btrfs-progs: remove btrfs_fs_info::leaf_data_size

[BUG]
There is a bug report that legacy code of "btrfs rescue chunk-recover"
is triggering false alerts from tree-checker, and refuse to work:

  # btrfs rescue chunk-recover /dev/nvme1n1p1
  Scanning: DONE in dev0
  corrupt leaf: root=1 block=13924671995904 slot=0, unexpected item end, have 16283 expect 0 <<< Note the "expect 0"
  leaf 13924671995904 items 11 free space 12709 generation 1589644 owner ROOT_TREE
  leaf 13924671995904 flags 0x1(WRITTEN) backref revision 1
  [...]
  Couldn't read tree root
  open with broken chunk error

[CAUSE]
The item end checks is from __btrfs_check_leaf() from tree-checker,
and for the first slot of a leaf, the expected end should be
BTRFS_LEAF_DATA_SIZE(), which is fetched from fs_info->leaf_data_size.

However for the fs_info opened by chunk recover, it's not going through
the regular open_ctree(), but open_ctree_with_broken_chunk(), which
doesn't populate that member and resulting BTRFS_LEAF_DATA_SIZE() to
return 0.

[FIX]
There is no need to cache leaf_data_size, as it can be easily calculated
using nodesize.

And kernel is already doing that, so follow the kernel to remove
btrfs_fs_info::leaf_data_size, and use a simple inline function to do
the calculation instead.

Pull-request: #1039
Reported-by: Mikhail Gavrilov <mikhail.v.gavrilov@gmail.com>
Link: https://lore.kernel.org/linux-btrfs/CABXGCsOug_bxVZ5CN1EM0sd9U4JAz=Jf5EB2TQe8gs9=KZvWEA@mail.gmail.com/
Signed-off-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

Author: adam900710

kernel-shared/ctree.h

@@ -69,8 +69,6 @@ static inline u32 __BTRFS_LEAF_DATA_SIZE(u32 nodesize)
 #define BTRFS_MIN_BLOCKSIZE	(SZ_4K)
 #endif
 
-#define BTRFS_LEAF_DATA_SIZE(fs_info) (fs_info->leaf_data_size)
-
 #define BTRFS_SUPER_INFO_OFFSET			(65536)
 #define BTRFS_SUPER_INFO_SIZE			(4096)
 
@@ -401,7 +399,6 @@ struct btrfs_fs_info {
 	u32 nodesize;
 	u32 sectorsize;
 	u32 stripesize;
-	u32 leaf_data_size;
 
 	/*
 	 * For open_ctree_fs_info() to hold the initial fd until close.
@@ -426,6 +423,11 @@ struct btrfs_fs_info {
 	struct super_block *sb;
 };
 
+static inline u32 BTRFS_LEAF_DATA_SIZE(const struct btrfs_fs_info *fs_info)
+{
+	return __BTRFS_LEAF_DATA_SIZE(fs_info->nodesize);
+}
+
 static inline bool btrfs_is_zoned(const struct btrfs_fs_info *fs_info)
 {
 	return fs_info->zoned != 0;

kernel-shared/disk-io.c

@@ -1604,7 +1604,6 @@ static struct btrfs_fs_info *__open_ctree_fd(int fp, struct open_ctree_args *oca
 	fs_info->stripesize = btrfs_super_stripesize(disk_super);
 	fs_info->csum_type = btrfs_super_csum_type(disk_super);
 	fs_info->csum_size = btrfs_super_csum_size(disk_super);
-	fs_info->leaf_data_size = __BTRFS_LEAF_DATA_SIZE(fs_info->nodesize);
 
 	ret = btrfs_check_fs_compatibility(fs_info->super_copy, flags);
 	if (ret)