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authorTrond Myklebust <trond.myklebust@hammerspace.com>2020-03-30 11:12:16 -0400
committerTrond Myklebust <trond.myklebust@hammerspace.com>2020-04-01 13:37:56 -0400
commita62f8e3bd836bf1abde1648a45e14afd050dbd23 (patch)
tree2c93e5b4f2768ac87a4fac37e453997096177d4f /fs/nfs
parent377840ee48cde0700678ef14141106bbd13e00b5 (diff)
NFS: Clean up nfs_lock_and_join_requests()
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>
Diffstat (limited to 'fs/nfs')
-rw-r--r--fs/nfs/pagelist.c74
-rw-r--r--fs/nfs/write.c91
2 files changed, 94 insertions, 71 deletions
diff --git a/fs/nfs/pagelist.c b/fs/nfs/pagelist.c
index f535a92403bf..261236157e33 100644
--- a/fs/nfs/pagelist.c
+++ b/fs/nfs/pagelist.c
@@ -131,6 +131,80 @@ 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
*
diff --git a/fs/nfs/write.c b/fs/nfs/write.c
index a6d7926b0653..832cf57ea442 100644
--- a/fs/nfs/write.c
+++ b/fs/nfs/write.c
@@ -380,34 +380,6 @@ static void nfs_end_page_writeback(struct nfs_page *req)
}
/*
- * nfs_unroll_locks_and_wait - unlock all newly locked reqs and wait on @req
- *
- * this is a helper function for nfs_lock_and_join_requests
- *
- * @inode - inode associated with request page group, must be holding inode lock
- * @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
- *
- * NOTE: this must be called holding page_group bit lock
- * which will be released before returning.
- *
- * returns 0 on success, < 0 on error.
- */
-static void
-nfs_unroll_locks(struct inode *inode, 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_destroy_unlinked_subrequests - destroy recently unlinked subrequests
*
* @destroy_list - request list (using wb_this_page) terminated by @old_head
@@ -487,7 +459,7 @@ nfs_lock_and_join_requests(struct page *page)
struct inode *inode = page_file_mapping(page)->host;
struct nfs_page *head, *subreq;
struct nfs_page *destroy_list = NULL;
- unsigned int total_bytes;
+ unsigned int pgbase, off, bytes;
int ret;
try_again:
@@ -520,49 +492,30 @@ try_again:
goto release_request;
/* lock each request in the page group */
- total_bytes = head->wb_bytes;
+ ret = nfs_page_group_lock_subrequests(head);
+ if (ret < 0)
+ goto release_request;
+
+ pgbase = head->wb_pgbase;
+ bytes = head->wb_bytes;
+ off = head->wb_offset;
for (subreq = head->wb_this_page; subreq != head;
subreq = subreq->wb_this_page) {
-
- if (!kref_get_unless_zero(&subreq->wb_kref)) {
- if (subreq->wb_offset == head->wb_offset + total_bytes)
- total_bytes += subreq->wb_bytes;
- continue;
- }
-
- while (!nfs_lock_request(subreq)) {
- /*
- * Unlock page to allow nfs_page_group_sync_on_bit()
- * to succeed
- */
- 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(inode, head, subreq);
- nfs_release_request(subreq);
- goto release_request;
- }
- }
- /*
- * Subrequests are always contiguous, non overlapping
- * and in order - but may be repeated (mirrored writes).
- */
- if (subreq->wb_offset == (head->wb_offset + total_bytes)) {
- /* keep track of how many bytes this group covers */
- total_bytes += subreq->wb_bytes;
- } else if (WARN_ON_ONCE(subreq->wb_offset < head->wb_offset ||
- ((subreq->wb_offset + subreq->wb_bytes) >
- (head->wb_offset + total_bytes)))) {
- nfs_page_group_unlock(head);
- nfs_unroll_locks(inode, head, subreq);
- nfs_unlock_and_release_request(subreq);
- ret = -EIO;
- goto release_request;
+ /* Subrequests should always form a contiguous range */
+ if (pgbase > subreq->wb_pgbase) {
+ off -= pgbase - subreq->wb_pgbase;
+ bytes += pgbase - subreq->wb_pgbase;
+ pgbase = subreq->wb_pgbase;
}
+ bytes = max(subreq->wb_pgbase + subreq->wb_bytes
+ - pgbase, bytes);
}
+ /* Set the head request's range to cover the former page group */
+ head->wb_pgbase = pgbase;
+ head->wb_bytes = bytes;
+ head->wb_offset = off;
+
/* Now that all requests are locked, make sure they aren't on any list.
* Commit list removal accounting is done after locks are dropped */
subreq = head;
@@ -576,10 +529,6 @@ try_again:
/* destroy list will be terminated by head */
destroy_list = head->wb_this_page;
head->wb_this_page = head;
-
- /* change head request to cover whole range that
- * the former page group covered */
- head->wb_bytes = total_bytes;
}
/* Postpone destruction of this request */