1 files changed, 28 insertions, 3 deletions

diff --git a/fs/btrfs/reada.c b/fs/btrfs/reada.c
index a955669519a2..96b93daa0bbb 100644
--- a/fs/btrfs/reada.c
+++ b/fs/btrfs/reada.c
@@ -27,6 +27,7 @@
 #include "volumes.h"
 #include "disk-io.h"
 #include "transaction.h"
+#include "dev-replace.h"
 
 #undef DEBUG
 
@@ -323,7 +324,6 @@ static struct reada_extent *reada_find_extent(struct btrfs_root *root,
         struct reada_extent *re = NULL;
         struct reada_extent *re_exist = NULL;
         struct btrfs_fs_info *fs_info = root->fs_info;
-        struct btrfs_mapping_tree *map_tree = &fs_info->mapping_tree;
         struct btrfs_bio *bbio = NULL;
         struct btrfs_device *dev;
         struct btrfs_device *prev_dev;
@@ -332,6 +332,7 @@ static struct reada_extent *reada_find_extent(struct btrfs_root *root,
         int nzones = 0;
         int i;
         unsigned long index = logical >> PAGE_CACHE_SHIFT;
+        int dev_replace_is_ongoing;
 
         spin_lock(&fs_info->reada_lock);
         re = radix_tree_lookup(&fs_info->reada_tree, index);
@@ -358,7 +359,8 @@ static struct reada_extent *reada_find_extent(struct btrfs_root *root,
          * map block
          */
         length = blocksize;
-        ret = btrfs_map_block(map_tree, REQ_WRITE, logical, &length, &bbio, 0);
+        ret = btrfs_map_block(fs_info, REQ_GET_READ_MIRRORS, logical, &length,
+                              &bbio, 0);
         if (ret || !bbio || length < blocksize)
                 goto error;
 
@@ -393,6 +395,7 @@ static struct reada_extent *reada_find_extent(struct btrfs_root *root,
         }
 
         /* insert extent in reada_tree + all per-device trees, all or nothing */
+        btrfs_dev_replace_lock(&fs_info->dev_replace);
         spin_lock(&fs_info->reada_lock);
         ret = radix_tree_insert(&fs_info->reada_tree, index, re);
         if (ret == -EEXIST) {
@@ -400,13 +403,17 @@ static struct reada_extent *reada_find_extent(struct btrfs_root *root,
                 BUG_ON(!re_exist);
                 re_exist->refcnt++;
                 spin_unlock(&fs_info->reada_lock);
+                btrfs_dev_replace_unlock(&fs_info->dev_replace);
                 goto error;
         }
         if (ret) {
                 spin_unlock(&fs_info->reada_lock);
+                btrfs_dev_replace_unlock(&fs_info->dev_replace);
                 goto error;
         }
         prev_dev = NULL;
+        dev_replace_is_ongoing = btrfs_dev_replace_is_ongoing(
+                        &fs_info->dev_replace);
         for (i = 0; i < nzones; ++i) {
                 dev = bbio->stripes[i].dev;
                 if (dev == prev_dev) {
@@ -419,21 +426,36 @@ static struct reada_extent *reada_find_extent(struct btrfs_root *root,
                          */
                         continue;
                 }
+                if (!dev->bdev) {
+                        /* cannot read ahead on missing device */
+                        continue;
+                }
+                if (dev_replace_is_ongoing &&
+                    dev == fs_info->dev_replace.tgtdev) {
+                        /*
+                         * as this device is selected for reading only as
+                         * a last resort, skip it for read ahead.
+                         */
+                        continue;
+                }
                 prev_dev = dev;
                 ret = radix_tree_insert(&dev->reada_extents, index, re);
                 if (ret) {
                         while (--i >= 0) {
                                 dev = bbio->stripes[i].dev;
                                 BUG_ON(dev == NULL);
+                                /* ignore whether the entry was inserted */
                                 radix_tree_delete(&dev->reada_extents, index);
                         }
                         BUG_ON(fs_info == NULL);
                         radix_tree_delete(&fs_info->reada_tree, index);
                         spin_unlock(&fs_info->reada_lock);
+                        btrfs_dev_replace_unlock(&fs_info->dev_replace);
                         goto error;
                 }
         }
         spin_unlock(&fs_info->reada_lock);
+        btrfs_dev_replace_unlock(&fs_info->dev_replace);
 
         kfree(bbio);
         return re;
@@ -915,7 +937,10 @@ struct reada_control *btrfs_reada_add(struct btrfs_root *root,
         generation = btrfs_header_generation(node);
         free_extent_buffer(node);
 
-        reada_add_block(rc, start, &max_key, level, generation);
+        if (reada_add_block(rc, start, &max_key, level, generation)) {
+                kfree(rc);
+                return ERR_PTR(-ENOMEM);
+        }
 
         reada_start_machine(root->fs_info);