From: Joel Becker Date: Wed, 26 Nov 2008 03:00:15 +0000 (-0800) Subject: ocfs2: Explain t_is_new in ocfs2_cp_xattr_cluster(). X-Git-Tag: v3.12-rc1~16803^2~48 X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=2b656c1d6fc5ba7791a360766780a212faed5705;p=kernel%2Fkernel-generic.git ocfs2: Explain t_is_new in ocfs2_cp_xattr_cluster(). I was unsure of the JOURNAL_ACCESS parameters in ocfs2_cp_xattr_cluster(). They're based on the function argument 't_is_new', but I couldn't quite figure out how t_is_new mapped to allocation. ocfs2_cp_xattr_cluster() actually overwrites the target, regardless of t_is_new. Well, I just figured it out. So I'm adding a big fat comment for those who come after me. ocfs2_divide_xattr_cluster() has the same behavior. Signed-off-by: Joel Becker Signed-off-by: Mark Fasheh --- diff --git a/fs/ocfs2/xattr.c b/fs/ocfs2/xattr.c index 4dba347..5efcf4e 100644 --- a/fs/ocfs2/xattr.c +++ b/fs/ocfs2/xattr.c @@ -3747,6 +3747,11 @@ static int ocfs2_divide_xattr_bucket(struct inode *inode, goto out; } + /* + * Hey, if we're overwriting t_bucket, what difference does + * ACCESS_CREATE vs ACCESS_WRITE make? See the comment in the + * same part of ocfs2_cp_xattr_bucket(). + */ ret = ocfs2_xattr_bucket_journal_access(handle, t_bucket, new_bucket_head ? OCFS2_JOURNAL_ACCESS_CREATE : @@ -3918,6 +3923,18 @@ static int ocfs2_cp_xattr_bucket(struct inode *inode, if (ret) goto out; + /* + * Hey, if we're overwriting t_bucket, what difference does + * ACCESS_CREATE vs ACCESS_WRITE make? Well, if we allocated a new + * cluster to fill, we came here from ocfs2_cp_xattr_cluster(), and + * it is really new - ACCESS_CREATE is required. But we also + * might have moved data out of t_bucket before extending back + * into it. ocfs2_add_new_xattr_bucket() can do this - its call + * to ocfs2_add_new_xattr_cluster() may have created a new extent + * and copied out the end of the old extent. Then it re-extends + * the old extent back to create space for new xattrs. That's + * how we get here, and the bucket isn't really new. + */ ret = ocfs2_xattr_bucket_journal_access(handle, t_bucket, t_is_new ? OCFS2_JOURNAL_ACCESS_CREATE :