writeback: Do not sort b_io list only because of block device inode
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>
diff --git a/fs/block_dev.c b/fs/block_dev.c
index 2091db8..2562330 100644
--- a/fs/block_dev.c
+++ b/fs/block_dev.c
@@ -606,7 +606,7 @@
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;
}
diff --git a/fs/fs-writeback.c b/fs/fs-writeback.c
index 3be5718..cabdece 100644
--- a/fs/fs-writeback.c
+++ b/fs/fs-writeback.c
@@ -68,7 +68,7 @@
{
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 @@
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 */
diff --git a/include/linux/fs.h b/include/linux/fs.h
index 65c2be2..61da2f1 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -2058,6 +2058,7 @@
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 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;
