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authorDavid Howells <dhowells@redhat.com>2012-12-20 21:52:36 +0000
committerDavid Howells <dhowells@redhat.com>2012-12-20 22:04:07 +0000
commitef778e7ae67cd426c30cad43378b908f5eb0bad5 (patch)
tree4893f19487cb99e8ec0eb835ec4391d952641a9c /fs/fscache/page.c
parent9f10523f891928330b7529da54c1a3cc65180b1a (diff)
FS-Cache: Provide proper invalidation
Provide a proper invalidation method rather than relying on the netfs retiring the cookie it has and getting a new one. The problem with this is that isn't easy for the netfs to make sure that it has completed/cancelled all its outstanding storage and retrieval operations on the cookie it is retiring. Instead, have the cache provide an invalidation method that will cancel or wait for all currently outstanding operations before invalidating the cache, and will cause new operations to queue up behind that. Whilst invalidation is in progress, some requests will be rejected until the cache can stack a barrier on the operation queue to cause new operations to be deferred behind it. Signed-off-by: David Howells <dhowells@redhat.com>
Diffstat (limited to 'fs/fscache/page.c')
-rw-r--r--fs/fscache/page.c51
1 files changed, 51 insertions, 0 deletions
diff --git a/fs/fscache/page.c b/fs/fscache/page.c
index b38b13d2a555..7bf9d2557052 100644
--- a/fs/fscache/page.c
+++ b/fs/fscache/page.c
@@ -361,6 +361,11 @@ int __fscache_read_or_alloc_page(struct fscache_cookie *cookie,
if (hlist_empty(&cookie->backing_objects))
goto nobufs;
+ if (test_bit(FSCACHE_COOKIE_INVALIDATING, &cookie->flags)) {
+ _leave(" = -ENOBUFS [invalidating]");
+ return -ENOBUFS;
+ }
+
ASSERTCMP(cookie->def->type, !=, FSCACHE_COOKIE_TYPE_INDEX);
ASSERTCMP(page, !=, NULL);
@@ -483,6 +488,11 @@ int __fscache_read_or_alloc_pages(struct fscache_cookie *cookie,
if (hlist_empty(&cookie->backing_objects))
goto nobufs;
+ if (test_bit(FSCACHE_COOKIE_INVALIDATING, &cookie->flags)) {
+ _leave(" = -ENOBUFS [invalidating]");
+ return -ENOBUFS;
+ }
+
ASSERTCMP(cookie->def->type, !=, FSCACHE_COOKIE_TYPE_INDEX);
ASSERTCMP(*nr_pages, >, 0);
ASSERT(!list_empty(pages));
@@ -591,6 +601,11 @@ int __fscache_alloc_page(struct fscache_cookie *cookie,
ASSERTCMP(cookie->def->type, !=, FSCACHE_COOKIE_TYPE_INDEX);
ASSERTCMP(page, !=, NULL);
+ if (test_bit(FSCACHE_COOKIE_INVALIDATING, &cookie->flags)) {
+ _leave(" = -ENOBUFS [invalidating]");
+ return -ENOBUFS;
+ }
+
if (fscache_wait_for_deferred_lookup(cookie) < 0)
return -ERESTARTSYS;
@@ -731,6 +746,37 @@ superseded:
}
/*
+ * Clear the pages pending writing for invalidation
+ */
+void fscache_invalidate_writes(struct fscache_cookie *cookie)
+{
+ struct page *page;
+ void *results[16];
+ int n, i;
+
+ _enter("");
+
+ while (spin_lock(&cookie->stores_lock),
+ n = radix_tree_gang_lookup_tag(&cookie->stores, results, 0,
+ ARRAY_SIZE(results),
+ FSCACHE_COOKIE_PENDING_TAG),
+ n > 0) {
+ for (i = n - 1; i >= 0; i--) {
+ page = results[i];
+ radix_tree_delete(&cookie->stores, page->index);
+ }
+
+ spin_unlock(&cookie->stores_lock);
+
+ for (i = n - 1; i >= 0; i--)
+ page_cache_release(results[i]);
+ }
+
+ spin_unlock(&cookie->stores_lock);
+ _leave("");
+}
+
+/*
* request a page be stored in the cache
* - returns:
* -ENOMEM - out of memory, nothing done
@@ -776,6 +822,11 @@ int __fscache_write_page(struct fscache_cookie *cookie,
fscache_stat(&fscache_n_stores);
+ if (test_bit(FSCACHE_COOKIE_INVALIDATING, &cookie->flags)) {
+ _leave(" = -ENOBUFS [invalidating]");
+ return -ENOBUFS;
+ }
+
op = kzalloc(sizeof(*op), GFP_NOIO | __GFP_NOMEMALLOC | __GFP_NORETRY);
if (!op)
goto nomem;