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From: Miklos Szeredi <miklos@szeredi.hu>
To: Al Viro <viro@ZenIV.linux.org.uk>
Cc: Miklos Szeredi <mszeredi@redhat.com>,
	overlayfs <linux-unionfs@vger.kernel.org>,
	linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 09/11] vfs: factor out inode_insert5()
Date: Tue, 12 Jun 2018 14:38:40 +0200	[thread overview]
Message-ID: <20180612123840.GJ23785@veci.piliscsaba.redhat.com> (raw)
In-Reply-To: <20180611164355.GV30522@ZenIV.linux.org.uk>

On Mon, Jun 11, 2018 at 05:43:55PM +0100, Al Viro wrote:
> On Mon, Jun 11, 2018 at 01:32:30PM +0200, Miklos Szeredi wrote:
> 
> > Incremental follows.  I think it's cleaner to initialize i_state and i_sb_list
> > up front (hence the use of new_inode()), but could just as well add to sb list
> > afterwards.
> 
> > ---
> > diff --git a/fs/inode.c b/fs/inode.c
> > index 0df41bb77e0f..03c0d7c1296f 100644
> > --- a/fs/inode.c
> > +++ b/fs/inode.c
> > @@ -1098,8 +1098,10 @@ struct inode *iget5_locked(struct super_block *sb, unsigned long hashval,
> >  
> >  		if (new) {
> >  			inode = inode_insert5(new, hashval, test, set, data);
> > -			if (unlikely(inode != new))
> > -				iput(new);
> > +			if (unlikely(inode != new)) {
> > +				inode_sb_list_del(inode);
> > +				destroy_inode(new);
> > +			}
> 
> The thing is, until you put it into the list, it's invisible to everyone other
> than iget5_locked() - no references in any shared data structures.  Which
> outweighs the "it's somewhat irregular in not being on the list" considerably,
> as far as the complexity of analysis goes, especially since there are inodes
> that never get on that list and it's not something exotic - all sockets and
> pipes are that way, for starters.  So IMO that should be dealt with in
> inode_insert5().

Not sure I understand.

We can put inode_sb_list_add() into inode_insert5().  Then what about users of
new_inode() + insert_inode_locked4()?  Those supply an inode that is already on
the sb list.

What about adding to the list after inode_insert5() in the new inode case.

This should be equivalent to what we do currently, AFAICS.

---
diff --git a/fs/inode.c b/fs/inode.c
index 0df41bb77e0f..ad03d4abc600 100644
--- a/fs/inode.c
+++ b/fs/inode.c
@@ -1094,12 +1094,14 @@ struct inode *iget5_locked(struct super_block *sb, unsigned long hashval,
 	struct inode *inode = ilookup5(sb, hashval, test, data);
 
 	if (!inode) {
-		struct inode *new = new_inode(sb);
+		struct inode *new = new_inode_pseudo(sb);
 
 		if (new) {
 			inode = inode_insert5(new, hashval, test, set, data);
 			if (unlikely(inode != new))
-				iput(new);
+				destroy_inode(new);
+			else
+				inode_sb_list_add(inode);
 		}
 	}
 	return inode;

  reply	other threads:[~2018-06-12 12:38 UTC|newest]

Thread overview: 22+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-05-29 14:41 [PATCH 00/11] overlayfs fixes Miklos Szeredi
2018-05-29 14:41 ` [PATCH 01/11] ovl: update documentation for unionmount-testsuite Miklos Szeredi
2018-05-29 14:41 ` [PATCH 02/11] ovl: remove WARN_ON() real inode attributes mismatch Miklos Szeredi
2018-05-29 14:41 ` [PATCH 03/11] ovl: strip debug argument from ovl_do_ helpers Miklos Szeredi
2018-05-29 14:41 ` [PATCH 04/11] ovl: struct cattr cleanups Miklos Szeredi
2018-05-29 14:41 ` [PATCH 05/11] ovl: return dentry from ovl_create_real() Miklos Szeredi
2018-05-29 15:24   ` Amir Goldstein
2018-05-30  8:28     ` Miklos Szeredi
2018-05-29 14:41 ` [PATCH 06/11] ovl: create helper ovl_create_temp() Miklos Szeredi
2018-05-29 14:41 ` [PATCH 07/11] ovl: make ovl_create_real() cope with vfs_mkdir() safely Miklos Szeredi
2018-05-29 15:29   ` Amir Goldstein
2018-05-30  8:18     ` Miklos Szeredi
2018-05-29 14:41 ` [PATCH 08/11] ovl: clean up copy-up error paths Miklos Szeredi
2018-05-29 14:41 ` [PATCH 09/11] vfs: factor out inode_insert5() Miklos Szeredi
2018-06-10  5:49   ` Al Viro
2018-06-10  6:02     ` Al Viro
2018-06-11  9:15       ` Miklos Szeredi
2018-06-11 11:32         ` Miklos Szeredi
2018-06-11 16:43           ` Al Viro
2018-06-12 12:38             ` Miklos Szeredi [this message]
2018-05-29 14:41 ` [PATCH 10/11] ovl: Pass argument to ovl_get_inode() in a structure Miklos Szeredi
2018-05-29 14:41 ` [PATCH 11/11] ovl: use inode_insert5() to hash a newly created inode Miklos Szeredi

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