I hate to be that guy and keep bugging you guys. Can I get an
acknowledgment of the original patch? It fixed a very real issue for
fscache users that occurs semi-frequently under moderate concurrency.
- M
On Mon, Dec 16, 2013 at 12:20 PM, Milosz Tanski <milosz@xxxxxxxxx> wrote:
> Hey guys it looks like this patch got lost in the shuffle. I checked
> out a recent kernel and learned this wasn't applied the hard way (by
> running into it).
>
> Can this please get applied to master as it fixes a real issue?
>
> Thanks,
> - Milosz
>
> On Mon, Nov 11, 2013 at 5:18 PM, David Howells <dhowells@xxxxxxxxxx> wrote:
>> Fix the handling of an attempt to store a page that is now beyond EOF. This
>> may happen, for example, if the page got pushed for storage before the netfs
>> file got truncated on the server. In such a case, we should just remove the
>> excessive pages from the cookie->stores radix tree and wake up the waiter.
>>
>> This can be seen in /proc/fs/fscache/stats on this line:
>>
>> Stores : ops=350 run=1895 pgs=1545 rxd=1727 olm=9
>>
>> where olm=N has N > 0.
>>
>> Reported-by: Milosz Tanski <milosz@xxxxxxxxx>
>> Signed-off-by: David Howells <dhowells@xxxxxxxxxx>
>> Acked-by: Milosz Tanski <milosz@xxxxxxxxx>
>> ---
>>
>> fs/fscache/page.c | 37 ++++++++++++++++++++++++++++++++++++-
>> 1 file changed, 36 insertions(+), 1 deletion(-)
>>
>> diff --git a/fs/fscache/page.c b/fs/fscache/page.c
>> index 7f5c658af755..b4730cf52aec 100644
>> --- a/fs/fscache/page.c
>> +++ b/fs/fscache/page.c
>> @@ -755,6 +755,7 @@ static void fscache_write_op(struct fscache_operation *_op)
>> struct fscache_object *object = op->op.object;
>> struct fscache_cookie *cookie;
>> struct page *page;
>> + pgoff_t index;
>> unsigned n;
>> void *results[1];
>> int ret;
>> @@ -803,7 +804,7 @@ static void fscache_write_op(struct fscache_operation *_op)
>> _debug("gang %d [%lx]", n, page->index);
>> if (page->index > op->store_limit) {
>> fscache_stat(&fscache_n_store_pages_over_limit);
>> - goto superseded;
>> + goto page_beyond_limit;
>> }
>>
>> radix_tree_tag_set(&cookie->stores, page->index,
>> @@ -829,6 +830,40 @@ static void fscache_write_op(struct fscache_operation *_op)
>> _leave("");
>> return;
>>
>> +page_beyond_limit:
>> + spin_unlock(&object->lock);
>> +
>> +page_beyond_limit_unlocked:
>> + /* pages that are now beyond the end of the storage object must have
>> + * their pending storage records cleared.
>> + */
>> + index = page->index;
>> + radix_tree_tag_clear(&cookie->stores, page->index,
>> + FSCACHE_COOKIE_PENDING_TAG);
>> + if (!radix_tree_tag_get(&cookie->stores, page->index,
>> + FSCACHE_COOKIE_STORING_TAG)) {
>> + fscache_stat(&fscache_n_store_radix_deletes);
>> + radix_tree_delete(&cookie->stores, page->index);
>> + page_cache_release(page);
>> + }
>> + if (!need_resched()) {
>> + n = radix_tree_gang_lookup_tag(&cookie->stores, results,
>> + index + 1, 1,
>> + FSCACHE_COOKIE_PENDING_TAG);
>> + if (n == 1) {
>> + page = results[0];
>> + goto page_beyond_limit_unlocked;
>> + }
>> + spin_unlock(&cookie->stores_lock);
>> + wake_up_bit(&cookie->flags, 0);
>> + } else {
>> + spin_unlock(&cookie->stores_lock);
>> + }
>> +
>> + fscache_enqueue_operation(&op->op);
>> + _leave("");
>> + return;
>> +
>> superseded:
>> /* this writer is going away and there aren't any more things to
>> * write */
>>
>
>
>
> --
> Milosz Tanski
> CTO
> 10 East 53rd Street, 37th floor
> New York, NY 10022
>
> p: 646-253-9055
> e: milosz@xxxxxxxxx
--
Milosz Tanski
CTO
10 East 53rd Street, 37th floor
New York, NY 10022
p: 646-253-9055
e: milosz@xxxxxxxxx
--
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