git push locks up forever, file protocol

Hi,

We have a remote repo accessed using the 'file:' protocol, mounted over Samba using drvfs into a WSL2 instance of Ubuntu 20.04.

We find a 'git push' waits forever. git version 2.25.1

Over a local LAN this works fine, but over a VPN this fails, hinting at some sort of race condition.

Output from strace hints that git is trying (and failing) to read from a closed file handle.

Final output from strace:

----------- openat(AT_FDCWD, ".git/objects/ad/065dad4384ae8c81c120c562985078d1f7b34b", O_RDONLY|O_CLOEXEC) = 3 fstat(3, {st_mode=S_IFREG|0444, st_size=152, ...}) = 0 mmap(NULL, 152, PROT_READ, MAP_PRIVATE, 3, 0) = 0x7f3e0e4af000 close(3)                                = 0 munmap(0x7f3e0e4af000, 152)             = 0 openat(AT_FDCWD, ".git/objects/30/2508dfe5201db6c000ebf17b0c69e3afb31218", O_RDONLY|O_CLOEXEC) = 3 fstat(3, {st_mode=S_IFREG|0555, st_size=214, ...}) = 0 mmap(NULL, 214, PROT_READ, MAP_PRIVATE, 3, 0) = 0x7f3e0e4af000 close(3)                                = 0 munmap(0x7f3e0e4af000, 214)             = 0 openat(AT_FDCWD, ".git/objects/d2/2323ec2ec40a74fbd519509662254c3cfda206", O_RDONLY|O_CLOEXEC) = 3 fstat(3, {st_mode=S_IFREG|0444, st_size=161, ...}) = 0 mmap(NULL, 161, PROT_READ, MAP_PRIVATE, 3, 0) = 0x7f3e0e4af000 close(3)                                = 0 munmap(0x7f3e0e4af000, 161)             = 0 access(".git/hooks/pre-push", X_OK)     = -1 ENOENT (No such file or directory) write(4, "00953ea50e3c1f49c33f7dbbb5e3a310"..., 149) = 149 write(4, "0000", 4)                     = 4 pipe([3, 6])                            = 0 fcntl(6, F_GETFD)                       = 0 fcntl(6, F_SETFD, FD_CLOEXEC)           = 0 mmap(NULL, 8392704, PROT_NONE, MAP_PRIVATE|MAP_ANONYMOUS|MAP_STACK, -1, 0) = 0x7f3e0d641000 mprotect(0x7f3e0d642000, 8388608, PROT_READ|PROT_WRITE) = 0 clone(child_stack=0x7f3e0de40fb0, flags=CLONE_VM|CLONE_FS|CLONE_FILES|CLONE_SIGHAND|CLONE_THREAD|CLONE_SYSVSEM|CLONE_SETTLS|CLONE_PARENT_SETTID|CLONE_CHILD_CLEARTID, parent_tid=[12802], tls=0x7f3e0de41700, child_tidptr=0x7f3e0de419d0) = 12802 pipe([7, 8])                            = 0 stat("/usr/lib/git-core/git", {st_mode=S_IFREG|0755, st_size=3093072, ...}) = 0 pipe([9, 10])                           = 0 rt_sigprocmask(SIG_SETMASK, ~[RTMIN RT_1], [], 8) = 0 clone(child_stack=NULL, flags=CLONE_CHILD_CLEARTID|CLONE_CHILD_SETTID|SIGCHLD, child_tidptr=0x7f3e0e1dae50) = 12803 rt_sigprocmask(SIG_SETMASK, [], NULL, 8) = 0 close(10)                               = 0 read(9, "", 8)                          = 0 close(9)                                = 0 close(7)                                = 0 close(4)                                = 0 fcntl(8, F_GETFL)                       = 0x1 (flags O_WRONLY) openat(AT_FDCWD, ".git/objects/3e", O_RDONLY|O_NONBLOCK|O_CLOEXEC|O_DIRECTORY) = 4 fstat(4, {st_mode=S_IFDIR|0777, st_size=4096, ...}) = 0 getdents64(4, /* 22 entries */, 32768)  = 1328 getdents64(4, /* 0 entries */, 32768)   = 0 close(4)                                = 0 fstat(8, {st_mode=S_IFIFO|0600, st_size=0, ...}) = 0 write(8, "^3ea50e3c1f49c33f7dbbb5e3a31017f"..., 83) = 83 close(8)                                = 0 Enumerating objects: 31, done.ts: 1 Counting objects: 100% (31/31), done. Delta compression using up to 8 threads Compressing objects: 100% (23/23), done. Writing objects: 100% (23/23), 5.60 KiB | 212.00 KiB/s, done. Total 23 (delta 14), reused 0 (delta 0) [{WIFEXITED(s) && WEXITSTATUS(s) == 0}], 0, NULL) = 12803 --- SIGCHLD {si_signo=SIGCHLD, si_code=CLD_EXITED, si_pid=12803, si_uid=1000, si_status=0, si_utime=2, si_stime=6} --- read(3, ------------------ That last read from handle 3 (which is closed) lasts forever until you ctrl-c.

The abbreviated strace output, simply halting at the comma, is very odd.

Note the behaviour is the same with the file: protocol prefix and without.

j.