Btrfs: Split the extent_map code into two parts

There is now extent_map for mapping offsets in the file to disk and
extent_io for state tracking, IO submission and extent_bufers.

The new extent_map code shifts from [start,end] pairs to [start,len], and
pushes the locking out into the caller.  This allows a few performance
optimizations and is easier to use.

A number of extent_map usage bugs were fixed, mostly with failing
to remove extent_map entries when changing the file.

Signed-off-by: Chris Mason <chris.mason@oracle.com>

1 files changed, 26 insertions, 188 deletions

diff --git a/fs/btrfs/extent_map.h b/fs/btrfs/extent_map.h
index ea60f5447b5b..56314217cfc0 100644
--- a/fs/btrfs/extent_map.h
+++ b/fs/btrfs/extent_map.h
@@ -3,215 +3,53 @@
 
 #include <linux/rbtree.h>
 
+#define EXTENT_MAP_LAST_BYTE (u64)-4
 #define EXTENT_MAP_HOLE (u64)-3
 #define EXTENT_MAP_INLINE (u64)-2
 #define EXTENT_MAP_DELALLOC (u64)-1
 
-/* bits for the extent state */
-#define EXTENT_DIRTY 1
-#define EXTENT_WRITEBACK (1 << 1)
-#define EXTENT_UPTODATE (1 << 2)
-#define EXTENT_LOCKED (1 << 3)
-#define EXTENT_NEW (1 << 4)
-#define EXTENT_DELALLOC (1 << 5)
-#define EXTENT_DEFRAG (1 << 6)
-#define EXTENT_DEFRAG_DONE (1 << 7)
-#define EXTENT_BUFFER_FILLED (1 << 8)
-#define EXTENT_CSUM (1 << 9)
-#define EXTENT_IOBITS (EXTENT_LOCKED | EXTENT_WRITEBACK)
-
-/*
- * page->private values.  Every page that is controlled by the extent
- * map has page->private set to one.
- */
-#define EXTENT_PAGE_PRIVATE 1
-#define EXTENT_PAGE_PRIVATE_FIRST_PAGE 3
-
-
-struct extent_map_ops {
-        int (*fill_delalloc)(struct inode *inode, u64 start, u64 end);
-        int (*writepage_io_hook)(struct page *page, u64 start, u64 end);
-        int (*readpage_io_hook)(struct page *page, u64 start, u64 end);
-        int (*readpage_end_io_hook)(struct page *page, u64 start, u64 end);
-        void (*writepage_end_io_hook)(struct page *page, u64 start, u64 end);
-};
-
-struct extent_map_tree {
-        struct rb_root map;
-        struct rb_root state;
-        struct address_space *mapping;
-        u64 dirty_bytes;
-        rwlock_t lock;
-        struct extent_map_ops *ops;
-        spinlock_t lru_lock;
-        struct list_head buffer_lru;
-        int lru_size;
-};
-
-/* note, this must start with the same fields as fs/extent_map.c:tree_entry */
 struct extent_map {
-        u64 start;
-        u64 end; /* inclusive */
-        int in_tree;
         struct rb_node rb_node;
-        /* block_start and block_end are in bytes */
+
+        /* all of these are in bytes */
+        u64 start;
+        u64 len;
         u64 block_start;
-        u64 block_end; /* inclusive */
+        unsigned long flags;
         struct block_device *bdev;
         atomic_t refs;
-};
-
-/* note, this must start with the same fields as fs/extent_map.c:tree_entry */
-struct extent_state {
-        u64 start;
-        u64 end; /* inclusive */
         int in_tree;
-        struct rb_node rb_node;
-        wait_queue_head_t wq;
-        atomic_t refs;
-        unsigned long state;
-
-        /* for use by the FS */
-        u64 private;
-
-        struct list_head list;
 };
 
-struct extent_buffer {
-        u64 start;
-        unsigned long len;
-        char *map_token;
-        char *kaddr;
-        unsigned long map_start;
-        unsigned long map_len;
-        struct page *first_page;
-        struct list_head lru;
-        atomic_t refs;
-        int flags;
+struct extent_map_tree {
+        struct rb_root map;
+        struct extent_map *last;
+        spinlock_t lock;
 };
 
-typedef struct extent_map *(get_extent_t)(struct inode *inode,
-                                          struct page *page,
-                                          size_t page_offset,
-                                          u64 start, u64 end,
-                                          int create);
+static inline u64 extent_map_end(struct extent_map *em)
+{
+        if (em->start + em->len < em->start)
+                return (u64)-1;
+        return em->start + em->len;
+}
+
+static inline u64 extent_map_block_end(struct extent_map *em)
+{
+        if (em->block_start + em->len < em->block_start)
+                return (u64)-1;
+        return em->block_start + em->len;
+}
 
-void extent_map_tree_init(struct extent_map_tree *tree,
-                          struct address_space *mapping, gfp_t mask);
-void extent_map_tree_empty_lru(struct extent_map_tree *tree);
+void extent_map_tree_init(struct extent_map_tree *tree, gfp_t mask);
 struct extent_map *lookup_extent_mapping(struct extent_map_tree *tree,
-                                         u64 start, u64 end);
+                                         u64 start, u64 len);
 int add_extent_mapping(struct extent_map_tree *tree,
                        struct extent_map *em);
 int remove_extent_mapping(struct extent_map_tree *tree, struct extent_map *em);
-int try_release_extent_mapping(struct extent_map_tree *tree, struct page *page);
-int lock_extent(struct extent_map_tree *tree, u64 start, u64 end, gfp_t mask);
-int unlock_extent(struct extent_map_tree *tree, u64 start, u64 end, gfp_t mask);
+
 struct extent_map *alloc_extent_map(gfp_t mask);
 void free_extent_map(struct extent_map *em);
-int extent_read_full_page(struct extent_map_tree *tree, struct page *page,
-                          get_extent_t *get_extent);
 int __init extent_map_init(void);
 void extent_map_exit(void);
-
-u64 count_range_bits(struct extent_map_tree *tree,
-                     u64 *start, u64 search_end,
-                     u64 max_bytes, unsigned long bits);
-
-int test_range_bit(struct extent_map_tree *tree, u64 start, u64 end,
-                   int bits, int filled);
-int clear_extent_bits(struct extent_map_tree *tree, u64 start, u64 end,
-                      int bits, gfp_t mask);
-int set_extent_bits(struct extent_map_tree *tree, u64 start, u64 end,
-                    int bits, gfp_t mask);
-int set_extent_uptodate(struct extent_map_tree *tree, u64 start, u64 end,
-                        gfp_t mask);
-int set_extent_new(struct extent_map_tree *tree, u64 start, u64 end,
-                   gfp_t mask);
-int set_extent_dirty(struct extent_map_tree *tree, u64 start, u64 end,
-                     gfp_t mask);
-int clear_extent_dirty(struct extent_map_tree *tree, u64 start, u64 end,
-                       gfp_t mask);
-int set_extent_delalloc(struct extent_map_tree *tree, u64 start, u64 end,
-                     gfp_t mask);
-int find_first_extent_bit(struct extent_map_tree *tree, u64 start,
-                          u64 *start_ret, u64 *end_ret, int bits);
-int extent_invalidatepage(struct extent_map_tree *tree,
-                          struct page *page, unsigned long offset);
-int extent_write_full_page(struct extent_map_tree *tree, struct page *page,
-                          get_extent_t *get_extent,
-                          struct writeback_control *wbc);
-int extent_writepages(struct extent_map_tree *tree,
-                      struct address_space *mapping,
-                      get_extent_t *get_extent,
-                      struct writeback_control *wbc);
-int extent_readpages(struct extent_map_tree *tree,
-                     struct address_space *mapping,
-                     struct list_head *pages, unsigned nr_pages,
-                     get_extent_t get_extent);
-int extent_prepare_write(struct extent_map_tree *tree,
-                         struct inode *inode, struct page *page,
-                         unsigned from, unsigned to, get_extent_t *get_extent);
-int extent_commit_write(struct extent_map_tree *tree,
-                        struct inode *inode, struct page *page,
-                        unsigned from, unsigned to);
-sector_t extent_bmap(struct address_space *mapping, sector_t iblock,
-                get_extent_t *get_extent);
-int set_range_dirty(struct extent_map_tree *tree, u64 start, u64 end);
-int set_state_private(struct extent_map_tree *tree, u64 start, u64 private);
-int get_state_private(struct extent_map_tree *tree, u64 start, u64 *private);
-void set_page_extent_mapped(struct page *page);
-
-struct extent_buffer *alloc_extent_buffer(struct extent_map_tree *tree,
-                                          u64 start, unsigned long len,
-                                          struct page *page0,
-                                          gfp_t mask);
-struct extent_buffer *find_extent_buffer(struct extent_map_tree *tree,
-                                         u64 start, unsigned long len,
-                                          gfp_t mask);
-void free_extent_buffer(struct extent_buffer *eb);
-int read_extent_buffer_pages(struct extent_map_tree *tree,
-                             struct extent_buffer *eb, u64 start, int wait);
-
-static inline void extent_buffer_get(struct extent_buffer *eb)
-{
-        atomic_inc(&eb->refs);
-}
-
-int memcmp_extent_buffer(struct extent_buffer *eb, const void *ptrv,
-                          unsigned long start,
-                          unsigned long len);
-void read_extent_buffer(struct extent_buffer *eb, void *dst,
-                        unsigned long start,
-                        unsigned long len);
-void write_extent_buffer(struct extent_buffer *eb, const void *src,
-                         unsigned long start, unsigned long len);
-void copy_extent_buffer(struct extent_buffer *dst, struct extent_buffer *src,
-                        unsigned long dst_offset, unsigned long src_offset,
-                        unsigned long len);
-void memcpy_extent_buffer(struct extent_buffer *dst, unsigned long dst_offset,
-                           unsigned long src_offset, unsigned long len);
-void memmove_extent_buffer(struct extent_buffer *dst, unsigned long dst_offset,
-                           unsigned long src_offset, unsigned long len);
-void memset_extent_buffer(struct extent_buffer *eb, char c,
-                          unsigned long start, unsigned long len);
-int wait_on_extent_buffer_writeback(struct extent_map_tree *tree,
-                                    struct extent_buffer *eb);
-int clear_extent_buffer_dirty(struct extent_map_tree *tree,
-                              struct extent_buffer *eb);
-int set_extent_buffer_dirty(struct extent_map_tree *tree,
-                             struct extent_buffer *eb);
-int set_extent_buffer_uptodate(struct extent_map_tree *tree,
-                               struct extent_buffer *eb);
-int extent_buffer_uptodate(struct extent_map_tree *tree,
-                           struct extent_buffer *eb);
-int map_extent_buffer(struct extent_buffer *eb, unsigned long offset,
-                      unsigned long min_len, char **token, char **map,
-                      unsigned long *map_start,
-                      unsigned long *map_len, int km);
-int map_private_extent_buffer(struct extent_buffer *eb, unsigned long offset,
-                      unsigned long min_len, char **token, char **map,
-                      unsigned long *map_start,
-                      unsigned long *map_len, int km);
-void unmap_extent_buffer(struct extent_buffer *eb, char *token, int km);
 #endif