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BUG: KCSAN: data-race in __jbd2_journal_drop_transaction / start_this_handle

write to 0xffff888101bae878 of 8 bytes by task 3064 on cpu 1:
 jbd2_get_transaction fs/jbd2/transaction.c:125 [inline]
 start_this_handle+0xf1b/0x1250 fs/jbd2/transaction.c:416
 jbd2__journal_start+0x1fc/0x3b0 fs/jbd2/transaction.c:525
 __ext4_journal_start_sb+0x159/0x2d0 fs/ext4/ext4_jbd2.c:105
 __ext4_journal_start fs/ext4/ext4_jbd2.h:326 [inline]
 ext4_convert_unwritten_extents+0x13d/0x2d0 fs/ext4/extents.c:4766
 ext4_dio_write_end_io+0x88/0x100 fs/ext4/file.c:381
 iomap_dio_complete+0xb8/0x3c0 fs/iomap/direct-io.c:86
 iomap_dio_rw+0x4e/0x70 fs/iomap/direct-io.c:652
 ext4_dio_write_iter fs/ext4/file.c:568 [inline]
 ext4_file_write_iter+0xaa9/0x11f0 fs/ext4/file.c:678
 call_write_iter include/linux/fs.h:2163 [inline]
 do_iter_readv_writev+0x2de/0x380 fs/read_write.c:729
 do_iter_write+0x192/0x5c0 fs/read_write.c:855
 vfs_iter_write+0x4c/0x70 fs/read_write.c:896
 iter_file_splice_write+0x43a/0x790 fs/splice.c:689
 do_splice_from fs/splice.c:767 [inline]
 direct_splice_actor+0x80/0xa0 fs/splice.c:936
 splice_direct_to_actor+0x345/0x650 fs/splice.c:891
 do_splice_direct+0x106/0x190 fs/splice.c:979
 do_sendfile+0x63e/0xbb0 fs/read_write.c:1249
 __do_sys_sendfile64 fs/read_write.c:1314 [inline]
 __se_sys_sendfile64 fs/read_write.c:1300 [inline]
 __x64_sys_sendfile64+0x102/0x140 fs/read_write.c:1300
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x44/0xa0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae

read to 0xffff888101bae878 of 8 bytes by task 345 on cpu 0:
 __jbd2_journal_drop_transaction+0x1f0/0x2c0 fs/jbd2/checkpoint.c:803
 __jbd2_journal_remove_checkpoint+0x2d5/0x370 fs/jbd2/checkpoint.c:734
 jbd2_journal_commit_transaction+0x246e/0x3430 fs/jbd2/commit.c:1019
 kjournald2+0x268/0x490 fs/jbd2/journal.c:213
 kthread+0x262/0x280 kernel/kthread.c:319
 ret_from_fork+0x1f/0x30

value changed: 0x0000000000000000 -> 0xffff888130a8ff00

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 345 Comm: jbd2/sda1-8 Not tainted 5.15.0-rc6-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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