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);
 }