Merge branch 'for-linus-4.1' of git://git.kernel.org/pub/scm/linux/kernel/git/mason/linux-btrfs

Pull btrfs fixes from Chris Mason:
 "A few more btrfs fixes.

  These range from corners Filipe found in the new free space cache
  writeback to a grab bag of fixes from the list"

* 'for-linus-4.1' of git://git.kernel.org/pub/scm/linux/kernel/git/mason/linux-btrfs:
  Btrfs: btrfs_release_extent_buffer_page didn't free pages of dummy extent
  Btrfs: fill ->last_trans for delayed inode in btrfs_fill_inode.
  btrfs: unlock i_mutex after attempting to delete subvolume during send
  btrfs: check io_ctl_prepare_pages return in __btrfs_write_out_cache
  btrfs: fix race on ENOMEM in alloc_extent_buffer
  btrfs: handle ENOMEM in btrfs_alloc_tree_block
  Btrfs: fix find_free_dev_extent() malfunction in case device tree has hole
  Btrfs: don't check for delalloc_bytes in cache_save_setup
  Btrfs: fix deadlock when starting writeback of bg caches
  Btrfs: fix race between start dirty bg cache writeout and bg deletion

7 files changed, 118 insertions, 77 deletions

diff --git a/fs/btrfs/delayed-inode.c b/fs/btrfs/delayed-inode.c
index cde698a07d21..a2ae42720a6a 100644
--- a/fs/btrfs/delayed-inode.c
+++ b/fs/btrfs/delayed-inode.c
@@ -1802,6 +1802,8 @@ int btrfs_fill_inode(struct inode *inode, u32 *rdev)
         set_nlink(inode, btrfs_stack_inode_nlink(inode_item));
         inode_set_bytes(inode, btrfs_stack_inode_nbytes(inode_item));
         BTRFS_I(inode)->generation = btrfs_stack_inode_generation(inode_item);
+        BTRFS_I(inode)->last_trans = btrfs_stack_inode_transid(inode_item);
+
         inode->i_version = btrfs_stack_inode_sequence(inode_item);
         inode->i_rdev = 0;
         *rdev = btrfs_stack_inode_rdev(inode_item);
diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
index 1eef4ee01d1a..0ec8e228b89f 100644
--- a/fs/btrfs/extent-tree.c
+++ b/fs/btrfs/extent-tree.c
@@ -3178,8 +3178,8 @@ static int write_one_cache_group(struct btrfs_trans_handle *trans,
         bi = btrfs_item_ptr_offset(leaf, path->slots[0]);
         write_extent_buffer(leaf, &cache->item, bi, sizeof(cache->item));
         btrfs_mark_buffer_dirty(leaf);
-        btrfs_release_path(path);
 fail:
+        btrfs_release_path(path);
         if (ret)
                 btrfs_abort_transaction(trans, root, ret);
         return ret;
@@ -3305,8 +3305,7 @@ again:
 
         spin_lock(&block_group->lock);
         if (block_group->cached != BTRFS_CACHE_FINISHED ||
-            !btrfs_test_opt(root, SPACE_CACHE) ||
-            block_group->delalloc_bytes) {
+            !btrfs_test_opt(root, SPACE_CACHE)) {
                 /*
                  * don't bother trying to write stuff out _if_
                  * a) we're not cached,
@@ -3408,17 +3407,14 @@ int btrfs_start_dirty_block_groups(struct btrfs_trans_handle *trans,
         int loops = 0;
 
         spin_lock(&cur_trans->dirty_bgs_lock);
-        if (!list_empty(&cur_trans->dirty_bgs)) {
-                list_splice_init(&cur_trans->dirty_bgs, &dirty);
+        if (list_empty(&cur_trans->dirty_bgs)) {
+                spin_unlock(&cur_trans->dirty_bgs_lock);
+                return 0;
         }
+        list_splice_init(&cur_trans->dirty_bgs, &dirty);
         spin_unlock(&cur_trans->dirty_bgs_lock);
 
 again:
-        if (list_empty(&dirty)) {
-                btrfs_free_path(path);
-                return 0;
-        }
-
         /*
          * make sure all the block groups on our dirty list actually
          * exist
@@ -3431,18 +3427,16 @@ again:
                         return -ENOMEM;
         }
 
+        /*
+         * cache_write_mutex is here only to save us from balance or automatic
+         * removal of empty block groups deleting this block group while we are
+         * writing out the cache
+         */
+        mutex_lock(&trans->transaction->cache_write_mutex);
         while (!list_empty(&dirty)) {
                 cache = list_first_entry(&dirty,
                                          struct btrfs_block_group_cache,
                                          dirty_list);
-
-                /*
-                 * cache_write_mutex is here only to save us from balance
-                 * deleting this block group while we are writing out the
-                 * cache
-                 */
-                mutex_lock(&trans->transaction->cache_write_mutex);
-
                 /*
                  * this can happen if something re-dirties a block
                  * group that is already under IO.  Just wait for it to
@@ -3495,7 +3489,6 @@ again:
                 }
                 if (!ret)
                         ret = write_one_cache_group(trans, root, path, cache);
-                mutex_unlock(&trans->transaction->cache_write_mutex);
 
                 /* if its not on the io list, we need to put the block group */
                 if (should_put)
@@ -3503,7 +3496,16 @@ again:
 
                 if (ret)
                         break;
+
+                /*
+                 * Avoid blocking other tasks for too long. It might even save
+                 * us from writing caches for block groups that are going to be
+                 * removed.
+                 */
+                mutex_unlock(&trans->transaction->cache_write_mutex);
+                mutex_lock(&trans->transaction->cache_write_mutex);
         }
+        mutex_unlock(&trans->transaction->cache_write_mutex);
 
         /*
          * go through delayed refs for all the stuff we've just kicked off
@@ -3514,8 +3516,15 @@ again:
                 loops++;
                 spin_lock(&cur_trans->dirty_bgs_lock);
                 list_splice_init(&cur_trans->dirty_bgs, &dirty);
+                /*
+                 * dirty_bgs_lock protects us from concurrent block group
+                 * deletes too (not just cache_write_mutex).
+                 */
+                if (!list_empty(&dirty)) {
+                        spin_unlock(&cur_trans->dirty_bgs_lock);
+                        goto again;
+                }
                 spin_unlock(&cur_trans->dirty_bgs_lock);
-                goto again;
         }
 
         btrfs_free_path(path);
@@ -7537,7 +7546,7 @@ static void unuse_block_rsv(struct btrfs_fs_info *fs_info,
  * returns the key for the extent through ins, and a tree buffer for
  * the first block of the extent through buf.
  *
- * returns the tree buffer or NULL.
+ * returns the tree buffer or an ERR_PTR on error.
  */
 struct extent_buffer *btrfs_alloc_tree_block(struct btrfs_trans_handle *trans,
                                         struct btrfs_root *root,
@@ -7548,6 +7557,7 @@ struct extent_buffer *btrfs_alloc_tree_block(struct btrfs_trans_handle *trans,
         struct btrfs_key ins;
         struct btrfs_block_rsv *block_rsv;
         struct extent_buffer *buf;
+        struct btrfs_delayed_extent_op *extent_op;
         u64 flags = 0;
         int ret;
         u32 blocksize = root->nodesize;
@@ -7568,13 +7578,14 @@ struct extent_buffer *btrfs_alloc_tree_block(struct btrfs_trans_handle *trans,
 
         ret = btrfs_reserve_extent(root, blocksize, blocksize,
                                    empty_size, hint, &ins, 0, 0);
-        if (ret) {
-                unuse_block_rsv(root->fs_info, block_rsv, blocksize);
-                return ERR_PTR(ret);
-        }
+        if (ret)
+                goto out_unuse;
 
         buf = btrfs_init_new_buffer(trans, root, ins.objectid, level);
-        BUG_ON(IS_ERR(buf)); /* -ENOMEM */
+        if (IS_ERR(buf)) {
+                ret = PTR_ERR(buf);
+                goto out_free_reserved;
+        }
 
         if (root_objectid == BTRFS_TREE_RELOC_OBJECTID) {
                 if (parent == 0)
@@ -7584,9 +7595,11 @@ struct extent_buffer *btrfs_alloc_tree_block(struct btrfs_trans_handle *trans,
                 BUG_ON(parent > 0);
 
         if (root_objectid != BTRFS_TREE_LOG_OBJECTID) {
-                struct btrfs_delayed_extent_op *extent_op;
                 extent_op = btrfs_alloc_delayed_extent_op();
-                BUG_ON(!extent_op); /* -ENOMEM */
+                if (!extent_op) {
+                        ret = -ENOMEM;
+                        goto out_free_buf;
+                }
                 if (key)
                         memcpy(&extent_op->key, key, sizeof(extent_op->key));
                 else
@@ -7601,13 +7614,24 @@ struct extent_buffer *btrfs_alloc_tree_block(struct btrfs_trans_handle *trans,
                 extent_op->level = level;
 
                 ret = btrfs_add_delayed_tree_ref(root->fs_info, trans,
-                                        ins.objectid,
-                                        ins.offset, parent, root_objectid,
-                                        level, BTRFS_ADD_DELAYED_EXTENT,
-                                        extent_op, 0);
-                BUG_ON(ret); /* -ENOMEM */
+                                                 ins.objectid, ins.offset,
+                                                 parent, root_objectid, level,
+                                                 BTRFS_ADD_DELAYED_EXTENT,
+                                                 extent_op, 0);
+                if (ret)
+                        goto out_free_delayed;
         }
         return buf;
+
+out_free_delayed:
+        btrfs_free_delayed_extent_op(extent_op);
+out_free_buf:
+        free_extent_buffer(buf);
+out_free_reserved:
+        btrfs_free_reserved_extent(root, ins.objectid, ins.offset, 0);
+out_unuse:
+        unuse_block_rsv(root->fs_info, block_rsv, blocksize);
+        return ERR_PTR(ret);
 }
 
 struct walk_control {
diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c
index 782f3bc4651d..43af5a61ad25 100644
--- a/fs/btrfs/extent_io.c
+++ b/fs/btrfs/extent_io.c
@@ -4560,36 +4560,37 @@ static void btrfs_release_extent_buffer_page(struct extent_buffer *eb)
         do {
                 index--;
                 page = eb->pages[index];
-                if (page && mapped) {
+                if (!page)
+                        continue;
+                if (mapped)
                         spin_lock(&page->mapping->private_lock);
+                /*
+                 * We do this since we'll remove the pages after we've
+                 * removed the eb from the radix tree, so we could race
+                 * and have this page now attached to the new eb.  So
+                 * only clear page_private if it's still connected to
+                 * this eb.
+                 */
+                if (PagePrivate(page) &&
+                    page->private == (unsigned long)eb) {
+                        BUG_ON(test_bit(EXTENT_BUFFER_DIRTY, &eb->bflags));
+                        BUG_ON(PageDirty(page));
+                        BUG_ON(PageWriteback(page));
                         /*
-                         * We do this since we'll remove the pages after we've
-                         * removed the eb from the radix tree, so we could race
-                         * and have this page now attached to the new eb.  So
-                         * only clear page_private if it's still connected to
-                         * this eb.
+                         * We need to make sure we haven't be attached
+                         * to a new eb.
                          */
-                        if (PagePrivate(page) &&
-                            page->private == (unsigned long)eb) {
-                                BUG_ON(test_bit(EXTENT_BUFFER_DIRTY, &eb->bflags));
-                                BUG_ON(PageDirty(page));
-                                BUG_ON(PageWriteback(page));
-                                /*
-                                 * We need to make sure we haven't be attached
-                                 * to a new eb.
-                                 */
-                                ClearPagePrivate(page);
-                                set_page_private(page, 0);
-                                /* One for the page private */
-                                page_cache_release(page);
-                        }
-                        spin_unlock(&page->mapping->private_lock);
-
-                }
-                if (page) {
-                        /* One for when we alloced the page */
+                        ClearPagePrivate(page);
+                        set_page_private(page, 0);
+                        /* One for the page private */
                         page_cache_release(page);
                 }
+
+                if (mapped)
+                        spin_unlock(&page->mapping->private_lock);
+
+                /* One for when we alloced the page */
+                page_cache_release(page);
         } while (index != 0);
 }
 
@@ -4870,6 +4871,7 @@ struct extent_buffer *alloc_extent_buffer(struct btrfs_fs_info *fs_info,
                                 mark_extent_buffer_accessed(exists, p);
                                 goto free_eb;
                         }
+                        exists = NULL;
 
                         /*
                          * Do this so attach doesn't complain and we need to
@@ -4933,12 +4935,12 @@ again:
         return eb;
 
 free_eb:
+        WARN_ON(!atomic_dec_and_test(&eb->refs));
         for (i = 0; i < num_pages; i++) {
                 if (eb->pages[i])
                         unlock_page(eb->pages[i]);
         }
 
-        WARN_ON(!atomic_dec_and_test(&eb->refs));
         btrfs_release_extent_buffer(eb);
         return exists;
 }
diff --git a/fs/btrfs/free-space-cache.c b/fs/btrfs/free-space-cache.c
index 81fa75a8e1f3..41c510b7cc11 100644
--- a/fs/btrfs/free-space-cache.c
+++ b/fs/btrfs/free-space-cache.c
@@ -1218,7 +1218,7 @@ out:
  *
  * This function writes out a free space cache struct to disk for quick recovery
  * on mount.  This will return 0 if it was successfull in writing the cache out,
- * and -1 if it was not.
+ * or an errno if it was not.
  */
 static int __btrfs_write_out_cache(struct btrfs_root *root, struct inode *inode,
                                    struct btrfs_free_space_ctl *ctl,
@@ -1235,12 +1235,12 @@ static int __btrfs_write_out_cache(struct btrfs_root *root, struct inode *inode,
         int must_iput = 0;
 
         if (!i_size_read(inode))
-                return -1;
+                return -EIO;
 
         WARN_ON(io_ctl->pages);
         ret = io_ctl_init(io_ctl, inode, root, 1);
         if (ret)
-                return -1;
+                return ret;
 
         if (block_group && (block_group->flags & BTRFS_BLOCK_GROUP_DATA)) {
                 down_write(&block_group->data_rwsem);
@@ -1258,7 +1258,9 @@ static int __btrfs_write_out_cache(struct btrfs_root *root, struct inode *inode,
         }
 
         /* Lock all pages first so we can lock the extent safely. */
-        io_ctl_prepare_pages(io_ctl, inode, 0);
+        ret = io_ctl_prepare_pages(io_ctl, inode, 0);
+        if (ret)
+                goto out;
 
         lock_extent_bits(&BTRFS_I(inode)->io_tree, 0, i_size_read(inode) - 1,
                          0, &cached_state);
diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index ada4d24ed11b..8bb013672aee 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -3632,25 +3632,28 @@ static void btrfs_read_locked_inode(struct inode *inode)
         BTRFS_I(inode)->generation = btrfs_inode_generation(leaf, inode_item);
         BTRFS_I(inode)->last_trans = btrfs_inode_transid(leaf, inode_item);
 
+        inode->i_version = btrfs_inode_sequence(leaf, inode_item);
+        inode->i_generation = BTRFS_I(inode)->generation;
+        inode->i_rdev = 0;
+        rdev = btrfs_inode_rdev(leaf, inode_item);
+
+        BTRFS_I(inode)->index_cnt = (u64)-1;
+        BTRFS_I(inode)->flags = btrfs_inode_flags(leaf, inode_item);
+
+cache_index:
         /*
          * If we were modified in the current generation and evicted from memory
          * and then re-read we need to do a full sync since we don't have any
          * idea about which extents were modified before we were evicted from
          * cache.
+         *
+         * This is required for both inode re-read from disk and delayed inode
+         * in delayed_nodes_tree.
          */
         if (BTRFS_I(inode)->last_trans == root->fs_info->generation)
                 set_bit(BTRFS_INODE_NEEDS_FULL_SYNC,
                         &BTRFS_I(inode)->runtime_flags);
 
-        inode->i_version = btrfs_inode_sequence(leaf, inode_item);
-        inode->i_generation = BTRFS_I(inode)->generation;
-        inode->i_rdev = 0;
-        rdev = btrfs_inode_rdev(leaf, inode_item);
-
-        BTRFS_I(inode)->index_cnt = (u64)-1;
-        BTRFS_I(inode)->flags = btrfs_inode_flags(leaf, inode_item);
-
-cache_index:
         path->slots[0]++;
         if (inode->i_nlink != 1 ||
             path->slots[0] >= btrfs_header_nritems(leaf))
diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
index b05653f182c2..1c22c6518504 100644
--- a/fs/btrfs/ioctl.c
+++ b/fs/btrfs/ioctl.c
@@ -2410,7 +2410,7 @@ static noinline int btrfs_ioctl_snap_destroy(struct file *file,
                         "Attempt to delete subvolume %llu during send",
                         dest->root_key.objectid);
                 err = -EPERM;
-                goto out_dput;
+                goto out_unlock_inode;
         }
 
         d_invalidate(dentry);
@@ -2505,6 +2505,7 @@ out_up_write:
                                 root_flags & ~BTRFS_ROOT_SUBVOL_DEAD);
                 spin_unlock(&dest->root_item_lock);
         }
+out_unlock_inode:
         mutex_unlock(&inode->i_mutex);
         if (!err) {
                 shrink_dcache_sb(root->fs_info->sb);
diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index 8bcd2a007517..96aebf3bcd5b 100644
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -1058,6 +1058,7 @@ static int contains_pending_extent(struct btrfs_trans_handle *trans,
         struct extent_map *em;
         struct list_head *search_list = &trans->transaction->pending_chunks;
         int ret = 0;
+        u64 physical_start = *start;
 
 again:
         list_for_each_entry(em, search_list, list) {
@@ -1068,9 +1069,9 @@ again:
                 for (i = 0; i < map->num_stripes; i++) {
                         if (map->stripes[i].dev != device)
                                 continue;
-                        if (map->stripes[i].physical >= *start + len ||
+                        if (map->stripes[i].physical >= physical_start + len ||
                             map->stripes[i].physical + em->orig_block_len <=
-                            *start)
+                            physical_start)
                                 continue;
                         *start = map->stripes[i].physical +
                                 em->orig_block_len;
@@ -1193,8 +1194,14 @@ again:
                          */
                         if (contains_pending_extent(trans, device,
                                                     &search_start,
-                                                    hole_size))
-                                hole_size = 0;
+                                                    hole_size)) {
+                                if (key.offset >= search_start) {
+                                        hole_size = key.offset - search_start;
+                                } else {
+                                        WARN_ON_ONCE(1);
+                                        hole_size = 0;
+                                }
+                        }
 
                         if (hole_size > max_hole_size) {
                                 max_hole_start = search_start;