GFS2: Allocate block for xattr at inode alloc time, if required

This is another step towards improving the allocation of xattr blocks at inode allocation time. Here we take advantage of Christoph's recent work on ACLs to allocate a block for the xattrs early if we know that we will be adding ACLs to the inode later on. The advantage of that is that it is much more likely that we'll get a contiguous run of two blocks where the first is the inode and the second is the xattr block. We still have to fall back to the original system in case we don't get the requested two contiguous blocks, or in case the ACLs are too large to fit into the block. Future patches will move more of the ACL setting code further up the gfs2_inode_create() function. Also, I'd like to be able to do the same thing with the xattrs from LSMs in due course, too. That way we should be able to slowly reduce the number of independent transactions, at least in the most common cases.

SWSteven Whitehouse committed 12 years ago