BUG: KCSAN: data-race in __xfs_buf_submit / xfs_buf_ioend

write to 0xffff88800db05e5c of 4 bytes by task 35 on cpu 1:
 xfs_buf_ioend+0x25b/0x370 fs/xfs/xfs_buf.c:1332
 xfs_buf_ioend_work+0x18/0x20 fs/xfs/xfs_buf.c:1378
 process_one_work+0x3e1/0x950 kernel/workqueue.c:2275
 worker_thread+0x616/0xa70 kernel/workqueue.c:2421
 kthread+0x20b/0x230 kernel/kthread.c:292
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:294

read to 0xffff88800db05e5c of 4 bytes by task 15757 on cpu 0:
 xfs_buf_iowait fs/xfs/xfs_buf.c:1636 [inline]
 __xfs_buf_submit+0x27d/0x600 fs/xfs/xfs_buf.c:1704
 xfs_buf_submit fs/xfs/xfs_buf.c:61 [inline]
 xfs_buf_read_uncached+0x120/0x1c0 fs/xfs/xfs_buf.c:935
 xfs_readsb+0xd6/0x3b0 fs/xfs/xfs_mount.c:302
 xfs_fs_fill_super+0x33b/0xeb0 fs/xfs/xfs_super.c:1418
 get_tree_bdev+0x2c2/0x3d0 fs/super.c:1292
 xfs_fs_get_tree+0x18/0x20 fs/xfs/xfs_super.c:1639
 vfs_get_tree+0x4a/0x1a0 fs/super.c:1497
 do_new_mount fs/namespace.c:2903 [inline]
 path_mount+0x11b9/0x1c00 fs/namespace.c:3233
 do_mount fs/namespace.c:3246 [inline]
 __do_sys_mount fs/namespace.c:3454 [inline]
 __se_sys_mount+0x23d/0x2e0 fs/namespace.c:3431
 __x64_sys_mount+0x63/0x70 fs/namespace.c:3431
 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: 15757 Comm: syz-executor.5 Tainted: G        W         5.12.0-rc6-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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XFS (loop5): Invalid superblock magic number