==================================================================
BUG: KCSAN: data-race in ext4_alloc_da_blocks / ext4_da_reserve_space

write to 0xffff8881364a3528 of 4 bytes by task 4959 on cpu 1:
 ext4_da_reserve_space+0x147/0x200 fs/ext4/inode.c:1491
 ext4_insert_delayed_block fs/ext4/inode.c:1656 [inline]
 ext4_da_map_blocks fs/ext4/inode.c:1770 [inline]
 ext4_da_get_block_prep+0x512/0x9b0 fs/ext4/inode.c:1834
 __block_write_begin_int+0x4a2/0x1060 fs/buffer.c:2031
 __block_write_begin+0x2b/0x40 fs/buffer.c:2081
 ext4_da_write_begin+0x4c8/0x820 fs/ext4/inode.c:3018
 generic_perform_write+0x196/0x3a0 mm/filemap.c:3660
 ext4_buffered_write_iter+0x2f2/0x3f0 fs/ext4/file.c:269
 ext4_dio_write_iter fs/ext4/file.c:587 [inline]
 ext4_file_write_iter+0xd01/0x11d0 fs/ext4/file.c:678
 call_write_iter include/linux/fs.h:2114 [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+0x4a/0x90 arch/x86/entry/common.c:47
 entry_SYSCALL_64_after_hwframe+0x44/0xae

read to 0xffff8881364a3528 of 4 bytes by task 4955 on cpu 0:
 ext4_alloc_da_blocks+0x1d/0xd0 fs/ext4/inode.c:3130
 ext4_release_file+0x5b/0x1d0 fs/ext4/file.c:141
 __fput+0x25b/0x4e0 fs/file_table.c:280
 ____fput+0x11/0x20 fs/file_table.c:313
 task_work_run+0xae/0x130 kernel/task_work.c:164
 tracehook_notify_resume include/linux/tracehook.h:189 [inline]
 exit_to_user_mode_loop kernel/entry/common.c:174 [inline]
 exit_to_user_mode_prepare+0x156/0x190 kernel/entry/common.c:208
 __syscall_exit_to_user_mode_work kernel/entry/common.c:290 [inline]
 syscall_exit_to_user_mode+0x20/0x40 kernel/entry/common.c:301
 do_syscall_64+0x56/0x90 arch/x86/entry/common.c:57
 entry_SYSCALL_64_after_hwframe+0x44/0xae

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 4955 Comm: syz-executor.3 Not tainted 5.13.0-rc2-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
==================================================================