From: Ryusuke Konishi Date: Wed, 8 Sep 2010 17:07:56 +0000 (+0900) Subject: nilfs2: simplify life cycle management of nilfs object X-Git-Tag: v2.6.37-rc1~150^2~18 X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=348fe8da13621b3d14ab2d156e74551611997017;p=profile%2Fivi%2Fkernel-x86-ivi.git nilfs2: simplify life cycle management of nilfs object This stops pre-allocating nilfs object in nilfs_get_sb routine, and stops managing its life cycle by reference counting. nilfs_find_or_create_nilfs() function, nilfs->ns_mount_mutex, nilfs_objects list, and the reference counter will be removed through the simplification. Signed-off-by: Ryusuke Konishi --- diff --git a/fs/nilfs2/ioctl.c b/fs/nilfs2/ioctl.c index 2ee6843..338858f 100644 --- a/fs/nilfs2/ioctl.c +++ b/fs/nilfs2/ioctl.c @@ -117,7 +117,7 @@ static int nilfs_ioctl_change_cpmode(struct inode *inode, struct file *filp, if (copy_from_user(&cpmode, argp, sizeof(cpmode))) goto out; - mutex_lock(&nilfs->ns_mount_mutex); + down_read(&inode->i_sb->s_umount); nilfs_transaction_begin(inode->i_sb, &ti, 0); ret = nilfs_cpfile_change_cpmode( @@ -127,7 +127,7 @@ static int nilfs_ioctl_change_cpmode(struct inode *inode, struct file *filp, else nilfs_transaction_commit(inode->i_sb); /* never fails */ - mutex_unlock(&nilfs->ns_mount_mutex); + up_read(&inode->i_sb->s_umount); out: mnt_drop_write(filp->f_path.mnt); return ret; diff --git a/fs/nilfs2/super.c b/fs/nilfs2/super.c index 2e58e7c..5893cb2 100644 --- a/fs/nilfs2/super.c +++ b/fs/nilfs2/super.c @@ -356,7 +356,7 @@ static void nilfs_put_super(struct super_block *sb) up_write(&nilfs->ns_sem); } - put_nilfs(sbi->s_nilfs); + destroy_nilfs(nilfs); sbi->s_super = NULL; sb->s_fs_info = NULL; kfree(sbi); @@ -836,15 +836,14 @@ static int nilfs_try_to_shrink_tree(struct dentry *root_dentry) * @sb: super_block * @data: mount options * @silent: silent mode flag - * @nilfs: the_nilfs struct * * This function is called exclusively by nilfs->ns_mount_mutex. * So, the recovery process is protected from other simultaneous mounts. */ static int -nilfs_fill_super(struct super_block *sb, void *data, int silent, - struct the_nilfs *nilfs) +nilfs_fill_super(struct super_block *sb, void *data, int silent) { + struct the_nilfs *nilfs; struct nilfs_sb_info *sbi; struct nilfs_root *fsroot; __u64 cno; @@ -855,14 +854,18 @@ nilfs_fill_super(struct super_block *sb, void *data, int silent, return -ENOMEM; sb->s_fs_info = sbi; + sbi->s_super = sb; - get_nilfs(nilfs); + nilfs = alloc_nilfs(sb->s_bdev); + if (!nilfs) { + err = -ENOMEM; + goto failed_sbi; + } sbi->s_nilfs = nilfs; - sbi->s_super = sb; err = init_nilfs(nilfs, sbi, (char *)data); if (err) - goto failed_sbi; + goto failed_nilfs; spin_lock_init(&sbi->s_inode_lock); INIT_LIST_HEAD(&sbi->s_dirty_files); @@ -885,14 +888,14 @@ nilfs_fill_super(struct super_block *sb, void *data, int silent, err = load_nilfs(nilfs, sbi); if (err) - goto failed_sbi; + goto failed_nilfs; cno = nilfs_last_cno(nilfs); err = nilfs_attach_checkpoint(sbi, cno, true, &fsroot); if (err) { printk(KERN_ERR "NILFS: error loading last checkpoint " "(checkpoint number=%llu).\n", (unsigned long long)cno); - goto failed_sbi; + goto failed_nilfs; } if (!(sb->s_flags & MS_RDONLY)) { @@ -921,8 +924,10 @@ nilfs_fill_super(struct super_block *sb, void *data, int silent, failed_checkpoint: nilfs_put_root(fsroot); + failed_nilfs: + destroy_nilfs(nilfs); + failed_sbi: - put_nilfs(nilfs); sb->s_fs_info = NULL; kfree(sbi); return err; @@ -1077,7 +1082,6 @@ nilfs_get_sb(struct file_system_type *fs_type, int flags, struct nilfs_super_data sd; struct super_block *s; fmode_t mode = FMODE_READ; - struct the_nilfs *nilfs; struct dentry *root_dentry; int err, s_new = false; @@ -1095,18 +1099,10 @@ nilfs_get_sb(struct file_system_type *fs_type, int flags, goto failed; } - nilfs = find_or_create_nilfs(sd.bdev); - if (!nilfs) { - err = -ENOMEM; - goto failed; - } - - mutex_lock(&nilfs->ns_mount_mutex); - s = sget(fs_type, nilfs_test_bdev_super, nilfs_set_bdev_super, sd.bdev); if (IS_ERR(s)) { err = PTR_ERR(s); - goto failed_unlock; + goto failed; } if (!s->s_root) { @@ -1120,10 +1116,9 @@ nilfs_get_sb(struct file_system_type *fs_type, int flags, strlcpy(s->s_id, bdevname(sd.bdev, b), sizeof(s->s_id)); sb_set_blocksize(s, block_size(sd.bdev)); - err = nilfs_fill_super(s, data, flags & MS_SILENT ? 1 : 0, - nilfs); + err = nilfs_fill_super(s, data, flags & MS_SILENT ? 1 : 0); if (err) - goto cancel_new; + goto failed_super; s->s_flags |= MS_ACTIVE; } else if (!sd.cno) { @@ -1153,17 +1148,12 @@ nilfs_get_sb(struct file_system_type *fs_type, int flags, if (sd.cno) { err = nilfs_attach_snapshot(s, sd.cno, &root_dentry); - if (err) { - if (s_new) - goto cancel_new; + if (err) goto failed_super; - } } else { root_dentry = dget(s->s_root); } - mutex_unlock(&nilfs->ns_mount_mutex); - put_nilfs(nilfs); if (!s_new) close_bdev_exclusive(sd.bdev, mode); @@ -1173,23 +1163,10 @@ nilfs_get_sb(struct file_system_type *fs_type, int flags, failed_super: deactivate_locked_super(s); - failed_unlock: - mutex_unlock(&nilfs->ns_mount_mutex); - put_nilfs(nilfs); - failed: - close_bdev_exclusive(sd.bdev, mode); - return err; - cancel_new: - /* Abandoning the newly allocated superblock */ - mutex_unlock(&nilfs->ns_mount_mutex); - put_nilfs(nilfs); - deactivate_locked_super(s); - /* - * This deactivate_locked_super() invokes close_bdev_exclusive(). - * We must finish all post-cleaning before this call; - * put_nilfs() needs the block device. - */ + failed: + if (!s_new) + close_bdev_exclusive(sd.bdev, mode); return err; } diff --git a/fs/nilfs2/the_nilfs.c b/fs/nilfs2/the_nilfs.c index 960c287..6eeb4f0 100644 --- a/fs/nilfs2/the_nilfs.c +++ b/fs/nilfs2/the_nilfs.c @@ -35,9 +35,6 @@ #include "segbuf.h" -static LIST_HEAD(nilfs_objects); -static DEFINE_SPINLOCK(nilfs_lock); - static int nilfs_valid_sb(struct nilfs_super_block *sbp); void nilfs_set_last_segment(struct the_nilfs *nilfs, @@ -61,16 +58,13 @@ void nilfs_set_last_segment(struct the_nilfs *nilfs, } /** - * alloc_nilfs - allocate the_nilfs structure + * alloc_nilfs - allocate a nilfs object * @bdev: block device to which the_nilfs is related * - * alloc_nilfs() allocates memory for the_nilfs and - * initializes its reference count and locks. - * * Return Value: On success, pointer to the_nilfs is returned. * On error, NULL is returned. */ -static struct the_nilfs *alloc_nilfs(struct block_device *bdev) +struct the_nilfs *alloc_nilfs(struct block_device *bdev) { struct the_nilfs *nilfs; @@ -79,12 +73,9 @@ static struct the_nilfs *alloc_nilfs(struct block_device *bdev) return NULL; nilfs->ns_bdev = bdev; - atomic_set(&nilfs->ns_count, 1); atomic_set(&nilfs->ns_ndirtyblks, 0); init_rwsem(&nilfs->ns_sem); - mutex_init(&nilfs->ns_mount_mutex); init_rwsem(&nilfs->ns_writer_sem); - INIT_LIST_HEAD(&nilfs->ns_list); INIT_LIST_HEAD(&nilfs->ns_gc_inodes); spin_lock_init(&nilfs->ns_last_segment_lock); nilfs->ns_cptree = RB_ROOT; @@ -95,67 +86,11 @@ static struct the_nilfs *alloc_nilfs(struct block_device *bdev) } /** - * find_or_create_nilfs - find or create nilfs object - * @bdev: block device to which the_nilfs is related - * - * find_nilfs() looks up an existent nilfs object created on the - * device and gets the reference count of the object. If no nilfs object - * is found on the device, a new nilfs object is allocated. - * - * Return Value: On success, pointer to the nilfs object is returned. - * On error, NULL is returned. - */ -struct the_nilfs *find_or_create_nilfs(struct block_device *bdev) -{ - struct the_nilfs *nilfs, *new = NULL; - - retry: - spin_lock(&nilfs_lock); - list_for_each_entry(nilfs, &nilfs_objects, ns_list) { - if (nilfs->ns_bdev == bdev) { - get_nilfs(nilfs); - spin_unlock(&nilfs_lock); - if (new) - put_nilfs(new); - return nilfs; /* existing object */ - } - } - if (new) { - list_add_tail(&new->ns_list, &nilfs_objects); - spin_unlock(&nilfs_lock); - return new; /* new object */ - } - spin_unlock(&nilfs_lock); - - new = alloc_nilfs(bdev); - if (new) - goto retry; - return NULL; /* insufficient memory */ -} - -/** - * put_nilfs - release a reference to the_nilfs - * @nilfs: the_nilfs structure to be released - * - * put_nilfs() decrements a reference counter of the_nilfs. - * If the reference count reaches zero, the_nilfs is freed. + * destroy_nilfs - destroy nilfs object + * @nilfs: nilfs object to be released */ -void put_nilfs(struct the_nilfs *nilfs) +void destroy_nilfs(struct the_nilfs *nilfs) { - spin_lock(&nilfs_lock); - if (!atomic_dec_and_test(&nilfs->ns_count)) { - spin_unlock(&nilfs_lock); - return; - } - list_del_init(&nilfs->ns_list); - spin_unlock(&nilfs_lock); - - /* - * Increment of ns_count never occurs below because the caller - * of get_nilfs() holds at least one reference to the_nilfs. - * Thus its exclusion control is not required here. - */ - might_sleep(); if (nilfs_loaded(nilfs)) { nilfs_mdt_destroy(nilfs->ns_sufile); diff --git a/fs/nilfs2/the_nilfs.h b/fs/nilfs2/the_nilfs.h index 7b43693..1908dc7 100644 --- a/fs/nilfs2/the_nilfs.h +++ b/fs/nilfs2/the_nilfs.h @@ -46,13 +46,10 @@ enum { /** * struct the_nilfs - struct to supervise multiple nilfs mount points * @ns_flags: flags - * @ns_count: reference count - * @ns_list: list head for nilfs_list * @ns_bdev: block device * @ns_bdi: backing dev info * @ns_writer: back pointer to writable nilfs_sb_info * @ns_sem: semaphore for shared states - * @ns_mount_mutex: mutex protecting mount process of nilfs * @ns_writer_sem: semaphore protecting ns_writer attach/detach * @ns_sbh: buffer heads of on-disk super blocks * @ns_sbp: pointers to super block data @@ -94,14 +91,11 @@ enum { */ struct the_nilfs { unsigned long ns_flags; - atomic_t ns_count; - struct list_head ns_list; struct block_device *ns_bdev; struct backing_dev_info *ns_bdi; struct nilfs_sb_info *ns_writer; struct rw_semaphore ns_sem; - struct mutex ns_mount_mutex; struct rw_semaphore ns_writer_sem; /* @@ -239,8 +233,8 @@ static inline int nilfs_sb_will_flip(struct the_nilfs *nilfs) } void nilfs_set_last_segment(struct the_nilfs *, sector_t, u64, __u64); -struct the_nilfs *find_or_create_nilfs(struct block_device *); -void put_nilfs(struct the_nilfs *); +struct the_nilfs *alloc_nilfs(struct block_device *bdev); +void destroy_nilfs(struct the_nilfs *nilfs); int init_nilfs(struct the_nilfs *, struct nilfs_sb_info *, char *); int load_nilfs(struct the_nilfs *, struct nilfs_sb_info *); int nilfs_discard_segments(struct the_nilfs *, __u64 *, size_t); @@ -256,12 +250,6 @@ void nilfs_fall_back_super_block(struct the_nilfs *); void nilfs_swap_super_block(struct the_nilfs *); -static inline void get_nilfs(struct the_nilfs *nilfs) -{ - /* Caller must have at least one reference of the_nilfs. */ - atomic_inc(&nilfs->ns_count); -} - static inline void nilfs_get_root(struct nilfs_root *root) { atomic_inc(&root->count);