1 files changed, 64 insertions, 69 deletions

diff --git a/fs/nfs/pagelist.c b/fs/nfs/pagelist.c
index 261236157e33..b9805d1dac75 100644
--- a/fs/nfs/pagelist.c
+++ b/fs/nfs/pagelist.c
@@ -454,15 +454,23 @@ nfs_create_request(struct nfs_open_context *ctx, struct page *page,
 }
 
 static struct nfs_page *
-nfs_create_subreq(struct nfs_page *req, struct nfs_page *last,
-		  unsigned int pgbase, unsigned int offset,
+nfs_create_subreq(struct nfs_page *req,
+		  unsigned int pgbase,
+		  unsigned int offset,
 		  unsigned int count)
 {
+	struct nfs_page *last;
 	struct nfs_page *ret;
 
 	ret = __nfs_create_request(req->wb_lock_context, req->wb_page,
 			pgbase, offset, count);
 	if (!IS_ERR(ret)) {
+		/* find the last request */
+		for (last = req->wb_head;
+		     last->wb_this_page != req->wb_head;
+		     last = last->wb_this_page)
+			;
+
 		nfs_lock_request(ret);
 		ret->wb_index = req->wb_index;
 		nfs_page_group_init(ret, last);
@@ -988,7 +996,7 @@ static bool nfs_match_lock_context(const struct nfs_lock_context *l1,
 }
 
 /**
- * nfs_can_coalesce_requests - test two requests for compatibility
+ * nfs_coalesce_size - test two requests for compatibility
  * @prev: pointer to nfs_page
  * @req: pointer to nfs_page
  * @pgio: pointer to nfs_pagio_descriptor
@@ -997,41 +1005,36 @@ static bool nfs_match_lock_context(const struct nfs_lock_context *l1,
  * page data area they describe is contiguous, and that their RPC
  * credentials, NFSv4 open state, and lockowners are the same.
  *
- * Return 'true' if this is the case, else return 'false'.
+ * Returns size of the request that can be coalesced
  */
-static bool nfs_can_coalesce_requests(struct nfs_page *prev,
+static unsigned int nfs_coalesce_size(struct nfs_page *prev,
 				      struct nfs_page *req,
 				      struct nfs_pageio_descriptor *pgio)
 {
-	size_t size;
 	struct file_lock_context *flctx;
 
 	if (prev) {
 		if (!nfs_match_open_context(nfs_req_openctx(req), nfs_req_openctx(prev)))
-			return false;
+			return 0;
 		flctx = d_inode(nfs_req_openctx(req)->dentry)->i_flctx;
 		if (flctx != NULL &&
 		    !(list_empty_careful(&flctx->flc_posix) &&
 		      list_empty_careful(&flctx->flc_flock)) &&
 		    !nfs_match_lock_context(req->wb_lock_context,
 					    prev->wb_lock_context))
-			return false;
+			return 0;
 		if (req_offset(req) != req_offset(prev) + prev->wb_bytes)
-			return false;
+			return 0;
 		if (req->wb_page == prev->wb_page) {
 			if (req->wb_pgbase != prev->wb_pgbase + prev->wb_bytes)
-				return false;
+				return 0;
 		} else {
 			if (req->wb_pgbase != 0 ||
 			    prev->wb_pgbase + prev->wb_bytes != PAGE_SIZE)
-				return false;
+				return 0;
 		}
 	}
-	size = pgio->pg_ops->pg_test(pgio, prev, req);
-	WARN_ON_ONCE(size > req->wb_bytes);
-	if (size && size < req->wb_bytes)
-		req->wb_bytes = size;
-	return size > 0;
+	return pgio->pg_ops->pg_test(pgio, prev, req);
 }
 
 /**
@@ -1039,15 +1042,16 @@ static bool nfs_can_coalesce_requests(struct nfs_page *prev,
  * @desc: destination io descriptor
  * @req: request
  *
- * Returns true if the request 'req' was successfully coalesced into the
- * existing list of pages 'desc'.
+ * If the request 'req' was successfully coalesced into the existing list
+ * of pages 'desc', it returns the size of req.
  */
-static int nfs_pageio_do_add_request(struct nfs_pageio_descriptor *desc,
-				     struct nfs_page *req)
+static unsigned int
+nfs_pageio_do_add_request(struct nfs_pageio_descriptor *desc,
+		struct nfs_page *req)
 {
 	struct nfs_pgio_mirror *mirror = nfs_pgio_current_mirror(desc);
-
 	struct nfs_page *prev = NULL;
+	unsigned int size;
 
 	if (mirror->pg_count != 0) {
 		prev = nfs_list_entry(mirror->pg_list.prev);
@@ -1067,11 +1071,12 @@ static int nfs_pageio_do_add_request(struct nfs_pageio_descriptor *desc,
 		return 0;
 	}
 
-	if (!nfs_can_coalesce_requests(prev, req, desc))
-		return 0;
+	size = nfs_coalesce_size(prev, req, desc);
+	if (size < req->wb_bytes)
+		return size;
 	nfs_list_move_request(req, &mirror->pg_list);
 	mirror->pg_count += req->wb_bytes;
-	return 1;
+	return req->wb_bytes;
 }
 
 /*
@@ -1111,7 +1116,8 @@ nfs_pageio_cleanup_request(struct nfs_pageio_descriptor *desc,
  * @req: request
  *
  * This may split a request into subrequests which are all part of the
- * same page group.
+ * same page group. If so, it will submit @req as the last one, to ensure
+ * the pointer to @req is still valid in case of failure.
  *
  * Returns true if the request 'req' was successfully coalesced into the
  * existing list of pages 'desc'.
@@ -1120,51 +1126,50 @@ static int __nfs_pageio_add_request(struct nfs_pageio_descriptor *desc,
 			   struct nfs_page *req)
 {
 	struct nfs_pgio_mirror *mirror = nfs_pgio_current_mirror(desc);
-
 	struct nfs_page *subreq;
-	unsigned int bytes_left = 0;
-	unsigned int offset, pgbase;
+	unsigned int size, subreq_size;
 
 	nfs_page_group_lock(req);
 
 	subreq = req;
-	bytes_left = subreq->wb_bytes;
-	offset = subreq->wb_offset;
-	pgbase = subreq->wb_pgbase;
-
-	do {
-		if (!nfs_pageio_do_add_request(desc, subreq)) {
-			/* make sure pg_test call(s) did nothing */
-			WARN_ON_ONCE(subreq->wb_bytes != bytes_left);
-			WARN_ON_ONCE(subreq->wb_offset != offset);
-			WARN_ON_ONCE(subreq->wb_pgbase != pgbase);
-
+	subreq_size = subreq->wb_bytes;
+	for(;;) {
+		size = nfs_pageio_do_add_request(desc, subreq);
+		if (size == subreq_size) {
+			/* We successfully submitted a request */
+			if (subreq == req)
+				break;
+			req->wb_pgbase += size;
+			req->wb_bytes -= size;
+			req->wb_offset += size;
+			subreq_size = req->wb_bytes;
+			subreq = req;
+			continue;
+		}
+		if (WARN_ON_ONCE(subreq != req)) {
+			nfs_page_group_unlock(req);
+			nfs_pageio_cleanup_request(desc, subreq);
+			subreq = req;
+			subreq_size = req->wb_bytes;
+			nfs_page_group_lock(req);
+		}
+		if (!size) {
+			/* Can't coalesce any more, so do I/O */
 			nfs_page_group_unlock(req);
 			desc->pg_moreio = 1;
 			nfs_pageio_doio(desc);
 			if (desc->pg_error < 0 || mirror->pg_recoalesce)
-				goto out_cleanup_subreq;
+				return 0;
 			/* retry add_request for this subreq */
 			nfs_page_group_lock(req);
 			continue;
 		}
-
-		/* check for buggy pg_test call(s) */
-		WARN_ON_ONCE(subreq->wb_bytes + subreq->wb_pgbase > PAGE_SIZE);
-		WARN_ON_ONCE(subreq->wb_bytes > bytes_left);
-		WARN_ON_ONCE(subreq->wb_bytes == 0);
-
-		bytes_left -= subreq->wb_bytes;
-		offset += subreq->wb_bytes;
-		pgbase += subreq->wb_bytes;
-
-		if (bytes_left) {
-			subreq = nfs_create_subreq(req, subreq, pgbase,
-					offset, bytes_left);
-			if (IS_ERR(subreq))
-				goto err_ptr;
-		}
-	} while (bytes_left > 0);
+		subreq = nfs_create_subreq(req, req->wb_pgbase,
+				req->wb_offset, size);
+		if (IS_ERR(subreq))
+			goto err_ptr;
+		subreq_size = size;
+	}
 
 	nfs_page_group_unlock(req);
 	return 1;
@@ -1172,10 +1177,6 @@ err_ptr:
 	desc->pg_error = PTR_ERR(subreq);
 	nfs_page_group_unlock(req);
 	return 0;
-out_cleanup_subreq:
-	if (req != subreq)
-		nfs_pageio_cleanup_request(desc, subreq);
-	return 0;
 }
 
 static int nfs_do_recoalesce(struct nfs_pageio_descriptor *desc)
@@ -1244,7 +1245,7 @@ int nfs_pageio_add_request(struct nfs_pageio_descriptor *desc,
 {
 	u32 midx;
 	unsigned int pgbase, offset, bytes;
-	struct nfs_page *dupreq, *lastreq;
+	struct nfs_page *dupreq;
 
 	pgbase = req->wb_pgbase;
 	offset = req->wb_offset;
@@ -1258,13 +1259,7 @@ int nfs_pageio_add_request(struct nfs_pageio_descriptor *desc,
 	for (midx = 1; midx < desc->pg_mirror_count; midx++) {
 		nfs_page_group_lock(req);
 
-		/* find the last request */
-		for (lastreq = req->wb_head;
-		     lastreq->wb_this_page != req->wb_head;
-		     lastreq = lastreq->wb_this_page)
-			;
-
-		dupreq = nfs_create_subreq(req, lastreq,
+		dupreq = nfs_create_subreq(req,
 				pgbase, offset, bytes);
 
 		nfs_page_group_unlock(req);