FS-Cache: Allow the current state of all objects to be dumped

     jiffy range covered, and the SECS field the equivalent number of seconds.

===========

OBJECT LIST

===========

If CONFIG_FSCACHE_OBJECT_LIST is enabled, the FS-Cache facility will maintain a

list of all the objects currently allocated and allow them to be viewed

through:

	/proc/fs/fscache/objects

This will look something like:

	[root@andromeda ~]# head /proc/fs/fscache/objects

	OBJECT   PARENT   STAT CHLDN OPS OOP IPR EX READS EM EV F S | NETFS_COOKIE_DEF TY FL NETFS_DATA       OBJECT_KEY, AUX_DATA

	======== ======== ==== ===== === === === == ===== == == = = | ================ == == ================ ================

	   17e4b        2 ACTV     0   0   0   0  0     0 7b  4 0 8 | NFS.fh           DT  0 ffff88001dd82820 010006017edcf8bbc93b43298fdfbe71e50b57b13a172c0117f38472, e567634700000000000000000000000063f2404a000000000000000000000000c9030000000000000000000063f2404a

	   1693a        2 ACTV     0   0   0   0  0     0 7b  4 0 8 | NFS.fh           DT  0 ffff88002db23380 010006017edcf8bbc93b43298fdfbe71e50b57b1e0162c01a2df0ea6, 420ebc4a000000000000000000000000420ebc4a0000000000000000000000000e1801000000000000000000420ebc4a

where the first set of columns before the '|' describe the object:

	COLUMN	DESCRIPTION

	=======	===============================================================

	OBJECT	Object debugging ID (appears as OBJ%x in some debug messages)

	PARENT	Debugging ID of parent object

	STAT	Object state

	CHLDN	Number of child objects of this object

	OPS	Number of outstanding operations on this object

	OOP	Number of outstanding child object management operations

	IPR

	EX	Number of outstanding exclusive operations

	READS	Number of outstanding read operations

	EM	Object's event mask

	EV	Events raised on this object

	F	Object flags

	S	Object slow-work work item flags

and the second set of columns describe the object's cookie, if present:

	COLUMN		DESCRIPTION

	===============	=======================================================

	NETFS_COOKIE_DEF Name of netfs cookie definition

	TY		Cookie type (IX - index, DT - data, hex - special)

	FL		Cookie flags

	NETFS_DATA	Netfs private data stored in the cookie

	OBJECT_KEY	Object key	} 1 column, with separating comma

	AUX_DATA	Object aux data	} presence may be configured

The data shown may be filtered by attaching the a key to an appropriate keyring

before viewing the file.  Something like:

		keyctl add user fscache:objlist <restrictions> @s

where <restrictions> are a selection of the following letters:

	K	Show hexdump of object key (don't show if not given)

	A	Show hexdump of object aux data (don't show if not given)

and the following paired letters:

	C	Show objects that have a cookie

	c	Show objects that don't have a cookie

	B	Show objects that are busy

	b	Show objects that aren't busy

	W	Show objects that have pending writes

	w	Show objects that don't have pending writes

	R	Show objects that have outstanding reads

	r	Show objects that don't have outstanding reads

	S	Show objects that have slow work queued

	s	Show objects that don't have slow work queued

If neither side of a letter pair is given, then both are implied.  For example:

	keyctl add user fscache:objlist KB @s

shows objects that are busy, and lists their object keys, but does not dump

their auxiliary data.  It also implies "CcWwRrSs", but as 'B' is given, 'b' is

not implied.

By default all objects and all fields will be shown.

=========

DEBUGGING

=========

		}

		cache = object->fscache.cache;

		fscache_object_destroy(&object->fscache);

		kmem_cache_free(cachefiles_object_jar, object);

		fscache_object_destroyed(cache);

	}

	shift = PAGE_SHIFT - inode->i_sb->s_blocksize_bits;

	op->op.flags = FSCACHE_OP_FAST;

	op->op.flags &= FSCACHE_OP_KEEP_FLAGS;

	op->op.flags |= FSCACHE_OP_FAST;

	op->op.processor = cachefiles_read_copier;

	pagevec_init(&pagevec, 0);

	pagevec_init(&pagevec, 0);

	op->op.flags = FSCACHE_OP_FAST;

	op->op.flags &= FSCACHE_OP_KEEP_FLAGS;

	op->op.flags |= FSCACHE_OP_FAST;

	op->op.processor = cachefiles_read_copier;

	INIT_LIST_HEAD(&backpages);

	  enabled by setting bits in /sys/modules/fscache/parameter/debug.

	  See Documentation/filesystems/caching/fscache.txt for more information.

config FSCACHE_OBJECT_LIST

	bool "Maintain global object list for debugging purposes"

	depends on FSCACHE && PROC_FS

	help

	  Maintain a global list of active fscache objects that can be

	  retrieved through /proc/fs/fscache/objects for debugging purposes

fscache-$(CONFIG_PROC_FS) += proc.o

fscache-$(CONFIG_FSCACHE_STATS) += stats.o

fscache-$(CONFIG_FSCACHE_HISTOGRAM) += histogram.o

fscache-$(CONFIG_FSCACHE_OBJECT_LIST) += object-list.o

obj-$(CONFIG_FSCACHE) := fscache.o