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BUG: KCSAN: data-race in ext4_fc_commit / ext4_fc_commit

write to 0xffff8881039c2710 of 8 bytes by task 11110 on cpu 1:
 ext4_fc_commit+0x1fb/0x18d0 fs/ext4/fast_commit.c:1199
 ext4_fsync_journal fs/ext4/fsync.c:115 [inline]
 ext4_sync_file+0x336/0x6e0 fs/ext4/fsync.c:174
 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+0xe5d/0x10b0 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+0x7a6/0xe20 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+0x39/0x80 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xae

read to 0xffff8881039c2710 of 8 bytes by task 11109 on cpu 0:
 ext4_fc_commit+0x1c9/0x18d0 fs/ext4/fast_commit.c:1199
 ext4_fsync_journal fs/ext4/fsync.c:115 [inline]
 ext4_sync_file+0x336/0x6e0 fs/ext4/fsync.c:174
 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+0xe5d/0x10b0 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+0x7a6/0xe20 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+0x39/0x80 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xae

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 11109 Comm: syz-executor.5 Not tainted 5.12.0-rc2-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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