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BUG: KCSAN: data-race in ext4_write_end / ext4_writepage

write to 0xffff8881345d8a48 of 8 bytes by task 15754 on cpu 0:
 i_size_write include/linux/fs.h:916 [inline]
 ext4_update_inode_size fs/ext4/ext4.h:3421 [inline]
 ext4_write_end+0x16e/0x6f0 fs/ext4/inode.c:1303
 generic_perform_write+0x251/0x3e0 mm/filemap.c:3781
 ext4_buffered_write_iter+0x305/0x400 fs/ext4/file.c:269
 ext4_file_write_iter+0x2e7/0x11f0
 call_write_iter include/linux/fs.h:2163 [inline]
 new_sync_write fs/read_write.c:507 [inline]
 vfs_write+0x7bc/0x900 fs/read_write.c:594
 ksys_write+0xd9/0x190 fs/read_write.c:647
 __do_sys_write fs/read_write.c:659 [inline]
 __se_sys_write fs/read_write.c:656 [inline]
 __x64_sys_write+0x3e/0x50 fs/read_write.c:656
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x44/0xa0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae

read to 0xffff8881345d8a48 of 8 bytes by task 344 on cpu 1:
 i_size_read include/linux/fs.h:894 [inline]
 ext4_writepage+0xc1/0xe80 fs/ext4/inode.c:2007
 __writepage+0x38/0xd0 mm/page-writeback.c:2320
 write_cache_pages+0x50a/0x840 mm/page-writeback.c:2255
 generic_writepages+0x7c/0xc0 mm/page-writeback.c:2346
 jbd2_journal_submit_inode_data_buffers+0xb2/0xe0 fs/jbd2/commit.c:206
 ext4_journal_submit_inode_data_buffers+0x55/0x110 fs/ext4/super.c:530
 journal_submit_data_buffers+0x109/0x260 fs/jbd2/commit.c:256
 jbd2_journal_commit_transaction+0x8e8/0x3430 fs/jbd2/commit.c:591
 kjournald2+0x268/0x490 fs/jbd2/journal.c:213
 kthread+0x262/0x280 kernel/kthread.c:319
 ret_from_fork+0x1f/0x30

value changed: 0x00000000007a5000 -> 0x00000000007a6000

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 344 Comm: jbd2/sda1-8 Not tainted 5.15.0-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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