1 files changed, 20 insertions, 7 deletions

diff --git a/fs/btrfs/backref.c b/fs/btrfs/backref.c
index f4e90748940a..bcec06750232 100644
--- a/fs/btrfs/backref.c
+++ b/fs/btrfs/backref.c
@@ -22,6 +22,7 @@
 #include "ulist.h"
 #include "transaction.h"
 #include "delayed-ref.h"
+#include "locking.h"
 
 /*
  * this structure records all encountered refs on the way up to the root
@@ -893,18 +894,22 @@ static char *iref_to_path(struct btrfs_root *fs_root, struct btrfs_path *path,
 	s64 bytes_left = size - 1;
 	struct extent_buffer *eb = eb_in;
 	struct btrfs_key found_key;
+	int leave_spinning = path->leave_spinning;
 
 	if (bytes_left >= 0)
 		dest[bytes_left] = '\0';
 
+	path->leave_spinning = 1;
 	while (1) {
 		len = btrfs_inode_ref_name_len(eb, iref);
 		bytes_left -= len;
 		if (bytes_left >= 0)
 			read_extent_buffer(eb, dest + bytes_left,
 						(unsigned long)(iref + 1), len);
-		if (eb != eb_in)
+		if (eb != eb_in) {
+			btrfs_tree_read_unlock_blocking(eb);
 			free_extent_buffer(eb);
+		}
 		ret = inode_ref_info(parent, 0, fs_root, path, &found_key);
 		if (ret > 0)
 			ret = -ENOENT;
@@ -919,8 +924,11 @@ static char *iref_to_path(struct btrfs_root *fs_root, struct btrfs_path *path,
 		slot = path->slots[0];
 		eb = path->nodes[0];
 		/* make sure we can use eb after releasing the path */
-		if (eb != eb_in)
+		if (eb != eb_in) {
 			atomic_inc(&eb->refs);
+			btrfs_tree_read_lock(eb);
+			btrfs_set_lock_blocking_rw(eb, BTRFS_READ_LOCK);
+		}
 		btrfs_release_path(path);
 
 		iref = btrfs_item_ptr(eb, slot, struct btrfs_inode_ref);
@@ -931,6 +939,7 @@ static char *iref_to_path(struct btrfs_root *fs_root, struct btrfs_path *path,
 	}
 
 	btrfs_release_path(path);
+	path->leave_spinning = leave_spinning;
 
 	if (ret)
 		return ERR_PTR(ret);
@@ -1247,7 +1256,7 @@ static int iterate_irefs(u64 inum, struct btrfs_root *fs_root,
 				struct btrfs_path *path,
 				iterate_irefs_t *iterate, void *ctx)
 {
-	int ret;
+	int ret = 0;
 	int slot;
 	u32 cur;
 	u32 len;
@@ -1259,7 +1268,8 @@ static int iterate_irefs(u64 inum, struct btrfs_root *fs_root,
 	struct btrfs_inode_ref *iref;
 	struct btrfs_key found_key;
 
-	while (1) {
+	while (!ret) {
+		path->leave_spinning = 1;
 		ret = inode_ref_info(inum, parent ? parent+1 : 0, fs_root, path,
 					&found_key);
 		if (ret < 0)
@@ -1275,6 +1285,8 @@ static int iterate_irefs(u64 inum, struct btrfs_root *fs_root,
 		eb = path->nodes[0];
 		/* make sure we can use eb after releasing the path */
 		atomic_inc(&eb->refs);
+		btrfs_tree_read_lock(eb);
+		btrfs_set_lock_blocking_rw(eb, BTRFS_READ_LOCK);
 		btrfs_release_path(path);
 
 		item = btrfs_item_nr(eb, slot);
@@ -1288,13 +1300,12 @@ static int iterate_irefs(u64 inum, struct btrfs_root *fs_root,
 				 (unsigned long long)found_key.objectid,
 				 (unsigned long long)fs_root->objectid);
 			ret = iterate(parent, iref, eb, ctx);
-			if (ret) {
-				free_extent_buffer(eb);
+			if (ret)
 				break;
-			}
 			len = sizeof(*iref) + name_len;
 			iref = (struct btrfs_inode_ref *)((char *)iref + len);
 		}
+		btrfs_tree_read_unlock_blocking(eb);
 		free_extent_buffer(eb);
 	}
 
@@ -1414,6 +1425,8 @@ struct inode_fs_paths *init_ipath(s32 total_bytes, struct btrfs_root *fs_root,
 
 void free_ipath(struct inode_fs_paths *ipath)
 {
+	if (!ipath)
+		return;
 	kfree(ipath->fspath);
 	kfree(ipath);
 }