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authorDavid Howells <dhowells@redhat.com>2009-11-19 21:11:04 +0300
committerDavid Howells <dhowells@redhat.com>2009-11-19 21:11:04 +0300
commit4fbf4291aa15926cd4fdca0ffe9122e89d0459db (patch)
treeec2195c39ef8117acea598af4a5c20c77f67aa0b /Documentation/filesystems
parent440f0affe247e9990c8f8778f1861da4fd7d5e50 (diff)
downloadlinux-4fbf4291aa15926cd4fdca0ffe9122e89d0459db.tar.xz
FS-Cache: Allow the current state of all objects to be dumped
Allow the current state of all fscache objects to be dumped by doing: cat /proc/fs/fscache/objects By default, all objects and all fields will be shown. This can be restricted by adding a suitable key to one of the caller's keyrings (such as the session keyring): keyctl add user fscache:objlist "<restrictions>" @s The <restrictions> are: 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 paired restrictions: 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 restriction 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. Signed-off-by: David Howells <dhowells@redhat.com>
Diffstat (limited to 'Documentation/filesystems')
-rw-r--r--Documentation/filesystems/caching/fscache.txt81
1 files changed, 81 insertions, 0 deletions
diff --git a/Documentation/filesystems/caching/fscache.txt b/Documentation/filesystems/caching/fscache.txt
index 9e94b9491d89..cac09e11ca30 100644
--- a/Documentation/filesystems/caching/fscache.txt
+++ b/Documentation/filesystems/caching/fscache.txt
@@ -299,6 +299,87 @@ proc files.
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
=========