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>
diff --git a/fs/nilfs2/super.c b/fs/nilfs2/super.c
index 3c9833e..5a8c5e4 100644
--- a/fs/nilfs2/super.c
+++ b/fs/nilfs2/super.c
@@ -67,8 +67,6 @@
static void nilfs_write_super(struct super_block *sb);
static int nilfs_remount(struct super_block *sb, int *flags, char *data);
-static int test_exclusive_mount(struct file_system_type *fs_type,
- struct block_device *bdev, int flags);
/**
* nilfs_error() - report failure condition on a filesystem
@@ -329,6 +327,10 @@
nilfs_commit_super(sbi, 1);
up_write(&nilfs->ns_sem);
}
+ down_write(&nilfs->ns_sem);
+ if (nilfs->ns_current == sbi)
+ nilfs->ns_current = NULL;
+ up_write(&nilfs->ns_sem);
nilfs_detach_checkpoint(sbi);
put_nilfs(sbi->s_nilfs);
@@ -880,6 +882,11 @@
goto failed_root;
}
+ down_write(&nilfs->ns_sem);
+ if (!nilfs_test_opt(sbi, SNAPSHOT))
+ nilfs->ns_current = sbi;
+ up_write(&nilfs->ns_sem);
+
return 0;
failed_root:
@@ -958,14 +965,16 @@
* by fsck since we originally mounted the partition.)
*/
down(&sb->s_bdev->bd_mount_sem);
- /* Check existing RW-mount */
- if (test_exclusive_mount(sb->s_type, sb->s_bdev, 0)) {
+ down_read(&nilfs->ns_sem);
+ if (nilfs->ns_current && nilfs->ns_current != sbi) {
printk(KERN_WARNING "NILFS (device %s): couldn't "
- "remount because a RW-mount exists.\n",
+ "remount because an RW-mount exists.\n",
sb->s_id);
+ up_read(&nilfs->ns_sem);
err = -EBUSY;
goto rw_remount_failed;
}
+ up_read(&nilfs->ns_sem);
if (sbi->s_snapshot_cno != nilfs_last_cno(nilfs)) {
printk(KERN_WARNING "NILFS (device %s): couldn't "
"remount because the current RO-mount is not "
@@ -984,6 +993,7 @@
down_write(&nilfs->ns_sem);
nilfs_setup_super(sbi);
+ nilfs->ns_current = sbi;
up_write(&nilfs->ns_sem);
up(&sb->s_bdev->bd_mount_sem);
@@ -1118,10 +1128,23 @@
}
down(&sd.bdev->bd_mount_sem);
- if (!sd.cno &&
- (err = test_exclusive_mount(fs_type, sd.bdev, flags ^ MS_RDONLY))) {
- err = (err < 0) ? : -EBUSY;
- goto failed_unlock;
+
+ if (!sd.cno) {
+ /*
+ * Check if an exclusive mount exists or not.
+ * Snapshot mounts coexist with a current mount
+ * (i.e. rw-mount or ro-mount), whereas rw-mount and
+ * ro-mount are mutually exclusive.
+ */
+ down_read(&nilfs->ns_sem);
+ if (nilfs->ns_current &&
+ ((nilfs->ns_current->s_super->s_flags ^ flags)
+ & MS_RDONLY)) {
+ up_read(&nilfs->ns_sem);
+ err = -EBUSY;
+ goto failed_unlock;
+ }
+ up_read(&nilfs->ns_sem);
}
/*
@@ -1182,57 +1205,6 @@
return err;
}
-static int nilfs_test_bdev_super3(struct super_block *s, void *data)
-{
- struct nilfs_super_data *sd = data;
- int ret;
-
- if (s->s_bdev != sd->bdev)
- return 0;
- if (down_read_trylock(&s->s_umount)) {
- ret = (s->s_flags & MS_RDONLY) && s->s_root &&
- nilfs_test_opt(NILFS_SB(s), SNAPSHOT);
- up_read(&s->s_umount);
- if (ret)
- return 0; /* ignore snapshot mounts */
- }
- return !((sd->flags ^ s->s_flags) & MS_RDONLY);
-}
-
-static int __false_bdev_super(struct super_block *s, void *data)
-{
-#if 0 /* XXX: workaround for lock debug. This is not good idea */
- up_write(&s->s_umount);
-#endif
- return -EFAULT;
-}
-
-/**
- * test_exclusive_mount - check whether an exclusive RW/RO mount exists or not.
- * fs_type: filesystem type
- * bdev: block device
- * flag: 0 (check rw-mount) or MS_RDONLY (check ro-mount)
- * res: pointer to an integer to store result
- *
- * This function must be called within a section protected by bd_mount_mutex.
- */
-static int test_exclusive_mount(struct file_system_type *fs_type,
- struct block_device *bdev, int flags)
-{
- struct super_block *s;
- struct nilfs_super_data sd = { .flags = flags, .bdev = bdev };
-
- s = sget(fs_type, nilfs_test_bdev_super3, __false_bdev_super, &sd);
- if (IS_ERR(s)) {
- if (PTR_ERR(s) != -EFAULT)
- return PTR_ERR(s);
- return 0; /* Not found */
- }
- up_write(&s->s_umount);
- deactivate_super(s);
- return 1; /* Found */
-}
-
struct file_system_type nilfs_fs_type = {
.owner = THIS_MODULE,
.name = "nilfs2",