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Qu Wenruo 082b6c970f btrfs: free anon block device right after subvolume deletion
[BUG]
When a lot of subvolumes are created, there is a user report about
transaction aborted caused by slow anonymous block device reclaim:

  BTRFS: Transaction aborted (error -24)
  WARNING: CPU: 17 PID: 17041 at fs/btrfs/transaction.c:1576 create_pending_snapshot+0xbc4/0xd10 [btrfs]
  RIP: 0010:create_pending_snapshot+0xbc4/0xd10 [btrfs]
  Call Trace:
   create_pending_snapshots+0x82/0xa0 [btrfs]
   btrfs_commit_transaction+0x275/0x8c0 [btrfs]
   btrfs_mksubvol+0x4b9/0x500 [btrfs]
   btrfs_ioctl_snap_create_transid+0x174/0x180 [btrfs]
   btrfs_ioctl_snap_create_v2+0x11c/0x180 [btrfs]
   btrfs_ioctl+0x11a4/0x2da0 [btrfs]
   do_vfs_ioctl+0xa9/0x640
   ksys_ioctl+0x67/0x90
   __x64_sys_ioctl+0x1a/0x20
   do_syscall_64+0x5a/0x110
   entry_SYSCALL_64_after_hwframe+0x44/0xa9
  ---[ end trace 33f2f83f3d5250e9 ]---
  BTRFS: error (device sda1) in create_pending_snapshot:1576: errno=-24 unknown
  BTRFS info (device sda1): forced readonly
  BTRFS warning (device sda1): Skipping commit of aborted transaction.
  BTRFS: error (device sda1) in cleanup_transaction:1831: errno=-24 unknown

[CAUSE]
The anonymous device pool is shared and its size is 1M. It's possible to
hit that limit if the subvolume deletion is not fast enough and the
subvolumes to be cleaned keep the ids allocated.

[WORKAROUND]
We can't avoid the anon device pool exhaustion but we can shorten the
time the id is attached to the subvolume root once the subvolume becomes
invisible to the user.

Reported-by: Greed Rong <greedrong@gmail.com>
Link: https://lore.kernel.org/linux-btrfs/CA+UqX+NTrZ6boGnWHhSeZmEY5J76CTqmYjO2S+=tHJX7nb9DPw@mail.gmail.com/
CC: stable@vger.kernel.org # 4.4+
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>
2020-07-27 12:55:38 +02:00
arch Merge branch 'parisc-5.8-2' of git://git.kernel.org/pub/scm/linux/kernel/git/deller/parisc-linux into master 2020-07-26 12:14:46 -07:00
block block-5.8-2020-07-10 2020-07-10 09:55:46 -07:00
certs .gitignore: add SPDX License Identifier 2020-03-25 11:50:48 +01:00
crypto keys: asymmetric: fix error return code in software_key_query() 2020-07-15 15:49:04 -07:00
Documentation Char/misc driver fixes for 5.8-rc7 2020-07-26 09:33:25 -07:00
drivers Char/misc driver fixes for 5.8-rc7 2020-07-26 09:33:25 -07:00
fs btrfs: free anon block device right after subvolume deletion 2020-07-27 12:55:38 +02:00
include btrfs: use __u16 for the return value of btrfs_qgroup_level() 2020-07-27 12:55:37 +02:00
init kbuild: fix CONFIG_CC_CAN_LINK(_STATIC) for cross-compilation with Clang 2020-07-02 00:57:45 +09:00
ipc mmap locking API: use coccinelle to convert mmap_sem rwsem call sites 2020-06-09 09:39:14 -07:00
kernel Fix a interaction/regression between uprobes based shared library tracing & GDB. 2020-07-25 13:55:38 -07:00
lib RISC-V Fixes for 5.8-rc5 (ideally) 2020-07-11 19:22:46 -07:00
LICENSES LICENSES: Rename other to deprecated 2019-05-03 06:34:32 -06:00
mm khugepaged: fix null-pointer dereference due to race 2020-07-24 12:42:41 -07:00
net Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net into master 2020-07-25 11:50:59 -07:00
samples samples/vfs: avoid warning in statx override 2020-07-03 16:15:25 -07:00
scripts Kbuild fixes for v5.8 (3rd) 2020-07-26 13:46:57 -07:00
security integrity/ima: switch to using __kernel_read 2020-07-08 08:27:57 +02:00
sound sound fixes for 5.8-rc7 2020-07-21 08:06:45 -07:00
tools Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net into master 2020-07-25 11:50:59 -07:00
usr bpfilter: match bit size of bpfilter_umh to that of the kernel 2020-05-17 18:52:01 +09:00
virt kvm: use more precise cast and do not drop __user 2020-07-02 05:39:31 -04:00
.clang-format block: add bio_for_each_bvec_all() 2020-05-25 11:25:24 +02:00
.cocciconfig
.get_maintainer.ignore Opt out of scripts/get_maintainer.pl 2019-05-16 10:53:40 -07:00
.gitattributes .gitattributes: use 'dts' diff driver for dts files 2019-12-04 19:44:11 -08:00
.gitignore .gitignore: Do not track defconfig from make savedefconfig 2020-07-05 16:15:46 +09:00
.mailmap mailmap: add entry for Mike Rapoport 2020-07-24 12:42:41 -07:00
COPYING COPYING: state that all contributions really are covered by this file 2020-02-10 13:32:20 -08:00
CREDITS mailmap: change email for Ricardo Ribalda 2020-05-25 18:59:59 -06:00
Kbuild kbuild: rename hostprogs-y/always to hostprogs/always-y 2020-02-04 01:53:07 +09:00
Kconfig kbuild: ensure full rebuild when the compiler is updated 2020-05-12 13:28:33 +09:00
MAINTAINERS Merge branch 'akpm' into master (patches from Andrew) 2020-07-24 14:24:35 -07:00
Makefile Linux 5.8-rc7 2020-07-26 14:14:06 -07:00
README Drop all 00-INDEX files from Documentation/ 2018-09-09 15:08:58 -06:00

Linux kernel
============

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.