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>
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27
fs/super.c
27
fs/super.c
@ -399,16 +399,14 @@ void drop_super(struct super_block *sb)
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EXPORT_SYMBOL(drop_super);
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static inline void write_super(struct super_block *sb)
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{
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lock_super(sb);
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if (sb->s_root && sb->s_dirt)
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if (sb->s_op->write_super)
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sb->s_op->write_super(sb);
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unlock_super(sb);
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}
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/*
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/**
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* sync_supers - helper for periodic superblock writeback
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*
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* Call the write_super method if present on all dirty superblocks in
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* the system. This is for the periodic writeback used by most older
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* filesystems. For data integrity superblock writeback use
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* sync_filesystems() instead.
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*
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* Note: check the dirty flag before waiting, so we don't
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* hold up the sync while mounting a device. (The newly
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* mounted device won't need syncing.)
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@ -420,12 +418,17 @@ void sync_supers(void)
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spin_lock(&sb_lock);
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restart:
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list_for_each_entry(sb, &super_blocks, s_list) {
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if (sb->s_dirt) {
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if (sb->s_op->write_super && sb->s_dirt) {
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sb->s_count++;
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spin_unlock(&sb_lock);
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down_read(&sb->s_umount);
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write_super(sb);
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lock_super(sb);
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if (sb->s_root && sb->s_dirt)
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sb->s_op->write_super(sb);
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unlock_super(sb);
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up_read(&sb->s_umount);
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spin_lock(&sb_lock);
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if (__put_super_and_need_restart(sb))
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goto restart;
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