Re: + cifs-remove-unneeded-checks.patch added to -mm tree

Re: + cifs-remove-unneeded-checks.patch added to -mm tree

[Christoph Hellwig]

On Mon, Apr 02, 2007 at 03:36:01PM -0500, Steve French wrote:
> I merged most of Christoph's cifs-remove-unneeded-checks patch into the
> cifs-2.6 development tree. The part I did not merge was a little harder
> to verify and vaguely reminded me of the old bug report.  The part I
> left out is attached (I don't mind leaving that part in mm a little
> longer to make sure it is safe).


diff -Nau /home/stevef/linux-2.6/fs/cifs/file.c /home/stevef/virtfs-2.6/fs/cifs/file.c
--- /home/stevef/linux-2.6/fs/cifs/file.c	2007-04-02 13:55:36.000000000 -0500
+++ /home/stevef/virtfs-2.6/fs/cifs/file.c	2007-04-02 13:48:29.000000000 -0500
@@ -352,8 +352,6 @@
 	int disposition = FILE_OPEN;
 	__u16 netfid;
 
-	if (inode == NULL)
-		return -EBADF;

This is cifs_reopen_file.  One of the callers (find_writable_file) calls
this with the &cifs_inode->vfs_inode as inode argument, which can't be
NULL per definition.  All other callers pass
file->f_path.dentry->d_inode as inode argument, which per definition is
not never zero, because there are not file structs arount that don't
point to an inode.

Note that you could nicely simplify the find_writable_file calling
conventions by not passing the inode argument explicitly at all, but
rather always deriving it from file->f_path.dentry->d_inode inside
the function body.

 	if (file->private_data) {
 		pCifsFile = (struct cifsFileInfo *)file->private_data;
 	} else
@@ -367,12 +365,6 @@
 		return 0;
 	}
 
-	if (file->f_path.dentry == NULL) {
-		up(&pCifsFile->fh_sem);
-		cFYI(1, ("failed file reopen, no valid name if dentry freed"));
-		FreeXid(xid);
-		return -EBADF;
-	}

@@ -784,6 +776,7 @@
 ssize_t cifs_user_write(struct file *file, const char __user *write_data,
 	size_t write_size, loff_t *poffset)
 {
+	struct inode *inode = file->f_path.dentry->d_inode;
 	int rc = 0;
 	unsigned int bytes_written = 0;
 	unsigned int total_written;
@@ -831,11 +824,6 @@
 					return -EBADF;
 			}
 			if (open_file->invalidHandle) {
-				if ((file->f_path.dentry == NULL) ||
-				    (file->f_path.dentry->d_inode == NULL)) {
-					FreeXid(xid);
-					return total_written;
-				}

Same again here, there's no fscking chance read/write could ever work
without a dentry or inode.

Re: + cifs-remove-unneeded-checks.patch added to -mm tree

[Steve French]

[-- Attachment #1: Type: text/plain, Size: 915 bytes --]

On Mon, 2007-04-02 at 13:51 -0500, Steven French wrote:
> akpm@linux-foundation.org wrote on 03/11/2007 03:57:40 AM:
> 
> > 
> > The patch titled
> >      cifs: remove unneeded checks
> > has been added to the -mm tree.  Its filename is
> >      cifs-remove-unneeded-checks.patch
> > 
> > ------------------------------------------------------
> > Subject: cifs: remove unneeded checks
> > From: Christoph Hellwig <hch@lst.de>
> > 
> > file->f_path.dentry or file->f_path.dentry.d_inode can't be NULL since at
> > least ten years, similar for all but very few arguments passed in from the
> > VFS.

I merged most of Christoph's cifs-remove-unneeded-checks patch into the
cifs-2.6 development tree. The part I did not merge was a little harder
to verify and vaguely reminded me of the old bug report.  The part I
left out is attached (I don't mind leaving that part in mm a little
longer to make sure it is safe).



[-- Attachment #2: cifs-remove-unneeded-checks-part2.patch --]
[-- Type: text/x-patch, Size: 3704 bytes --]

diff -Nau /home/stevef/linux-2.6/fs/cifs/file.c /home/stevef/virtfs-2.6/fs/cifs/file.c
--- /home/stevef/linux-2.6/fs/cifs/file.c	2007-04-02 13:55:36.000000000 -0500
+++ /home/stevef/virtfs-2.6/fs/cifs/file.c	2007-04-02 13:48:29.000000000 -0500
@@ -352,8 +352,6 @@
 	int disposition = FILE_OPEN;
 	__u16 netfid;
 
-	if (inode == NULL)
-		return -EBADF;
 	if (file->private_data) {
 		pCifsFile = (struct cifsFileInfo *)file->private_data;
 	} else
@@ -367,12 +365,6 @@
 		return 0;
 	}
 
-	if (file->f_path.dentry == NULL) {
-		up(&pCifsFile->fh_sem);
-		cFYI(1, ("failed file reopen, no valid name if dentry freed"));
-		FreeXid(xid);
-		return -EBADF;
-	}
 	cifs_sb = CIFS_SB(inode->i_sb);
 	pTcon = cifs_sb->tcon;
 /* can not grab rename sem here because various ops, including
@@ -784,6 +776,7 @@
 ssize_t cifs_user_write(struct file *file, const char __user *write_data,
 	size_t write_size, loff_t *poffset)
 {
+	struct inode *inode = file->f_path.dentry->d_inode;
 	int rc = 0;
 	unsigned int bytes_written = 0;
 	unsigned int total_written;
@@ -831,11 +824,6 @@
 					return -EBADF;
 			}
 			if (open_file->invalidHandle) {
-				if ((file->f_path.dentry == NULL) ||
-				    (file->f_path.dentry->d_inode == NULL)) {
-					FreeXid(xid);
-					return total_written;
-				}
 				/* we could deadlock if we called
 				   filemap_fdatawait from here so tell
 				   reopen_file not to flush data to server
@@ -868,21 +856,18 @@
 
 	cifs_stats_bytes_written(pTcon, total_written);
 
-	/* since the write may have blocked check these pointers again */
-	if ((file->f_path.dentry) && (file->f_path.dentry->d_inode)) {
-		struct inode *inode = file->f_path.dentry->d_inode;
 /* Do not update local mtime - server will set its actual value on write		
  *		inode->i_ctime = inode->i_mtime = 
  * 			current_fs_time(inode->i_sb);*/
-		if (total_written > 0) {
-			spin_lock(&inode->i_lock);
-			if (*poffset > file->f_path.dentry->d_inode->i_size)
-				i_size_write(file->f_path.dentry->d_inode,
-					*poffset);
-			spin_unlock(&inode->i_lock);
-		}
-		mark_inode_dirty_sync(file->f_path.dentry->d_inode);	
+	if (total_written > 0) {
+		spin_lock(&inode->i_lock);
+		if (*poffset > file->f_path.dentry->d_inode->i_size)
+			i_size_write(file->f_path.dentry->d_inode,
+				*poffset);
+		spin_unlock(&inode->i_lock);
 	}
+	mark_inode_dirty_sync(file->f_path.dentry->d_inode);
+
 	FreeXid(xid);
 	return total_written;
 }
@@ -988,19 +973,17 @@
 	cifs_stats_bytes_written(pTcon, total_written);
 
 	/* since the write may have blocked check these pointers again */
-	if ((file->f_path.dentry) && (file->f_path.dentry->d_inode)) {
 /*BB We could make this contingent on superblock ATIME flag too */
-/*		file->f_path.dentry->d_inode->i_ctime =
-		file->f_path.dentry->d_inode->i_mtime = CURRENT_TIME;*/
-		if (total_written > 0) {
-			spin_lock(&file->f_path.dentry->d_inode->i_lock);
-			if (*poffset > file->f_path.dentry->d_inode->i_size)
-				i_size_write(file->f_path.dentry->d_inode,
-					     *poffset);
-			spin_unlock(&file->f_path.dentry->d_inode->i_lock);
-		}
-		mark_inode_dirty_sync(file->f_path.dentry->d_inode);
+/*	file->f_path.dentry->d_inode->i_ctime =
+	file->f_path.dentry->d_inode->i_mtime = CURRENT_TIME;*/
+	if (total_written > 0) {
+		spin_lock(&file->f_path.dentry->d_inode->i_lock);
+		if (*poffset > file->f_path.dentry->d_inode->i_size)
+			i_size_write(file->f_path.dentry->d_inode,
+				     *poffset);
+		spin_unlock(&file->f_path.dentry->d_inode->i_lock);
 	}
+	mark_inode_dirty_sync(file->f_path.dentry->d_inode);
 	FreeXid(xid);
 	return total_written;
 }
Common subdirectories: /home/stevef/linux-2.6/fs/cifs/.tmp_versions and /home/stevef/virtfs-2.6/fs/cifs/.tmp_versions