```shell
pm=$(pgrep -u postgres -xo postgres)
sudo strace -ff -f -yy -s 256 \
    -e trace=%file,read,pread64,readv \
    -p "$pm" -o /tmp/pg.sys.trace


strace: Process 233035 attached
strace: Process 235357 attached
^Cstrace: Process 233035 detached


fatal_pid=$(grep 'FATAL:  "pg_tblspc' /tmp/pg.log | tail -1 | sed -n 's/.*\[\([0-9]\+\)\].*/\1/p'); echo "fatal_pid=$fatal_pid"

fatal_pid=235357


grep -n "PG_VERSION\|pg_tblspc/16384/PG_12_201909212/16385" /tmp/pg.sys.trace.$fatal_pid

18:access("pg_tblspc/16384/PG_12_201909212/16385", F_OK) = 0
19:openat(AT_FDCWD, "pg_tblspc/16384/PG_12_201909212/16385/PG_VERSION", O_RDONLY) = 4</zvfs/pg_ts_bench/PG_12_201909212/16385/PG_VERSION>
20:read(4</zvfs/pg_ts_bench/PG_12_201909212/16385/PG_VERSION>, "\0\0\0", 4096) = 3
21:read(4</zvfs/pg_ts_bench/PG_12_201909212/16385/PG_VERSION>, "", 4096) = 0



fatal_pid=$(grep 'FATAL:  "pg_tblspc' /tmp/pg.log | tail -1 | sed -n 's/.*\[\([0-9]\+\)\].*/\1/p'); echo "fatal_pid=$fatal_pid"

grep -n "\[zvfs\]\[rw-dbg\].*pid=${fatal_pid}" /tmp/pg.log | tail -n 120

6461:[zvfs][rw-dbg][pid=235357][tid=140193133607488][fd=4] read passthrough reason=fd_not_zvfs count=512
6462:[zvfs][rw-dbg][pid=235357][tid=140193133607488][fd=4] read passthrough ret=512 errno=0(OK)
```


```shell
sudo strace -ff -f -k -yy -s 256 -e trace=openat,read,pread64 -p "$pm" -o /tmp/pg.ktrace
```

调用链：

libc(__open64) -> _IO_file_open -> fopen -> AllocateFile -> ValidatePgVersion

是fopen，内部调用 libc_(__open64)