f2fs: add annotation for space utilization of regular/inline dentry
Add annotation to let us know more clearly about space utilization
information of regular dentry and inline dentry.
Signed-off-by: Chao Yu <chao2.yu@samsung.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
diff --git a/include/linux/f2fs_fs.h b/include/linux/f2fs_fs.h
index 920408a..25c6324 100644
--- a/include/linux/f2fs_fs.h
+++ b/include/linux/f2fs_fs.h
@@ -417,15 +417,25 @@
#define GET_DENTRY_SLOTS(x) ((x + F2FS_SLOT_LEN - 1) >> F2FS_SLOT_LEN_BITS)
-/* the number of dentry in a block */
-#define NR_DENTRY_IN_BLOCK 214
-
/* MAX level for dir lookup */
#define MAX_DIR_HASH_DEPTH 63
/* MAX buckets in one level of dir */
#define MAX_DIR_BUCKETS (1 << ((MAX_DIR_HASH_DEPTH / 2) - 1))
+/*
+ * space utilization of regular dentry and inline dentry
+ * regular dentry inline dentry
+ * bitmap 1 * 27 = 27 1 * 23 = 23
+ * reserved 1 * 3 = 3 1 * 7 = 7
+ * dentry 11 * 214 = 2354 11 * 182 = 2002
+ * filename 8 * 214 = 1712 8 * 182 = 1456
+ * total 4096 3488
+ *
+ * Note: there are more reserved space in inline dentry than in regular
+ * dentry, when converting inline dentry we should handle this carefully.
+ */
+#define NR_DENTRY_IN_BLOCK 214 /* the number of dentry in a block */
#define SIZE_OF_DIR_ENTRY 11 /* by byte */
#define SIZE_OF_DENTRY_BITMAP ((NR_DENTRY_IN_BLOCK + BITS_PER_BYTE - 1) / \
BITS_PER_BYTE)
