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BUG: KCSAN: data-race in ext4_alloc_da_blocks / ext4_da_reserve_space

read-write to 0xffff8880166ada78 of 4 bytes by task 16572 on cpu 1:
 ext4_da_reserve_space+0x120/0x1f0 fs/ext4/inode.c:1492
 ext4_insert_delayed_block fs/ext4/inode.c:1657 [inline]
 ext4_da_map_blocks fs/ext4/inode.c:1771 [inline]
 ext4_da_get_block_prep+0x512/0x9a0 fs/ext4/inode.c:1835
 ext4_block_write_begin+0x414/0xc00 fs/ext4/inode.c:1077
 ext4_da_write_begin+0x50a/0xaf0 fs/ext4/inode.c:3016
 generic_perform_write+0x196/0x3a0 mm/filemap.c:3408
 ext4_buffered_write_iter+0x2e5/0x3d0 fs/ext4/file.c:270
 ext4_file_write_iter+0x45e/0x1090 fs/ext4/file.c:503
 call_write_iter include/linux/fs.h:1901 [inline]
 new_sync_write fs/read_write.c:518 [inline]
 vfs_write+0x6d4/0x7c0 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+0x39/0x80 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

read to 0xffff8880166ada78 of 4 bytes by task 16578 on cpu 0:
 ext4_alloc_da_blocks+0x1d/0x100 fs/ext4/inode.c:3131
 ext4_release_file+0x5b/0x1d0 fs/ext4/file.c:142
 __fput+0x24b/0x4e0 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+0x16b/0x1a0 kernel/entry/common.c:201
 __syscall_exit_to_user_mode_work kernel/entry/common.c:291 [inline]
 syscall_exit_to_user_mode+0x20/0x40 kernel/entry/common.c:302
 do_syscall_64+0x45/0x80 arch/x86/entry/common.c:56
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 16578 Comm: syz-executor.3 Not tainted 5.11.0-rc3-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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