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  1. 17 3月, 2020 1 次提交
    • Y
      pagecache: support percpu refcount to imporve performance · 8b9ea901
      由 Yunfeng Ye 提交于 
      euleros inclusion
category: feature
feature: pagecache percpu refcount
bugzilla: 31398
CVE: NA

-------------------------------------------------

The pagecache manages the file physical pages, and the life cycle of
page is managed by atomic counting. With the increasing number of cpu
cores, the cost of atomic counting is very large when reading file
pagecaches at large concurrent.

For example, when running nginx http application, the biggest hotspot is
found in the atomic operation of find_get_entry():

 11.94% [kernel] [k] find_get_entry
  7.45% [kernel] [k] do_tcp_sendpages
  6.12% [kernel] [k] generic_file_buffered_read

So we using the percpu refcount mechanism to fix this problem. and the
test result show that the read performance of nginx http can be improved
by 100%：

  worker   original(requests/sec)   percpu(requests/sec)   imporve
  64       759656.87                1627088.95             114.2%

Notes: we use page->lru to save percpu information, so the pages with
percpu attribute will not be recycled by memory recycling process, we
should avoid grow the file size unlimited.
Signed-off-by: NYunfeng Ye <yeyunfeng@huawei.com>
Reviewed-by: NKefeng Wang <wangkefeng.wang@huawei.com>
Signed-off-by: NYang Yingliang <yangyingliang@huawei.com>
      8b9ea901
  3. 12 3月, 2020 2 次提交
    • Q
      btrfs: tree-checker: Remove comprehensive root owner check · 217d3ab7
      由 Qu Wenruo 提交于 
      mainline inclusion
from mainline-5.2-rc1
commit ff2ac107
category: bugfix
bugzilla: NA
CVE: CVE-2019-19036
---------------------------

Commit 1ba98d08 ("Btrfs: detect corruption when non-root leaf has
zero item") introduced comprehensive root owner checker.

However it's pretty expensive tree search to locate the owner root,
especially when it get reused by mandatory read and write time
tree-checker.

This patch will remove that check, and completely rely on owner based
empty leaf check, which is much faster and still works fine for most
case.

And since we skip the old root owner check, now write time tree check
can be merged with btrfs_check_leaf_full().
Signed-off-by: NQu Wenruo <wqu@suse.com>
Signed-off-by: NDavid Sterba <dsterba@suse.com>
Conflict:
	fs/btrfs/tree-checker.c
Signed-off-by: NYufen Yu <yuyufen@huawei.com>
Reviewed-by: Nzhangyi (F) <yi.zhang@huawei.com>
Signed-off-by: NYang Yingliang <yangyingliang@huawei.com>
      217d3ab7
    • Z
      xfs: add agf freeblocks verify in xfs_agf_verify · 095cb0e6
      由 Zheng Bin 提交于 
      mainline inclusion
from mainline-v5.6
commit d0c7feaf
category: bugfix
bugzilla: 30215
CVE: NA

---------------------------

We recently used fuzz(hydra) to test XFS and automatically generate
tmp.img(XFS v5 format, but some metadata is wrong)

xfs_repair information(just one AG):
agf_freeblks 0, counted 3224 in ag 0
agf_longest 536874136, counted 3224 in ag 0
sb_fdblocks 613, counted 3228

Test as follows:
mount tmp.img tmpdir
cp file1M tmpdir
sync

In 4.19-stable, sync will stuck, the reason is:
xfs_mountfs
  xfs_check_summary_counts
    if ((!xfs_sb_version_haslazysbcount(&mp->m_sb) ||
       XFS_LAST_UNMOUNT_WAS_CLEAN(mp)) &&
       !xfs_fs_has_sickness(mp, XFS_SICK_FS_COUNTERS))
	return 0;  -->just return, incore sb_fdblocks still be 613
    xfs_initialize_perag_data

cp file1M tmpdir -->ok(write file to pagecache)
sync -->stuck(write pagecache to disk)
xfs_map_blocks
  xfs_iomap_write_allocate
    while (count_fsb != 0) {
      nimaps = 0;
      while (nimaps == 0) { --> endless loop
         nimaps = 1;
         xfs_bmapi_write(..., &nimaps) --> nimaps becomes 0 again
xfs_bmapi_write
  xfs_bmap_alloc
    xfs_bmap_btalloc
      xfs_alloc_vextent
        xfs_alloc_fix_freelist
          xfs_alloc_space_available -->fail(agf_freeblks is 0)

In linux-next, sync not stuck, cause commit c2b31643 ("xfs:
use the latest extent at writeback delalloc conversion time") remove
the above while, dmesg is as follows:
[   55.250114] XFS (loop0): page discard on page ffffea0008bc7380, inode 0x1b0c, offset 0.

Users do not know why this page is discard, the better soultion is:
1. Like xfs_repair, make sure sb_fdblocks is equal to counted
(xfs_initialize_perag_data did this, who is not called at this mount)
2. Add agf verify, if fail, will tell users to repair

This patch use the second soultion.
Signed-off-by: NZheng Bin <zhengbin13@huawei.com>
Signed-off-by: NRen Xudong <renxudong1@huawei.com>
Reviewed-by: NDarrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: NDarrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: NZheng Bin <zhengbin13@huawei.com>
Reviewed-by: Nzhangyi (F) <yi.zhang@huawei.com>
Signed-off-by: NYang Yingliang <yangyingliang@huawei.com>
      095cb0e6
  5. 05 3月, 2020 37 次提交