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NFS: Clean up nfs_lock_and_join_requests()

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Clean up nfs_lock_and_join_requests() to simplify the calculation
of the range covered by the page group, taking into account the
presence of mirrors.

Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
This commit is contained in:
Trond Myklebust
2020-03-30 11:12:16 -04:00
parent 377840ee48
commit a62f8e3bd8
3 changed files with 95 additions and 71 deletions
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74
fs/nfs/pagelist.c
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@@ -130,6 +130,80 @@ nfs_async_iocounter_wait(struct rpc_task *task, struct nfs_lock_context *l_ctx)
}
EXPORT_SYMBOL_GPL(nfs_async_iocounter_wait);
/*
* nfs_unroll_locks - unlock all newly locked reqs and wait on @req
* @head: head request of page group, must be holding head lock
* @req: request that couldn't lock and needs to wait on the req bit lock
*
* This is a helper function for nfs_lock_and_join_requests
* returns 0 on success, < 0 on error.
*/
static void
nfs_unroll_locks(struct nfs_page *head, struct nfs_page *req)
{
struct nfs_page *tmp;
/* relinquish all the locks successfully grabbed this run */
for (tmp = head->wb_this_page ; tmp != req; tmp = tmp->wb_this_page) {
if (!kref_read(&tmp->wb_kref))
continue;
nfs_unlock_and_release_request(tmp);
}
}
/*
* nfs_page_group_lock_subreq - try to lock a subrequest
* @head: head request of page group
* @subreq: request to lock
*
* This is a helper function for nfs_lock_and_join_requests which
* must be called with the head request and page group both locked.
* On error, it returns with the page group unlocked.
*/
static int
nfs_page_group_lock_subreq(struct nfs_page *head, struct nfs_page *subreq)
{
int ret;
if (!kref_get_unless_zero(&subreq->wb_kref))
return 0;
while (!nfs_lock_request(subreq)) {
nfs_page_group_unlock(head);
ret = nfs_wait_on_request(subreq);
if (!ret)
ret = nfs_page_group_lock(head);
if (ret < 0) {
nfs_unroll_locks(head, subreq);
nfs_release_request(subreq);
return ret;
}
}
return 0;
}
/*
* nfs_page_group_lock_subrequests - try to lock the subrequests
* @head: head request of page group
*
* This is a helper function for nfs_lock_and_join_requests which
* must be called with the head request and page group both locked.
* On error, it returns with the page group unlocked.
*/
int nfs_page_group_lock_subrequests(struct nfs_page *head)
{
struct nfs_page *subreq;
int ret;
/* lock each request in the page group */
for (subreq = head->wb_this_page; subreq != head;
subreq = subreq->wb_this_page) {
ret = nfs_page_group_lock_subreq(head, subreq);
if (ret < 0)
return ret;
}
return 0;
}
/*
* nfs_page_set_headlock - set the request PG_HEADLOCK
* @req: request that is to be locked