ext4: drop i_state_flags on architectures with 64-bit longs
We can store the dynamic inode state flags in the high bits of
EXT4_I(inode)->i_flags, and eliminate i_state_flags. This saves 8
bytes from the size of ext4_inode_info structure, which when
multiplied by the number of the number of in the inode cache, can save
a lot of memory.
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
index 50e3d24..2fb531c 100644
--- a/fs/ext4/ext4.h
+++ b/fs/ext4/ext4.h
@@ -764,7 +764,9 @@
*/
ext4_group_t i_block_group;
ext4_lblk_t i_dir_start_lookup;
+#if (BITS_PER_LONG < 64)
unsigned long i_state_flags; /* Dynamic state flags */
+#endif
unsigned long i_flags;
#ifdef CONFIG_EXT4_FS_XATTR
@@ -1239,22 +1241,36 @@
EXT4_STATE_DELALLOC_RESERVED, /* blks already reserved for delalloc */
};
-#define EXT4_INODE_BIT_FNS(name, field) \
+#define EXT4_INODE_BIT_FNS(name, field, offset) \
static inline int ext4_test_inode_##name(struct inode *inode, int bit) \
{ \
- return test_bit(bit, &EXT4_I(inode)->i_##field); \
+ return test_bit(bit + (offset), &EXT4_I(inode)->i_##field); \
} \
static inline void ext4_set_inode_##name(struct inode *inode, int bit) \
{ \
- set_bit(bit, &EXT4_I(inode)->i_##field); \
+ set_bit(bit + (offset), &EXT4_I(inode)->i_##field); \
} \
static inline void ext4_clear_inode_##name(struct inode *inode, int bit) \
{ \
- clear_bit(bit, &EXT4_I(inode)->i_##field); \
+ clear_bit(bit + (offset), &EXT4_I(inode)->i_##field); \
}
-EXT4_INODE_BIT_FNS(flag, flags)
-EXT4_INODE_BIT_FNS(state, state_flags)
+EXT4_INODE_BIT_FNS(flag, flags, 0)
+#if (BITS_PER_LONG < 64)
+EXT4_INODE_BIT_FNS(state, state_flags, 0)
+
+static inline void ext4_clear_state_flags(struct ext4_inode_info *ei)
+{
+ (ei)->i_state_flags = 0;
+}
+#else
+EXT4_INODE_BIT_FNS(state, flags, 32)
+
+static inline void ext4_clear_state_flags(struct ext4_inode_info *ei)
+{
+ /* We depend on the fact that callers will set i_flags */
+}
+#endif
#else
/* Assume that user mode programs are passing in an ext4fs superblock, not
* a kernel struct super_block. This will allow us to call the feature-test