makefs: zfs dataset mountpoints are considered non-empty
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Authored by tsoome on Mon, Jul 28, 12:23 PM.

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rG507f8523f5f6: makefs: zfs dataset mountpoints are considered non-empty

Summary

The dataset mountpoints get link count and size calculated by
content of dataset root directory, but this will break libzfs
dir_is_empty_stat() test.

For fix, we need to check if the directory is mountpoint for
dataset, and calculate the link count and size accordingly.

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rG FreeBSD src repository

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Unit

Tests Not Applicable

Event Timeline

tsoome created this revision.Mon, Jul 28, 12:23 PM

Herald added subscribers: delphij, imp. · View Herald TranscriptMon, Jul 28, 12:23 PM

tsoome requested review of this revision.Mon, Jul 28, 12:23 PM

Harbormaster completed remote builds in B65796: Diff 159280.Mon, Jul 28, 12:23 PM

tsoome added a parent revision: D51592: makefs: clean up warnings.Mon, Jul 28, 12:23 PM

tsoome added a reviewer: markj.Mon, Jul 28, 12:39 PM

tsoome retitled this revision from makefs: zfs dataset mountpoints are considered not empty to makefs: zfs dataset mountpoints are considered non-empty.Mon, Jul 28, 12:55 PM

Could you please describe the problematic scenario? I'd like to add a regression test for it.

In D51593#1178387, @markj wrote:

Could you please describe the problematic scenario? I'd like to add a regression test for it.

this one is tricky;) because it is not revealed in FreeBSD. With illumos:

root@balrog:/home/tsoome# lofiadm -a proto.zpool 
/dev/lofi/1
root@balrog:/home/tsoome# zpool import -d /dev/rlofi -R /mnt zroot
cannot mount '/mnt/usr': directory is not empty
root@balrog:/home/tsoome# ls -la /mnt/usr
total 26
drwxr-xr-x  34 pynfs    1001          45 juuli 16 11:02 .
drwxr-xr-x  23 pynfs    1001          26 juuli 28 20:06 ..
root@balrog:/home/tsoome# ls -lid /mnt/usr
      7347 drwxr-xr-x  34 pynfs    1001          45 juuli 16 11:02 /mnt/usr
root@balrog:/home/tsoome# 
root@balrog:/home/tsoome# zdb -bbbb -dddd -vvvvv -e -p /dev/rlofi/  zroot/ROOT/default 7347
Dataset zroot/ROOT/default [ZPL], ID 30, cr_txg 3, 392M, 50 objects, rootbp DVA[0]=<0:5809b000:1000> DVA[1]=<0:5809c000:1000> [L0 DMU objset] fletcher4 uncompressed unencrypted LE contiguous unique double size=1000L/1000P birth=14L/14P fill=50 cksum=8e1880a04:1c68d9c87576:2f362835924373:36157f932b07e846

    Object  lvl   iblk   dblk  dsize  dnsize  lsize   %full  type
      7347    1   128K     4K     4K    512     4K  100.00  ZFS directory (K=fletcher4) (Z=inherit)
                                               168   bonus  System attributes
        dnode flags: USED_BYTES 
        dnode maxblkid: 0
        path    /usr
        uid     1001
        gid     1001
        atime   Wed Jul 16 11:02:42 2025
        mtime   Wed Jul 16 11:02:42 2025
        ctime   Fri Jul 25 20:04:55 2025
        crtime  Wed Jul 16 11:02:42 2025
        gen     1
        mode    40755
        size    45
        parent  5
        links   34
        pflags  40800000044
        microzap: 4096 bytes, 0 entries

Indirect blocks:
               0 L0 DVA[0]=<0:831f000:1000> [L0 ZFS directory] fletcher4 uncompressed unencrypted LE contiguous unique single size=1000L/1000P birth=4L/4P fill=1 cksum=c7270b7e:31b709091f0:63618b63465af:849282bb35ff4e6

                segment [0000000000000000, 0000000000001000) size    4K

So, indeed, it is created with nlinks 34 and size 45 ("normal" empty directory should have 2 links and size 2). Using overlay mount:

root@balrog:/home/tsoome# zfs mount -O zroot/ROOT/default/usr
root@balrog:/home/tsoome# ls -lid /mnt/usr
         5 drwxr-xr-x  33 pynfs    1001          44 juuli 16 11:02 /mnt/usr

And with fix applied:

root@balrog:/home/tsoome# lofiadm -a proto.zpool 
/dev/lofi/1
root@balrog:/home/tsoome# zpool import -d /dev/rlofi -R /mnt zroot
root@balrog:/home/tsoome# ls -ld /mnt/usr
drwxr-xr-x  33 1000     staff         44 juuli 16 11:02 /mnt/usr
root@balrog:/home/tsoome# ls -ldi /mnt/usr
         5 drwxr-xr-x  33 1000     staff         44 juuli 16 11:02 /mnt/usr
root@balrog:/home/tsoome# zfs umount zroot/ROOT/default/usr
root@balrog:/home/tsoome# ls -ldi /mnt/usr
     10617 drwxr-xr-x   2 1000     staff          2 juuli 16 11:02 /mnt/usr
root@balrog:/home/tsoome# 
root@balrog:/home/tsoome# zdb -bbbb -dddd -vvvvv -e -p /dev/rlofi/  zroot/ROOT/default 10617
Dataset zroot/ROOT/default [ZPL], ID 30, cr_txg 3, 392M, 50 objects, rootbp DVA[0]=<0:5337d000:1000> DVA[1]=<0:5809e000:1000> [L0 DMU objset] fletcher4 uncompressed unencrypted LE contiguous unique double size=1000L/1000P birth=14L/14P fill=50 cksum=a7a65b7d2:1f9e00393b50:31f3613496a5d8:36ebe93c4db0e7f3

    Object  lvl   iblk   dblk  dsize  dnsize  lsize   %full  type
     10617    1   128K     4K     4K    512     4K  100.00  ZFS directory (K=fletcher4) (Z=inherit)
                                               168   bonus  System attributes
        dnode flags: USED_BYTES 
        dnode maxblkid: 0
        path    /usr
        uid     1000
        gid     10
        atime   Wed Jul 16 11:02:42 2025
        mtime   Wed Jul 16 11:02:42 2025
        ctime   Wed Jul 16 11:02:42 2025
        crtime  Wed Jul 16 11:02:42 2025
        gen     1
        mode    40755
        size    2
        parent  5
        links   2
        pflags  40800000044
        microzap: 4096 bytes, 0 entries

Indirect blocks:
               0 L0 DVA[0]=<0:18272000:1000> [L0 ZFS directory] fletcher4 uncompressed unencrypted LE contiguous unique single size=1000L/1000P birth=4L/4P fill=1 cksum=f5f5456f:3d60b8ccda7:7aa71237b866e:a38f36b4dc3367f

                segment [0000000000000000, 0000000000001000) size    4K

root@balrog:/home/tsoome#

I understand now, thank you.

usr.sbin/makefs/zfs/fs.c
409

This revision is now accepted and ready to land.Tue, Jul 29, 7:59 PM

Hmm, I see a couple of test failures with this change. Please hold off on pushing until I report back.

In D51593#1179127, @markj wrote:

Hmm, I see a couple of test failures with this change. Please hold off on pushing until I report back.

It's unrelated. There is a race which arises when tests are run in parallel and zfs.ko is not loaded initially. Please go ahead.

Closed by commit rG507f8523f5f6: makefs: zfs dataset mountpoints are considered non-empty (authored by tsoome). · Explain WhyTue, Jul 29, 9:02 PM

This revision was automatically updated to reflect the committed changes.

tsoome added a commit: rG507f8523f5f6: makefs: zfs dataset mountpoints are considered non-empty.

Revision Contents
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Path

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usr.sbin/

makefs/

zfs/

fs.c

42 lines

Diff 159428

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makefs: zfs dataset mountpoints are considered non-emptyClosedPublicActions