[GIT PULL] FS-Cache: Fixes for dead objects handling and operation cancellation

From: David Howells
Date: Thu Apr 02 2015 - 09:59:50 EST

Hi Linus,

Could you pull these FS-Cache fixes please?

The main thrust of the fixes are:

(1) Handle a race between operation submission on an object (eg. reading data
from that object) and the object transitioning to the dead state. The
race shows up as an assertion at fs/cachefiles/interface.c:339 indicating
that the dead object still has operations queued against it.

(2) Permit in-progress operations to be cancelled under some circumstances,
otherwise we can unexpectedly see operations in progress on a killed
object. This shows up as an assertion on fs/fscache/operation.c:432.

(3) Pass initialised ops through fscache_put_operation() rather than freeing
them directly. This allows better cleanup handling.

(4) The cancellation method for an operation wasn't being called everwhere
that was necessary, leaving the operation in an unclean state. This
shows up as an assertion at fs/fscache/page.c:261.

To help find and monitor these the patches also added better accounting for
operations and objects through /proc/fs/fscache/stats.

The only difference between this and fscache-fixes-20150226 is that I've
merged reviews/acks into the commits.

The following changes since commit b2b89ebfc0f0287e20516a5443d93af309b800cf:

Merge tag 'locks-v3.20-2' of git://git.samba.org/jlayton/linux (2015-02-18 10:21:47 -0800)

are available in the git repository at:

git://git.kernel.org/pub/scm/linux/kernel/git/dhowells/linux-fs.git tags/fscache-fixes-20150402

for you to fetch changes up to 4a47132ff472a0c2c5441baeb50cf97f2580bc43:

FS-Cache: Retain the netfs context in the retrieval op earlier (2015-04-02 14:28:53 +0100)

FS-Cache fixes

David Howells (13):
FS-Cache: Count culled objects and objects rejected due to lack of space
FS-Cache: Move fscache_report_unexpected_submission() to make it more available
FS-Cache: When submitting an op, cancel it if the target object is dying
FS-Cache: Handle a new operation submitted against a killed object
FS-Cache: Synchronise object death state change vs operation submission
FS-Cache: fscache_object_is_dead() has wrong logic, kill it
FS-Cache: Permit fscache_cancel_op() to cancel in-progress operations too
FS-Cache: Out of line fscache_operation_init()
FS-Cache: Count the number of initialised operations
FS-Cache: Fix cancellation of in-progress operation
FS-Cache: Put an aborted initialised op so that it is accounted correctly
FS-Cache: The operation cancellation method needs calling in more places
FS-Cache: Retain the netfs context in the retrieval op earlier

Documentation/filesystems/caching/backend-api.txt | 23 ++
Documentation/filesystems/caching/fscache.txt | 7 +-
fs/cachefiles/internal.h | 1 -
fs/cachefiles/namei.c | 33 ++-
fs/fscache/cookie.c | 8 +-
fs/fscache/internal.h | 12 +-
fs/fscache/object.c | 69 +++++-
fs/fscache/operation.c | 254 ++++++++++++++--------
fs/fscache/page.c | 86 ++++----
fs/fscache/stats.c | 14 +-
include/linux/fscache-cache.h | 55 +++--
11 files changed, 378 insertions(+), 184 deletions(-)
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