NFSv4.1: add generic layer hooks for pnfs COMMIT

We create three major hooks for the pnfs code.

pnfs_mark_request_commit() is called during writeback_done from
nfs_mark_request_commit, which gives the driver an opportunity to
claim it wants control over commiting a particular req.

pnfs_choose_commit_list() is called from nfs_scan_list
to choose which list a given req should be added to, based on
where we intend to send it for COMMIT.  It is up to the driver
to have preallocated list headers for each destination it may need.

pnfs_commit_list() is how the driver actually takes control, it is
used instead of nfs_commit_list().

In order to pass information between the above functions, we create
a union in nfs_page to hold a lseg (which is possible because the req is
not on any list while in transition), and add some flags to indicate
if we need to use the pnfs code.

Signed-off-by: Fred Isaman <iisaman@netapp.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

1 files changed, 26 insertions, 15 deletions

diff --git a/fs/nfs/write.c b/fs/nfs/write.c
index f5f005e9db48..6927a18b6891 100644
--- a/fs/nfs/write.c
+++ b/fs/nfs/write.c
@@ -441,7 +441,7 @@ nfs_mark_request_dirty(struct nfs_page *req)
  * Add a request to the inode's commit list.
  */
 static void
-nfs_mark_request_commit(struct nfs_page *req)
+nfs_mark_request_commit(struct nfs_page *req, struct pnfs_layout_segment *lseg)
 {
 	struct inode *inode = req->wb_context->path.dentry->d_inode;
 	struct nfs_inode *nfsi = NFS_I(inode);
@@ -453,6 +453,7 @@ nfs_mark_request_commit(struct nfs_page *req)
 			NFS_PAGE_TAG_COMMIT);
 	nfsi->ncommit++;
 	spin_unlock(&inode->i_lock);
+	pnfs_mark_request_commit(req, lseg);
 	inc_zone_page_state(req->wb_page, NR_UNSTABLE_NFS);
 	inc_bdi_stat(req->wb_page->mapping->backing_dev_info, BDI_RECLAIMABLE);
 	__mark_inode_dirty(inode, I_DIRTY_DATASYNC);
@@ -481,10 +482,11 @@ int nfs_write_need_commit(struct nfs_write_data *data)
 }
 
 static inline
-int nfs_reschedule_unstable_write(struct nfs_page *req)
+int nfs_reschedule_unstable_write(struct nfs_page *req,
+				  struct nfs_write_data *data)
 {
 	if (test_and_clear_bit(PG_NEED_COMMIT, &req->wb_flags)) {
-		nfs_mark_request_commit(req);
+		nfs_mark_request_commit(req, data->lseg);
 		return 1;
 	}
 	if (test_and_clear_bit(PG_NEED_RESCHED, &req->wb_flags)) {
@@ -495,7 +497,7 @@ int nfs_reschedule_unstable_write(struct nfs_page *req)
 }
 #else
 static inline void
-nfs_mark_request_commit(struct nfs_page *req)
+nfs_mark_request_commit(struct nfs_page *req, struct pnfs_layout_segment *lseg)
 {
 }
 
@@ -512,7 +514,8 @@ int nfs_write_need_commit(struct nfs_write_data *data)
 }
 
 static inline
-int nfs_reschedule_unstable_write(struct nfs_page *req)
+int nfs_reschedule_unstable_write(struct nfs_page *req,
+				  struct nfs_write_data *data)
 {
 	return 0;
 }
@@ -615,9 +618,11 @@ static struct nfs_page *nfs_try_to_update_request(struct inode *inode,
 	}
 
 	if (nfs_clear_request_commit(req) &&
-			radix_tree_tag_clear(&NFS_I(inode)->nfs_page_tree,
-				req->wb_index, NFS_PAGE_TAG_COMMIT) != NULL)
+	    radix_tree_tag_clear(&NFS_I(inode)->nfs_page_tree,
+				 req->wb_index, NFS_PAGE_TAG_COMMIT) != NULL) {
 		NFS_I(inode)->ncommit--;
+		pnfs_clear_request_commit(req);
+	}
 
 	/* Okay, the request matches. Update the region */
 	if (offset < req->wb_offset) {
@@ -765,11 +770,12 @@ int nfs_updatepage(struct file *file, struct page *page,
 	return status;
 }
 
-static void nfs_writepage_release(struct nfs_page *req)
+static void nfs_writepage_release(struct nfs_page *req,
+				  struct nfs_write_data *data)
 {
 	struct page *page = req->wb_page;
 
-	if (PageError(req->wb_page) || !nfs_reschedule_unstable_write(req))
+	if (PageError(req->wb_page) || !nfs_reschedule_unstable_write(req, data))
 		nfs_inode_remove_request(req);
 	nfs_clear_page_tag_locked(req);
 	nfs_end_page_writeback(page);
@@ -1087,7 +1093,7 @@ static void nfs_writeback_release_partial(void *calldata)
 
 out:
 	if (atomic_dec_and_test(&req->wb_complete))
-		nfs_writepage_release(req);
+		nfs_writepage_release(req, data);
 	nfs_writedata_release(calldata);
 }
 
@@ -1154,7 +1160,7 @@ static void nfs_writeback_release_full(void *calldata)
 
 		if (nfs_write_need_commit(data)) {
 			memcpy(&req->wb_verf, &data->verf, sizeof(req->wb_verf));
-			nfs_mark_request_commit(req);
+			nfs_mark_request_commit(req, data->lseg);
 			dprintk(" marked for commit\n");
 			goto next;
 		}
@@ -1357,14 +1363,15 @@ static void nfs_init_commit(struct nfs_write_data *data,
 	nfs_fattr_init(&data->fattr);
 }
 
-static void nfs_retry_commit(struct list_head *page_list)
+static void nfs_retry_commit(struct list_head *page_list,
+		      struct pnfs_layout_segment *lseg)
 {
 	struct nfs_page *req;
 
 	while (!list_empty(page_list)) {
 		req = nfs_list_entry(page_list->next);
 		nfs_list_remove_request(req);
-		nfs_mark_request_commit(req);
+		nfs_mark_request_commit(req, lseg);
 		dec_zone_page_state(req->wb_page, NR_UNSTABLE_NFS);
 		dec_bdi_stat(req->wb_page->mapping->backing_dev_info,
 			     BDI_RECLAIMABLE);
@@ -1389,7 +1396,7 @@ nfs_commit_list(struct inode *inode, struct list_head *head, int how)
 	nfs_init_commit(data, head);
 	return nfs_initiate_commit(data, NFS_CLIENT(inode), data->mds_ops, how);
  out_bad:
-	nfs_retry_commit(head);
+	nfs_retry_commit(head, NULL);
 	nfs_commit_clear_lock(NFS_I(inode));
 	return -ENOMEM;
 }
@@ -1477,7 +1484,11 @@ int nfs_commit_inode(struct inode *inode, int how)
 	res = nfs_scan_commit(inode, &head, 0, 0);
 	spin_unlock(&inode->i_lock);
 	if (res) {
-		int error = nfs_commit_list(inode, &head, how);
+		int error;
+
+		error = pnfs_commit_list(inode, &head, how);
+		if (error == PNFS_NOT_ATTEMPTED)
+			error = nfs_commit_list(inode, &head, how);
 		if (error < 0)
 			return error;
 		if (!may_wait)