afs: Don't pass vnode pointer around in afs_writeback struct

Don't pass the vnode pointer around in the afs_writeback struct as the
struct may get freed, yet we still need the pointer.  Pass it around
separately.
Signed-off-by: David Howells <dhowells@redhat.com>

fs/afs/file.c

@@ -481,6 +481,7 @@ static void afs_invalidatepage(struct page *page, unsigned int offset,
 			       unsigned int length)
 {
 	struct afs_writeback *wb = (struct afs_writeback *) page_private(page);
+	struct afs_vnode *vnode = AFS_FS_I(page->mapping->host);
 
 	_enter("{%lu},%u,%u", page->index, offset, length);
 
@@ -490,7 +491,6 @@ static void afs_invalidatepage(struct page *page, unsigned int offset,
 	if (offset == 0 && length == PAGE_SIZE) {
 #ifdef CONFIG_AFS_FSCACHE
 		if (PageFsCache(page)) {
-			struct afs_vnode *vnode = AFS_FS_I(page->mapping->host);
 			fscache_wait_on_page_write(vnode->cache, page);
 			fscache_uncache_page(vnode->cache, page);
 		}
@@ -499,7 +499,7 @@ static void afs_invalidatepage(struct page *page, unsigned int offset,
 		if (PagePrivate(page)) {
 			if (wb && !PageWriteback(page)) {
 				set_page_private(page, 0);
-				afs_put_writeback(wb);
+				afs_put_writeback(vnode, wb);
 			}
 
 			if (!page_private(page))
@@ -535,7 +535,7 @@ static int afs_releasepage(struct page *page, gfp_t gfp_flags)
 	if (PagePrivate(page)) {
 		if (wb) {
 			set_page_private(page, 0);
-			afs_put_writeback(wb);
+			afs_put_writeback(vnode, wb);
 		}
 		ClearPagePrivate(page);
 	}

fs/afs/fsclient.c

@@ -1164,13 +1164,13 @@ static const struct afs_call_type afs_RXFSStoreData64 = {
  * store a set of pages to a very large file
  */
 static int afs_fs_store_data64(struct afs_server *server,
+			       struct afs_vnode *vnode,
 			       struct afs_writeback *wb,
 			       pgoff_t first, pgoff_t last,
 			       unsigned offset, unsigned to,
 			       loff_t size, loff_t pos, loff_t i_size,
 			       bool async)
 {
-	struct afs_vnode *vnode = wb->vnode;
 	struct afs_call *call;
 	__be32 *bp;
 
@@ -1223,12 +1223,13 @@ static int afs_fs_store_data64(struct afs_server *server,
 /*
  * store a set of pages
  */
-int afs_fs_store_data(struct afs_server *server, struct afs_writeback *wb,
+int afs_fs_store_data(struct afs_server *server,
+		      struct afs_vnode *vnode,
+		      struct afs_writeback *wb,
 		      pgoff_t first, pgoff_t last,
 		      unsigned offset, unsigned to,
 		      bool async)
 {
-	struct afs_vnode *vnode = wb->vnode;
 	struct afs_call *call;
 	loff_t size, pos, i_size;
 	__be32 *bp;
@@ -1251,7 +1252,8 @@ int afs_fs_store_data(struct afs_server *server, struct afs_writeback *wb,
 	       (unsigned long long) i_size);
 
 	if (pos >> 32 || i_size >> 32 || size >> 32 || (pos + size) >> 32)
-		return afs_fs_store_data64(server, wb, first, last, offset, to,
+		return afs_fs_store_data64(server, vnode, wb,
+					   first, last, offset, to,
 					   size, pos, i_size, async);
 
 	call = afs_alloc_flat_call(&afs_RXFSStoreData,

fs/afs/internal.h

@@ -147,7 +147,6 @@ struct afs_read {
 struct afs_writeback {
 	struct list_head	link;		/* link in vnode->writebacks */
 	struct work_struct	writer;		/* work item to perform the writeback */
-	struct afs_vnode	*vnode;		/* vnode to which this write applies */
 	struct key		*key;		/* owner of this write */
 	wait_queue_head_t	waitq;		/* completion and ready wait queue */
 	pgoff_t			first;		/* first page in batch */
@@ -512,7 +511,8 @@ extern int afs_fs_symlink(struct afs_server *, struct key *,
 extern int afs_fs_rename(struct afs_server *, struct key *,
 			 struct afs_vnode *, const char *,
 			 struct afs_vnode *, const char *, bool);
-extern int afs_fs_store_data(struct afs_server *, struct afs_writeback *,
+extern int afs_fs_store_data(struct afs_server *, struct afs_vnode *,
+			     struct afs_writeback *,
 			     pgoff_t, pgoff_t, unsigned, unsigned, bool);
 extern int afs_fs_setattr(struct afs_server *, struct key *,
 			  struct afs_vnode *, struct iattr *, bool);
@@ -683,8 +683,8 @@ extern int afs_vnode_symlink(struct afs_vnode *, struct key *, const char *,
 			     struct afs_file_status *, struct afs_server **);
 extern int afs_vnode_rename(struct afs_vnode *, struct afs_vnode *,
 			    struct key *, const char *, const char *);
-extern int afs_vnode_store_data(struct afs_writeback *, pgoff_t, pgoff_t,
-				unsigned, unsigned);
+extern int afs_vnode_store_data(struct afs_vnode *, struct afs_writeback *,
+				pgoff_t, pgoff_t, unsigned, unsigned);
 extern int afs_vnode_setattr(struct afs_vnode *, struct key *, struct iattr *);
 extern int afs_vnode_get_volume_status(struct afs_vnode *, struct key *,
 				       struct afs_volume_status *);
@@ -708,7 +708,7 @@ extern int afs_volume_release_fileserver(struct afs_vnode *,
  * write.c
  */
 extern int afs_set_page_dirty(struct page *);
-extern void afs_put_writeback(struct afs_writeback *);
+extern void afs_put_writeback(struct afs_vnode *, struct afs_writeback *);
 extern int afs_write_begin(struct file *file, struct address_space *mapping,
 			loff_t pos, unsigned len, unsigned flags,
 			struct page **pagep, void **fsdata);

fs/afs/vnode.c

@@ -766,11 +766,11 @@ int afs_vnode_rename(struct afs_vnode *orig_dvnode,
 /*
  * write to a file
  */
-int afs_vnode_store_data(struct afs_writeback *wb, pgoff_t first, pgoff_t last,
+int afs_vnode_store_data(struct afs_vnode *vnode, struct afs_writeback *wb,
+			 pgoff_t first, pgoff_t last,
 			 unsigned offset, unsigned to)
 {
 	struct afs_server *server;
-	struct afs_vnode *vnode = wb->vnode;
 	int ret;
 
 	_enter("%s{%x:%u.%u},%x,%lx,%lx,%x,%x",
@@ -794,8 +794,8 @@ int afs_vnode_store_data(struct afs_writeback *wb, pgoff_t first, pgoff_t last,
 
 		_debug("USING SERVER: %08x\n", ntohl(server->addr.s_addr));
 
-		ret = afs_fs_store_data(server, wb, first, last, offset, to,
-					false);
+		ret = afs_fs_store_data(server, vnode, wb,
+					first, last, offset, to, false);
 
 	} while (!afs_volume_release_fileserver(vnode, server, ret));
 

fs/afs/write.c

@@ -16,7 +16,8 @@
 #include <linux/pagevec.h>
 #include "internal.h"
 
-static int afs_write_back_from_locked_page(struct afs_writeback *wb,
+static int afs_write_back_from_locked_page(struct afs_vnode *vnode,
+					   struct afs_writeback *wb,
 					   struct page *page);
 
 /*
@@ -30,12 +31,12 @@ int afs_set_page_dirty(struct page *page)
 
 /*
  * unlink a writeback record because its usage has reached zero
- * - must be called with the wb->vnode->writeback_lock held
+ * - must be called with the vnode->writeback_lock held
  */
-static void afs_unlink_writeback(struct afs_writeback *wb)
+static void afs_unlink_writeback(struct afs_vnode *vnode,
+				 struct afs_writeback *wb)
 {
 	struct afs_writeback *front;
-	struct afs_vnode *vnode = wb->vnode;
 
 	list_del_init(&wb->link);
 	if (!list_empty(&vnode->writebacks)) {
@@ -64,15 +65,13 @@ static void afs_free_writeback(struct afs_writeback *wb)
 /*
  * dispose of a reference to a writeback record
  */
-void afs_put_writeback(struct afs_writeback *wb)
+void afs_put_writeback(struct afs_vnode *vnode, struct afs_writeback *wb)
 {
-	struct afs_vnode *vnode = wb->vnode;
-
 	_enter("{%d}", wb->usage);
 
 	spin_lock(&vnode->writeback_lock);
 	if (--wb->usage == 0)
-		afs_unlink_writeback(wb);
+		afs_unlink_writeback(vnode, wb);
 	else
 		wb = NULL;
 	spin_unlock(&vnode->writeback_lock);
@@ -140,7 +139,6 @@ int afs_write_begin(struct file *file, struct address_space *mapping,
 	candidate = kzalloc(sizeof(*candidate), GFP_KERNEL);
 	if (!candidate)
 		return -ENOMEM;
-	candidate->vnode = vnode;
 	candidate->first = candidate->last = index;
 	candidate->offset_first = from;
 	candidate->to_last = to;
@@ -232,16 +230,16 @@ int afs_write_begin(struct file *file, struct address_space *mapping,
 		wb->state = AFS_WBACK_CONFLICTING;
 	spin_unlock(&vnode->writeback_lock);
 	if (clear_page_dirty_for_io(page)) {
-		ret = afs_write_back_from_locked_page(wb, page);
+		ret = afs_write_back_from_locked_page(vnode, wb, page);
 		if (ret < 0) {
-			afs_put_writeback(candidate);
+			afs_put_writeback(vnode, candidate);
 			_leave(" = %d", ret);
 			return ret;
 		}
 	}
 
 	/* the page holds a ref on the writeback record */
-	afs_put_writeback(wb);
+	afs_put_writeback(vnode, wb);
 	set_page_private(page, 0);
 	ClearPagePrivate(page);
 	goto try_again;
@@ -341,7 +339,8 @@ static void afs_kill_pages(struct afs_vnode *vnode, bool error,
  * synchronously write back the locked page and any subsequent non-locked dirty
  * pages also covered by the same writeback record
  */
-static int afs_write_back_from_locked_page(struct afs_writeback *wb,
+static int afs_write_back_from_locked_page(struct afs_vnode *vnode,
+					   struct afs_writeback *wb,
 					   struct page *primary_page)
 {
 	struct page *pages[8], *page;
@@ -368,7 +367,7 @@ static int afs_write_back_from_locked_page(struct afs_writeback *wb,
 		n = wb->last - start + 1;
 		if (n > ARRAY_SIZE(pages))
 			n = ARRAY_SIZE(pages);
-		n = find_get_pages_contig(wb->vnode->vfs_inode.i_mapping,
+		n = find_get_pages_contig(vnode->vfs_inode.i_mapping,
 					  start, n, pages);
 		_debug("fgpc %u", n);
 		if (n == 0)
@@ -420,12 +419,12 @@ static int afs_write_back_from_locked_page(struct afs_writeback *wb,
 
 	_debug("write back %lx[%u..] to %lx[..%u]", first, offset, last, to);
 
-	ret = afs_vnode_store_data(wb, first, last, offset, to);
+	ret = afs_vnode_store_data(vnode, wb, first, last, offset, to);
 	if (ret < 0) {
 		switch (ret) {
 		case -EDQUOT:
 		case -ENOSPC:
-			mapping_set_error(wb->vnode->vfs_inode.i_mapping, -ENOSPC);
+			mapping_set_error(vnode->vfs_inode.i_mapping, -ENOSPC);
 			break;
 		case -EROFS:
 		case -EIO:
@@ -434,8 +433,8 @@ static int afs_write_back_from_locked_page(struct afs_writeback *wb,
 		case -ENOENT:
 		case -ENOMEDIUM:
 		case -ENXIO:
-			afs_kill_pages(wb->vnode, true, first, last);
-			mapping_set_error(wb->vnode->vfs_inode.i_mapping, -EIO);
+			afs_kill_pages(vnode, true, first, last);
+			mapping_set_error(vnode->vfs_inode.i_mapping, -EIO);
 			break;
 		case -EACCES:
 		case -EPERM:
@@ -443,7 +442,7 @@ static int afs_write_back_from_locked_page(struct afs_writeback *wb,
 		case -EKEYEXPIRED:
 		case -EKEYREJECTED:
 		case -EKEYREVOKED:
-			afs_kill_pages(wb->vnode, false, first, last);
+			afs_kill_pages(vnode, false, first, last);
 			break;
 		default:
 			break;
@@ -462,6 +461,7 @@ static int afs_write_back_from_locked_page(struct afs_writeback *wb,
  */
 int afs_writepage(struct page *page, struct writeback_control *wbc)
 {
+	struct afs_vnode *vnode = AFS_FS_I(page->mapping->host);
 	struct afs_writeback *wb;
 	int ret;
 
@@ -470,7 +470,7 @@ int afs_writepage(struct page *page, struct writeback_control *wbc)
 	wb = (struct afs_writeback *) page_private(page);
 	ASSERT(wb != NULL);
 
-	ret = afs_write_back_from_locked_page(wb, page);
+	ret = afs_write_back_from_locked_page(vnode, wb, page);
 	unlock_page(page);
 	if (ret < 0) {
 		_leave(" = %d", ret);
@@ -490,6 +490,7 @@ static int afs_writepages_region(struct address_space *mapping,
 				 struct writeback_control *wbc,
 				 pgoff_t index, pgoff_t end, pgoff_t *_next)
 {
+	struct afs_vnode *vnode = AFS_FS_I(mapping->host);
 	struct afs_writeback *wb;
 	struct page *page;
 	int ret, n;
@@ -535,13 +536,13 @@ static int afs_writepages_region(struct address_space *mapping,
 		wb = (struct afs_writeback *) page_private(page);
 		ASSERT(wb != NULL);
 
-		spin_lock(&wb->vnode->writeback_lock);
+		spin_lock(&vnode->writeback_lock);
 		wb->state = AFS_WBACK_WRITING;
-		spin_unlock(&wb->vnode->writeback_lock);
+		spin_unlock(&vnode->writeback_lock);
 
 		if (!clear_page_dirty_for_io(page))
 			BUG();
-		ret = afs_write_back_from_locked_page(wb, page);
+		ret = afs_write_back_from_locked_page(vnode, wb, page);
 		unlock_page(page);
 		put_page(page);
 		if (ret < 0) {
@@ -633,7 +634,7 @@ void afs_pages_written_back(struct afs_vnode *vnode, struct afs_call *call)
 		}
 		free_wb = false;
 		if (wb->usage == 0) {
-			afs_unlink_writeback(wb);
+			afs_unlink_writeback(vnode, wb);
 			free_wb = true;
 		}
 		spin_unlock(&vnode->writeback_lock);
@@ -727,7 +728,6 @@ int afs_fsync(struct file *file, loff_t start, loff_t end, int datasync)
 		ret = -ENOMEM;
 		goto out;
 	}
-	wb->vnode = vnode;
 	wb->first = 0;
 	wb->last = -1;
 	wb->offset_first = 0;
@@ -747,7 +747,7 @@ int afs_fsync(struct file *file, loff_t start, loff_t end, int datasync)
 	/* push all the outstanding writebacks to the server */
 	ret = afs_writeback_all(vnode);
 	if (ret < 0) {
-		afs_put_writeback(wb);
+		afs_put_writeback(vnode, wb);
 		_leave(" = %d [wb]", ret);
 		goto out;
 	}
@@ -756,7 +756,7 @@ int afs_fsync(struct file *file, loff_t start, loff_t end, int datasync)
 	ret = wait_event_interruptible(wb->waitq,
 				       wb->state == AFS_WBACK_COMPLETE ||
 				       vnode->writebacks.next == &wb->link);
-	afs_put_writeback(wb);
+	afs_put_writeback(vnode, wb);
 	_leave(" = %d", ret);
 out:
 	inode_unlock(inode);