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Commit 2b656c1d authored by Joel Becker's avatar Joel Becker Committed by Mark Fasheh
Browse files

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: default avatarJoel Becker <joel.becker@oracle.com>
Signed-off-by: default avatarMark Fasheh <mfasheh@suse.com>
parent 15d60929

fs/ocfs2/xattr.c

+17 −0
Original line number Original line Diff line number Diff line
@@ -3747,6 +3747,11 @@ static int ocfs2_divide_xattr_bucket(struct inode *inode, 
		goto out;

		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,

	ret = ocfs2_xattr_bucket_journal_access(handle, t_bucket,

						new_bucket_head ?

						new_bucket_head ?

						OCFS2_JOURNAL_ACCESS_CREATE :

						OCFS2_JOURNAL_ACCESS_CREATE :
@@ -3918,6 +3923,18 @@ static int ocfs2_cp_xattr_bucket(struct inode *inode, 
	if (ret)

	if (ret)

		goto out;

		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,

	ret = ocfs2_xattr_bucket_journal_access(handle, t_bucket,

						t_is_new ?

						t_is_new ?

						OCFS2_JOURNAL_ACCESS_CREATE :

						OCFS2_JOURNAL_ACCESS_CREATE :