nilfs2: get rid of sget use for checking if current mount is present
This stops using sget() for checking if an r/w-mount or an r/o-mount exists on the device. This elimination uses a back pointer to the current mount added to nilfs object. Signed-off-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp> Cc: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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@ -67,8 +67,6 @@ MODULE_LICENSE("GPL");
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static void nilfs_write_super(struct super_block *sb);
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static int nilfs_remount(struct super_block *sb, int *flags, char *data);
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static int test_exclusive_mount(struct file_system_type *fs_type,
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struct block_device *bdev, int flags);
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/**
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* nilfs_error() - report failure condition on a filesystem
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@ -329,6 +327,10 @@ static void nilfs_put_super(struct super_block *sb)
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nilfs_commit_super(sbi, 1);
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up_write(&nilfs->ns_sem);
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}
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down_write(&nilfs->ns_sem);
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if (nilfs->ns_current == sbi)
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nilfs->ns_current = NULL;
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up_write(&nilfs->ns_sem);
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nilfs_detach_checkpoint(sbi);
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put_nilfs(sbi->s_nilfs);
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@ -880,6 +882,11 @@ nilfs_fill_super(struct super_block *sb, void *data, int silent,
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goto failed_root;
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}
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down_write(&nilfs->ns_sem);
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if (!nilfs_test_opt(sbi, SNAPSHOT))
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nilfs->ns_current = sbi;
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up_write(&nilfs->ns_sem);
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return 0;
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failed_root:
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@ -958,14 +965,16 @@ static int nilfs_remount(struct super_block *sb, int *flags, char *data)
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* by fsck since we originally mounted the partition.)
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*/
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down(&sb->s_bdev->bd_mount_sem);
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/* Check existing RW-mount */
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if (test_exclusive_mount(sb->s_type, sb->s_bdev, 0)) {
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down_read(&nilfs->ns_sem);
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if (nilfs->ns_current && nilfs->ns_current != sbi) {
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printk(KERN_WARNING "NILFS (device %s): couldn't "
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"remount because a RW-mount exists.\n",
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"remount because an RW-mount exists.\n",
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sb->s_id);
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up_read(&nilfs->ns_sem);
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err = -EBUSY;
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goto rw_remount_failed;
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}
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up_read(&nilfs->ns_sem);
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if (sbi->s_snapshot_cno != nilfs_last_cno(nilfs)) {
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printk(KERN_WARNING "NILFS (device %s): couldn't "
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"remount because the current RO-mount is not "
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@ -984,6 +993,7 @@ static int nilfs_remount(struct super_block *sb, int *flags, char *data)
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down_write(&nilfs->ns_sem);
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nilfs_setup_super(sbi);
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nilfs->ns_current = sbi;
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up_write(&nilfs->ns_sem);
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up(&sb->s_bdev->bd_mount_sem);
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@ -1118,10 +1128,23 @@ nilfs_get_sb(struct file_system_type *fs_type, int flags,
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}
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down(&sd.bdev->bd_mount_sem);
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if (!sd.cno &&
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(err = test_exclusive_mount(fs_type, sd.bdev, flags ^ MS_RDONLY))) {
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err = (err < 0) ? : -EBUSY;
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goto failed_unlock;
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if (!sd.cno) {
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/*
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* Check if an exclusive mount exists or not.
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* Snapshot mounts coexist with a current mount
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* (i.e. rw-mount or ro-mount), whereas rw-mount and
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* ro-mount are mutually exclusive.
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*/
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down_read(&nilfs->ns_sem);
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if (nilfs->ns_current &&
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((nilfs->ns_current->s_super->s_flags ^ flags)
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& MS_RDONLY)) {
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up_read(&nilfs->ns_sem);
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err = -EBUSY;
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goto failed_unlock;
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}
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up_read(&nilfs->ns_sem);
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}
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/*
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@ -1182,57 +1205,6 @@ nilfs_get_sb(struct file_system_type *fs_type, int flags,
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return err;
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}
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static int nilfs_test_bdev_super3(struct super_block *s, void *data)
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{
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struct nilfs_super_data *sd = data;
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int ret;
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if (s->s_bdev != sd->bdev)
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return 0;
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if (down_read_trylock(&s->s_umount)) {
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ret = (s->s_flags & MS_RDONLY) && s->s_root &&
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nilfs_test_opt(NILFS_SB(s), SNAPSHOT);
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up_read(&s->s_umount);
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if (ret)
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return 0; /* ignore snapshot mounts */
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}
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return !((sd->flags ^ s->s_flags) & MS_RDONLY);
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}
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static int __false_bdev_super(struct super_block *s, void *data)
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{
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#if 0 /* XXX: workaround for lock debug. This is not good idea */
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up_write(&s->s_umount);
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#endif
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return -EFAULT;
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}
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/**
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* test_exclusive_mount - check whether an exclusive RW/RO mount exists or not.
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* fs_type: filesystem type
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* bdev: block device
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* flag: 0 (check rw-mount) or MS_RDONLY (check ro-mount)
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* res: pointer to an integer to store result
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*
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* This function must be called within a section protected by bd_mount_mutex.
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*/
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static int test_exclusive_mount(struct file_system_type *fs_type,
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struct block_device *bdev, int flags)
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{
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struct super_block *s;
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struct nilfs_super_data sd = { .flags = flags, .bdev = bdev };
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s = sget(fs_type, nilfs_test_bdev_super3, __false_bdev_super, &sd);
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if (IS_ERR(s)) {
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if (PTR_ERR(s) != -EFAULT)
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return PTR_ERR(s);
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return 0; /* Not found */
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}
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up_write(&s->s_umount);
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deactivate_super(s);
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return 1; /* Found */
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}
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struct file_system_type nilfs_fs_type = {
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.owner = THIS_MODULE,
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.name = "nilfs2",
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@ -50,6 +50,7 @@ enum {
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* @ns_sem: semaphore for shared states
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* @ns_writer_mutex: mutex protecting ns_writer attach/detach
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* @ns_writer_refcount: number of referrers on ns_writer
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* @ns_current: back pointer to current mount
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* @ns_sbh: buffer heads of on-disk super blocks
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* @ns_sbp: pointers to super block data
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* @ns_sbwtime: previous write time of super blocks
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@ -98,6 +99,8 @@ struct the_nilfs {
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struct mutex ns_writer_mutex;
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atomic_t ns_writer_refcount;
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struct nilfs_sb_info *ns_current;
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/*
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* used for
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* - loading the latest checkpoint exclusively.
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