Re: [PATCH] clean up OCFS2 nlink handling

Mark Fasheh
2006-08-04T21:39:17Z

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@us.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@us.ibm.com>
Signed-off-by: Mark Fasheh <mark.fasheh@oracle.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);