[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>
diff --git a/fs/xfs/xfs_bmap.c b/fs/xfs/xfs_bmap.c
index 64a02ea..2d702e4 100644
--- a/fs/xfs/xfs_bmap.c
+++ b/fs/xfs/xfs_bmap.c
@@ -3575,10 +3575,11 @@
}
/*
- * 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.
+ * Search the extent records for the entry containing block 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). Else, *lastxp will be set to the index
+ * of the found entry; *gotp will contain the entry.
*/
xfs_bmbt_rec_t * /* pointer to found extent entry */
xfs_bmap_search_multi_extents(
@@ -3589,36 +3590,38 @@
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.
+ * Initialize the extent entry structure to catch access to
+ * uninitialized br_startblock field.
*/
- 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;
+ gotp->br_startoff = 0xffa5a5a5a5a5a5a5LL;
+ gotp->br_blockcount = 0xa55a5a5a5a5a5a5aLL;
+ gotp->br_state = XFS_EXT_INVALID;
+#if XFS_BIG_BLKNOS
+ gotp->br_startblock = 0xffffa5a5a5a5a5a5LL;
+#else
+ gotp->br_startblock = 0xffffa5a5;
+#endif
+ prevp->br_startoff = NULLFILEOFF;
+
+ ep = xfs_iext_bno_to_ext(ifp, bno, &lastx);
+ if (lastx > 0) {
+ xfs_bmbt_get_all(xfs_iext_get_ext(ifp, lastx - 1), prevp);
+ }
+ if (lastx < (ifp->if_bytes / (uint)sizeof(xfs_bmbt_rec_t))) {
+ xfs_bmbt_get_all(ep, gotp);
+ *eofp = 0;
} else {
- base = &ifp->if_u1.if_extents[0];
- nextents = ifp->if_bytes / (uint)sizeof(xfs_bmbt_rec_t);
- lastx = ifp->if_lastex;
+ if (lastx > 0) {
+ *gotp = *prevp;
+ }
+ *eofp = 1;
+ ep = NULL;
}
- 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;
- }
+ *lastxp = lastx;
return ep;
}