From: Trond Myklebust <trond.myklebust@xxxxxxxxxxxxxxx>
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@xxxxxxxxxxxxxxx>
---
fs/nfs/pagelist.c | 74 ++++++++++++++++++++++++++++++++
fs/nfs/write.c | 91 +++++++++-------------------------------
include/linux/nfs_page.h | 1 +
3 files changed, 95 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
@@ -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
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
@@ -379,34 +379,6 @@ static void nfs_end_page_writeback(struct nfs_page *req)
clear_bdi_congested(inode_to_bdi(inode), BLK_RW_ASYNC);
}
-/*
- * 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
*
@@ -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 @@ nfs_lock_and_join_requests(struct page *page)
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 @@ nfs_lock_and_join_requests(struct page *page)
/* 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 */
diff --git a/include/linux/nfs_page.h b/include/linux/nfs_page.h
index 7e9419d74b86..dd205bc6bc58 100644
--- a/include/linux/nfs_page.h
+++ b/include/linux/nfs_page.h
@@ -139,6 +139,7 @@ extern size_t nfs_generic_pg_test(struct nfs_pageio_descriptor *desc,
extern int nfs_wait_on_request(struct nfs_page *);
extern void nfs_unlock_request(struct nfs_page *req);
extern void nfs_unlock_and_release_request(struct nfs_page *);
+extern int nfs_page_group_lock_subrequests(struct nfs_page *head);
extern int nfs_page_group_lock(struct nfs_page *);
extern void nfs_page_group_unlock(struct nfs_page *);
extern bool nfs_page_group_sync_on_bit(struct nfs_page *, unsigned int);
--
2.25.1
