Btrfs: Fix disk_i_size update corner case

There are some cases file extents are inserted without involving
ordered struct. In these cases, we update disk_i_size directly,
without checking pending ordered extent and DELALLOC bit. This
patch extends btrfs_ordered_update_i_size() to handle these cases.

Signed-off-by: Yan Zheng <zheng.yan@oracle.com>
Signed-off-by: Chris Mason <chris.mason@oracle.com>

4 files changed, 127 insertions, 56 deletions

diff --git a/fs/btrfs/btrfs_inode.h b/fs/btrfs/btrfs_inode.h
index f6783a42f010..3f1f50d9d916 100644
--- a/fs/btrfs/btrfs_inode.h
+++ b/fs/btrfs/btrfs_inode.h
@@ -44,9 +44,6 @@ struct btrfs_inode {
          */
         struct extent_io_tree io_failure_tree;
 
-        /* held while inesrting or deleting extents from files */
-        struct mutex extent_mutex;
-
         /* held while logging the inode in tree-log.c */
         struct mutex log_mutex;
 
@@ -166,7 +163,7 @@ static inline struct btrfs_inode *BTRFS_I(struct inode *inode)
 
 static inline void btrfs_i_size_write(struct inode *inode, u64 size)
 {
-        inode->i_size = size;
+        i_size_write(inode, size);
         BTRFS_I(inode)->disk_i_size = size;
 }
 
diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index ef250be49cdb..fa57247887e3 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -188,8 +188,18 @@ static noinline int insert_inline_extent(struct btrfs_trans_handle *trans,
         btrfs_mark_buffer_dirty(leaf);
         btrfs_free_path(path);
 
+        /*
+         * we're an inline extent, so nobody can
+         * extend the file past i_size without locking
+         * a page we already have locked.
+         *
+         * We must do any isize and inode updates
+         * before we unlock the pages.  Otherwise we
+         * could end up racing with unlink.
+         */
         BTRFS_I(inode)->disk_i_size = inode->i_size;
         btrfs_update_inode(trans, root, inode);
+
         return 0;
 fail:
         btrfs_free_path(path);
@@ -415,7 +425,6 @@ again:
                                                     start, end,
                                                     total_compressed, pages);
                 }
-                btrfs_end_transaction(trans, root);
                 if (ret == 0) {
                         /*
                          * inline extent creation worked, we don't need
@@ -429,9 +438,11 @@ again:
                              EXTENT_CLEAR_DELALLOC |
                              EXTENT_CLEAR_ACCOUNTING |
                              EXTENT_SET_WRITEBACK | EXTENT_END_WRITEBACK);
-                        ret = 0;
+
+                        btrfs_end_transaction(trans, root);
                         goto free_pages_out;
                 }
+                btrfs_end_transaction(trans, root);
         }
 
         if (will_compress) {
@@ -542,7 +553,6 @@ static noinline int submit_compressed_extents(struct inode *inode,
         if (list_empty(&async_cow->extents))
                 return 0;
 
-        trans = btrfs_join_transaction(root, 1);
 
         while (!list_empty(&async_cow->extents)) {
                 async_extent = list_entry(async_cow->extents.next,
@@ -589,19 +599,15 @@ retry:
                 lock_extent(io_tree, async_extent->start,
                             async_extent->start + async_extent->ram_size - 1,
                             GFP_NOFS);
-                /*
-                 * here we're doing allocation and writeback of the
-                 * compressed pages
-                 */
-                btrfs_drop_extent_cache(inode, async_extent->start,
-                                        async_extent->start +
-                                        async_extent->ram_size - 1, 0);
 
+                trans = btrfs_join_transaction(root, 1);
                 ret = btrfs_reserve_extent(trans, root,
                                            async_extent->compressed_size,
                                            async_extent->compressed_size,
                                            0, alloc_hint,
                                            (u64)-1, &ins, 1);
+                btrfs_end_transaction(trans, root);
+
                 if (ret) {
                         int i;
                         for (i = 0; i < async_extent->nr_pages; i++) {
@@ -617,6 +623,14 @@ retry:
                         goto retry;
                 }
 
+                /*
+                 * here we're doing allocation and writeback of the
+                 * compressed pages
+                 */
+                btrfs_drop_extent_cache(inode, async_extent->start,
+                                        async_extent->start +
+                                        async_extent->ram_size - 1, 0);
+
                 em = alloc_extent_map(GFP_NOFS);
                 em->start = async_extent->start;
                 em->len = async_extent->ram_size;
@@ -648,8 +662,6 @@ retry:
                                                BTRFS_ORDERED_COMPRESSED);
                 BUG_ON(ret);
 
-                btrfs_end_transaction(trans, root);
-
                 /*
                  * clear dirty, set writeback and unlock the pages.
                  */
@@ -671,13 +683,11 @@ retry:
                                     async_extent->nr_pages);
 
                 BUG_ON(ret);
-                trans = btrfs_join_transaction(root, 1);
                 alloc_hint = ins.objectid + ins.offset;
                 kfree(async_extent);
                 cond_resched();
         }
 
-        btrfs_end_transaction(trans, root);
         return 0;
 }
 
@@ -741,6 +751,7 @@ static noinline int cow_file_range(struct inode *inode,
                                      EXTENT_CLEAR_DIRTY |
                                      EXTENT_SET_WRITEBACK |
                                      EXTENT_END_WRITEBACK);
+
                         *nr_written = *nr_written +
                              (end - start + PAGE_CACHE_SIZE) / PAGE_CACHE_SIZE;
                         *page_started = 1;
@@ -1727,18 +1738,27 @@ static int btrfs_finish_ordered_io(struct inode *inode, u64 start, u64 end)
                 }
         }
 
-        trans = btrfs_join_transaction(root, 1);
-
         if (!ordered_extent)
                 ordered_extent = btrfs_lookup_ordered_extent(inode, start);
         BUG_ON(!ordered_extent);
-        if (test_bit(BTRFS_ORDERED_NOCOW, &ordered_extent->flags))
-                goto nocow;
+        if (test_bit(BTRFS_ORDERED_NOCOW, &ordered_extent->flags)) {
+                BUG_ON(!list_empty(&ordered_extent->list));
+                ret = btrfs_ordered_update_i_size(inode, 0, ordered_extent);
+                if (!ret) {
+                        trans = btrfs_join_transaction(root, 1);
+                        ret = btrfs_update_inode(trans, root, inode);
+                        BUG_ON(ret);
+                        btrfs_end_transaction(trans, root);
+                }
+                goto out;
+        }
 
         lock_extent(io_tree, ordered_extent->file_offset,
                     ordered_extent->file_offset + ordered_extent->len - 1,
                     GFP_NOFS);
 
+        trans = btrfs_join_transaction(root, 1);
+
         if (test_bit(BTRFS_ORDERED_COMPRESSED, &ordered_extent->flags))
                 compressed = 1;
         if (test_bit(BTRFS_ORDERED_PREALLOC, &ordered_extent->flags)) {
@@ -1765,22 +1785,20 @@ static int btrfs_finish_ordered_io(struct inode *inode, u64 start, u64 end)
         unlock_extent(io_tree, ordered_extent->file_offset,
                     ordered_extent->file_offset + ordered_extent->len - 1,
                     GFP_NOFS);
-nocow:
         add_pending_csums(trans, inode, ordered_extent->file_offset,
                           &ordered_extent->list);
 
-        mutex_lock(&BTRFS_I(inode)->extent_mutex);
-        btrfs_ordered_update_i_size(inode, ordered_extent);
-        btrfs_update_inode(trans, root, inode);
-        btrfs_remove_ordered_extent(inode, ordered_extent);
-        mutex_unlock(&BTRFS_I(inode)->extent_mutex);
-
+        /* this also removes the ordered extent from the tree */
+        btrfs_ordered_update_i_size(inode, 0, ordered_extent);
+        ret = btrfs_update_inode(trans, root, inode);
+        BUG_ON(ret);
+        btrfs_end_transaction(trans, root);
+out:
         /* once for us */
         btrfs_put_ordered_extent(ordered_extent);
         /* once for the tree */
         btrfs_put_ordered_extent(ordered_extent);
 
-        btrfs_end_transaction(trans, root);
         return 0;
 }
 
@@ -3562,7 +3580,6 @@ static noinline void init_btrfs_i(struct inode *inode)
         INIT_LIST_HEAD(&BTRFS_I(inode)->ordered_operations);
         RB_CLEAR_NODE(&BTRFS_I(inode)->rb_node);
         btrfs_ordered_inode_tree_init(&BTRFS_I(inode)->ordered_tree);
-        mutex_init(&BTRFS_I(inode)->extent_mutex);
         mutex_init(&BTRFS_I(inode)->log_mutex);
 }
 
diff --git a/fs/btrfs/ordered-data.c b/fs/btrfs/ordered-data.c
index 5799bc46a309..9b16073bb875 100644
--- a/fs/btrfs/ordered-data.c
+++ b/fs/btrfs/ordered-data.c
@@ -291,16 +291,16 @@ int btrfs_put_ordered_extent(struct btrfs_ordered_extent *entry)
 
 /*
  * remove an ordered extent from the tree.  No references are dropped
- * but, anyone waiting on this extent is woken up.
+ * and you must wake_up entry->wait.  You must hold the tree mutex
+ * while you call this function.
  */
-int btrfs_remove_ordered_extent(struct inode *inode,
+static int __btrfs_remove_ordered_extent(struct inode *inode,
                                 struct btrfs_ordered_extent *entry)
 {
         struct btrfs_ordered_inode_tree *tree;
         struct rb_node *node;
 
         tree = &BTRFS_I(inode)->ordered_tree;
-        mutex_lock(&tree->mutex);
         node = &entry->rb_node;
         rb_erase(node, &tree->tree);
         tree->last = NULL;
@@ -326,9 +326,26 @@ int btrfs_remove_ordered_extent(struct inode *inode,
         }
         spin_unlock(&BTRFS_I(inode)->root->fs_info->ordered_extent_lock);
 
+        return 0;
+}
+
+/*
+ * remove an ordered extent from the tree.  No references are dropped
+ * but any waiters are woken.
+ */
+int btrfs_remove_ordered_extent(struct inode *inode,
+                                struct btrfs_ordered_extent *entry)
+{
+        struct btrfs_ordered_inode_tree *tree;
+        int ret;
+
+        tree = &BTRFS_I(inode)->ordered_tree;
+        mutex_lock(&tree->mutex);
+        ret = __btrfs_remove_ordered_extent(inode, entry);
         mutex_unlock(&tree->mutex);
         wake_up(&entry->wait);
-        return 0;
+
+        return ret;
 }
 
 /*
@@ -589,7 +606,7 @@ out:
  * After an extent is done, call this to conditionally update the on disk
  * i_size.  i_size is updated to cover any fully written part of the file.
  */
-int btrfs_ordered_update_i_size(struct inode *inode,
+int btrfs_ordered_update_i_size(struct inode *inode, u64 offset,
                                 struct btrfs_ordered_extent *ordered)
 {
         struct btrfs_ordered_inode_tree *tree = &BTRFS_I(inode)->ordered_tree;
@@ -597,18 +614,30 @@ int btrfs_ordered_update_i_size(struct inode *inode,
         u64 disk_i_size;
         u64 new_i_size;
         u64 i_size_test;
+        u64 i_size = i_size_read(inode);
         struct rb_node *node;
+        struct rb_node *prev = NULL;
         struct btrfs_ordered_extent *test;
+        int ret = 1;
+
+        if (ordered)
+                offset = entry_end(ordered);
 
         mutex_lock(&tree->mutex);
         disk_i_size = BTRFS_I(inode)->disk_i_size;
 
+        /* truncate file */
+        if (disk_i_size > i_size) {
+                BTRFS_I(inode)->disk_i_size = i_size;
+                ret = 0;
+                goto out;
+        }
+
         /*
          * if the disk i_size is already at the inode->i_size, or
          * this ordered extent is inside the disk i_size, we're done
          */
-        if (disk_i_size >= inode->i_size ||
-            ordered->file_offset + ordered->len <= disk_i_size) {
+        if (disk_i_size == i_size || offset <= disk_i_size) {
                 goto out;
         }
 
@@ -616,8 +645,7 @@ int btrfs_ordered_update_i_size(struct inode *inode,
          * we can't update the disk_isize if there are delalloc bytes
          * between disk_i_size and  this ordered extent
          */
-        if (test_range_bit(io_tree, disk_i_size,
-                           ordered->file_offset + ordered->len - 1,
+        if (test_range_bit(io_tree, disk_i_size, offset - 1,
                            EXTENT_DELALLOC, 0, NULL)) {
                 goto out;
         }
@@ -626,20 +654,32 @@ int btrfs_ordered_update_i_size(struct inode *inode,
          * if we find an ordered extent then we can't update disk i_size
          * yet
          */
-        node = &ordered->rb_node;
-        while (1) {
-                node = rb_prev(node);
-                if (!node)
-                        break;
+        if (ordered) {
+                node = rb_prev(&ordered->rb_node);
+        } else {
+                prev = tree_search(tree, offset);
+                /*
+                 * we insert file extents without involving ordered struct,
+                 * so there should be no ordered struct cover this offset
+                 */
+                if (prev) {
+                        test = rb_entry(prev, struct btrfs_ordered_extent,
+                                        rb_node);
+                        BUG_ON(offset_in_entry(test, offset));
+                }
+                node = prev;
+        }
+        while (node) {
                 test = rb_entry(node, struct btrfs_ordered_extent, rb_node);
                 if (test->file_offset + test->len <= disk_i_size)
                         break;
-                if (test->file_offset >= inode->i_size)
+                if (test->file_offset >= i_size)
                         break;
                 if (test->file_offset >= disk_i_size)
                         goto out;
+                node = rb_prev(node);
         }
-        new_i_size = min_t(u64, entry_end(ordered), i_size_read(inode));
+        new_i_size = min_t(u64, offset, i_size);
 
         /*
          * at this point, we know we can safely update i_size to at least
@@ -647,7 +687,14 @@ int btrfs_ordered_update_i_size(struct inode *inode,
          * walk forward and see if ios from higher up in the file have
          * finished.
          */
-        node = rb_next(&ordered->rb_node);
+        if (ordered) {
+                node = rb_next(&ordered->rb_node);
+        } else {
+                if (prev)
+                        node = rb_next(prev);
+                else
+                        node = rb_first(&tree->tree);
+        }
         i_size_test = 0;
         if (node) {
                 /*
@@ -655,10 +702,10 @@ int btrfs_ordered_update_i_size(struct inode *inode,
                  * between our ordered extent and the next one.
                  */
                 test = rb_entry(node, struct btrfs_ordered_extent, rb_node);
-                if (test->file_offset > entry_end(ordered))
+                if (test->file_offset > offset)
                         i_size_test = test->file_offset;
         } else {
-                i_size_test = i_size_read(inode);
+                i_size_test = i_size;
         }
 
         /*
@@ -667,15 +714,25 @@ int btrfs_ordered_update_i_size(struct inode *inode,
          * are no delalloc bytes in this area, it is safe to update
          * disk_i_size to the end of the region.
          */
-        if (i_size_test > entry_end(ordered) &&
-            !test_range_bit(io_tree, entry_end(ordered), i_size_test - 1,
-                           EXTENT_DELALLOC, 0, NULL)) {
-                new_i_size = min_t(u64, i_size_test, i_size_read(inode));
+        if (i_size_test > offset &&
+            !test_range_bit(io_tree, offset, i_size_test - 1,
+                            EXTENT_DELALLOC, 0, NULL)) {
+                new_i_size = min_t(u64, i_size_test, i_size);
         }
         BTRFS_I(inode)->disk_i_size = new_i_size;
+        ret = 0;
 out:
+        /*
+         * we need to remove the ordered extent with the tree lock held
+         * so that other people calling this function don't find our fully
+         * processed ordered entry and skip updating the i_size
+         */
+        if (ordered)
+                __btrfs_remove_ordered_extent(inode, ordered);
         mutex_unlock(&tree->mutex);
-        return 0;
+        if (ordered)
+                wake_up(&ordered->wait);
+        return ret;
 }
 
 /*
diff --git a/fs/btrfs/ordered-data.h b/fs/btrfs/ordered-data.h
index f82e87488ca8..4fa20398aec1 100644
--- a/fs/btrfs/ordered-data.h
+++ b/fs/btrfs/ordered-data.h
@@ -150,7 +150,7 @@ void btrfs_start_ordered_extent(struct inode *inode,
 int btrfs_wait_ordered_range(struct inode *inode, u64 start, u64 len);
 struct btrfs_ordered_extent *
 btrfs_lookup_first_ordered_extent(struct inode * inode, u64 file_offset);
-int btrfs_ordered_update_i_size(struct inode *inode,
+int btrfs_ordered_update_i_size(struct inode *inode, u64 offset,
                                 struct btrfs_ordered_extent *ordered);
 int btrfs_find_ordered_sum(struct inode *inode, u64 offset, u64 disk_bytenr, u32 *sum);
 int btrfs_wait_ordered_extents(struct btrfs_root *root, int nocow_only);