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BUG: KCSAN: data-race in __ext4_update_other_inode_time / writeback_single_inode

write to 0xffff888105ef3c88 of 8 bytes by task 31077 on cpu 1:
 writeback_single_inode+0x143/0x590 fs/fs-writeback.c:1577
 sync_inode fs/fs-writeback.c:2624 [inline]
 sync_inode_metadata+0x57/0x80 fs/fs-writeback.c:2644
 ext4_fsync_nojournal fs/ext4/fsync.c:92 [inline]
 ext4_sync_file+0x359/0x670 fs/ext4/fsync.c:170
 vfs_fsync_range+0x107/0x120 fs/sync.c:200
 generic_write_sync include/linux/fs.h:2843 [inline]
 iomap_dio_complete+0x2d5/0x3c0 fs/iomap/direct-io.c:127
 iomap_dio_rw+0x4e/0x70 fs/iomap/direct-io.c:644
 ext4_dio_write_iter fs/ext4/file.c:551 [inline]
 ext4_file_write_iter+0xa4f/0x11d0 fs/ext4/file.c:661
 call_write_iter include/linux/fs.h:1977 [inline]
 do_iter_readv_writev+0x2cb/0x360 fs/read_write.c:740
 do_iter_write+0x112/0x4c0 fs/read_write.c:866
 vfs_iter_write+0x4c/0x70 fs/read_write.c:907
 iter_file_splice_write+0x40a/0x750 fs/splice.c:689
 do_splice_from fs/splice.c:767 [inline]
 direct_splice_actor+0x80/0xa0 fs/splice.c:936
 splice_direct_to_actor+0x345/0x650 fs/splice.c:891
 do_splice_direct+0xf5/0x170 fs/splice.c:979
 do_sendfile+0x773/0xda0 fs/read_write.c:1260
 __do_sys_sendfile64 fs/read_write.c:1325 [inline]
 __se_sys_sendfile64 fs/read_write.c:1311 [inline]
 __x64_sys_sendfile64+0xf2/0x130 fs/read_write.c:1311
 do_syscall_64+0x34/0x50 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xae

read to 0xffff888105ef3c88 of 8 bytes by task 31053 on cpu 0:
 inode_is_dirtytime_only include/linux/fs.h:2286 [inline]
 __ext4_update_other_inode_time+0x48/0x5c0 fs/ext4/inode.c:4965
 ext4_update_other_inodes_time fs/ext4/inode.c:5008 [inline]
 ext4_do_update_inode fs/ext4/inode.c:5137 [inline]
 ext4_mark_iloc_dirty+0x12e6/0x1750 fs/ext4/inode.c:5726
 __ext4_mark_inode_dirty+0x4db/0x5b0 fs/ext4/inode.c:5920
 ext4_dirty_inode+0x86/0xa0 fs/ext4/inode.c:5949
 __mark_inode_dirty+0x77/0x6c0 fs/fs-writeback.c:2274
 mark_inode_dirty include/linux/fs.h:2267 [inline]
 generic_write_end+0x157/0x180 fs/buffer.c:2203
 ext4_da_write_end+0x59b/0x730 fs/ext4/inode.c:3112
 generic_perform_write+0x23e/0x3a0 mm/filemap.c:3586
 ext4_buffered_write_iter+0x2f2/0x3f0 fs/ext4/file.c:269
 ext4_file_write_iter+0x2e7/0x11d0 fs/ext4/file.c:502
 call_write_iter include/linux/fs.h:1977 [inline]
 new_sync_write fs/read_write.c:518 [inline]
 vfs_write+0x69d/0x770 fs/read_write.c:605
 ksys_write+0xce/0x180 fs/read_write.c:658
 __do_sys_write fs/read_write.c:670 [inline]
 __se_sys_write fs/read_write.c:667 [inline]
 __x64_sys_write+0x3e/0x50 fs/read_write.c:667
 do_syscall_64+0x34/0x50 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xae

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 31053 Comm: syz-executor.1 Tainted: G        W         5.12.0-rc8-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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