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writeback: Do not sort b_io list only because of block device inode

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It is very likely that block device inode will be part of BDI dirty list
as well. However it doesn't make sence to sort inodes on the b_io list
just because of this inode (as it contains buffers all over the device
anyway). So save some CPU cycles which is valuable since we hold relatively
contented wb->list_lock.

Signed-off-by: Jan Kara <jack@suse.cz>
This commit is contained in:
Jan Kara 2013-07-09 22:36:45 +08:00 committed by Fengguang Wu
parent 8bb495e3f0
commit a8855990e3
3 changed files with 12 additions and 4 deletions
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2
fs/block_dev.c
View File

@ -606,7 +606,7 @@ static struct block_device *bd_acquire(struct inode *inode)
return bdev;
}
static inline int sb_is_blkdev_sb(struct super_block *sb)
int sb_is_blkdev_sb(struct super_block *sb)
{
return sb == blockdev_superblock;
}

8
fs/fs-writeback.c
View File

@ -68,7 +68,7 @@ static inline struct backing_dev_info *inode_to_bdi(struct inode *inode)
{
struct super_block *sb = inode->i_sb;
if (strcmp(sb->s_type->name, "bdev") == 0)
if (sb_is_blkdev_sb(sb))
return inode->i_mapping->backing_dev_info;
return sb->s_bdi;
@ -250,11 +250,13 @@ static int move_expired_inodes(struct list_head *delaying_queue,
if (work->older_than_this &&
inode_dirtied_after(inode, *work->older_than_this))
break;
list_move(&inode->i_wb_list, &tmp);
moved++;
if (sb_is_blkdev_sb(inode->i_sb))
continue;
if (sb && sb != inode->i_sb)
do_sb_sort = 1;
sb = inode->i_sb;
list_move(&inode->i_wb_list, &tmp);
moved++;
}
/* just one sb in list, splice to dispatch_queue and we're done */

6
include/linux/fs.h
View File

@ -2058,6 +2058,7 @@ extern struct super_block *freeze_bdev(struct block_device *);
extern void emergency_thaw_all(void);
extern int thaw_bdev(struct block_device *bdev, struct super_block *sb);
extern int fsync_bdev(struct block_device *);
extern int sb_is_blkdev_sb(struct super_block *sb);
#else
static inline void bd_forget(struct inode *inode) {}
static inline int sync_blockdev(struct block_device *bdev) { return 0; }
@ -2077,6 +2078,11 @@ static inline int thaw_bdev(struct block_device *bdev, struct super_block *sb)
static inline void iterate_bdevs(void (*f)(struct block_device *, void *), void *arg)
{
}
static inline int sb_is_blkdev_sb(struct super_block *sb)
{
return 0;
}
#endif
extern int sync_filesystem(struct super_block *);
extern const struct file_operations def_blk_fops;