HDFS-11929. Document missing processor of hdfs oiv_legacy command. Contributed by LiXin Ge.

(cherry picked from commit 5ec71639cf41858c687781445b8360d50cad5b55)

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/tools/offlineImageViewer/OfflineImageViewer.java

@@ -94,7 +94,7 @@ public class OfflineImageViewer {
           + "Optional command line arguments:\n"
           + "-p,--processor <arg>   Select which type of processor to apply\n"
           + "                       against image file."
-          + " (Ls|XML|Delimited|Indented|FileDistribution).\n"
+          + " (Ls|XML|Delimited|Indented|FileDistribution|NameDistribution).\n"
           + "-h,--help              Display usage information and exit\n"
           + "-printToScreen         For processors that write to a file, also\n"
           + "                       output to screen. On large image files this\n"

hadoop-hdfs-project/hadoop-hdfs/src/site/markdown/HDFSCommands.md

@@ -219,7 +219,7 @@ Usage: `hdfs oiv_legacy [OPTIONS] -i INPUT_FILE -o OUTPUT_FILE`
 
 | COMMAND\_OPTION | Description |
 |:---- |:---- |
-| `-p`\|`--processor` *processor* | Specify the image processor to apply against the image file. Valid options are Ls (default), XML, Delimited, Indented, and FileDistribution. |
+| `-p`\|`--processor` *processor* | Specify the image processor to apply against the image file. Valid options are Ls (default), XML, Delimited, Indented, FileDistribution and NameDistribution. |
 | `-maxSize` *size* | Specify the range [0, maxSize] of file sizes to be analyzed in bytes (128GB by default). This option is used with FileDistribution processor. |
 | `-step` *size* | Specify the granularity of the distribution in bytes (2MB by default). This option is used with FileDistribution processor. |
 | `-format` | Format the output result in a human-readable fashion rather than a number of bytes. (false by default). This option is used with FileDistribution processor. |

hadoop-hdfs-project/hadoop-hdfs/src/site/markdown/HdfsImageViewer.md

@@ -175,7 +175,7 @@ Due to the internal layout changes introduced by the ProtocolBuffer-based fsimag
 |:---- |:---- |
 | `-i`\|`--inputFile` *input file* | Specify the input fsimage file to process. Required. |
 | `-o`\|`--outputFile` *output file* | Specify the output filename, if the specified output processor generates one. If the specified file already exists, it is silently overwritten. Required. |
-| `-p`\|`--processor` *processor* | Specify the image processor to apply against the image file. Valid options are Ls (default), XML, Delimited, Indented, and FileDistribution. |
+| `-p`\|`--processor` *processor* | Specify the image processor to apply against the image file. Valid options are Ls (default), XML, Delimited, Indented, FileDistribution and NameDistribution. |
 | `-maxSize` *size* | Specify the range [0, maxSize] of file sizes to be analyzed in bytes (128GB by default). This option is used with FileDistribution processor. |
 | `-step` *size* | Specify the granularity of the distribution in bytes (2MB by default). This option is used with FileDistribution processor. |
 | `-format` | Format the output result in a human-readable fashion rather than a number of bytes. (false by default). This option is used with FileDistribution processor. |