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UBIFS: use bit-fields to store compression type

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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>
This commit is contained in:
Artem Bityutskiy 2008-11-01 14:20:50 +02:00
parent 062e4fee44
commit a1dc080c27
2 changed files with 11 additions and 3 deletions
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8
fs/ubifs/super.c
View file

@ -2020,6 +2020,14 @@ static int __init ubifs_init(void)
BUILD_BUG_ON(UBIFS_INO_NODE_SZ != 160);
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.

6
fs/ubifs/ubifs.h
View file

@ -386,12 +386,12 @@ struct ubifs_inode {
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 @@ struct ubifs_mount_opts {
* @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 @@ struct ubifs_mount_opts {
* @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 @@ struct ubifs_info {
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 @@ struct ubifs_info {
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);