linux-ext4 - [PATCH 0/3] ext4: Fix potential races when performing online resizing

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Message-ID: <20200219030851.2678-1-surajjs@amazon.com>
Date:   Tue, 18 Feb 2020 19:08:48 -0800
From:   Suraj Jitindar Singh <surajjs@...zon.com>
To:     <linux-ext4@...r.kernel.org>
CC:     <tytso@....edu>, <sblbir@...zon.com>, <sjitindarsingh@...il.com>,
        "Suraj Jitindar Singh" <surajjs@...zon.com>
Subject: [PATCH 0/3] ext4: Fix potential races when performing online resizing

This patch series fixes 2 additional races between array resizing and
array element access when performing online resizing of the arrays
s_group_info and s_flex_groups.

These patches apply on top of the patch:
[PATCH RFC] ext4: fix potential race between online resizing and write operations

The macro sbi_array_rcu_deref() is introduced for simplicity but can be
removed if undesired.

Tested by performing the following:
truncate -s 100G /tmp/foo
sudo bash -c 'while true; do dd if=/dev/zero of=/mnt/xxx bs=1M count=1; sync; \
rm /mnt/xxx; done' &
while true; do mkfs.ext4 -b 1024 -E resize=26213883 /tmp/foo 2096635 -F; \
sudo mount -o loop /tmp/foo /mnt; sudo resize2fs /dev/loop0 26213883; \
sudo umount /mnt; done

Suraj Jitindar Singh (3):
  ext4: introduce macro sbi_array_rcu_deref() to access rcu protected
    fields
  ext4: fix potential race between s_group_info online resizing and
    access
  ext4: fix potential race between s_flex_groups online resizing and
    access

 fs/ext4/balloc.c  | 11 +++++-----
 fs/ext4/ext4.h    | 25 +++++++++++++++++----
 fs/ext4/ialloc.c  | 21 +++++++++++-------
 fs/ext4/mballoc.c | 19 ++++++++++------
 fs/ext4/resize.c  |  4 ++--
 fs/ext4/super.c   | 56 ++++++++++++++++++++++++++++++++---------------
 6 files changed, 91 insertions(+), 45 deletions(-)

-- 
2.17.1