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BUG: KCSAN: data-race in ext4_alloc_da_blocks / ext4_da_reserve_space

write to 0xffff88801bc66518 of 4 bytes by task 19332 on cpu 1:
 ext4_da_reserve_space+0x12b/0x1f0 fs/ext4/inode.c:1493
 ext4_insert_delayed_block fs/ext4/inode.c:1658 [inline]
 ext4_da_map_blocks fs/ext4/inode.c:1772 [inline]
 ext4_da_get_block_prep+0x512/0x9b0 fs/ext4/inode.c:1836
 ext4_block_write_begin+0x414/0xc20 fs/ext4/inode.c:1078
 ext4_da_write_begin+0x50f/0xaf0 fs/ext4/inode.c:3017
 generic_perform_write+0x196/0x3a0 mm/filemap.c:3575
 ext4_buffered_write_iter+0x2e5/0x3e0 fs/ext4/file.c:269
 ext4_file_write_iter+0x48a/0x10b0 fs/ext4/file.c:502
 call_write_iter include/linux/fs.h:1977 [inline]
 aio_write+0x2b9/0x3a0 fs/aio.c:1581
 __io_submit_one fs/aio.c:1840 [inline]
 io_submit_one+0x814/0x1280 fs/aio.c:1883
 __do_sys_io_submit fs/aio.c:1942 [inline]
 __se_sys_io_submit+0xf5/0x270 fs/aio.c:1912
 __x64_sys_io_submit+0x3f/0x50 fs/aio.c:1912
 do_syscall_64+0x39/0x80 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xae

read to 0xffff88801bc66518 of 4 bytes by task 19340 on cpu 0:
 ext4_alloc_da_blocks+0x1d/0x100 fs/ext4/inode.c:3132
 ext4_release_file+0x5b/0x1d0 fs/ext4/file.c:141
 __fput+0x263/0x4f0 fs/file_table.c:280
 ____fput+0x11/0x20 fs/file_table.c:313
 task_work_run+0x8e/0x110 kernel/task_work.c:140
 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+0x17c/0x1b0 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+0x45/0x80 arch/x86/entry/common.c:56
 entry_SYSCALL_64_after_hwframe+0x44/0xae

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 19340 Comm: syz-executor.3 Not tainted 5.12.0-rc4-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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