zdb: Fix zdb '-O|-r' options with -e/exported zpool

[akashb-22]

Motivation and Context

Signed-off-by: Akash B akash-b@hpe.com
For a given zpool used by lustre (dataset) which consists of many files and directories, where we were not able to use zdb -O option to get the objectid for the path which was reported by zpool status -v and was failing with below errors. The zpools are generally created with cachefile=none option, so zdb -e +option is generally used to debug.

-snip-of-zpool-status-
errors: Permanent errors have been detected in the following files:

        pool-mds65/mdt65:/oi.9/0x200000009:0x0:0x0
-snip-

# zdb -e pool-mds65/mdt65 -O oi.9/0x200000009:0x0:0x0
failed to hold dataset 'pool-mds65/mdt65': No such file or directory

# zdb -e -p . pool-oss0/ost0 -O file1
failed to hold dataset 'pool-oss0/ost0': No such file or directory

# zdb -e -p . pool-oss0/ost0 -O file1 -vvv
failed to hold dataset 'pool-oss0/ost0': No such file or directory

# zdb -e pool-oss0/ost0 -r file1 /tmp/filecopy1 -p.
failed to hold dataset 'pool-oss0/ost0': No such file or directory
zdb: internal error: No such file or directory

Description

zdb with '-e' or exported zpool doesn't work along with '-O' and '-r' options as we process them before '-e' has been processed.

Below errors are seen:

~> zdb -e pool-mds65/mdt65 -O oi.9/0x200000009:0x0:0x0 
failed to hold dataset 'pool-mds65/mdt65': No such file or directory

~> zdb -e pool-oss0/ost0 -r file1 /tmp/filecopy1 -p. 
failed to hold dataset 'pool-oss0/ost0': No such file or directory
zdb: internal error: No such file or directory

We need to make sure to process '-O|-r' options after the '-e' option has been processed, which imports the pool to the namespace if it's not in the cachefile.

Issue reproduced with:

# truncate -s 1G file1 file2 file3 file4 file5 file6 file7 file8 file9 file10 file11 file12 file13 file14 file15
# pwd
/root/test/files
# zpool create -f -o cachefile=none -o failmode=panic -O canmount=off pool-oss0 draid2:11d:2s /root/test/files/file1 /root/test/files/file2 /root/test/files/file3 /root/test/files/file4 /root/test/files/file5 /root/test/files/file6 /root/test/files/file7 /root/test/files/file8 /root/test/files/file9 /root/test/files/file10 /root/test/files/file11 /root/test/files/file12 /root/test/files/file13 /root/test/files/file14 /root/test/files/file15
# zfs create -o mountpoint=/mnt/ost0 pool-oss0/ost0
# zfs set recordsize=4M pool-oss0/ost0
# touch /mnt/ost0/file1
# zpool sync -f pool-oss0
# zpool export -f -a
# 
# zdb -e -p . pool-oss0/ost0 -O file1 -vvv
failed to hold dataset 'pool-oss0/ost0': No such file or directory
# zdb -e -p. pool-oss0/ost0 -r file1 /tmp/filecopy1
failed to hold dataset 'pool-oss0/ost0': No such file or directory
zdb: internal error: No such file or directory
#
# zdb -dddddd pool-oss0/ost0 -e -p. 2 | grep path
        path    /file1

with the fix applied:

# zdb -e -p . pool-oss0/ost0 -O file1 -vvv

    Object  lvl   iblk   dblk  dsize  dnsize  lsize   %full  type
         2    1   128K    512      0     512    512    0.00  ZFS plain file (K=inherit) (Z=inherit=lz4)
                                               176   bonus  System attributes
        dnode flags: USERUSED_ACCOUNTED USEROBJUSED_ACCOUNTED
        dnode maxblkid: 0
        uid     0
        gid     0
        atime   Thu Nov 16 06:23:50 2023
        mtime   Thu Nov 16 06:23:50 2023
        ctime   Thu Nov 16 06:23:50 2023
        crtime  Thu Nov 16 06:23:50 2023
        gen     16
        mode    100644
        size    0
        parent  34
        links   1
        pflags  840800000004
Indirect blocks:

# zdb -e -p. pool-oss0/ost0 -r file1 /tmp/filecopy1
Copying object 2 to file /tmp/filecopy1
Object 2 is 0 bytes

How Has This Been Tested?

Tested locally in KVM and server along with lustre.
ZTS.

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.