linux-kernel - Re: [PATCH 08/32] Unionfs: cache-coherency

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Date:	Mon, 3 Sep 2007 08:48:53 +0200 (CEST)
From:	Jan Engelhardt <jengelh@...putergmbh.de>
To:	Josef 'Jeff' Sipek <jsipek@...sunysb.edu>
cc:	akpm@...ux-foundation.org, linux-kernel@...r.kernel.org,
	linux-fsdevel@...r.kernel.org, hch@...radead.org,
	viro@....linux.org.uk, bharata@...ux.vnet.ibm.com,
	j.blunck@...harburg.de, Erez Zadok <ezk@...sunysb.edu>
Subject: Re: [PATCH 08/32] Unionfs: cache-coherency - update inode times


On Sep 2 2007 22:20, Josef 'Jeff' Sipek wrote:
>-static ssize_t unionfs_write(struct file * file, const char __user * buf,
>+
>+static ssize_t unionfs_write(struct file *file, const char __user *buf,
> 			     size_t count, loff_t *ppos)
> {
> 	int err = 0;
> 
> 	unionfs_read_lock(file->f_path.dentry->d_sb);
>-
> 	if ((err = unionfs_file_revalidate(file, 1)))
> 		goto out;
> 
> 	err = do_sync_write(file, buf, count, ppos);
>+	/* update our inode times upon a successful lower write */
>+	if (err >= 0)
>+		unionfs_copy_attr_times(file->f_path.dentry->d_inode);

So, revisiting the question of inotifying, write() is indeed a case which
warrants notification (I think). Just was not sure what callers
unionfs_copy_attr_times can have.

>@@ -245,6 +245,12 @@ static struct dentry *unionfs_lookup(struct inode *parent,
> 		nd->dentry = path_save.dentry;
> 		nd->mnt = path_save.mnt;
> 	}
>+	if (!IS_ERR(ret)) {
>+		if (ret)
>+			dentry = ret;
>+		/* parent times may have changed */
>+		unionfs_copy_attr_times(dentry->d_parent->d_inode);
>+	}

On lookup? No inotify if you ask me...


>@@ -675,8 +681,11 @@ out:
> 
> 	kfree(name);
> 
>+	if (!err)
>+		unionfs_copy_attr_times(dentry->d_inode);
> 	unionfs_unlock_dentry(dentry);
> 	unionfs_read_unlock(dentry->d_sb);
>+
> 	return err;
> }
> 

Can't decide ;-)

>@@ -1006,6 +1015,8 @@ static int unionfs_permission(struct inode *inode, int mask,
> 			break;
> 		}
> 	}
>+	/* sync times which may have changed (asynchronously) below */
>+	unionfs_copy_attr_times(inode);
> 
> out:
> 	return err;

permission => readonly operation => no inotify

>diff --git a/fs/unionfs/unlink.c b/fs/unionfs/unlink.c
>index 822bffe..7ad19ec 100644
>--- a/fs/unionfs/unlink.c
>+++ b/fs/unionfs/unlink.c
>@@ -41,6 +41,9 @@ static int unionfs_unlink_whiteout(struct inode *dir, struct dentry *dentry)
> 	dget(lower_dentry);
> 	if (!(err = is_robranch_super(dentry->d_sb, bindex)))
> 		err = vfs_unlink(lower_dir_dentry->d_inode, lower_dentry);
>+	/* if vfs_unlink succeeded, update our inode's times */
>+	if (!err)
>+		unionfs_copy_attr_times(dentry->d_inode);
> 	dput(lower_dentry);
> 	fsstack_copy_attr_times(dir, lower_dir_dentry->d_inode);
> 	unlock_dir(lower_dir_dentry);

unlink => write operation => inotify



	Jan
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