aboutsummaryrefslogtreecommitdiffstats
path: root/fs/nfs/blocklayout/extents.c
diff options
context:
space:
mode:
authorFred Isaman <iisaman@citi.umich.edu>2011-07-30 20:52:45 -0400
committerTrond Myklebust <Trond.Myklebust@netapp.com>2011-07-31 12:18:16 -0400
commit03341d2cc91c700fc38883e572043a6a8f17dd5c (patch)
treeb5e25d8597188adac536b24158f51ed99e0b10f9 /fs/nfs/blocklayout/extents.c
parenta60d2ebd93d3c5db5b6913c4844b8e6bd3b5538e (diff)
pnfsblock: merge extents
Replace a stub, so that extents underlying the layouts are properly added, merged, or ignored as necessary. Signed-off-by: Fred Isaman <iisaman@citi.umich.edu> [pnfsblock: delete the new node before put it] Signed-off-by: Mingyang Guo <guomingyang@nrchpc.ac.cn> Signed-off-by: Benny Halevy <bhalevy@panasas.com> Signed-off-by: Peng Tao <peng_tao@emc.com> Signed-off-by: Benny Halevy <bhalevy@tonian.com> Signed-off-by: Jim Rees <rees@umich.edu> Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
Diffstat (limited to 'fs/nfs/blocklayout/extents.c')
-rw-r--r--fs/nfs/blocklayout/extents.c106
1 files changed, 106 insertions, 0 deletions
diff --git a/fs/nfs/blocklayout/extents.c b/fs/nfs/blocklayout/extents.c
index d0ca7604d33..ee4891f3249 100644
--- a/fs/nfs/blocklayout/extents.c
+++ b/fs/nfs/blocklayout/extents.c
@@ -87,3 +87,109 @@ static void print_elist(struct list_head *list)
}
dprintk("****************\n");
}
+
+static inline int
+extents_consistent(struct pnfs_block_extent *old, struct pnfs_block_extent *new)
+{
+ /* Note this assumes new->be_f_offset >= old->be_f_offset */
+ return (new->be_state == old->be_state) &&
+ ((new->be_state == PNFS_BLOCK_NONE_DATA) ||
+ ((new->be_v_offset - old->be_v_offset ==
+ new->be_f_offset - old->be_f_offset) &&
+ new->be_mdev == old->be_mdev));
+}
+
+/* Adds new to appropriate list in bl, modifying new and removing existing
+ * extents as appropriate to deal with overlaps.
+ *
+ * See bl_find_get_extent for list constraints.
+ *
+ * Refcount on new is already set. If end up not using it, or error out,
+ * need to put the reference.
+ *
+ * bl->bl_ext_lock is held by caller.
+ */
+int
+bl_add_merge_extent(struct pnfs_block_layout *bl,
+ struct pnfs_block_extent *new)
+{
+ struct pnfs_block_extent *be, *tmp;
+ sector_t end = new->be_f_offset + new->be_length;
+ struct list_head *list;
+
+ dprintk("%s enter with be=%p\n", __func__, new);
+ print_bl_extent(new);
+ list = &bl->bl_extents[bl_choose_list(new->be_state)];
+ print_elist(list);
+
+ /* Scan for proper place to insert, extending new to the left
+ * as much as possible.
+ */
+ list_for_each_entry_safe(be, tmp, list, be_node) {
+ if (new->be_f_offset < be->be_f_offset)
+ break;
+ if (end <= be->be_f_offset + be->be_length) {
+ /* new is a subset of existing be*/
+ if (extents_consistent(be, new)) {
+ dprintk("%s: new is subset, ignoring\n",
+ __func__);
+ bl_put_extent(new);
+ return 0;
+ } else
+ goto out_err;
+ } else if (new->be_f_offset <=
+ be->be_f_offset + be->be_length) {
+ /* new overlaps or abuts existing be */
+ if (extents_consistent(be, new)) {
+ /* extend new to fully replace be */
+ new->be_length += new->be_f_offset -
+ be->be_f_offset;
+ new->be_f_offset = be->be_f_offset;
+ new->be_v_offset = be->be_v_offset;
+ dprintk("%s: removing %p\n", __func__, be);
+ list_del(&be->be_node);
+ bl_put_extent(be);
+ } else if (new->be_f_offset !=
+ be->be_f_offset + be->be_length)
+ goto out_err;
+ }
+ }
+ /* Note that if we never hit the above break, be will not point to a
+ * valid extent. However, in that case &be->be_node==list.
+ */
+ list_add_tail(&new->be_node, &be->be_node);
+ dprintk("%s: inserting new\n", __func__);
+ print_elist(list);
+ /* Scan forward for overlaps. If we find any, extend new and
+ * remove the overlapped extent.
+ */
+ be = list_prepare_entry(new, list, be_node);
+ list_for_each_entry_safe_continue(be, tmp, list, be_node) {
+ if (end < be->be_f_offset)
+ break;
+ /* new overlaps or abuts existing be */
+ if (extents_consistent(be, new)) {
+ if (end < be->be_f_offset + be->be_length) {
+ /* extend new to fully cover be */
+ end = be->be_f_offset + be->be_length;
+ new->be_length = end - new->be_f_offset;
+ }
+ dprintk("%s: removing %p\n", __func__, be);
+ list_del(&be->be_node);
+ bl_put_extent(be);
+ } else if (end != be->be_f_offset) {
+ list_del(&new->be_node);
+ goto out_err;
+ }
+ }
+ dprintk("%s: after merging\n", __func__);
+ print_elist(list);
+ /* FIXME - The per-list consistency checks have all been done,
+ * should now check cross-list consistency.
+ */
+ return 0;
+
+ out_err:
+ bl_put_extent(new);
+ return -EIO;
+}