btrfs: add function to create and return an ordered extent

Currently, btrfs_add_ordered_extent allocates a new ordered extent, adds
it to the rb_tree, but doesn't return a referenced pointer to the
caller. There are cases where it is useful for the creator of a new
ordered_extent to hang on to such a pointer, so add a new function
btrfs_alloc_ordered_extent which is the same as
btrfs_add_ordered_extent, except it takes an additional reference count
and returns a pointer to the ordered_extent. Implement
btrfs_add_ordered_extent as btrfs_alloc_ordered_extent followed by
dropping the new reference and handling the IS_ERR case.

The type of flags in btrfs_alloc_ordered_extent and
btrfs_add_ordered_extent is changed from unsigned int to unsigned long
so it's unified with the other ordered extent functions.

Reviewed-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Naohiro Aota <naohiro.aota@wdc.com>
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Tested-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: Boris Burkov <boris@bur.io>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

diff --git a/fs/btrfs/ordered-data.c b/fs/btrfs/ordered-data.c
index 6c24b69e2d0a372c0990093652a7272773341cfa..d600f90e1dba4fce224137cadf44eb90fd150229 100644 (file)
--- a/fs/btrfs/ordered-data.c
+++ b/fs/btrfs/ordered-data.c
@@ -160,14 +160,16 @@ static inline struct rb_node *tree_search(struct btrfs_ordered_inode_tree *tree,
  * @compress_type:   Compression algorithm used for data.
  *
  * Most of these parameters correspond to &struct btrfs_file_extent_item. The
- * tree is given a single reference on the ordered extent that was inserted.
+ * tree is given a single reference on the ordered extent that was inserted, and
+ * the returned pointer is given a second reference.
  *
- * Return: 0 or -ENOMEM.
+ * Return: the new ordered extent or error pointer.
  */
-int btrfs_add_ordered_extent(struct btrfs_inode *inode, u64 file_offset,
-                            u64 num_bytes, u64 ram_bytes, u64 disk_bytenr,
-                            u64 disk_num_bytes, u64 offset, unsigned flags,
-                            int compress_type)
+struct btrfs_ordered_extent *btrfs_alloc_ordered_extent(
+                       struct btrfs_inode *inode, u64 file_offset,
+                       u64 num_bytes, u64 ram_bytes, u64 disk_bytenr,
+                       u64 disk_num_bytes, u64 offset, unsigned long flags,
+                       int compress_type)
 {
        struct btrfs_root *root = inode->root;
        struct btrfs_fs_info *fs_info = root->fs_info;
@@ -181,7 +183,7 @@ int btrfs_add_ordered_extent(struct btrfs_inode *inode, u64 file_offset,
                /* For nocow write, we can release the qgroup rsv right now */
                ret = btrfs_qgroup_free_data(inode, NULL, file_offset, num_bytes);
                if (ret < 0)
-                       return ret;
+                       return ERR_PTR(ret);
                ret = 0;
        } else {
                /*
@@ -190,11 +192,11 @@ int btrfs_add_ordered_extent(struct btrfs_inode *inode, u64 file_offset,
                 */
                ret = btrfs_qgroup_release_data(inode, file_offset, num_bytes);
                if (ret < 0)
-                       return ret;
+                       return ERR_PTR(ret);
        }
        entry = kmem_cache_zalloc(btrfs_ordered_extent_cache, GFP_NOFS);
        if (!entry)
-               return -ENOMEM;
+               return ERR_PTR(-ENOMEM);
 
        entry->file_offset = file_offset;
        entry->num_bytes = num_bytes;
@@ -256,6 +258,32 @@ int btrfs_add_ordered_extent(struct btrfs_inode *inode, u64 file_offset,
        btrfs_mod_outstanding_extents(inode, 1);
        spin_unlock(&inode->lock);
 
+       /* One ref for the returned entry to match semantics of lookup. */
+       refcount_inc(&entry->refs);
+
+       return entry;
+}
+
+/*
+ * Add a new btrfs_ordered_extent for the range, but drop the reference instead
+ * of returning it to the caller.
+ */
+int btrfs_add_ordered_extent(struct btrfs_inode *inode, u64 file_offset,
+                            u64 num_bytes, u64 ram_bytes, u64 disk_bytenr,
+                            u64 disk_num_bytes, u64 offset, unsigned flags,
+                            int compress_type)
+{
+       struct btrfs_ordered_extent *ordered;
+
+       ordered = btrfs_alloc_ordered_extent(inode, file_offset, num_bytes,
+                                            ram_bytes, disk_bytenr,
+                                            disk_num_bytes, offset, flags,
+                                            compress_type);
+
+       if (IS_ERR(ordered))
+               return PTR_ERR(ordered);
+       btrfs_put_ordered_extent(ordered);
+
        return 0;
 }
 

diff --git a/fs/btrfs/ordered-data.h b/fs/btrfs/ordered-data.h
index eb40cb39f842e6627f04ec174e06bb918d9af43b..c00a5a3f060fa2d6e7f077602f7534f45f79695a 100644 (file)
--- a/fs/btrfs/ordered-data.h
+++ b/fs/btrfs/ordered-data.h
@@ -178,6 +178,11 @@ void btrfs_mark_ordered_io_finished(struct btrfs_inode *inode,
 bool btrfs_dec_test_ordered_pending(struct btrfs_inode *inode,
                                    struct btrfs_ordered_extent **cached,
                                    u64 file_offset, u64 io_size);
+struct btrfs_ordered_extent *btrfs_alloc_ordered_extent(
+                       struct btrfs_inode *inode, u64 file_offset,
+                       u64 num_bytes, u64 ram_bytes, u64 disk_bytenr,
+                       u64 disk_num_bytes, u64 offset, unsigned long flags,
+                       int compress_type);
 int btrfs_add_ordered_extent(struct btrfs_inode *inode, u64 file_offset,
                             u64 num_bytes, u64 ram_bytes, u64 disk_bytenr,
                             u64 disk_num_bytes, u64 offset, unsigned flags,