[RFC] [PATCH 7/8] inode-diet: Use a union for i_blocks and i_size, i_rdev and i_devices

Theodore Tso
2006-06-19T15:31:38Z

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The i_blocks and i_size fields are only used for regular files. So we
move them into the union, along with i_rdev and i_devices, which are
only used by block or character devices.

Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>

Index: linux-2.6.17/include/linux/fs.h
===================================================================
--- linux-2.6.17.orig/include/linux/fs.h 2006-06-18 19:59:59.000000000 -0400
+++ linux-2.6.17/include/linux/fs.h 2006-06-19 07:29:36.000000000 -0400
@@ -486,15 +486,12 @@
unsigned int i_nlink;
uid_t i_uid;
gid_t i_gid;
- dev_t i_rdev;
loff_t i_size;
struct timespec i_atime;
struct timespec i_mtime;
struct timespec i_ctime;
unsigned int i_blkbits;
unsigned long i_version;
- blkcnt_t i_blocks;
- unsigned short i_bytes;
spinlock_t i_lock; /* i_blocks, i_bytes, maybe i_size */
struct mutex i_mutex;
struct rw_semaphore i_alloc_sem;
@@ -507,11 +504,20 @@
#ifdef CONFIG_QUOTA
struct dquot *i_dquot[MAXQUOTAS];
#endif
- struct list_head i_devices;
union {
struct pipe_inode_info *i_pipe;
- struct block_device *i_bdev;
- struct cdev *i_cdev;
+ struct {
+ union {
+ struct block_device *i_bdev;
+ struct cdev *i_cdev;
+ };
+ dev_t i_rdev;
+ struct list_head i_devices;
+ };
+ struct {
+ unsigned short i_bytes;
+ blkcnt_t i_blocks;
+ };
};

__u32 i_generation;

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