cifs: pass instantiated filp back after open call

The current scheme of sticking open files on a list and assuming that
cifs_open will scoop them off of it is broken and leads to "Busy
inodes after umount..." errors at unmount time.

The problem is that there is no guarantee that cifs_open will always
be called after a ->lookup or ->create operation. If there are
permissions or other problems, then it's quite likely that it *won't*
be called.

Fix this by fully instantiating the filp whenever the file is created
and pass that filp back to the VFS. If there is a problem, the VFS
can clean up the references.

Signed-off-by: Jeff Layton <jlayton@redhat.com>
Reviewed-and-Tested-by: Suresh Jayaraman <sjayaraman@suse.de>

fs/cifs/dir.c

@@ -25,6 +25,7 @@
 #include <linux/slab.h>
 #include <linux/namei.h>
 #include <linux/mount.h>
+#include <linux/file.h>
 #include "cifsfs.h"
 #include "cifspdu.h"
 #include "cifsglob.h"
@@ -184,6 +185,8 @@ cifs_new_fileinfo(struct inode *newinode, __u16 fileHandle,
 	}
 	write_unlock(&GlobalSMBSeslock);
 
+	file->private_data = pCifsFile;
+
 	return pCifsFile;
 }
 
@@ -463,14 +466,22 @@ cifs_create(struct inode *inode, struct dentry *direntry, int mode,
 
 	if (newinode && nd && (nd->flags & LOOKUP_OPEN)) {
 		struct cifsFileInfo *pfile_info;
-		/*
-		 * cifs_fill_filedata() takes care of setting cifsFileInfo
-		 * pointer to file->private_data.
-		 */
-		pfile_info = cifs_new_fileinfo(newinode, fileHandle, NULL,
+		struct file *filp;
+
+		filp = lookup_instantiate_filp(nd, direntry, generic_file_open);
+		if (IS_ERR(filp)) {
+			rc = PTR_ERR(filp);
+			CIFSSMBClose(xid, tcon, fileHandle);
+			goto cifs_create_out;
+		}
+
+		pfile_info = cifs_new_fileinfo(newinode, fileHandle, filp,
 					       nd->path.mnt, oflags);
-		if (pfile_info == NULL)
+		if (pfile_info == NULL) {
+			fput(filp);
+			CIFSSMBClose(xid, tcon, fileHandle);
 			rc = -ENOMEM;
+		}
 	} else {
 		CIFSSMBClose(xid, tcon, fileHandle);
 	}
@@ -717,15 +728,23 @@ cifs_lookup(struct inode *parent_dir_inode, struct dentry *direntry,
 			direntry->d_op = &cifs_dentry_ops;
 		d_add(direntry, newInode);
 		if (posix_open) {
-			cfile = cifs_new_fileinfo(newInode, fileHandle, NULL,
+			filp = lookup_instantiate_filp(nd, direntry,
+						       generic_file_open);
+			if (IS_ERR(filp)) {
+				rc = PTR_ERR(filp);
+				CIFSSMBClose(xid, pTcon, fileHandle);
+				goto lookup_out;
+			}
+
+			cfile = cifs_new_fileinfo(newInode, fileHandle, filp,
 						  nd->path.mnt,
 						  nd->intent.open.flags);
 			if (cfile == NULL) {
+				fput(filp);
 				CIFSSMBClose(xid, pTcon, fileHandle);
 				rc = -ENOMEM;
 				goto lookup_out;
 			}
-			filp = lookup_instantiate_filp(nd, direntry, NULL);
 		}
 		/* since paths are not looked up by component - the parent
 		   directories are presumed to be good here */

fs/cifs/file.c

@@ -162,38 +162,6 @@ cifs_posix_open_inode_helper(struct inode *inode, struct file *file,
 	return 0;
 }
 
-static struct cifsFileInfo *
-cifs_fill_filedata(struct file *file)
-{
-	struct list_head *tmp;
-	struct cifsFileInfo *pCifsFile = NULL;
-	struct cifsInodeInfo *pCifsInode = NULL;
-
-	/* search inode for this file and fill in file->private_data */
-	pCifsInode = CIFS_I(file->f_path.dentry->d_inode);
-	read_lock(&GlobalSMBSeslock);
-	list_for_each(tmp, &pCifsInode->openFileList) {
-		pCifsFile = list_entry(tmp, struct cifsFileInfo, flist);
-		if ((pCifsFile->pfile == NULL) &&
-		    (pCifsFile->pid == current->tgid)) {
-			/* mode set in cifs_create */
-
-			/* needed for writepage */
-			pCifsFile->pfile = file;
-			file->private_data = pCifsFile;
-			break;
-		}
-	}
-	read_unlock(&GlobalSMBSeslock);
-
-	if (file->private_data != NULL) {
-		return pCifsFile;
-	} else if ((file->f_flags & O_CREAT) && (file->f_flags & O_EXCL))
-			cERROR(1, "could not find file instance for "
-				   "new file %p", file);
-	return NULL;
-}
-
 /* all arguments to this function must be checked for validity in caller */
 static inline int cifs_open_inode_helper(struct inode *inode, struct file *file,
 	struct cifsInodeInfo *pCifsInode, struct cifsFileInfo *pCifsFile,
@@ -256,7 +224,7 @@ int cifs_open(struct inode *inode, struct file *file)
 	__u32 oplock;
 	struct cifs_sb_info *cifs_sb;
 	struct cifsTconInfo *tcon;
-	struct cifsFileInfo *pCifsFile;
+	struct cifsFileInfo *pCifsFile = NULL;
 	struct cifsInodeInfo *pCifsInode;
 	char *full_path = NULL;
 	int desiredAccess;
@@ -270,12 +238,6 @@ int cifs_open(struct inode *inode, struct file *file)
 	tcon = cifs_sb->tcon;
 
 	pCifsInode = CIFS_I(file->f_path.dentry->d_inode);
-	pCifsFile = cifs_fill_filedata(file);
-	if (pCifsFile) {
-		rc = 0;
-		FreeXid(xid);
-		return rc;
-	}
 
 	full_path = build_path_from_dentry(file->f_path.dentry);
 	if (full_path == NULL) {
@@ -315,7 +277,6 @@ int cifs_open(struct inode *inode, struct file *file)
 				rc = -ENOMEM;
 				goto out;
 			}
-			file->private_data = pCifsFile;
 
 			cifs_posix_open_inode_helper(inode, file, pCifsInode,
 						     oplock, netfid);
@@ -401,8 +362,7 @@ int cifs_open(struct inode *inode, struct file *file)
 
 	pCifsFile = cifs_new_fileinfo(inode, netfid, file, file->f_path.mnt,
 					file->f_flags);
-	file->private_data = pCifsFile;
-	if (file->private_data == NULL) {
+	if (pCifsFile == NULL) {
 		rc = -ENOMEM;
 		goto out;
 	}