==================================================================
BUG: KCSAN: data-race in ext4_handle_inode_extension / generic_file_buffered_read

write to 0xffff8880bb35d9f8 of 8 bytes by task 25699 on cpu 1:
 i_size_write include/linux/fs.h:896 [inline]
 ext4_update_inode_size fs/ext4/ext4.h:3109 [inline]
 ext4_handle_inode_extension+0x214/0x530 fs/ext4/file.c:331
 ext4_dio_write_iter fs/ext4/file.c:549 [inline]
 ext4_file_write_iter+0xd8c/0xfd0 fs/ext4/file.c:653
 call_write_iter include/linux/fs.h:1907 [inline]
 do_iter_readv_writev+0x321/0x3c0 fs/read_write.c:694
 do_iter_write+0x10e/0x470 fs/read_write.c:999
 vfs_iter_write+0x4c/0x70 fs/read_write.c:1040
 iter_file_splice_write+0x41a/0x770 fs/splice.c:750
 do_splice_from fs/splice.c:846 [inline]
 direct_splice_actor+0x95/0x160 fs/splice.c:1016
 splice_direct_to_actor+0x365/0x660 fs/splice.c:971
 do_splice_direct+0xf2/0x170 fs/splice.c:1059
 do_sendfile+0x562/0xb10 fs/read_write.c:1521
 __do_sys_sendfile64 fs/read_write.c:1582 [inline]
 __se_sys_sendfile64 fs/read_write.c:1568 [inline]
 __x64_sys_sendfile64+0xf2/0x130 fs/read_write.c:1568
 do_syscall_64+0x71/0x120 arch/x86/entry/common.c:359
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

read to 0xffff8880bb35d9f8 of 8 bytes by task 25701 on cpu 0:
 i_size_read include/linux/fs.h:874 [inline]
 generic_file_buffered_read+0xf31/0x1750 mm/filemap.c:2088
 generic_file_read_iter+0x7d/0x3e0 mm/filemap.c:2307
 ext4_file_read_iter+0x2dd/0x410 fs/ext4/file.c:73
 call_read_iter include/linux/fs.h:1901 [inline]
 generic_file_splice_read+0x22a/0x310 fs/splice.c:312
 do_splice_to fs/splice.c:870 [inline]
 splice_direct_to_actor+0x2a8/0x660 fs/splice.c:950
 do_splice_direct+0xf2/0x170 fs/splice.c:1059
 do_sendfile+0x562/0xb10 fs/read_write.c:1521
 __do_sys_sendfile64 fs/read_write.c:1576 [inline]
 __se_sys_sendfile64 fs/read_write.c:1568 [inline]
 __x64_sys_sendfile64+0xa9/0x130 fs/read_write.c:1568
 do_syscall_64+0x71/0x120 arch/x86/entry/common.c:359
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 25701 Comm: syz-executor.3 Not tainted 5.8.0-rc2-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
==================================================================