[XFS] 929045 567344 This mod introduces multi-level in-core file extent

functionality, building upon the new layout introduced in mod
xfs-linux:xfs-kern:207390a.  The new multi-level extent allocations are
only required for heavily fragmented files, so the old-style linear extent
list is used on files until the extents reach a pre-determined size of 4k.
4k buffers are used because this is the system page size on Linux i386 and
systems with larger page sizes don't seem to gain much, if anything, by
using their native page size as the extent buffer size. Also, using 4k
extent buffers everywhere provides a consistent interface for CXFS across
different platforms.  The 4k extent buffers are managed by an indirection
array (xfs_ext_irec_t) which is basically just a pointer array with a bit
of extra information to keep track of the number of extents in each buffer
as well as the extent offset of each buffer.  Major changes include:  -
Add multi-level in-core file extent functionality to the xfs_iext_  
subroutines introduced in mod:	xfs-linux:xfs-kern:207390a  - Introduce 13
new subroutines which add functionality for multi-level   in-core file
extents:	 xfs_iext_add_indirect_multi()	      
xfs_iext_remove_indirect()	   xfs_iext_realloc_indirect()	      
xfs_iext_indirect_to_direct()	      xfs_iext_bno_to_irec()	    
xfs_iext_idx_to_irec()	       xfs_iext_irec_init()	   
xfs_iext_irec_new()	    xfs_iext_irec_remove()	  
xfs_iext_irec_compact() 	xfs_iext_irec_compact_pages()	     
xfs_iext_irec_compact_full()	     xfs_iext_irec_update_extoffs()

SGI-PV: 928864
SGI-Modid: xfs-linux-melb:xfs-kern:207393a

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

1 files changed, 51 insertions, 8 deletions

diff --git a/fs/xfs/xfs_bmap.c b/fs/xfs/xfs_bmap.c
index 53c47a181f875..81a95b684b6b5 100644
--- a/fs/xfs/xfs_bmap.c
+++ b/fs/xfs/xfs_bmap.c
@@ -3423,6 +3423,7 @@ xfs_bmap_local_to_extents(
 		xfs_bmap_forkoff_reset(args.mp, ip, whichfork);
 		xfs_idata_realloc(ip, -ifp->if_bytes, whichfork);
 		xfs_iext_add(ifp, 0, 1);
+		ASSERT((ifp->if_flags & (XFS_IFEXTENTS|XFS_IFEXTIREC)) == XFS_IFEXTENTS);
 		ep = xfs_iext_get_ext(ifp, 0);
 		xfs_bmbt_set_allf(ep, 0, args.fsbno, 1, XFS_EXT_NORM);
 		xfs_bmap_trace_post_update(fname, "new", ip, 0, whichfork);
@@ -3552,6 +3553,54 @@ xfs_bmap_do_search_extents(
 }
 
 /*
+ * Call xfs_bmap_do_search_extents() to search for the extent
+ * record containing block bno. If in multi-level in-core extent
+ * allocation mode, find and extract the target extent buffer,
+ * otherwise just use the direct extent list.
+ */
+xfs_bmbt_rec_t *			/* pointer to found extent entry */
+xfs_bmap_search_multi_extents(
+	xfs_ifork_t	*ifp,		/* inode fork pointer */
+	xfs_fileoff_t	bno,		/* block number searched for */
+	int		*eofp,		/* out: end of file found */
+	xfs_extnum_t	*lastxp,	/* out: last extent index */
+	xfs_bmbt_irec_t	*gotp,		/* out: extent entry found */
+	xfs_bmbt_irec_t	*prevp)		/* out: previous extent entry found */
+{
+	xfs_bmbt_rec_t	*base;		/* base of extent records */
+	xfs_bmbt_rec_t	*ep;		/* extent record pointer */
+	xfs_ext_irec_t	*erp = NULL;	/* indirection array pointer */
+	xfs_extnum_t	lastx;		/* last extent index */
+	xfs_extnum_t	nextents;	/* number of file extents */
+
+	/*
+	 * For multi-level extent allocation mode, find the
+	 * target extent list and pass only the contiguous
+	 * list to xfs_bmap_do_search_extents. Convert lastx
+	 * from a file extent index to an index within the
+	 * target extent list.
+	 */
+	if (ifp->if_flags & XFS_IFEXTIREC) {
+		int	erp_idx = 0;
+		erp = xfs_iext_bno_to_irec(ifp, bno, &erp_idx);
+		base = erp->er_extbuf;
+		nextents = erp->er_extcount;
+		lastx = ifp->if_lastex - erp->er_extoff;
+	} else {
+		base = &ifp->if_u1.if_extents[0];
+		nextents = ifp->if_bytes / (uint)sizeof(xfs_bmbt_rec_t);
+		lastx = ifp->if_lastex;
+	}
+	ep = xfs_bmap_do_search_extents(base, lastx, nextents, bno,
+					eofp, lastxp, gotp, prevp);
+	/* Convert lastx back to file-based index */
+	if (ifp->if_flags & XFS_IFEXTIREC) {
+		*lastxp += erp->er_extoff;
+	}
+	return ep;
+}
+
+/*
  * Search the extents list for the inode, for the extent containing bno.
  * If bno lies in a hole, point to the next entry.  If bno lies past eof,
  * *eofp will be set, and *prevp will contain the last entry (null if none).
@@ -3569,20 +3618,14 @@ xfs_bmap_search_extents(
 	xfs_bmbt_irec_t *prevp)         /* out: previous extent entry found */
 {
 	xfs_ifork_t	*ifp;		/* inode fork pointer */
-	xfs_bmbt_rec_t  *base;          /* base of extent list */
-	xfs_extnum_t    lastx;          /* last extent index used */
-	xfs_extnum_t    nextents;       /* number of file extents */
 	xfs_bmbt_rec_t  *ep;            /* extent record pointer */
 	int		rt;		/* realtime flag    */
 
 	XFS_STATS_INC(xs_look_exlist);
 	ifp = XFS_IFORK_PTR(ip, whichfork);
-	lastx = ifp->if_lastex;
-	nextents = ifp->if_bytes / (uint)sizeof(xfs_bmbt_rec_t);
-	base = &ifp->if_u1.if_extents[0];
 
-	ep = xfs_bmap_do_search_extents(base, lastx, nextents, bno, eofp,
-					  lastxp, gotp, prevp);
+	ep = xfs_bmap_search_multi_extents(ifp, bno, eofp, lastxp, gotp, prevp);
+
 	rt = (whichfork == XFS_DATA_FORK) && XFS_IS_REALTIME_INODE(ip);
 	if (unlikely(!rt && !gotp->br_startblock && (*lastxp != NULLEXTNUM))) {
                 cmn_err(CE_PANIC,"Access to block zero: fs: <%s> inode: %lld "