Re: WARNING: at fs/inode.c:280 drop_nlink+0x31/0x33()

[Jeff Layton <jlayton@redhat.com>]

On Fri, 31 Aug 2012 11:03:45 -0700
Nick Pasich <Nick@NickAndBarb.net> wrote:

> On Fri, Aug 31, 2012 at 09:21:38AM -0700, Jeff Layton wrote:
> > On Fri, 31 Aug 2012 08:32:06 -0700
> > Nick Pasich <Nick@NickAndBarb.net> wrote:
> > 
> > > On Fri, Aug 31, 2012 at 12:00:26PM +0400, Pavel Shilovsky wrote:
> > > > 2012/8/31 Nick Pasich <Nick@nickandbarb.net>:
> > > > > Jeff,
> > > > >
> > > > > I applied this patch to Kernel 3.5.3 from Pavel and the
> > > > > the warning is gone with no problems.
> > > > >
> > > > > Thanks,
> > > > >
> > > > > --( Nick Pasich
> > > > >
> > > > > ##########################################################
> > > > >
> > > > > From df2d6b1fbf2401c5ee04f2ac143ea0954e3a87a6 Mon Sep 17 00:00:00 2001
> > > > > From: Pavel Shilovsky <pshilovsky@samba.org>
> > > > > Date: Fri, 13 Jul 2012 11:59:45 +0400
> > > > > Subject: [PATCH] CIFS: Protect i_nlink from being negative
> > > > >
> > > > > that can cause warning messages.
> > > > >
> > > > > Signed-off-by: Pavel Shilovsky <pshilovsky@samba.org>
> > > > > ---
> > > > >  fs/cifs/inode.c |   13 +++++++++++--
> > > > >  1 files changed, 11 insertions(+), 2 deletions(-)
> > > > >
> > > > > diff --git a/fs/cifs/inode.c b/fs/cifs/inode.c
> > > > > index 7354877..88afb1a 100644
> > > > > --- a/fs/cifs/inode.c
> > > > > +++ b/fs/cifs/inode.c
> > > > > @@ -1110,6 +1110,15 @@ undo_setattr:
> > > > >                 goto out_close;
> > > > >  }
> > > > >
> > > > > +/* copied from fs/nfs/dir.c with small changes */
> > > > > +static void
> > > > > +cifs_drop_nlink(struct inode *inode)
> > > > > +{
> > > > > +       spin_lock(&inode->i_lock);
> > > > > +       if (inode->i_nlink > 0)
> > > > > +               drop_nlink(inode);
> > > > > +       spin_unlock(&inode->i_lock);
> > > > > +}
> > > > >
> > > > >  /*
> > > > >   * If dentry->d_inode is null (usually meaning the cached dentry
> > > > > @@ -1166,13 +1175,13 @@ retry_std_delete:
> > > > >  psx_del_no_retry:
> > > > >                 if (!rc) {
> > > > >                                 if (inode)
> > > > > -                       drop_nlink(inode);
> > > > > +                       cifs_drop_nlink(inode);
> > > > >                 } else if (rc == -ENOENT) {
> > > > >                                 d_drop(dentry);
> > > > >                 } else if (rc == -ETXTBSY) {
> > > > >                                 rc = cifs_rename_pending_delete(full_path, dentry, xid);
> > > > >                                 if (rc == 0)
> > > > > -                       drop_nlink(inode);
> > > > > +                       cifs_drop_nlink(inode);
> > > > >                 } else if ((rc == -EACCES) && (dosattr == 0) && inode) {
> > > > >                                 attrs = kzalloc(sizeof(*attrs), GFP_KERNEL);
> > > > >                                 if (attrs == NULL) {
> > > > > --
> > > > > 1.7.3.3
> > > > >
> > > > > ##########################################################
> > > > >
> > > > > --
> > > > > To unsubscribe from this list: send the line "unsubscribe linux-cifs" in
> > > > > the body of a message to majordomo@vger.kernel.org
> > > > > More majordomo info at  http://vger.kernel.org/majordomo-info.html
> > > > 
> > > > This one fixes only a part of the problem. Now we have another patch
> > > > for this problem:
> > > > 
> > > > https://git.samba.org/sfrench/?p=sfrench/cifs-2.6.git;a=commitdiff;h=b7ca69289680cf631fb20b7d436467c4ec1153cd;hp=6dab7ede9390d4d937cb89feca932e4fd575d2da
> > > > 
> > > > -- 
> > > > Best regards,
> > > > Pavel Shilovsky.
> > > 
> > > 
> > > 
> > > Since I'm using kernel 3.5.3 , I get an error on hunk 7 of the patch.
> > > 
> > > I can do it by hand... But I want to check with you first.
> > > 
> > > Thanks,
> > > 
> > > --( Nick Pasich )--
> > > 
> > 
> > If you fix it up by hand, consider submitting it as a backport for the
> > stable series as well.
> > 
> > -- 
> > Jeff Layton <jlayton@redhat.com>
> 
> Jeff / Pavel,
> 
> Here are my changes on hunk #7 that allow patching 3.5.3
> 
> Check it out....
> 
> --( Nick Pasich )--
> 
> 
> 
> ##############################################################################
> 
> diff -u a/fs/cifs/inode.c b/fs/cifs/inode.c
> --- a/fs/cifs/inode.c
> +++ b/fs/cifs/inode.c
> @@ -124,10 +124,10 @@
>  {
>  	struct cifsInodeInfo *cifs_i = CIFS_I(inode);
>  	struct cifs_sb_info *cifs_sb = CIFS_SB(inode->i_sb);
> -	unsigned long oldtime = cifs_i->time;
>  
>  	cifs_revalidate_cache(inode, fattr);
>  
> +	spin_lock(&inode->i_lock);
>  	inode->i_atime = fattr->cf_atime;
>  	inode->i_mtime = fattr->cf_mtime;
>  	inode->i_ctime = fattr->cf_ctime;
> @@ -148,9 +148,6 @@
>  	else
>  		cifs_i->time = jiffies;
>  
> -	cFYI(1, "inode 0x%p old_time=%ld new_time=%ld", inode,
> -		 oldtime, cifs_i->time);
> -
>  	cifs_i->delete_pending = fattr->cf_flags & CIFS_FATTR_DELETE_PENDING;
>  
>  	cifs_i->server_eof = fattr->cf_eof;
> @@ -158,7 +155,6 @@
>  	 * Can't safely change the file size here if the client is writing to
>  	 * it due to potential races.
>  	 */
> -	spin_lock(&inode->i_lock);
>  	if (is_size_safe_to_change(cifs_i, fattr->cf_eof)) {
>  		i_size_write(inode, fattr->cf_eof);
>  
> @@ -909,12 +905,14 @@
>  
>  	if (rc && tcon->ipc) {
>  		cFYI(1, "ipc connection - fake read inode");
> +		spin_lock(&inode->i_lock);
>  		inode->i_mode |= S_IFDIR;
>  		set_nlink(inode, 2);
>  		inode->i_op = &cifs_ipc_inode_ops;
>  		inode->i_fop = &simple_dir_operations;
>  		inode->i_uid = cifs_sb->mnt_uid;
>  		inode->i_gid = cifs_sb->mnt_gid;
> +		spin_unlock(&inode->i_lock);
>  	} else if (rc) {
>  		iget_failed(inode);
>  		inode = ERR_PTR(rc);
> @@ -1159,6 +1157,15 @@
>  	goto out_close;
>  }
>  
> +/* copied from fs/nfs/dir.c with small changes */
> +static void
> +cifs_drop_nlink(struct inode *inode)
> +{
> +	spin_lock(&inode->i_lock);
> +	if (inode->i_nlink > 0)
> +		drop_nlink(inode);
> +	spin_unlock(&inode->i_lock);
> +}
>  
>  /*
>   * If dentry->d_inode is null (usually meaning the cached dentry
> @@ -1216,13 +1223,13 @@
>  psx_del_no_retry:
>  	if (!rc) {
>  		if (inode)
> -			drop_nlink(inode);
> +			cifs_drop_nlink(inode);
>  	} else if (rc == -ENOENT) {
>  		d_drop(dentry);
>  	} else if (rc == -ETXTBSY) {
>  		rc = cifs_rename_pending_delete(full_path, dentry, xid);
>  		if (rc == 0)
> -			drop_nlink(inode);
> +			cifs_drop_nlink(inode);
>  	} else if ((rc == -EACCES) && (dosattr == 0) && inode) {
>  		attrs = kzalloc(sizeof(*attrs), GFP_KERNEL);
>  		if (attrs == NULL) {
> @@ -1369,9 +1376,10 @@
>  		d_instantiate(direntry, newinode);
>  		 /* setting nlink not necessary except in cases where we
>  		  * failed to get it from the server or was set bogus */
> +	 	spin_lock(&direntry->d_inode->i_lock);
>  		if ((direntry->d_inode) && (direntry->d_inode->i_nlink < 2))
>  			set_nlink(direntry->d_inode, 2);
> -
> +	 	spin_unlock(&direntry->d_inode->i_lock);
>  		mode &= ~current_umask();
>  		/* must turn on setgid bit if parent dir has it */
>  		if (inode->i_mode & S_ISGID)
> diff -u a/fs/cifs/link.c b/fs/cifs/link.c
> --- a/fs/cifs/link.c
> +++ b/fs/cifs/link.c
> @@ -433,7 +433,9 @@
>  	if (old_file->d_inode) {
>  		cifsInode = CIFS_I(old_file->d_inode);
>  		if (rc == 0) {
> +			spin_lock(&old_file->d_inode->i_lock);
>  			inc_nlink(old_file->d_inode);
> +			spin_unlock(&old_file->d_inode->i_lock);
>  /* BB should we make this contingent on superblock flag NOATIME? */
>  /*			old_file->d_inode->i_ctime = CURRENT_TIME;*/
>  			/* parent dir timestamps will update from srv
> ##############################################################################
> --
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Looks good to me. You can add:

Reviewed-by: Jeff Layton <jlayton@redhat.com>