btrfs: new define for the inline extent data start

Use a common definition for the inline data start so we don't have to
open-code it and introduce bugs like "Btrfs: fix wrong max inline data
size limit" fixed.

Signed-off-by: David Sterba <dsterba@suse.cz>

2 files changed, 9 insertions, 10 deletions

diff --git a/fs/btrfs/ctree.c b/fs/btrfs/ctree.c
index 39021bf2df9a..533657c508e2 100644
--- a/fs/btrfs/ctree.c
+++ b/fs/btrfs/ctree.c
@@ -4625,8 +4625,7 @@ void btrfs_truncate_item(struct btrfs_root *root, struct btrfs_path *path,
                                 ptr = btrfs_item_ptr_offset(leaf, slot);
                                 memmove_extent_buffer(leaf, ptr,
                                       (unsigned long)fi,
-                                      offsetof(struct btrfs_file_extent_item,
-                                                 disk_bytenr));
+                                      BTRFS_FILE_EXTENT_INLINE_DATA_START);
                         }
                 }
 
diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
index dd79ba7ee3ea..bae025a20e63 100644
--- a/fs/btrfs/ctree.h
+++ b/fs/btrfs/ctree.h
@@ -385,9 +385,11 @@ struct btrfs_header {
                                      sizeof(struct btrfs_key_ptr))
 #define __BTRFS_LEAF_DATA_SIZE(bs) ((bs) - sizeof(struct btrfs_header))
 #define BTRFS_LEAF_DATA_SIZE(r) (__BTRFS_LEAF_DATA_SIZE(r->nodesize))
+#define BTRFS_FILE_EXTENT_INLINE_DATA_START             \
+                (offsetof(struct btrfs_file_extent_item, disk_bytenr))
 #define BTRFS_MAX_INLINE_DATA_SIZE(r) (BTRFS_LEAF_DATA_SIZE(r) - \
                                         sizeof(struct btrfs_item) - \
-                                        offsetof(struct btrfs_file_extent_item, disk_bytenr))
+                                        BTRFS_FILE_EXTENT_INLINE_DATA_START)
 #define BTRFS_MAX_XATTR_SIZE(r) (BTRFS_LEAF_DATA_SIZE(r) - \
                                  sizeof(struct btrfs_item) -\
                                  sizeof(struct btrfs_dir_item))
@@ -896,6 +898,8 @@ struct btrfs_file_extent_item {
         /*
          * disk space consumed by the extent, checksum blocks are included
          * in these numbers
+         *
+         * At this offset in the structure, the inline extent data start.
          */
         __le64 disk_bytenr;
         __le64 disk_num_bytes;
@@ -3043,14 +3047,12 @@ BTRFS_SETGET_STACK_FUNCS(stack_file_extent_compression,
 static inline unsigned long
 btrfs_file_extent_inline_start(struct btrfs_file_extent_item *e)
 {
-        unsigned long offset = (unsigned long)e;
-        offset += offsetof(struct btrfs_file_extent_item, disk_bytenr);
-        return offset;
+        return (unsigned long)e + BTRFS_FILE_EXTENT_INLINE_DATA_START;
 }
 
 static inline u32 btrfs_file_extent_calc_inline_size(u32 datasize)
 {
-        return offsetof(struct btrfs_file_extent_item, disk_bytenr) + datasize;
+        return BTRFS_FILE_EXTENT_INLINE_DATA_START + datasize;
 }
 
 BTRFS_SETGET_FUNCS(file_extent_disk_bytenr, struct btrfs_file_extent_item,
@@ -3080,9 +3082,7 @@ BTRFS_SETGET_FUNCS(file_extent_other_encoding, struct btrfs_file_extent_item,
 static inline u32 btrfs_file_extent_inline_item_len(struct extent_buffer *eb,
                                                     struct btrfs_item *e)
 {
-        unsigned long offset;
-        offset = offsetof(struct btrfs_file_extent_item, disk_bytenr);
-        return btrfs_item_size(eb, e) - offset;
+        return btrfs_item_size(eb, e) - BTRFS_FILE_EXTENT_INLINE_DATA_START;
 }
 
 /* this returns the number of file bytes represented by the inline item.