Btrfs: Don't drop extent_map cache during releasepage on the btree inode

The btree inode should only have a single extent_map in the cache,
it doesn't make sense to ever drop it.

Signed-off-by: Chris Mason <chris.mason@oracle.com>

1 files changed, 14 insertions, 9 deletions

diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index 76ee7a4ae00c..2de2b00afebc 100644
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -76,13 +76,12 @@ struct extent_map *btree_get_extent(struct inode *inode, struct page *page,
         struct extent_map *em;
         int ret;
 
-again:
         spin_lock(&em_tree->lock);
         em = lookup_extent_mapping(em_tree, start, len);
         spin_unlock(&em_tree->lock);
-        if (em) {
+        if (em)
                 goto out;
-        }
+
         em = alloc_extent_map(GFP_NOFS);
         if (!em) {
                 em = ERR_PTR(-ENOMEM);
@@ -95,15 +94,21 @@ again:
 
         spin_lock(&em_tree->lock);
         ret = add_extent_mapping(em_tree, em);
-        spin_unlock(&em_tree->lock);
-
         if (ret == -EEXIST) {
                 free_extent_map(em);
-                em = NULL;
-                goto again;
+                em = lookup_extent_mapping(em_tree, start, len);
+                if (em)
+                        ret = 0;
+                else
+                        ret = -EIO;
         } else if (ret) {
-                em = ERR_PTR(ret);
+                free_extent_map(em);
+                em = NULL;
         }
+        spin_unlock(&em_tree->lock);
+
+        if (ret)
+                em = ERR_PTR(ret);
 out:
         return em;
 }
@@ -496,7 +501,7 @@ static int btree_releasepage(struct page *page, gfp_t gfp_flags)
         }
         tree = &BTRFS_I(page->mapping->host)->io_tree;
         map = &BTRFS_I(page->mapping->host)->extent_tree;
-        ret = try_release_extent_mapping(map, tree, page, gfp_flags);
+        ret = try_release_extent_state(map, tree, page, gfp_flags);
         if (ret == 1) {
                 invalidate_extent_lru(tree, page_offset(page), PAGE_CACHE_SIZE);
                 ClearPagePrivate(page);