[XFS] There are a few problems with the new

xfs_bmap_search_multi_extents() wrapper function that I introduced in mod
xfs-linux:xfs-kern:207393a. The function was added as a wrapper around
xfs_bmap_do_search_extents() to avoid breaking the top-of-tree CXFS
interface.  The idea of the function was basically to extract the target
extent buffer (if muli- level extent allocation mode), then call
xfs_bmap_do_search_extents() with either a pointer to the first extent in
the target buffer or a pointer to the first extent in the file, depending
on which extent mode was being used.  However, in addition to locating the
target extent record for block bno, xfs_bmap_do_search_extents() also sets
four parameters needed by the caller: *lastx, *eofp, *gotp, *prevp. 
Passing only the target extent buffer to xfs_bmap_do_search_extents()
causes *eofp to be set incorrectly if the extent is at the end of the
target list but there are actually more extents in the next er_extbuf.
Likewise, if the extent is the first one in the buffer but NOT the first
in the file, *prevp is incorrectly set to NULL.  Adding the needed
functionality to xfs_bmap_search_multi_extents() to re-set any incorrectly
set fields is redundant and makes the call to xfs_bmap_do_search_extents()
not make much sense when multi-level extent allocation mode is being used.
 This mod basically extracts the two functional components from
xfs_bmap_do_search_extents(), with the intent of obsoleting/removing
xfs_bmap_do_search_extents() after the CXFS mult-level in-core extent
changes are checked in.  The two components are:  1) The binary search to
locate the target extent record, and 2) Setting the four parameters needed
by the caller (*lastx, *eofp, *gotp, *prevp).  Component 1: I created a
new function in xfs_inode.c called xfs_iext_bno_to_ext(), which executes
the binary search to find the target extent record.
xfs_bmap_search_multi_extents() has been modified to call
xfs_iext_bno_to_ext() rather than xfs_bmap_do_search_extents().  Component
2: The parameter setting functionality has been added to
xfs_bmap_search_multi_extents(), eliminating the need for
xfs_bmap_do_search_extents().  These changes make the removal of
xfs_bmap_do_search_extents() trival once the CXFS changes are in place. 
They also allow us to maintain the current XFS interface, using the new
search function introduced in mod xfs-linux:xfs-kern:207393a.

SGI-PV: 928864
SGI-Modid: xfs-linux-melb:xfs-kern:207866a

Signed-off-by: Mandy Kirkconnell <alkirkco@sgi.com>
Signed-off-by: Nathan Scott <nathans@sgi.com>

1 files changed, 1 insertions, 0 deletions

diff --git a/fs/xfs/xfs_inode.h b/fs/xfs/xfs_inode.h
index 3c1df1d642fa..006396764cbc 100644
--- a/fs/xfs/xfs_inode.h
+++ b/fs/xfs/xfs_inode.h
@@ -478,6 +478,7 @@ void		xfs_iext_indirect_to_direct(xfs_ifork_t *);
 void            xfs_iext_direct_to_inline(xfs_ifork_t *, xfs_extnum_t);
 void            xfs_iext_inline_to_direct(xfs_ifork_t *, int);
 void            xfs_iext_destroy(xfs_ifork_t *);
+xfs_bmbt_rec_t  *xfs_iext_bno_to_ext(xfs_ifork_t *, xfs_fileoff_t, int *);
 xfs_ext_irec_t  *xfs_iext_bno_to_irec(xfs_ifork_t *, xfs_fileoff_t, int *);
 xfs_ext_irec_t  *xfs_iext_idx_to_irec(xfs_ifork_t *, xfs_extnum_t *, int *, int);
 void            xfs_iext_irec_init(xfs_ifork_t *);