UBIFS: use bit-fields to store compression type
Save a 4 bytes of RAM per 'struct inode' by stroring inode
compression type in bit-filed, instead of using 'int'.
Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>
diff --git a/fs/ubifs/super.c b/fs/ubifs/super.c
index d80b2aef..21b4103 100644
--- a/fs/ubifs/super.c
+++ b/fs/ubifs/super.c
@@ -2021,6 +2021,14 @@
BUILD_BUG_ON(UBIFS_REF_NODE_SZ != 64);
/*
+ * We use 2 bit wide bit-fields to store compression type, which should
+ * be amended if more compressors are added. The bit-fields are:
+ * @compr_type in 'struct ubifs_inode' and @default_compr in
+ * 'struct ubifs_info'.
+ */
+ BUILD_BUG_ON(UBIFS_COMPR_TYPES_CNT > 4);
+
+ /*
* We require that PAGE_CACHE_SIZE is greater-than-or-equal-to
* UBIFS_BLOCK_SIZE. It is assumed that both are powers of 2.
*/
diff --git a/fs/ubifs/ubifs.h b/fs/ubifs/ubifs.h
index 46b1725..4d76aba 100644
--- a/fs/ubifs/ubifs.h
+++ b/fs/ubifs/ubifs.h
@@ -386,12 +386,12 @@
unsigned int dirty:1;
unsigned int xattr:1;
unsigned int bulk_read:1;
+ unsigned int compr_type:2;
struct mutex ui_mutex;
spinlock_t ui_lock;
loff_t synced_i_size;
loff_t ui_size;
int flags;
- int compr_type;
pgoff_t last_page_read;
pgoff_t read_in_a_row;
int data_len;
@@ -946,6 +946,7 @@
* @no_chk_data_crc: do not check CRCs when reading data nodes (except during
* recovery)
* @bulk_read: enable bulk-reads
+ * @default_compr: default compression algorithm (%UBIFS_COMPR_LZO, etc)
*
* @tnc_mutex: protects the Tree Node Cache (TNC), @zroot, @cnext, @enext, and
* @calc_idx_sz
@@ -986,7 +987,6 @@
* @main_lebs: count of LEBs in the main area
* @main_first: first LEB of the main area
* @main_bytes: main area size in bytes
- * @default_compr: default compression algorithm (%UBIFS_COMPR_LZO, etc)
*
* @key_hash_type: type of the key hash
* @key_hash: direntry key hash function
@@ -1196,6 +1196,7 @@
unsigned int big_lpt:1;
unsigned int no_chk_data_crc:1;
unsigned int bulk_read:1;
+ unsigned int default_compr:2;
struct mutex tnc_mutex;
struct ubifs_zbranch zroot;
@@ -1237,7 +1238,6 @@
int main_lebs;
int main_first;
long long main_bytes;
- int default_compr;
uint8_t key_hash_type;
uint32_t (*key_hash)(const char *str, int len);