cleanup sync_supers

Merge the write_super helper into sync_super and move the check for
->write_super earlier so that we can avoid grabbing a reference to
a superblock that doesn't have it.

While we're at it also add a little comment documenting sync_supers.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
This commit is contained in:
Christoph Hellwig 2009-05-05 16:08:56 +02:00 committed by Al Viro
parent f3da392e9f
commit e500475338

View file

@ -399,16 +399,14 @@ void drop_super(struct super_block *sb)
EXPORT_SYMBOL(drop_super);
static inline void write_super(struct super_block *sb)
{
lock_super(sb);
if (sb->s_root && sb->s_dirt)
if (sb->s_op->write_super)
sb->s_op->write_super(sb);
unlock_super(sb);
}
/*
/**
* sync_supers - helper for periodic superblock writeback
*
* Call the write_super method if present on all dirty superblocks in
* the system. This is for the periodic writeback used by most older
* filesystems. For data integrity superblock writeback use
* sync_filesystems() instead.
*
* Note: check the dirty flag before waiting, so we don't
* hold up the sync while mounting a device. (The newly
* mounted device won't need syncing.)
@ -420,12 +418,17 @@ void sync_supers(void)
spin_lock(&sb_lock);
restart:
list_for_each_entry(sb, &super_blocks, s_list) {
if (sb->s_dirt) {
if (sb->s_op->write_super && sb->s_dirt) {
sb->s_count++;
spin_unlock(&sb_lock);
down_read(&sb->s_umount);
write_super(sb);
lock_super(sb);
if (sb->s_root && sb->s_dirt)
sb->s_op->write_super(sb);
unlock_super(sb);
up_read(&sb->s_umount);
spin_lock(&sb_lock);
if (__put_super_and_need_restart(sb))
goto restart;