages, called from btrfs_clone_extent_buffer(),
or we're attaching btree inode pages, called from alloc_extent_buffer().
For the latter case, we should hold page->mapping->private_lock to avoid
parallel changes to page->private.
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Josef Bacik [Fri, 23 Oct 2020 13:58:11 +0000 (09:58 -0400)]
btrfs: protect fs_info->caching_block_groups by block_group_cache_lock
I got the following lockdep splat
======================================================
WARNING: possible circular locking dependency detected
5.9.0+ #101 Not tainted
------------------------------------------------------
btrfs-cleaner/3445 is trying to acquire lock:
ffff89dbec39ab48 (btrfs-root-00){++++}-{3:3}, at: __btrfs_tree_read_lock+0x32/0x170
but task is already holding lock:
ffff89dbeaf28a88 (&fs_info->commit_root_sem){++++}-{3:3}, at: btrfs_find_all_roots+0x41/0x80
which lock already depends on the new lock.
the existing dependency chain (in reverse order) is:
-> #2 (&fs_info->commit_root_sem){++++}-{3:3}:
down_write+0x3d/0x70
btrfs_cache_block_group+0x2d5/0x510
find_free_extent+0xb6e/0x12f0
btrfs_reserve_extent+0xb3/0x1b0
btrfs_alloc_tree_block+0xb1/0x330
alloc_tree_block_no_bg_flush+0x4f/0x60
__btrfs_cow_block+0x11d/0x580
btrfs_cow_block+0x10c/0x220
commit_cowonly_roots+0x47/0x2e0
btrfs_commit_transaction+0x595/0xbd0
sync_filesystem+0x74/0x90
generic_shutdown_super+0x22/0x100
kill_anon_super+0x14/0x30
btrfs_kill_super+0x12/0x20
deactivate_locked_super+0x36/0xa0
cleanup_mnt+0x12d/0x190
task_work_run+0x5c/0xa0
exit_to_user_mode_prepare+0x1df/0x200
syscall_exit_to_user_mode+0x54/0x280
entry_SYSCALL_64_after_hwframe+0x44/0xa9
-> #1 (&space_info->groups_sem){++++}-{3:3}:
down_read+0x40/0x130
find_free_extent+0x2ed/0x12f0
btrfs_reserve_extent+0xb3/0x1b0
btrfs_alloc_tree_block+0xb1/0x330
alloc_tree_block_no_bg_flush+0x4f/0x60
__btrfs_cow_block+0x11d/0x580
btrfs_cow_block+0x10c/0x220
commit_cowonly_roots+0x47/0x2e0
btrfs_commit_transaction+0x595/0xbd0
sync_filesystem+0x74/0x90
generic_shutdown_super+0x22/0x100
kill_anon_super+0x14/0x30
btrfs_kill_super+0x12/0x20
deactivate_locked_super+0x36/0xa0
cleanup_mnt+0x12d/0x190
task_work_run+0x5c/0xa0
exit_to_user_mode_prepare+0x1df/0x200
syscall_exit_to_user_mode+0x54/0x280
entry_SYSCALL_64_after_hwframe+0x44/0xa9
-> #0 (btrfs-root-00){++++}-{3:3}:
__lock_acquire+0x1167/0x2150
lock_acquire+0xb9/0x3d0
down_read_nested+0x43/0x130
__btrfs_tree_read_lock+0x32/0x170
__btrfs_read_lock_root_node+0x3a/0x50
btrfs_search_slot+0x614/0x9d0
btrfs_find_root+0x35/0x1b0
btrfs_read_tree_root+0x61/0x120
btrfs_get_root_ref+0x14b/0x600
find_parent_nodes+0x3e6/0x1b30
btrfs_find_all_roots_safe+0xb4/0x130
btrfs_find_all_roots+0x60/0x80
btrfs_qgroup_trace_extent_post+0x27/0x40
btrfs_add_delayed_data_ref+0x3fd/0x460
btrfs_free_extent+0x42/0x100
__btrfs_mod_ref+0x1d7/0x2f0
walk_up_proc+0x11c/0x400
walk_up_tree+0xf0/0x180
btrfs_drop_snapshot+0x1c7/0x780
btrfs_clean_one_deleted_snapshot+0xfb/0x110
cleaner_kthread+0xd4/0x140
kthread+0x13a/0x150
ret_from_fork+0x1f/0x30
other info that might help us debug this:
Chain exists of:
btrfs-root-00 --> &space_info->groups_sem --> &fs_info->commit_root_sem
Possible unsafe locking scenario:
CPU0 CPU1
---- ----
lock(&fs_info->commit_root_sem);
lock(&space_info->groups_sem);
lock(&fs_info->commit_root_sem);
lock(btrfs-root-00);
*** DEADLOCK ***
3 locks held by btrfs-cleaner/3445:
#0:
ffff89dbeaf28838 (&fs_info->cleaner_mutex){+.+.}-{3:3}, at: cleaner_kthread+0x6e/0x140
#1:
ffff89dbeb6c7640 (sb_internal){.+.+}-{0:0}, at: start_transaction+0x40b/0x5c0
#2:
ffff89dbeaf28a88 (&fs_info->commit_root_sem){++++}-{3:3}, at: btrfs_find_all_roots+0x41/0x80
stack backtrace:
CPU: 0 PID: 3445 Comm: btrfs-cleaner Not tainted 5.9.0+ #101
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.13.0-2.fc32 04/01/2014
Call Trace:
dump_stack+0x8b/0xb0
check_noncircular+0xcf/0xf0
__lock_acquire+0x1167/0x2150
? __bfs+0x42/0x210
lock_acquire+0xb9/0x3d0
? __btrfs_tree_read_lock+0x32/0x170
down_read_nested+0x43/0x130
? __btrfs_tree_read_lock+0x32/0x170
__btrfs_tree_read_lock+0x32/0x170
__btrfs_read_lock_root_node+0x3a/0x50
btrfs_search_slot+0x614/0x9d0
? find_held_lock+0x2b/0x80
btrfs_find_root+0x35/0x1b0
? do_raw_spin_unlock+0x4b/0xa0
btrfs_read_tree_root+0x61/0x120
btrfs_get_root_ref+0x14b/0x600
find_parent_nodes+0x3e6/0x1b30
btrfs_find_all_roots_safe+0xb4/0x130
btrfs_find_all_roots+0x60/0x80
btrfs_qgroup_trace_extent_post+0x27/0x40
btrfs_add_delayed_data_ref+0x3fd/0x460
btrfs_free_extent+0x42/0x100
__btrfs_mod_ref+0x1d7/0x2f0
walk_up_proc+0x11c/0x400
walk_up_tree+0xf0/0x180
btrfs_drop_snapshot+0x1c7/0x780
? btrfs_clean_one_deleted_snapshot+0x73/0x110
btrfs_clean_one_deleted_snapshot+0xfb/0x110
cleaner_kthread+0xd4/0x140
? btrfs_alloc_root+0x50/0x50
kthread+0x13a/0x150
? kthread_create_worker_on_cpu+0x40/0x40
ret_from_fork+0x1f/0x30
while testing another lockdep fix. This happens because we're using the
commit_root_sem to protect fs_info->caching_block_groups, which creates
a dependency on the groups_sem -> commit_root_sem, which is problematic
because we will allocate blocks while holding tree roots. Fix this by
making the list itself protected by the fs_info->block_group_cache_lock.
Reviewed-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Josef Bacik [Fri, 23 Oct 2020 13:58:10 +0000 (09:58 -0400)]
btrfs: load free space cache asynchronously
While documenting the usage of the commit_root_sem, I noticed that we do
not actually take the commit_root_sem in the case of the free space
cache. This is problematic because we're supposed to hold that sem
while we're reading the commit roots, which is what we do for the free
space cache.
The reason I did it inline when I originally wrote the code was because
there's the case of unpinning where we need to make sure that the free
space cache is loaded if we're going to use the free space cache. But
we can accomplish the same thing by simply waiting for the cache to be
loaded.
Rework this code to load the free space cache asynchronously. This
allows us to greatly cleanup the caching code because now it's all
shared by the various caching methods. We also are now in a position to
have the commit_root semaphore held while we're loading the free space
cache. And finally our modification of ->last_byte_to_unpin is removed
because it can be handled in the proper way on commit.
Some care must be taken when replaying the log, when we expect that the
free space cache will be read entirely before we start excluding space
to replay. This could lead to overwriting space during replay.
Reviewed-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Josef Bacik [Fri, 23 Oct 2020 13:58:09 +0000 (09:58 -0400)]
btrfs: load the free space cache inode extents from commit root
Historically we've allowed recursive locking specifically for the free
space inode. This is because we are only doing reads and know that it's
safe. However we don't actually need this feature, we can get away with
reading the commit root for the extents. In fact if we want to allow
asynchronous loading of the free space cache we have to use the commit
root, otherwise we will deadlock.
Switch to using the commit root for the file extents. These are only
read at load time, and are replaced as soon as we start writing the
cache out to disk. The cache is never read again, so this is
legitimate. This matches what we do for the inode itself, as we read
that from the commit root as well.
Reviewed-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Josef Bacik [Fri, 23 Oct 2020 13:58:08 +0000 (09:58 -0400)]
btrfs: load free space cache into a temporary ctl
The free space cache has been special in that we would load it right
away instead of farming the work off to a worker thread. This resulted
in some weirdness that had to be taken into account for this fact,
namely that if we every found a block group being cached the fast way we
had to wait for it to finish, because we could get the cache before it
had been validated and we may throw the cache away.
To handle this particular case instead create a temporary
btrfs_free_space_ctl to load the free space cache into. Then once we've
validated that it makes sense, copy it's contents into the actual
block_group->free_space_ctl. This allows us to avoid the problems of
needing to wait for the caching to complete, we can clean up the discard
extent handling stuff in __load_free_space_cache, and we no longer need
to do the merge_space_tree() because the space is added one by one into
the real free_space_ctl. This will allow further reworks of how we
handle loading the free space cache.
Reviewed-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Josef Bacik [Fri, 23 Oct 2020 13:58:07 +0000 (09:58 -0400)]
btrfs: cleanup btrfs_discard_update_discardable usage
This passes in the block_group and the free_space_ctl, but we can get
this from the block group itself. Part of this is because we call it
from __load_free_space_cache, which can be called for the inode cache as
well.
Move that call into the block group specific load section, wrap it in
the right lock that we need for the assertion (but otherwise this is
safe without the lock because this happens in single-thread context).
Fix up the arguments to only take the block group. Add a lockdep_assert
as well for good measure to make sure we don't mess up the locking
again.
Reviewed-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Josef Bacik [Fri, 23 Oct 2020 13:58:06 +0000 (09:58 -0400)]
btrfs: explicitly protect ->last_byte_to_unpin in unpin_extent_range
Currently unpin_extent_range happens in the transaction commit context,
so we are protected from ->last_byte_to_unpin changing while we're
unpinning, because any new transactions would have to wait for us to
complete before modifying ->last_byte_to_unpin.
However in the future we may want to change how this works, for instance
with async unpinning or other such TODO items. To prepare for that
future explicitly protect ->last_byte_to_unpin with the commit_root_sem
so we are sure it won't change while we're doing our work.
Reviewed-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Josef Bacik [Fri, 23 Oct 2020 13:58:05 +0000 (09:58 -0400)]
btrfs: update last_byte_to_unpin in switch_commit_roots
While writing an explanation for the need of the commit_root_sem for
btrfs_prepare_extent_commit, I realized we have a slight hole that could
result in leaked space if we have to do the old style caching. Consider
the following scenario
commit root
+----+----+----+----+----+----+----+
|\\\\| |\\\\|\\\\| |\\\\|\\\\|
+----+----+----+----+----+----+----+
0 1 2 3 4 5 6 7
new commit root
+----+----+----+----+----+----+----+
| | | |\\\\| | |\\\\|
+----+----+----+----+----+----+----+
0 1 2 3 4 5 6 7
Prior to this patch, we run btrfs_prepare_extent_commit, which updates
the last_byte_to_unpin, and then we subsequently run
switch_commit_roots. In this example lets assume that
caching_ctl->progress == 1 at btrfs_prepare_extent_commit() time, which
means that cache->last_byte_to_unpin == 1. Then we go and do the
switch_commit_roots(), but in the meantime the caching thread has made
some more progress, because we drop the commit_root_sem and re-acquired
it. Now caching_ctl->progress == 3. We swap out the commit root and
carry on to unpin.
The race can happen like:
1) The caching thread was running using the old commit root when it
found the extent for [2, 3);
2) Then it released the commit_root_sem because it was in the last
item of a leaf and the semaphore was contended, and set ->progress
to 3 (value of 'last'), as the last extent item in the current leaf
was for the extent for range [2, 3);
3) Next time it gets the commit_root_sem, will start using the new
commit root and search for a key with offset 3, so it never finds
the hole for [2, 3).
So the caching thread never saw [2, 3) as free space in any of the
commit roots, and by the time finish_extent_commit() was called for
the range [0, 3), ->last_byte_to_unpin was 1, so it only returned the
subrange [0, 1) to the free space cache, skipping [2, 3).
In the unpin code we have last_byte_to_unpin == 1, so we unpin [0,1),
but do not unpin [2,3). However because caching_ctl->progress == 3 we
do not see the newly freed section of [2,3), and thus do not add it to
our free space cache. This results in us missing a chunk of free space
in memory (on disk too, unless we have a power failure before writing
the free space cache to disk).
Fix this by making sure the ->last_byte_to_unpin is set at the same time
that we swap the commit roots, this ensures that we will always be
consistent.
CC: stable@vger.kernel.org # 5.8+
Reviewed-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
[ update changelog with Filipe's review comments ]
Signed-off-by: David Sterba <dsterba@suse.com>
Josef Bacik [Fri, 23 Oct 2020 13:58:04 +0000 (09:58 -0400)]
btrfs: do not shorten unpin len for caching block groups
While fixing up our ->last_byte_to_unpin locking I noticed that we will
shorten len based on ->last_byte_to_unpin if we're caching when we're
adding back the free space. This is correct for the free space, as we
cannot unpin more than ->last_byte_to_unpin, however we use len to
adjust the ->bytes_pinned counters and such, which need to track the
actual pinned usage. This could result in
WARN_ON(space_info->bytes_pinned) triggering at unmount time.
Fix this by using a local variable for the amount to add to free space
cache, and leave len untouched in this case.
CC: stable@vger.kernel.org # 5.4+
Reviewed-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: David Sterba <dsterba@suse.com>
David Sterba [Thu, 29 Oct 2020 14:33:45 +0000 (15:33 +0100)]
btrfs: reorder extent buffer members for better packing
After the rwsem replaced the tree lock implementation, the extent buffer
got smaller but leaving some holes behind. By changing log_index type
and reordering, we can squeeze the size further to 240 bytes, measured on
release config on x86_64. Log_index spans only 3 values and needs to be
signed.
Before:
struct extent_buffer {
u64 start; /* 0 8 */
long unsigned int len; /* 8 8 */
long unsigned int bflags; /* 16 8 */
struct btrfs_fs_info * fs_info; /* 24 8 */
spinlock_t refs_lock; /* 32 4 */
atomic_t refs; /* 36 4 */
atomic_t io_pages; /* 40 4 */
int read_mirror; /* 44 4 */
struct callback_head callback_head __attribute__((__aligned__(8))); /* 48 16 */
/* --- cacheline 1 boundary (64 bytes) --- */
pid_t lock_owner; /* 64 4 */
bool lock_recursed; /* 68 1 */
/* XXX 3 bytes hole, try to pack */
struct rw_semaphore lock; /* 72 40 */
short int log_index; /* 112 2 */
/* XXX 6 bytes hole, try to pack */
struct page * pages[16]; /* 120 128 */
/* size: 248, cachelines: 4, members: 14 */
/* sum members: 239, holes: 2, sum holes: 9 */
/* forced alignments: 1 */
/* last cacheline: 56 bytes */
} __attribute__((__aligned__(8)));
After:
struct extent_buffer {
u64 start; /* 0 8 */
long unsigned int len; /* 8 8 */
long unsigned int bflags; /* 16 8 */
struct btrfs_fs_info * fs_info; /* 24 8 */
spinlock_t refs_lock; /* 32 4 */
atomic_t refs; /* 36 4 */
atomic_t io_pages; /* 40 4 */
int read_mirror; /* 44 4 */
struct callback_head callback_head __attribute__((__aligned__(8))); /* 48 16 */
/* --- cacheline 1 boundary (64 bytes) --- */
pid_t lock_owner; /* 64 4 */
bool lock_recursed; /* 68 1 */
s8 log_index; /* 69 1 */
/* XXX 2 bytes hole, try to pack */
struct rw_semaphore lock; /* 72 40 */
struct page * pages[16]; /* 112 128 */
/* size: 240, cachelines: 4, members: 14 */
/* sum members: 238, holes: 1, sum holes: 2 */
/* forced alignments: 1 */
/* last cacheline: 48 bytes */
} __attribute__((__aligned__(8)));
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Josef Bacik [Thu, 20 Aug 2020 15:46:11 +0000 (11:46 -0400)]
btrfs: locking: rip out path->leave_spinning
We no longer distinguish between blocking and spinning, so rip out all
this code.
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Josef Bacik [Thu, 20 Aug 2020 15:46:10 +0000 (11:46 -0400)]
btrfs: locking: remove all the blocking helpers
Now that we're using a rw_semaphore we no longer need to indicate if a
lock is blocking or not, nor do we need to flip the entire path from
blocking to spinning. Remove these helpers and all the places they are
called.
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
David Sterba [Tue, 30 Jun 2020 15:44:49 +0000 (17:44 +0200)]
btrfs: scrub: remove local copy of csum_size from context
The context structure unnecessarily stores copy of the checksum size,
that can be now easily obtained from fs_info.
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: David Sterba <dsterba@suse.com>
David Sterba [Tue, 30 Jun 2020 15:42:23 +0000 (17:42 +0200)]
btrfs: check integrity: remove local copy of csum_size
The state structure unnecessarily stores copy of the checksum size, that
can be now easily obtained from fs_info.
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: David Sterba <dsterba@suse.com>
David Sterba [Tue, 30 Jun 2020 16:04:02 +0000 (18:04 +0200)]
btrfs: remove unnecessary local variables for checksum size
Remove local variable that is then used just once and replace it with
fs_info::csum_size.
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: David Sterba <dsterba@suse.com>
David Sterba [Thu, 2 Jul 2020 09:27:30 +0000 (11:27 +0200)]
btrfs: switch cached fs_info::csum_size from u16 to u32
The fs_info value is 32bit, switch also the local u16 variables. This
leads to a better assembly code generated due to movzwl.
This simple change will shave some bytes on x86_64 and release config:
text data bss dec hex filename
1090000 17980 14912
1122892 11224c pre/btrfs.ko
1089794 17980 14912
1122686 11217e post/btrfs.ko
DELTA: -206
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: David Sterba <dsterba@suse.com>
David Sterba [Tue, 30 Jun 2020 00:01:31 +0000 (02:01 +0200)]
btrfs: use cached value of fs_info::csum_size everywhere
btrfs_get_16 shows up in the system performance profiles (helper to read
16bit values from on-disk structures). This is partially because of the
checksum size that's frequently read along with data reads/writes, other
u16 uses are from item size or directory entries.
Replace all calls to btrfs_super_csum_size by the cached value from
fs_info.
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Reviewed-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
David Sterba [Thu, 2 Jul 2020 08:54:11 +0000 (10:54 +0200)]
btrfs: precalculate checksums per leaf once
btrfs_csum_bytes_to_leaves shows up in system profiles, which makes it a
candidate for optimizations. After the 64bit division has been replaced
by shift, there's still a calculation done each time the function is
called: checksums per leaf.
As this is a constant value for the entire filesystem lifetime, we
can calculate it once at mount time and reuse. This also allows to
reduce the division to 64bit/32bit as we know the constant will always
fit the 32bit type.
Replace the open-coded rounding up with a macro that internally handles
the 64bit division and as it's now a short function, make it static
inline (slight code increase, slight stack usage reduction).
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: David Sterba <dsterba@suse.com>
David Sterba [Thu, 2 Jul 2020 09:10:18 +0000 (11:10 +0200)]
btrfs: store precalculated csum_size in fs_info
In many places we need the checksum size and it is inefficient to read
it from the raw superblock. Store the value into fs_info, actual use
will be in followup patches. The size is u32 as it allows to generate
better assembly than with u16.
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: David Sterba <dsterba@suse.com>
David Sterba [Wed, 1 Jul 2020 19:19:09 +0000 (21:19 +0200)]
btrfs: replace s_blocksize_bits with fs_info::sectorsize_bits
The value of super_block::s_blocksize_bits is the same as
fs_info::sectorsize_bits, but we don't need to do the extra dereferences
in many functions and storing the bits as u32 (in fs_info) generates
shorter assembly.
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Reviewed-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
David Sterba [Wed, 1 Jul 2020 19:07:40 +0000 (21:07 +0200)]
btrfs: replace div_u64 by shift in free_space_bitmap_size
Change free_space_bitmap_size to take btrfs_fs_info so we can get the
sectorsize_bits to do calculations.
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Reviewed-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>