btrfs: make the delalloc block rsv per inode

The way we handle delalloc metadata reservations has gotten
progressively more complicated over the years.  There is so much cruft
and weirdness around keeping the reserved count and outstanding counters
consistent and handling the error cases that it's impossible to
understand.

Fix this by making the delalloc block rsv per-inode.  This way we can
calculate the actual size of the outstanding metadata reservations every
time we make a change, and then reserve the delta based on that amount.
This greatly simplifies the code everywhere, and makes the error
handling in btrfs_delalloc_reserve_metadata far less terrifying.

Signed-off-by: Josef Bacik <jbacik@fb.com>
Signed-off-by: David Sterba <dsterba@suse.com>

1 files changed, 9 insertions, 17 deletions

diff --git a/fs/btrfs/btrfs_inode.h b/fs/btrfs/btrfs_inode.h
index 427c8738a3bd..63f0ccc92a71 100644
--- a/fs/btrfs/btrfs_inode.h
+++ b/fs/btrfs/btrfs_inode.h
@@ -36,14 +36,13 @@
 #define BTRFS_INODE_ORPHAN_META_RESERVED	1
 #define BTRFS_INODE_DUMMY			2
 #define BTRFS_INODE_IN_DEFRAG			3
-#define BTRFS_INODE_DELALLOC_META_RESERVED	4
-#define BTRFS_INODE_HAS_ORPHAN_ITEM		5
-#define BTRFS_INODE_HAS_ASYNC_EXTENT		6
-#define BTRFS_INODE_NEEDS_FULL_SYNC		7
-#define BTRFS_INODE_COPY_EVERYTHING		8
-#define BTRFS_INODE_IN_DELALLOC_LIST		9
-#define BTRFS_INODE_READDIO_NEED_LOCK		10
-#define BTRFS_INODE_HAS_PROPS		        11
+#define BTRFS_INODE_HAS_ORPHAN_ITEM		4
+#define BTRFS_INODE_HAS_ASYNC_EXTENT		5
+#define BTRFS_INODE_NEEDS_FULL_SYNC		6
+#define BTRFS_INODE_COPY_EVERYTHING		7
+#define BTRFS_INODE_IN_DELALLOC_LIST		8
+#define BTRFS_INODE_READDIO_NEED_LOCK		9
+#define BTRFS_INODE_HAS_PROPS		        10
 
 /* in memory btrfs inode */
 struct btrfs_inode {
@@ -176,7 +175,8 @@ struct btrfs_inode {
 	 * of extent items we've reserved metadata for.
 	 */
 	unsigned outstanding_extents;
-	unsigned reserved_extents;
+
+	struct btrfs_block_rsv block_rsv;
 
 	/*
 	 * Cached values of inode properties
@@ -278,14 +278,6 @@ static inline void btrfs_mod_outstanding_extents(struct btrfs_inode *inode,
 						  mod);
 }
 
-static inline void btrfs_mod_reserved_extents(struct btrfs_inode *inode, int mod)
-{
-	lockdep_assert_held(&inode->lock);
-	inode->reserved_extents += mod;
-	if (btrfs_is_free_space_inode(inode))
-		return;
-}
-
 static inline int btrfs_inode_in_log(struct btrfs_inode *inode, u64 generation)
 {
 	int ret = 0;