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@xxxxxxxxxxxxx>
Cc: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
---
fs/nilfs2/super.c | 92 +++++++++++++++++--------------------------------
fs/nilfs2/the_nilfs.h | 3 ++
2 files changed, 35 insertions(+), 60 deletions(-)
diff --git a/fs/nilfs2/super.c b/fs/nilfs2/super.c
index bdb479a..0a62901 100644
--- a/fs/nilfs2/super.c
+++ b/fs/nilfs2/super.c
@@ -66,8 +66,6 @@ MODULE_DESCRIPTION("A New Implementation of the Log-structured Filesystem "
MODULE_LICENSE("GPL");
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
@@ -323,6 +321,10 @@ static void nilfs_put_super(struct super_block *sb)
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);
@@ -870,6 +872,11 @@ nilfs_fill_super(struct super_block *sb, void *data, int silent,
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:
@@ -946,14 +953,16 @@ static int nilfs_remount(struct super_block *sb, int *flags, char *data)
* 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 "
@@ -972,6 +981,7 @@ static int nilfs_remount(struct super_block *sb, int *flags, char *data)
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);
@@ -1104,10 +1114,23 @@ nilfs_get_sb(struct file_system_type *fs_type, int flags,
}
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);
}
/*
@@ -1168,57 +1191,6 @@ nilfs_get_sb(struct file_system_type *fs_type, int flags,
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",
diff --git a/fs/nilfs2/the_nilfs.h b/fs/nilfs2/the_nilfs.h
index 116caf9..99f7e29 100644
--- a/fs/nilfs2/the_nilfs.h
+++ b/fs/nilfs2/the_nilfs.h
@@ -50,6 +50,7 @@ enum {
* @ns_sem: semaphore for shared states
* @ns_writer_mutex: mutex protecting ns_writer attach/detach
* @ns_writer_refcount: number of referrers on ns_writer
+ * @ns_current: back pointer to current mount
* @ns_sbh: buffer heads of on-disk super blocks
* @ns_sbp: pointers to super block data
* @ns_sbwtime: previous write time of super blocks
@@ -98,6 +99,8 @@ struct the_nilfs {
struct mutex ns_writer_mutex;
atomic_t ns_writer_refcount;
+ struct nilfs_sb_info *ns_current;
+
/*
* used for
* - loading the latest checkpoint exclusively.
--
1.6.2
--
To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
