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 <joel.becker@oracle.com> Signed-off-by: Mark Fasheh <mfasheh@suse.com>
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@ -3747,6 +3747,11 @@ static int ocfs2_divide_xattr_bucket(struct inode *inode,
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goto out;
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goto out;
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}
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}
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/*
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* Hey, if we're overwriting t_bucket, what difference does
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* ACCESS_CREATE vs ACCESS_WRITE make? See the comment in the
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* same part of ocfs2_cp_xattr_bucket().
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*/
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ret = ocfs2_xattr_bucket_journal_access(handle, t_bucket,
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ret = ocfs2_xattr_bucket_journal_access(handle, t_bucket,
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new_bucket_head ?
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new_bucket_head ?
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OCFS2_JOURNAL_ACCESS_CREATE :
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OCFS2_JOURNAL_ACCESS_CREATE :
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@ -3918,6 +3923,18 @@ static int ocfs2_cp_xattr_bucket(struct inode *inode,
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if (ret)
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if (ret)
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goto out;
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goto out;
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/*
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* Hey, if we're overwriting t_bucket, what difference does
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* ACCESS_CREATE vs ACCESS_WRITE make? Well, if we allocated a new
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* cluster to fill, we came here from ocfs2_cp_xattr_cluster(), and
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* it is really new - ACCESS_CREATE is required. But we also
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* might have moved data out of t_bucket before extending back
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* into it. ocfs2_add_new_xattr_bucket() can do this - its call
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* to ocfs2_add_new_xattr_cluster() may have created a new extent
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* and copied out the end of the old extent. Then it re-extends
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* the old extent back to create space for new xattrs. That's
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* how we get here, and the bucket isn't really new.
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*/
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ret = ocfs2_xattr_bucket_journal_access(handle, t_bucket,
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ret = ocfs2_xattr_bucket_journal_access(handle, t_bucket,
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t_is_new ?
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t_is_new ?
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OCFS2_JOURNAL_ACCESS_CREATE :
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OCFS2_JOURNAL_ACCESS_CREATE :
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