* [PATCH] FS-Cache: Fix handling of an attempt to store a page that is now beyond EOF
@ 2013-11-11 22:18 David Howells
2013-11-11 23:32 ` Fwd: " Milosz Tanski
2013-12-16 17:20 ` Milosz Tanski
0 siblings, 2 replies; 4+ messages in thread
From: David Howells @ 2013-11-11 22:18 UTC (permalink / raw)
To: torvalds; +Cc: linux-cachefs, linux-kernel, Milosz Tanski
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@adfin.com>
Signed-off-by: David Howells <dhowells@redhat.com>
Acked-by: Milosz Tanski <milosz@adfin.com>
---
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- goto superseded;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 */
^ permalink raw reply related [flat|nested] 4+ messages in thread* Fwd: [PATCH] FS-Cache: Fix handling of an attempt to store a page that is now beyond EOF
2013-11-11 22:18 [PATCH] FS-Cache: Fix handling of an attempt to store a page that is now beyond EOF David Howells
@ 2013-11-11 23:32 ` Milosz Tanski
2013-12-16 17:20 ` Milosz Tanski
1 sibling, 0 replies; 4+ messages in thread
From: Milosz Tanski @ 2013-11-11 23:32 UTC (permalink / raw)
To: ceph-devel
For those of you working on fscache.
---------- Forwarded message ----------
From: David Howells <dhowells@redhat.com>
Date: Mon, Nov 11, 2013 at 5:18 PM
Subject: [PATCH] FS-Cache: Fix handling of an attempt to store a page
that is now beyond EOF
To: torvalds@linux-foundation.org
Cc: linux-cachefs@redhat.com, linux-kernel@vger.kernel.org, Milosz
Tanski <milosz@adfin.com>
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@adfin.com>
Signed-off-by: David Howells <dhowells@redhat.com>
Acked-by: Milosz Tanski <milosz@adfin.com>
---
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@adfin.com
^ permalink raw reply related [flat|nested] 4+ messages in thread* Re: [PATCH] FS-Cache: Fix handling of an attempt to store a page that is now beyond EOF
2013-11-11 22:18 [PATCH] FS-Cache: Fix handling of an attempt to store a page that is now beyond EOF David Howells
2013-11-11 23:32 ` Fwd: " Milosz Tanski
@ 2013-12-16 17:20 ` Milosz Tanski
2013-12-17 23:59 ` Milosz Tanski
1 sibling, 1 reply; 4+ messages in thread
From: Milosz Tanski @ 2013-12-16 17:20 UTC (permalink / raw)
To: David Howells; +Cc: torvalds, linux-cachefs, linux-kernel
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@redhat.com> 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@adfin.com>
> Signed-off-by: David Howells <dhowells@redhat.com>
> Acked-by: Milosz Tanski <milosz@adfin.com>
> ---
>
> 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@adfin.com
^ permalink raw reply [flat|nested] 4+ messages in thread* Re: [PATCH] FS-Cache: Fix handling of an attempt to store a page that is now beyond EOF
2013-12-16 17:20 ` Milosz Tanski
@ 2013-12-17 23:59 ` Milosz Tanski
0 siblings, 0 replies; 4+ messages in thread
From: Milosz Tanski @ 2013-12-17 23:59 UTC (permalink / raw)
To: David Howells
Cc: torvalds, linux-cachefs, linux-kernel, linux-fsdevel, ceph-devel
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@adfin.com> 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@redhat.com> 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@adfin.com>
>> Signed-off-by: David Howells <dhowells@redhat.com>
>> Acked-by: Milosz Tanski <milosz@adfin.com>
>> ---
>>
>> 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@adfin.com
--
Milosz Tanski
CTO
10 East 53rd Street, 37th floor
New York, NY 10022
p: 646-253-9055
e: milosz@adfin.com
^ permalink raw reply [flat|nested] 4+ messages in thread
end of thread, other threads:[~2013-12-17 23:59 UTC | newest]
Thread overview: 4+ messages (download: mbox.gz / follow: Atom feed)
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2013-11-11 22:18 [PATCH] FS-Cache: Fix handling of an attempt to store a page that is now beyond EOF David Howells
2013-11-11 23:32 ` Fwd: " Milosz Tanski
2013-12-16 17:20 ` Milosz Tanski
2013-12-17 23:59 ` Milosz Tanski
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