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BUG: KCSAN: data-race in ext4_ext_insert_extent / ext4_mark_iloc_dirty

write to 0xffff888128d734cc of 4 bytes by task 15850 on cpu 1:
 ext4_ext_store_pblock fs/ext4/ext4_extents.h:252 [inline]
 ext4_ext_insert_extent+0x8f9/0x25d0 fs/ext4/extents.c:2115
 ext4_ext_map_blocks+0xbc7/0x20f0 fs/ext4/extents.c:4466
 ext4_map_blocks+0x230/0xcf0 fs/ext4/inode.c:622
 ext4_iomap_alloc fs/ext4/inode.c:3401 [inline]
 ext4_iomap_begin+0x280/0x4a0 fs/ext4/inode.c:3440
 iomap_apply+0xd4/0x660 fs/iomap/apply.c:46
 iomap_dio_rw+0x67e/0x9a0 fs/iomap/direct-io.c:498
 ext4_dio_write_iter fs/ext4/file.c:532 [inline]
 ext4_file_write_iter+0xb84/0xd30 fs/ext4/file.c:640
 call_write_iter include/linux/fs.h:1901 [inline]
 do_iter_readv_writev+0x4a7/0x5d0 fs/read_write.c:693
 do_iter_write fs/read_write.c:998 [inline]
 do_iter_write+0x137/0x3a0 fs/read_write.c:979
 vfs_iter_write+0x56/0x80 fs/read_write.c:1039
 iter_file_splice_write+0x530/0x830 fs/splice.c:760
 do_splice_from fs/splice.c:863 [inline]
 direct_splice_actor+0x97/0xb0 fs/splice.c:1037
 splice_direct_to_actor+0x22f/0x540 fs/splice.c:992
 do_splice_direct+0x152/0x1d0 fs/splice.c:1080
 do_sendfile+0x396/0x810 fs/read_write.c:1520
 __do_sys_sendfile64 fs/read_write.c:1581 [inline]
 __se_sys_sendfile64 fs/read_write.c:1567 [inline]
 __x64_sys_sendfile64+0x121/0x140 fs/read_write.c:1567
 do_syscall_64+0xc7/0x390 arch/x86/entry/common.c:294
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

read to 0xffff888128d734cc of 4 bytes by task 15811 on cpu 0:
 ext4_do_update_inode fs/ext4/inode.c:4997 [inline]
 ext4_mark_iloc_dirty+0x9f0/0x1500 fs/ext4/inode.c:5578
 ext4_mark_inode_dirty+0xe6/0x420 fs/ext4/inode.c:5771
 ext4_dirty_inode+0xad/0xd0 fs/ext4/inode.c:5802
 __mark_inode_dirty+0x5b7/0x940 fs/fs-writeback.c:2258
 generic_update_time+0x184/0x270 fs/inode.c:1681
 update_time+0x7d/0x90 fs/inode.c:1694
 touch_atime+0x13f/0x150 fs/inode.c:1765
 file_accessed include/linux/fs.h:2220 [inline]
 splice_direct_to_actor+0x4a1/0x540 fs/splice.c:1010
 do_splice_direct+0x152/0x1d0 fs/splice.c:1080
 do_sendfile+0x396/0x810 fs/read_write.c:1520
 __do_sys_sendfile64 fs/read_write.c:1581 [inline]
 __se_sys_sendfile64 fs/read_write.c:1567 [inline]
 __x64_sys_sendfile64+0x121/0x140 fs/read_write.c:1567
 do_syscall_64+0xc7/0x390 arch/x86/entry/common.c:294
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 15811 Comm: syz-executor.1 Not tainted 5.6.0-rc1-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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