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 - goto superseded;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
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