Re: [PATCH 00/13] FS-Cache: Fix a number of bugs that occur when the cache runs out of space

[Jeff Layton <jeff.layton@primarydata.com>]

On Thu, 26 Feb 2015 14:01:55 +0000
David Howells <dhowells@redhat.com> wrote:

> 
> Attached are a bunch of patches that progressively fix bugs that can occur
> when the cache hits the hard "must maintain X free space" limit and starts
> rejecting requests.
> 
> The commit ensubjected "FS-Cache: Synchronise object death state change vs
> operation submission" is the main bug I was looking for.  Some of the other
> patches fix other bugs I found along the way and the remaining patches are
> changes pulled out of the bugfixes to make the bugfix commits more narrowly
> targeted.
> 
> Note that I added some new stats:
> 
> 	Ops    : ini=836360 dfr=19 rel=836360 gc=19
> 
> The ini=N field here indicates the number of fscache_operation structs that
> were initialised and should match the rel=M value.
> 
> 	CacheEv: nsp=3425 stl=0 rtr=0 cul=0
> 
> Indicates counts of certain cache backend events: nsp=N shows how many objects
> were rejected due to lack of space in the cache, stl=N shows how many objects
> were found to be stale upon reuse and thus discarded, rtr=N how many objects
> were retired and cul=N shows how many inactive objects were culled.
> 
> These can also be found here:
> 
> 	http://git.kernel.org/cgit/linux/kernel/git/dhowells/linux-fs.git/log/?h=fscache-fixes
> 
> tagged with:
> 
> 	fscache-fixes-20150226
> 
> David
> ---
> 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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I've looked over these patches. While I haven't looked at the fscache
code in quite a while, these all look reasonably sane to me (and it
looks like there are some good bugfixes in here).

Acked-by: Jeff Layton <jeff.layton@primarydata.com>