[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_inode.c b/fs/xfs/xfs_inode.c
index 580fa07..a16df2d 100644
--- a/fs/xfs/xfs_inode.c
+++ b/fs/xfs/xfs_inode.c
@@ -4266,11 +4266,80 @@
}
/*
+ * Return a pointer to the extent record for file system block bno.
+ */
+xfs_bmbt_rec_t * /* pointer to found extent record */
+xfs_iext_bno_to_ext(
+ xfs_ifork_t *ifp, /* inode fork pointer */
+ xfs_fileoff_t bno, /* block number to search for */
+ xfs_extnum_t *idxp) /* index of target extent */
+{
+ xfs_bmbt_rec_t *base; /* pointer to first extent */
+ xfs_filblks_t blockcount = 0; /* number of blocks in extent */
+ xfs_bmbt_rec_t *ep = NULL; /* pointer to target extent */
+ xfs_ext_irec_t *erp = NULL; /* indirection array pointer */
+ int high; /* upper boundry in search */
+ xfs_extnum_t idx = 0; /* index of target extent */
+ int low; /* lower boundry in search */
+ xfs_extnum_t nextents; /* number of file extents */
+ xfs_fileoff_t startoff = 0; /* start offset of extent */
+
+ nextents = ifp->if_bytes / (uint)sizeof(xfs_bmbt_rec_t);
+ if (nextents == 0) {
+ *idxp = 0;
+ return NULL;
+ }
+ low = 0;
+ if (ifp->if_flags & XFS_IFEXTIREC) {
+ /* Find target extent list */
+ int erp_idx = 0;
+ erp = xfs_iext_bno_to_irec(ifp, bno, &erp_idx);
+ base = erp->er_extbuf;
+ high = erp->er_extcount - 1;
+ } else {
+ base = ifp->if_u1.if_extents;
+ high = nextents - 1;
+ }
+ /* Binary search extent records */
+ while (low <= high) {
+ idx = (low + high) >> 1;
+ ep = base + idx;
+ startoff = xfs_bmbt_get_startoff(ep);
+ blockcount = xfs_bmbt_get_blockcount(ep);
+ if (bno < startoff) {
+ high = idx - 1;
+ } else if (bno >= startoff + blockcount) {
+ low = idx + 1;
+ } else {
+ /* Convert back to file-based extent index */
+ if (ifp->if_flags & XFS_IFEXTIREC) {
+ idx += erp->er_extoff;
+ }
+ *idxp = idx;
+ return ep;
+ }
+ }
+ /* Convert back to file-based extent index */
+ if (ifp->if_flags & XFS_IFEXTIREC) {
+ idx += erp->er_extoff;
+ }
+ if (bno >= startoff + blockcount) {
+ if (++idx == nextents) {
+ ep = NULL;
+ } else {
+ ep = xfs_iext_get_ext(ifp, idx);
+ }
+ }
+ *idxp = idx;
+ return ep;
+}
+
+/*
* Return a pointer to the indirection array entry containing the
* extent record for filesystem block bno. Store the index of the
* target irec in *erp_idxp.
*/
-xfs_ext_irec_t *
+xfs_ext_irec_t * /* pointer to found extent record */
xfs_iext_bno_to_irec(
xfs_ifork_t *ifp, /* inode fork pointer */
xfs_fileoff_t bno, /* block number to search for */
@@ -4278,7 +4347,7 @@
{
xfs_ext_irec_t *erp = NULL; /* indirection array pointer */
xfs_ext_irec_t *erp_next; /* next indirection array entry */
- xfs_extnum_t erp_idx; /* indirection array index */
+ int erp_idx; /* indirection array index */
int nlists; /* number of extent irec's (lists) */
int high; /* binary search upper limit */
int low; /* binary search lower limit */
