du: add --inodes option

This new option can be used to find directories with a huge
amount of files.  The GNU find utility has the printf format
"%h" which prints the number of entries in a directory, but
this is non-cumulative and doesn't handle hard links.

* src/du.c (struct duinfo): Add new member for counting inodes.
(duinfo_init): Initialize inodes member with Zero.
(duinfo_set): Set inodes counter to 1.
(duinfo_add): Sum up the 2 given inodes counters.
(opt_inodes): Add new boolean flag to remember if the --inodes
option has been specified.
(INODES_OPTION): Add new enum value to be used ...
(long_options): ... here.
(usage): Add description of the new option.
(print_size): Pass inodes counter or size to print_only_size,
depending on the inodes mode.
(process_file): Adapt threshold handling: with --inodes, print or
elide the entries according to the struct member inodes.
(main): Add a case for accepting the new INODES_OPTION.
Print a warning diagnostic when --inodes is used together with the
option --apparent-size or -b.
Reset the output_block_size to 1 ... and thus ignoring the
options -m and -k.
* tests/du/inodes.sh: Add a new test.
* tests/local.mk (all_tests): Mention it.
* doc/coreutils.texi (du invocation): Document the new option.
* NEWS: Mention the new option.

1 files changed, 26 insertions, 1 deletions

diff --git a/doc/coreutils.texi b/doc/coreutils.texi
index b8d40b4f5..40bff7ae9 100644
--- a/doc/coreutils.texi
+++ b/doc/coreutils.texi
@@ -11424,6 +11424,18 @@ Equivalent to @option{--dereference-args} (@option{-D}).
 
 @optHumanReadable
 
+@itemx --inodes
+@opindex --inodes
+@cindex inode usage, dereferencing in @command{du}
+List inode usage information instead of block usage.
+This option is useful for finding directories which contain many files, and
+therefore eat up most of the inodes space of a file system (see @command{df},
+option @option{--inodes}).
+It can well be combined with the options @option{-a}, @option{-c},
+@option{-h}, @option{-l}, @option{-s}, @option{-S}, @option{-t} and
+@option{-x}; however, passing other options regarding the block size, for
+example @option{-b}, @option{-m} and @option{--apparent-size}, is ignored.
+
 @item -k
 @opindex -k
 @cindex kibibytes for file sizes
@@ -11485,7 +11497,9 @@ Display only a total for each argument.
 @itemx --threshold=@var{size}
 @opindex -t
 @opindex --threshold
-Exclude entries based on a given @var{size} (@pxref{Block size}).
+Exclude entries based on a given @var{size}.  The @var{size} refers to used
+blocks in normal mode (@pxref{Block size}), or inodes count in conjunction
+with the @option{--inodes} option.
 
 If @var{size} is positive, then @command{du} will only print entries with a size
 greater than or equal to that.
@@ -11501,6 +11515,10 @@ Please note that the @option{--threshold} option can be combined with the
 @option{--apparent-size} option, and in this case would elide entries based on
 its apparent size.
 
+Please note that the @option{--threshold} option can be combined with the
+@option{--inodes} option, and in this case would elide entries based on
+its inodes count.
+
 Here's how you would use @option{--threshold} to find directories with a size
 greater than or equal to 200 megabytes:
 
@@ -11515,6 +11533,13 @@ note the @option{-a} - with an apparent size smaller than or equal to 500 bytes:
 du -a -t -500 --apparent-size
 @end example
 
+Here's how you would use @option{--threshold} to find directories on the root
+file system with more than 20000 inodes used in the directory tree below:
+
+@example
+du --inodes -x --threshold=20000 /
+@end example
+
 
 @item --time
 @opindex --time