NFS: Replace NFS_I(inode)->req_lock with inode->i_lock

There is no justification for keeping a special spinlock for the exclusive
use of the NFS writeback code.

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

4 files changed, 46 insertions, 51 deletions

diff --git a/fs/nfs/inode.c b/fs/nfs/inode.c
index 01fc8ab0c562..9d5124166d20 100644
--- a/fs/nfs/inode.c
+++ b/fs/nfs/inode.c
@@ -1154,7 +1154,6 @@ static void init_once(void * foo, struct kmem_cache * cachep, unsigned long flag
         struct nfs_inode *nfsi = (struct nfs_inode *) foo;
 
         inode_init_once(&nfsi->vfs_inode);
-        spin_lock_init(&nfsi->req_lock);
         INIT_LIST_HEAD(&nfsi->open_files);
         INIT_LIST_HEAD(&nfsi->access_cache_entry_lru);
         INIT_LIST_HEAD(&nfsi->access_cache_inode_lru);
diff --git a/fs/nfs/pagelist.c b/fs/nfs/pagelist.c
index 8d2642f24b8f..f56dae5216f4 100644
--- a/fs/nfs/pagelist.c
+++ b/fs/nfs/pagelist.c
@@ -126,12 +126,13 @@ static int nfs_set_page_tag_locked(struct nfs_page *req)
  */
 void nfs_clear_page_tag_locked(struct nfs_page *req)
 {
-        struct nfs_inode *nfsi = NFS_I(req->wb_context->path.dentry->d_inode);
+        struct inode *inode = req->wb_context->path.dentry->d_inode;
+        struct nfs_inode *nfsi = NFS_I(inode);
 
         if (req->wb_page != NULL) {
-                spin_lock(&nfsi->req_lock);
+                spin_lock(&inode->i_lock);
                 radix_tree_tag_clear(&nfsi->nfs_page_tree, req->wb_index, NFS_PAGE_TAG_LOCKED);
-                spin_unlock(&nfsi->req_lock);
+                spin_unlock(&inode->i_lock);
         }
         nfs_unlock_request(req);
 }
@@ -390,7 +391,7 @@ void nfs_pageio_cond_complete(struct nfs_pageio_descriptor *desc, pgoff_t index)
  * If the number of requests is set to 0, the entire address_space
  * starting at index idx_start, is scanned.
  * The requests are *not* checked to ensure that they form a contiguous set.
- * You must be holding the inode's req_lock when calling this function
+ * You must be holding the inode's i_lock when calling this function
  */
 int nfs_scan_list(struct nfs_inode *nfsi,
                 struct list_head *dst, pgoff_t idx_start,
@@ -430,7 +431,7 @@ int nfs_scan_list(struct nfs_inode *nfsi,
                         }
                 }
                 /* for latency reduction */
-                cond_resched_lock(&nfsi->req_lock);
+                cond_resched_lock(&nfsi->vfs_inode.i_lock);
         }
 out:
         return res;
diff --git a/fs/nfs/write.c b/fs/nfs/write.c
index 9ef9ec746bfb..73ac992ece85 100644
--- a/fs/nfs/write.c
+++ b/fs/nfs/write.c
@@ -124,12 +124,12 @@ static struct nfs_page *nfs_page_find_request_locked(struct page *page)
 
 static struct nfs_page *nfs_page_find_request(struct page *page)
 {
+        struct inode *inode = page->mapping->host;
         struct nfs_page *req = NULL;
-        spinlock_t *req_lock = &NFS_I(page->mapping->host)->req_lock;
 
-        spin_lock(req_lock);
+        spin_lock(&inode->i_lock);
         req = nfs_page_find_request_locked(page);
-        spin_unlock(req_lock);
+        spin_unlock(&inode->i_lock);
         return req;
 }
 
@@ -251,16 +251,16 @@ static void nfs_end_page_writeback(struct page *page)
 static int nfs_page_async_flush(struct nfs_pageio_descriptor *pgio,
                                 struct page *page)
 {
+        struct inode *inode = page->mapping->host;
+        struct nfs_inode *nfsi = NFS_I(inode);
         struct nfs_page *req;
-        struct nfs_inode *nfsi = NFS_I(page->mapping->host);
-        spinlock_t *req_lock = &nfsi->req_lock;
         int ret;
 
-        spin_lock(req_lock);
+        spin_lock(&inode->i_lock);
         for(;;) {
                 req = nfs_page_find_request_locked(page);
                 if (req == NULL) {
-                        spin_unlock(req_lock);
+                        spin_unlock(&inode->i_lock);
                         return 1;
                 }
                 if (nfs_lock_request_dontget(req))
@@ -270,28 +270,28 @@ static int nfs_page_async_flush(struct nfs_pageio_descriptor *pgio,
                  *       succeed provided that someone hasn't already marked the
                  *       request as dirty (in which case we don't care).
                  */
-                spin_unlock(req_lock);
+                spin_unlock(&inode->i_lock);
                 ret = nfs_wait_on_request(req);
                 nfs_release_request(req);
                 if (ret != 0)
                         return ret;
-                spin_lock(req_lock);
+                spin_lock(&inode->i_lock);
         }
         if (test_bit(PG_NEED_COMMIT, &req->wb_flags)) {
                 /* This request is marked for commit */
-                spin_unlock(req_lock);
+                spin_unlock(&inode->i_lock);
                 nfs_unlock_request(req);
                 nfs_pageio_complete(pgio);
                 return 1;
         }
         if (nfs_set_page_writeback(page) != 0) {
-                spin_unlock(req_lock);
+                spin_unlock(&inode->i_lock);
                 BUG();
         }
         radix_tree_tag_set(&nfsi->nfs_page_tree, req->wb_index,
                         NFS_PAGE_TAG_LOCKED);
         ret = test_bit(PG_NEED_FLUSH, &req->wb_flags);
-        spin_unlock(req_lock);
+        spin_unlock(&inode->i_lock);
         nfs_pageio_add_request(pgio, req);
         return ret;
 }
@@ -412,7 +412,7 @@ static void nfs_inode_remove_request(struct nfs_page *req)
 
         BUG_ON (!NFS_WBACK_BUSY(req));
 
-        spin_lock(&nfsi->req_lock);
+        spin_lock(&inode->i_lock);
         set_page_private(req->wb_page, 0);
         ClearPagePrivate(req->wb_page);
         radix_tree_delete(&nfsi->nfs_page_tree, req->wb_index);
@@ -420,11 +420,11 @@ static void nfs_inode_remove_request(struct nfs_page *req)
                 __set_page_dirty_nobuffers(req->wb_page);
         nfsi->npages--;
         if (!nfsi->npages) {
-                spin_unlock(&nfsi->req_lock);
+                spin_unlock(&inode->i_lock);
                 nfs_end_data_update(inode);
                 iput(inode);
         } else
-                spin_unlock(&nfsi->req_lock);
+                spin_unlock(&inode->i_lock);
         nfs_clear_request(req);
         nfs_release_request(req);
 }
@@ -458,13 +458,13 @@ nfs_mark_request_commit(struct nfs_page *req)
         struct inode *inode = req->wb_context->path.dentry->d_inode;
         struct nfs_inode *nfsi = NFS_I(inode);
 
-        spin_lock(&nfsi->req_lock);
+        spin_lock(&inode->i_lock);
         nfsi->ncommit++;
         set_bit(PG_NEED_COMMIT, &(req)->wb_flags);
         radix_tree_tag_set(&nfsi->nfs_page_tree,
                         req->wb_index,
                         NFS_PAGE_TAG_COMMIT);
-        spin_unlock(&nfsi->req_lock);
+        spin_unlock(&inode->i_lock);
         inc_zone_page_state(req->wb_page, NR_UNSTABLE_NFS);
         __mark_inode_dirty(inode, I_DIRTY_DATASYNC);
 }
@@ -534,10 +534,10 @@ static int nfs_wait_on_requests_locked(struct inode *inode, pgoff_t idx_start, u
                 BUG_ON(!NFS_WBACK_BUSY(req));
 
                 kref_get(&req->wb_kref);
-                spin_unlock(&nfsi->req_lock);
+                spin_unlock(&inode->i_lock);
                 error = nfs_wait_on_request(req);
                 nfs_release_request(req);
-                spin_lock(&nfsi->req_lock);
+                spin_lock(&inode->i_lock);
                 if (error < 0)
                         return error;
                 res++;
@@ -602,7 +602,6 @@ static struct nfs_page * nfs_update_request(struct nfs_open_context* ctx,
 {
         struct address_space *mapping = page->mapping;
         struct inode *inode = mapping->host;
-        struct nfs_inode *nfsi = NFS_I(inode);
         struct nfs_page         *req, *new = NULL;
         pgoff_t         rqend, end;
 
@@ -612,13 +611,13 @@ static struct nfs_page * nfs_update_request(struct nfs_open_context* ctx,
                 /* Loop over all inode entries and see if we find
                  * A request for the page we wish to update
                  */
-                spin_lock(&nfsi->req_lock);
+                spin_lock(&inode->i_lock);
                 req = nfs_page_find_request_locked(page);
                 if (req) {
                         if (!nfs_lock_request_dontget(req)) {
                                 int error;
 
-                                spin_unlock(&nfsi->req_lock);
+                                spin_unlock(&inode->i_lock);
                                 error = nfs_wait_on_request(req);
                                 nfs_release_request(req);
                                 if (error < 0) {
@@ -628,7 +627,7 @@ static struct nfs_page * nfs_update_request(struct nfs_open_context* ctx,
                                 }
                                 continue;
                         }
-                        spin_unlock(&nfsi->req_lock);
+                        spin_unlock(&inode->i_lock);
                         if (new)
                                 nfs_release_request(new);
                         break;
@@ -639,14 +638,14 @@ static struct nfs_page * nfs_update_request(struct nfs_open_context* ctx,
                         nfs_lock_request_dontget(new);
                         error = nfs_inode_add_request(inode, new);
                         if (error) {
-                                spin_unlock(&nfsi->req_lock);
+                                spin_unlock(&inode->i_lock);
                                 nfs_unlock_request(new);
                                 return ERR_PTR(error);
                         }
-                        spin_unlock(&nfsi->req_lock);
+                        spin_unlock(&inode->i_lock);
                         return new;
                 }
-                spin_unlock(&nfsi->req_lock);
+                spin_unlock(&inode->i_lock);
 
                 new = nfs_create_request(ctx, inode, page, offset, bytes);
                 if (IS_ERR(new))
@@ -974,9 +973,9 @@ static void nfs_writeback_done_partial(struct rpc_task *task, void *calldata)
         }
 
         if (nfs_write_need_commit(data)) {
-                spinlock_t *req_lock = &NFS_I(page->mapping->host)->req_lock;
+                struct inode *inode = page->mapping->host;
 
-                spin_lock(req_lock);
+                spin_lock(&inode->i_lock);
                 if (test_bit(PG_NEED_RESCHED, &req->wb_flags)) {
                         /* Do nothing we need to resend the writes */
                 } else if (!test_and_set_bit(PG_NEED_COMMIT, &req->wb_flags)) {
@@ -987,7 +986,7 @@ static void nfs_writeback_done_partial(struct rpc_task *task, void *calldata)
                         clear_bit(PG_NEED_COMMIT, &req->wb_flags);
                         dprintk(" server reboot detected\n");
                 }
-                spin_unlock(req_lock);
+                spin_unlock(&inode->i_lock);
         } else
                 dprintk(" OK\n");
 
@@ -1277,13 +1276,12 @@ static const struct rpc_call_ops nfs_commit_ops = {
 
 int nfs_commit_inode(struct inode *inode, int how)
 {
-        struct nfs_inode *nfsi = NFS_I(inode);
         LIST_HEAD(head);
         int res;
 
-        spin_lock(&nfsi->req_lock);
+        spin_lock(&inode->i_lock);
         res = nfs_scan_commit(inode, &head, 0, 0);
-        spin_unlock(&nfsi->req_lock);
+        spin_unlock(&inode->i_lock);
         if (res) {
                 int error = nfs_commit_list(inode, &head, how);
                 if (error < 0)
@@ -1301,7 +1299,6 @@ static inline int nfs_commit_list(struct inode *inode, struct list_head *head, i
 long nfs_sync_mapping_wait(struct address_space *mapping, struct writeback_control *wbc, int how)
 {
         struct inode *inode = mapping->host;
-        struct nfs_inode *nfsi = NFS_I(inode);
         pgoff_t idx_start, idx_end;
         unsigned int npages = 0;
         LIST_HEAD(head);
@@ -1323,7 +1320,7 @@ long nfs_sync_mapping_wait(struct address_space *mapping, struct writeback_contr
                 }
         }
         how &= ~FLUSH_NOCOMMIT;
-        spin_lock(&nfsi->req_lock);
+        spin_lock(&inode->i_lock);
         do {
                 ret = nfs_wait_on_requests_locked(inode, idx_start, npages);
                 if (ret != 0)
@@ -1334,18 +1331,19 @@ long nfs_sync_mapping_wait(struct address_space *mapping, struct writeback_contr
                 if (pages == 0)
                         break;
                 if (how & FLUSH_INVALIDATE) {
-                        spin_unlock(&nfsi->req_lock);
+                        spin_unlock(&inode->i_lock);
                         nfs_cancel_commit_list(&head);
                         ret = pages;
-                        spin_lock(&nfsi->req_lock);
+                        spin_lock(&inode->i_lock);
                         continue;
                 }
                 pages += nfs_scan_commit(inode, &head, 0, 0);
-                spin_unlock(&nfsi->req_lock);
+                spin_unlock(&inode->i_lock);
                 ret = nfs_commit_list(inode, &head, how);
-                spin_lock(&nfsi->req_lock);
+                spin_lock(&inode->i_lock);
+
         } while (ret >= 0);
-        spin_unlock(&nfsi->req_lock);
+        spin_unlock(&inode->i_lock);
         return ret;
 }
 
@@ -1439,7 +1437,6 @@ int nfs_set_page_dirty(struct page *page)
 {
         struct address_space *mapping = page->mapping;
         struct inode *inode;
-        spinlock_t *req_lock;
         struct nfs_page *req;
         int ret;
 
@@ -1448,18 +1445,17 @@ int nfs_set_page_dirty(struct page *page)
         inode = mapping->host;
         if (!inode)
                 goto out_raced;
-        req_lock = &NFS_I(inode)->req_lock;
-        spin_lock(req_lock);
+        spin_lock(&inode->i_lock);
         req = nfs_page_find_request_locked(page);
         if (req != NULL) {
                 /* Mark any existing write requests for flushing */
                 ret = !test_and_set_bit(PG_NEED_FLUSH, &req->wb_flags);
-                spin_unlock(req_lock);
+                spin_unlock(&inode->i_lock);
                 nfs_release_request(req);
                 return ret;
         }
         ret = __set_page_dirty_nobuffers(page);
-        spin_unlock(req_lock);
+        spin_unlock(&inode->i_lock);
         return ret;
 out_raced:
         return !TestSetPageDirty(page);
diff --git a/include/linux/nfs_fs.h b/include/linux/nfs_fs.h
index bf24151d63be..cf395351cdd4 100644
--- a/include/linux/nfs_fs.h
+++ b/include/linux/nfs_fs.h
@@ -156,7 +156,6 @@ struct nfs_inode {
         /*
          * This is the list of dirty unwritten pages.
          */
-        spinlock_t              req_lock;
         struct radix_tree_root  nfs_page_tree;
 
         unsigned long           ncommit,