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authorWeston Andros Adamson <dros@primarydata.com>2014-07-11 10:20:46 -0400
committerTrond Myklebust <trond.myklebust@primarydata.com>2014-07-12 16:51:41 -0400
commit85710a837c2026aae80b7c64187edf1f10027b0b (patch)
tree9b8ac697b4bc8aa635a6b97432bc76113703a85a
parent17089a29a25a3bfe8d14520cd866b7d635ffe5ba (diff)
nfs: nfs_page should take a ref on the head req
nfs_pages that aren't the the head of a group must take a reference on the head as long as ->wb_head is set to it. This stops the head from hitting a refcount of 0 while there is still an active nfs_page for the page group. This avoids kref warnings in the writeback code when the page group head is found and referenced. Signed-off-by: Weston Andros Adamson <dros@primarydata.com> Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
-rw-r--r--fs/nfs/pagelist.c10
1 files changed, 10 insertions, 0 deletions
diff --git a/fs/nfs/pagelist.c b/fs/nfs/pagelist.c
index 7368b2130a41..05a63593a61f 100644
--- a/fs/nfs/pagelist.c
+++ b/fs/nfs/pagelist.c
@@ -239,15 +239,21 @@ nfs_page_group_init(struct nfs_page *req, struct nfs_page *prev)
WARN_ON_ONCE(prev == req);
if (!prev) {
+ /* a head request */
req->wb_head = req;
req->wb_this_page = req;
} else {
+ /* a subrequest */
WARN_ON_ONCE(prev->wb_this_page != prev->wb_head);
WARN_ON_ONCE(!test_bit(PG_HEADLOCK, &prev->wb_head->wb_flags));
req->wb_head = prev->wb_head;
req->wb_this_page = prev->wb_this_page;
prev->wb_this_page = req;
+ /* All subrequests take a ref on the head request until
+ * nfs_page_group_destroy is called */
+ kref_get(&req->wb_head->wb_kref);
+
/* grab extra ref if head request has extra ref from
* the write/commit path to handle handoff between write
* and commit lists */
@@ -271,6 +277,10 @@ nfs_page_group_destroy(struct kref *kref)
struct nfs_page *req = container_of(kref, struct nfs_page, wb_kref);
struct nfs_page *tmp, *next;
+ /* subrequests must release the ref on the head request */
+ if (req->wb_head != req)
+ nfs_release_request(req->wb_head);
+
if (!nfs_page_group_sync_on_bit(req, PG_TEARDOWN))
return;