FreeBSD/Linux Kernel Cross Reference
sys/contrib/openzfs/cmd/zvol_wait

     #!/bin/sh
     
     count_zvols() {
             if [ -z "$zvols" ]; then
                     echo 0
             else
                     echo "$zvols" | wc -l
             fi
     }
    
    filter_out_zvols_with_links() {
            echo "$zvols" | tr ' ' '+' | while read -r zvol; do
                    if ! [ -L "/dev/zvol/$zvol" ]; then
                            echo "$zvol"
                    fi
            done | tr '+' ' '
    }
    
    filter_out_deleted_zvols() {
            OIFS="$IFS"
            IFS="
    "
            # shellcheck disable=SC2086
            zfs list -H -o name $zvols 2>/dev/null
            IFS="$OIFS"
    }
    
    list_zvols() {
            read -r default_volmode < /sys/module/zfs/parameters/zvol_volmode
            zfs list -t volume -H -o \
                name,volmode,receive_resume_token,redact_snaps,keystatus |
                while IFS=" " read -r name volmode token redacted keystatus; do # IFS=\t here!
    
                    # /dev links are not created for zvols with volmode = "none",
                    # redacted zvols, or encrypted zvols for which the key has not
                    # been loaded.
                    [ "$volmode" = "none" ] && continue
                    [ "$volmode" = "default" ] && [ "$default_volmode" = "3" ] &&
                        continue
                    [ "$redacted" = "-" ] || continue
                    [ "$keystatus" = "unavailable" ] && continue
    
                    # We also ignore partially received zvols if it is
                    # not an incremental receive, as those won't even have a block
                    # device minor node created yet.
                    if [ "$token" != "-" ]; then
    
                            # Incremental receives create an invisible clone that
                            # is not automatically displayed by zfs list.
                            if ! zfs list "$name/%recv" >/dev/null 2>&1; then
                                    continue
                            fi
                    fi
                    echo "$name"
            done
    }
    
    zvols=$(list_zvols)
    zvols_count=$(count_zvols)
    if [ "$zvols_count" -eq 0 ]; then
            echo "No zvols found, nothing to do."
            exit 0
    fi
    
    echo "Testing $zvols_count zvol links"
    
    outer_loop=0
    while [ "$outer_loop" -lt 20 ]; do
            outer_loop=$((outer_loop + 1))
    
            old_zvols_count=$(count_zvols)
    
            inner_loop=0
            while [ "$inner_loop" -lt 30 ]; do
                    inner_loop=$((inner_loop + 1))
    
                    zvols="$(filter_out_zvols_with_links)"
    
                    zvols_count=$(count_zvols)
                    if [ "$zvols_count" -eq 0 ]; then
                            echo "All zvol links are now present."
                            exit 0
                    fi
                    sleep 1
            done
    
            echo "Still waiting on $zvols_count zvol links ..."
            #
            # Although zvols should normally not be deleted at boot time,
            # if that is the case then their links will be missing and
            # we would stall.
            #
            if [ "$old_zvols_count" -eq "$zvols_count" ]; then
                    echo "No progress since last loop."
                    echo "Checking if any zvols were deleted."
    
                    zvols=$(filter_out_deleted_zvols)
                    zvols_count=$(count_zvols)
    
                   if [ "$old_zvols_count" -ne "$zvols_count" ]; then
                           echo "$((old_zvols_count - zvols_count)) zvol(s) deleted."
                   fi
   
                   if [ "$zvols_count" -ne 0 ]; then
                           echo "Remaining zvols:"
                           echo "$zvols"
                   else
                           echo "All zvol links are now present."
                           exit 0
                   fi
           fi
   
           #
           # zvol_count made some progress - let's stay in this loop.
           #
           if [ "$old_zvols_count" -gt "$zvols_count" ]; then
                   outer_loop=$((outer_loop - 1))
           fi
   done
   
   echo "Timed out waiting on zvol links"
   exit 1

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