From 00ce1cf8e055e37150b9fc0d27614fc955244fb3 Mon Sep 17 00:00:00 2001
From: Fred Isaman <iisaman@citi.umich.edu>
Date: Sat, 30 Jul 2011 20:52:48 -0400
Subject: [PATCH] --- yaml --- r: 261828 b: refs/heads/master c:
 6d742ba538f98164f3c5e05cdcadb4ec6ddf504f h: refs/heads/master v: v3

---
 [refs]                                 |  2 +-
 trunk/fs/nfs/blocklayout/blocklayout.h |  3 ++
 trunk/fs/nfs/blocklayout/extents.c     | 47 ++++++++++++++++++++++++++
 3 files changed, 51 insertions(+), 1 deletion(-)

diff --git a/[refs] b/[refs]
index c88d383593b4..ef257b3e7ece 100644
--- a/[refs]
+++ b/[refs]
@@ -1,2 +1,2 @@
 ---
-refs/heads/master: e9437ccef92a28ba4c9009404bb8c9b5672dc54a
+refs/heads/master: 6d742ba538f98164f3c5e05cdcadb4ec6ddf504f
diff --git a/trunk/fs/nfs/blocklayout/blocklayout.h b/trunk/fs/nfs/blocklayout/blocklayout.h
index d645880f61a0..3e1b5fc152d7 100644
--- a/trunk/fs/nfs/blocklayout/blocklayout.h
+++ b/trunk/fs/nfs/blocklayout/blocklayout.h
@@ -153,6 +153,9 @@ int nfs4_blk_process_layoutget(struct pnfs_layout_hdr *lo,
 void bl_free_block_dev(struct pnfs_block_dev *bdev);
 
 /* extents.c */
+struct pnfs_block_extent *
+bl_find_get_extent(struct pnfs_block_layout *bl, sector_t isect,
+		struct pnfs_block_extent **cow_read);
 void bl_put_extent(struct pnfs_block_extent *be);
 struct pnfs_block_extent *bl_alloc_extent(void);
 int bl_add_merge_extent(struct pnfs_block_layout *bl,
diff --git a/trunk/fs/nfs/blocklayout/extents.c b/trunk/fs/nfs/blocklayout/extents.c
index ee4891f32492..8fa93e23cb24 100644
--- a/trunk/fs/nfs/blocklayout/extents.c
+++ b/trunk/fs/nfs/blocklayout/extents.c
@@ -193,3 +193,50 @@ bl_add_merge_extent(struct pnfs_block_layout *bl,
 	bl_put_extent(new);
 	return -EIO;
 }
+
+/* Returns extent, or NULL.  If a second READ extent exists, it is returned
+ * in cow_read, if given.
+ *
+ * The extents are kept in two seperate ordered lists, one for READ and NONE,
+ * one for READWRITE and INVALID.  Within each list, we assume:
+ * 1. Extents are ordered by file offset.
+ * 2. For any given isect, there is at most one extents that matches.
+ */
+struct pnfs_block_extent *
+bl_find_get_extent(struct pnfs_block_layout *bl, sector_t isect,
+	    struct pnfs_block_extent **cow_read)
+{
+	struct pnfs_block_extent *be, *cow, *ret;
+	int i;
+
+	dprintk("%s enter with isect %llu\n", __func__, (u64)isect);
+	cow = ret = NULL;
+	spin_lock(&bl->bl_ext_lock);
+	for (i = 0; i < EXTENT_LISTS; i++) {
+		list_for_each_entry_reverse(be, &bl->bl_extents[i], be_node) {
+			if (isect >= be->be_f_offset + be->be_length)
+				break;
+			if (isect >= be->be_f_offset) {
+				/* We have found an extent */
+				dprintk("%s Get %p (%i)\n", __func__, be,
+					atomic_read(&be->be_refcnt.refcount));
+				kref_get(&be->be_refcnt);
+				if (!ret)
+					ret = be;
+				else if (be->be_state != PNFS_BLOCK_READ_DATA)
+					bl_put_extent(be);
+				else
+					cow = be;
+				break;
+			}
+		}
+		if (ret &&
+		    (!cow_read || ret->be_state != PNFS_BLOCK_INVALID_DATA))
+			break;
+	}
+	spin_unlock(&bl->bl_ext_lock);
+	if (cow_read)
+		*cow_read = cow;
+	print_bl_extent(ret);
+	return ret;
+}