1 files changed, 48 insertions, 8 deletions

diff --git a/fs/btrfs/ctree.c b/fs/btrfs/ctree.c
index e5b2533b691a..fedf8b9f03a2 100644
--- a/fs/btrfs/ctree.c
+++ b/fs/btrfs/ctree.c
@@ -1325,12 +1325,12 @@ static noinline int reada_for_balance(struct btrfs_root *root,
         int ret = 0;
         int blocksize;
 
-        parent = path->nodes[level - 1];
+        parent = path->nodes[level + 1];
         if (!parent)
                 return 0;
 
         nritems = btrfs_header_nritems(parent);
-        slot = path->slots[level];
+        slot = path->slots[level + 1];
         blocksize = btrfs_level_size(root, level);
 
         if (slot > 0) {
@@ -1341,7 +1341,7 @@ static noinline int reada_for_balance(struct btrfs_root *root,
                         block1 = 0;
                 free_extent_buffer(eb);
         }
-        if (slot < nritems) {
+        if (slot + 1 < nritems) {
                 block2 = btrfs_node_blockptr(parent, slot + 1);
                 gen = btrfs_node_ptr_generation(parent, slot + 1);
                 eb = btrfs_find_tree_block(root, block2, blocksize);
@@ -1351,7 +1351,11 @@ static noinline int reada_for_balance(struct btrfs_root *root,
         }
         if (block1 || block2) {
                 ret = -EAGAIN;
+
+                /* release the whole path */
                 btrfs_release_path(root, path);
+
+                /* read the blocks */
                 if (block1)
                         readahead_tree_block(root, block1, blocksize, 0);
                 if (block2)
@@ -1361,7 +1365,7 @@ static noinline int reada_for_balance(struct btrfs_root *root,
                         eb = read_tree_block(root, block1, blocksize, 0);
                         free_extent_buffer(eb);
                 }
-                if (block1) {
+                if (block2) {
                         eb = read_tree_block(root, block2, blocksize, 0);
                         free_extent_buffer(eb);
                 }
@@ -1465,6 +1469,7 @@ read_block_for_search(struct btrfs_trans_handle *trans,
         u32 blocksize;
         struct extent_buffer *b = *eb_ret;
         struct extent_buffer *tmp;
+        int ret;
 
         blocknr = btrfs_node_blockptr(b, slot);
         gen = btrfs_node_ptr_generation(b, slot);
@@ -1472,6 +1477,10 @@ read_block_for_search(struct btrfs_trans_handle *trans,
 
         tmp = btrfs_find_tree_block(root, blocknr, blocksize);
         if (tmp && btrfs_buffer_uptodate(tmp, gen)) {
+                /*
+                 * we found an up to date block without sleeping, return
+                 * right away
+                 */
                 *eb_ret = tmp;
                 return 0;
         }
@@ -1479,18 +1488,34 @@ read_block_for_search(struct btrfs_trans_handle *trans,
         /*
          * reduce lock contention at high levels
          * of the btree by dropping locks before
-         * we read.
+         * we read.  Don't release the lock on the current
+         * level because we need to walk this node to figure
+         * out which blocks to read.
          */
-        btrfs_release_path(NULL, p);
+        btrfs_unlock_up_safe(p, level + 1);
+        btrfs_set_path_blocking(p);
+
         if (tmp)
                 free_extent_buffer(tmp);
         if (p->reada)
                 reada_for_search(root, p, level, slot, key->objectid);
 
+        btrfs_release_path(NULL, p);
+
+        ret = -EAGAIN;
         tmp = read_tree_block(root, blocknr, blocksize, gen);
-        if (tmp)
+        if (tmp) {
+                /*
+                 * If the read above didn't mark this buffer up to date,
+                 * it will never end up being up to date.  Set ret to EIO now
+                 * and give up so that our caller doesn't loop forever
+                 * on our EAGAINs.
+                 */
+                if (!btrfs_buffer_uptodate(tmp, 0))
+                        ret = -EIO;
                 free_extent_buffer(tmp);
-        return -EAGAIN;
+        }
+        return ret;
 }
 
 /*
@@ -1689,6 +1714,9 @@ cow_done:
                         if (ret == -EAGAIN)
                                 goto again;
 
+                        if (ret == -EIO)
+                                goto done;
+
                         if (!p->skip_locking) {
                                 int lret;
 
@@ -1731,6 +1759,8 @@ done:
          */
         if (!p->leave_spinning)
                 btrfs_set_path_blocking(p);
+        if (ret < 0)
+                btrfs_release_path(root, p);
         return ret;
 }
 
@@ -4205,6 +4235,11 @@ again:
                 if (ret == -EAGAIN)
                         goto again;
 
+                if (ret < 0) {
+                        btrfs_release_path(root, path);
+                        goto done;
+                }
+
                 if (!path->skip_locking) {
                         ret = btrfs_try_spin_lock(next);
                         if (!ret) {
@@ -4239,6 +4274,11 @@ again:
                 if (ret == -EAGAIN)
                         goto again;
 
+                if (ret < 0) {
+                        btrfs_release_path(root, path);
+                        goto done;
+                }
+
                 if (!path->skip_locking) {
                         btrfs_assert_tree_locked(path->nodes[level]);
                         ret = btrfs_try_spin_lock(next);