linux-kernel - Re: [PATCH] clean up OCFS2 nlink handling

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Message-ID: <20060804213856.GP29686@ca-server1.us.oracle.com>
Date:	Fri, 4 Aug 2006 14:38:56 -0700
From:	Mark Fasheh <mark.fasheh@...cle.com>
To:	Dave Hansen <haveblue@...ibm.com>
Cc:	linux-kernel@...r.kernel.org, viro@....linux.org.uk,
	herbert@...hfloor.at, hch@...radead.org
Subject: Re: [PATCH] clean up OCFS2 nlink handling

Hi Dave,

On Fri, Aug 04, 2006 at 02:01:32PM -0700, Dave Hansen wrote:
> OK, I hope this does it.
I think the last part of your patch is bad :/ At any rate, I think the
attached patch fixes up the last hunk for you. HTH.


From: Dave Hansen <haveblue@...ibm.com>

OCFS2 does some operations on i_nlink, then reverts them if some
of its operations fail to complete.  This does not fit in well
with the inode_drop_nlink() logic where we expect i_nlink to stay
at zero once it gets there.

So, delay all of the nlink operations until we're sure that the
operations have completed.  Also, introduce a small helper to
check whether an inode has proper "unlinkable" i_nlink counts
no matter whether it is a directory or regular inode.

Signed-off-by: Dave Hansen <haveblue@...ibm.com>
Signed-off-by: Mark Fasheh <mark.fasheh@...cle.com>

diff --git a/fs/ocfs2/namei.c b/fs/ocfs2/namei.c
index 0673862..666953b 100644
--- a/fs/ocfs2/namei.c
+++ b/fs/ocfs2/namei.c
@@ -744,11 +744,23 @@ bail:
 	return err;
 }
 
+static inline inode_is_unlinkable(struct inode *inode)
+{
+	if (S_ISDIR(inode->i_mode)) {
+	       	if (inode->i_nlink == 2)
+			return 1;
+		return 0;
+	}
+
+	if (inode->i_nlink == 1)
+		return 1;
+	return 0;
+}
+
 static int ocfs2_unlink(struct inode *dir,
 			struct dentry *dentry)
 {
 	int status;
-	unsigned int saved_nlink = 0;
 	struct inode *inode = dentry->d_inode;
 	struct ocfs2_super *osb = OCFS2_SB(dir->i_sb);
 	u64 blkno;
@@ -760,6 +772,7 @@ static int ocfs2_unlink(struct inode *di
 	struct buffer_head *dirent_bh = NULL;
 	char orphan_name[OCFS2_ORPHAN_NAMELEN + 1];
 	struct buffer_head *orphan_entry_bh = NULL;
+	unsigned int future_nlink;
 
 	mlog_entry("(0x%p, 0x%p, '%.*s')\n", dir, dentry,
 		   dentry->d_name.len, dentry->d_name.name);
@@ -823,18 +836,11 @@ static int ocfs2_unlink(struct inode *di
 		}
 	}
 
-	/* There are still a few steps left until we can consider the
-	 * unlink to have succeeded. Save off nlink here before
-	 * modification so we can set it back in case we hit an issue
-	 * before commit. */
-	saved_nlink = inode->i_nlink;
-	if (S_ISDIR(inode->i_mode))
-		inode->i_nlink = 0;
+	if (S_ISDIR(inode->i_mode) && (inode->i_nlink == 2))
+		future_nlink = 0;
 	else
-		inode->i_nlink--;
-
-	status = ocfs2_request_unlink_vote(inode, dentry,
-					   (unsigned int) inode->i_nlink);
+		future_nlink = inode->i_nlink - 1;
+	status = ocfs2_request_unlink_vote(inode, dentry, future_nlink);
 	if (status < 0) {
 		/* This vote should succeed under all normal
 		 * circumstances. */
@@ -842,7 +848,7 @@ static int ocfs2_unlink(struct inode *di
 		goto leave;
 	}
 
-	if (!inode->i_nlink) {
+	if (inode_is_unlinkable(inode)) {
 		status = ocfs2_prepare_orphan_dir(osb, handle, inode,
 						  orphan_name,
 						  &orphan_entry_bh);
@@ -869,7 +875,7 @@ static int ocfs2_unlink(struct inode *di
 
 	fe = (struct ocfs2_dinode *) fe_bh->b_data;
 
-	if (!inode->i_nlink) {
+	if (inode_is_unlinkable(inode)) {
 		status = ocfs2_orphan_add(osb, handle, inode, fe, orphan_name,
 					  orphan_entry_bh);
 		if (status < 0) {
@@ -885,10 +891,10 @@ static int ocfs2_unlink(struct inode *di
 		goto leave;
 	}
 
-	/* We can set nlink on the dinode now. clear the saved version
-	 * so that it doesn't get set later. */
+	if (S_ISDIR(inode->i_mode))
+		inode_drop_nlink(inode);
+	inode_drop_nlink(inode);
 	fe->i_links_count = cpu_to_le16(inode->i_nlink);
-	saved_nlink = 0;
 
 	status = ocfs2_journal_dirty(handle, fe_bh);
 	if (status < 0) {
@@ -897,19 +903,16 @@ static int ocfs2_unlink(struct inode *di
 	}
 
 	if (S_ISDIR(inode->i_mode)) {
-		dir->i_nlink--;
+		inode_drop_nlink(dir);
 		status = ocfs2_mark_inode_dirty(handle, dir,
 						parent_node_bh);
 		if (status < 0) {
 			mlog_errno(status);
-			dir->i_nlink++;
+			inode_inc_nlink(dir);
 		}
 	}
 
 leave:
-	if (status < 0 && saved_nlink)
-		inode->i_nlink = saved_nlink;
-
 	if (handle)
 		ocfs2_commit_trans(handle);
 
-
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