Fix ZDB to dump projid for projectquota enabled

[jsai20]

Motivation and Context

Description

ZDB is supposed to dump "projid" via dump_znode(), when projectquota is enabled.

static void
dump_znode(objset_t *os, uint64_t object, void *data, size_t size) {
...
    if (dmu_objset_projectquota_enabled(os) && (pflags & ZFS_PROJID)) {
	uint64_t projid;

	if (sa_lookup(hdl, sa_attr_table[ZPL_PROJID], &projid,
	    sizeof (uint64_t)) == 0)
		(void) printf("\tprojid %llu\n", (u_longlong_t)projid);
    }
...
}

But its not dumping "projid", even for project quota enabled.

dmu_objset_projectquota_enabled() does following 3 checks,

boolean_t
dmu_objset_projectquota_enabled(objset_t *os)
{
        return (file_cbs[os->os_phys->os_type] != NULL &&
            DMU_PROJECTUSED_DNODE(os) != NULL &&
            spa_feature_is_enabled(os->os_spa,
		SPA_FEATURE_PROJECT_QUOTA));
}

It fails on file_cbs[] check. file_cbs[] gets initialised via dmu_objset_register_type(); which is not done for the ZDB, its done for the kernel via zfs_init().

Register a dummy callback handle for the DMU_OST_ZFS type in ZDB main() function to dump the projid for projectquota enabled.

How Has This Been Tested?

$ zfs list
NAME             USED  AVAIL  REFER  MOUNTPOINT
mytestpool       179K   832M    25K  /mytestpool
mytestpool/fs1    25K   832M    25K  /mytestpool/fs1
$ ls -i /mytestpool/fs1/file1
2 /mytestpool/fs1/file1
$ sudo zfs project /mytestpool/fs1/file1
  100 - /mytestpool/fs1/file1
$

zdb dump of ino 2 without fix doesn't list projid field.

$ sudo zdb -ddddd mytestpool/fs1 2
Dataset mytestpool/fs1 [ZPL], ID 144, cr_txg 11, 25K, 9 objects, rootbp DVA[0]=<0:2c00bc00:200> DVA[1]=<0:3000bc00:200> [L0 DMU objset] fletcher4 lz4 unencrypted LE contiguous unique double size=1000L/200P birth=178L/178P fill=9 cksum=000000117b3a1df4:000005f259dca352:000111b9fd9582ee:002278be1dfbd514

    Object  lvl   iblk   dblk  dsize  dnsize  lsize   %full  type
         2    1   128K    512      0     512    512    0.00  ZFS plain file
                                               184   bonus  System attributes
        dnode flags: USERUSED_ACCOUNTED USEROBJUSED_ACCOUNTED
        dnode maxblkid: 0
        path    /file1
        uid     0
        gid     0
        atime   Sat Jun 22 13:03:02 2024
        mtime   Sat Jun 22 13:03:02 2024
        ctime   Sat Jun 22 13:03:02 2024
        crtime  Sat Jun 22 13:03:02 2024
        gen     56
        mode    100600
        size    0
        parent  34
        links   1
        pflags  840800000004
        xattr   3
Indirect blocks:

zdb dump of ino 2 with Fix lists projid field.

$ sudo ./zdb -ddddd mytestpool/fs1 2
Dataset mytestpool/fs1 [ZPL], ID 144, cr_txg 11, 25K, 9 objects, rootbp DVA[0]=<0:2c00bc00:200> DVA[1]=<0:3000bc00:200> [L0 DMU objset] fletcher4 lz4 unencrypted LE contiguous unique double size=1000L/200P birth=178L/178P fill=9 cksum=000000117b3a1df4:000005f259dca352:000111b9fd9582ee:002278be1dfbd514

    Object  lvl   iblk   dblk  dsize  dnsize  lsize   %full  type
         2    1   128K    512      0     512    512    0.00  ZFS plain file
                                               184   bonus  System attributes
        dnode flags: USERUSED_ACCOUNTED USEROBJUSED_ACCOUNTED
        dnode maxblkid: 0
        path    /file1
        uid     0
        gid     0
        atime   Sat Jun 22 13:03:02 2024
        mtime   Sat Jun 22 13:03:02 2024
        ctime   Sat Jun 22 13:03:02 2024
        crtime  Sat Jun 22 13:03:02 2024
        gen     56
        mode    100600
        size    0
        parent  34
        links   1
        pflags  840800000004
        projid  100
        xattr   3
Indirect blocks:

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Performance enhancement (non-breaking change which improves efficiency)
• Code cleanup (non-breaking change which makes code smaller or more readable)
• Breaking change (fix or feature that would cause existing functionality to change)
• Library ABI change (libzfs, libzfs_core, libnvpair, libuutil and libzfsbootenv)
• Documentation (a change to man pages or other documentation)

Checklist:

• My code follows the OpenZFS code style requirements.
• I have updated the documentation accordingly.
• I have read the contributing document.
• I have added tests to cover my changes.
• I have run the ZFS Test Suite with this change applied.
• All commit messages are properly formatted and contain Signed-off-by.