inode->i_devices is a list_head used to link device inodes to the corresponding block_device or cdev. This patch makes block_device and cdev usfe ptrset to keep track of the inodes instead of linking inode->i_devices allowing removal of the field and thus reduction of struct inode by two pointers.
The conversion is staright-forward. list_add() is replaced with preloaded ptrset_add(), list_del_init() with ptrset_del(), and list iteration with ptrset_for_each(). The only part which isn't direct one-to-one mapping is the error handling after ptrset_add() failure. The saved two pointers will be used by cgroup writback support. Signed-off-by: Tejun Heo <[email protected]> Cc: Alexander Viro <[email protected]> Cc: Jens Axboe <[email protected]> Cc: Christoph Hellwig <[email protected]> --- fs/block_dev.c | 39 +++++++++++++++++++++++---------------- fs/char_dev.c | 25 +++++++++++++++---------- fs/inode.c | 1 - include/linux/cdev.h | 4 ++-- include/linux/fs.h | 4 ++-- 5 files changed, 42 insertions(+), 31 deletions(-) --- a/fs/block_dev.c +++ b/fs/block_dev.c @@ -458,7 +458,7 @@ static void init_once(void *foo) memset(bdev, 0, sizeof(*bdev)); mutex_init(&bdev->bd_mutex); - INIT_LIST_HEAD(&bdev->bd_inodes); + ptrset_init(&bdev->bd_inodes); INIT_LIST_HEAD(&bdev->bd_list); #ifdef CONFIG_SYSFS INIT_LIST_HEAD(&bdev->bd_holder_disks); @@ -470,7 +470,7 @@ static void init_once(void *foo) static inline void __bd_forget(struct inode *inode) { - list_del_init(&inode->i_devices); + ptrset_del(inode, &inode->i_bdev->bd_inodes); inode->i_bdev = NULL; inode->i_mapping = &inode->i_data; } @@ -478,14 +478,15 @@ static inline void __bd_forget(struct in static void bdev_evict_inode(struct inode *inode) { struct block_device *bdev = &BDEV_I(inode)->bdev; - struct list_head *p; + struct ptrset_iter iter; + struct inode *bd_inode; + truncate_inode_pages_final(&inode->i_data); invalidate_inode_buffers(inode); /* is it needed here? */ clear_inode(inode); spin_lock(&bdev_lock); - while ( (p = bdev->bd_inodes.next) != &bdev->bd_inodes ) { - __bd_forget(list_entry(p, struct inode, i_devices)); - } + ptrset_for_each(bd_inode, &bdev->bd_inodes, &iter) + __bd_forget(bd_inode); list_del_init(&bdev->bd_list); spin_unlock(&bdev_lock); } @@ -634,20 +635,26 @@ static struct block_device *bd_acquire(s bdev = bdget(inode->i_rdev); if (bdev) { + ptrset_preload(GFP_KERNEL); spin_lock(&bdev_lock); if (!inode->i_bdev) { - /* - * We take an additional reference to bd_inode, - * and it's released in clear_inode() of inode. - * So, we can access it via ->i_mapping always - * without igrab(). - */ - ihold(bdev->bd_inode); - inode->i_bdev = bdev; - inode->i_mapping = bdev->bd_inode->i_mapping; - list_add(&inode->i_devices, &bdev->bd_inodes); + if (!ptrset_add(inode, &bdev->bd_inodes, GFP_NOWAIT)) { + /* + * We take an additional reference to bd_inode, + * and it's released in clear_inode() of inode. + * So, we can access it via ->i_mapping always + * without igrab(). + */ + ihold(bdev->bd_inode); + inode->i_bdev = bdev; + inode->i_mapping = bdev->bd_inode->i_mapping; + } else { + bdput(bdev); + bdev = NULL; + } } spin_unlock(&bdev_lock); + ptrset_preload_end(); } return bdev; } --- a/fs/char_dev.c +++ b/fs/char_dev.c @@ -383,16 +383,20 @@ static int chrdev_open(struct inode *ino if (!kobj) return -ENXIO; new = container_of(kobj, struct cdev, kobj); + ptrset_preload(GFP_KERNEL); spin_lock(&cdev_lock); /* Check i_cdev again in case somebody beat us to it while we dropped the lock. */ p = inode->i_cdev; if (!p) { - inode->i_cdev = p = new; - list_add(&inode->i_devices, &p->list); - new = NULL; + ret = ptrset_add(inode, &new->inodes, GFP_NOWAIT); + if (!ret) { + inode->i_cdev = p = new; + new = NULL; + } } else if (!cdev_get(p)) ret = -ENXIO; + ptrset_preload_end(); } else if (!cdev_get(p)) ret = -ENXIO; spin_unlock(&cdev_lock); @@ -422,18 +426,19 @@ static int chrdev_open(struct inode *ino void cd_forget(struct inode *inode) { spin_lock(&cdev_lock); - list_del_init(&inode->i_devices); + ptrset_del(inode, &inode->i_cdev->inodes); inode->i_cdev = NULL; spin_unlock(&cdev_lock); } static void cdev_purge(struct cdev *cdev) { + struct inode *inode; + struct ptrset_iter iter; + spin_lock(&cdev_lock); - while (!list_empty(&cdev->list)) { - struct inode *inode; - inode = container_of(cdev->list.next, struct inode, i_devices); - list_del_init(&inode->i_devices); + ptrset_for_each(inode, &cdev->inodes, &iter) { + ptrset_del(inode, &cdev->inodes); inode->i_cdev = NULL; } spin_unlock(&cdev_lock); @@ -543,7 +548,7 @@ struct cdev *cdev_alloc(void) { struct cdev *p = kzalloc(sizeof(struct cdev), GFP_KERNEL); if (p) { - INIT_LIST_HEAD(&p->list); + ptrset_init(&p->inodes); kobject_init(&p->kobj, &ktype_cdev_dynamic); } return p; @@ -560,7 +565,7 @@ struct cdev *cdev_alloc(void) void cdev_init(struct cdev *cdev, const struct file_operations *fops) { memset(cdev, 0, sizeof *cdev); - INIT_LIST_HEAD(&cdev->list); + ptrset_init(&cdev->inodes); kobject_init(&cdev->kobj, &ktype_cdev_default); cdev->ops = fops; } --- a/fs/inode.c +++ b/fs/inode.c @@ -366,7 +366,6 @@ void inode_init_once(struct inode *inode { memset(inode, 0, sizeof(*inode)); INIT_HLIST_NODE(&inode->i_hash); - INIT_LIST_HEAD(&inode->i_devices); INIT_LIST_HEAD(&inode->i_wb_list); INIT_LIST_HEAD(&inode->i_lru); address_space_init_once(&inode->i_data); --- a/include/linux/cdev.h +++ b/include/linux/cdev.h @@ -3,7 +3,7 @@ #include <linux/kobject.h> #include <linux/kdev_t.h> -#include <linux/list.h> +#include <linux/ptrset.h> struct file_operations; struct inode; @@ -13,7 +13,7 @@ struct cdev { struct kobject kobj; struct module *owner; const struct file_operations *ops; - struct list_head list; + struct ptrset inodes; dev_t dev; unsigned int count; }; --- a/include/linux/fs.h +++ b/include/linux/fs.h @@ -28,6 +28,7 @@ #include <linux/uidgid.h> #include <linux/lockdep.h> #include <linux/percpu-rwsem.h> +#include <linux/ptrset.h> #include <linux/blk_types.h> #include <asm/byteorder.h> @@ -426,7 +427,7 @@ struct block_device { struct inode * bd_inode; /* will die */ struct super_block * bd_super; struct mutex bd_mutex; /* open/close mutex */ - struct list_head bd_inodes; + struct ptrset bd_inodes; void * bd_claiming; void * bd_holder; int bd_holders; @@ -609,7 +610,6 @@ struct inode { #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; -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
