Hi, is function inode_lock() the thing which controls what lots of comments call "i_mutex" ? I am in particular riddling over this comment in include/linux/fs.h : /* * NOTE: unlike i_size_read(), i_size_write() does need locking around it * (normally i_mutex), otherwise on 32bit/SMP an update of i_size_seqcount * can be lost, resulting in subsequent i_size_read() calls spinning forever. */ because i cannot find any example in the git tree by grep -r mutex_unlock'.*[^a-z]'i_mutex . and the same for mutex_lock or mutex_trylock. But i see lots of comments mentioning an "i_mutex" structure element by grep -r '.*->'i_mutex . The nearest discovery to what i search for is in include/linux/fs.h static inline void inode_lock(struct inode *inode) It has lots of call instances in the code. But in contrast to "->imutex" i found not a glimpse of documentation. (Well it has enough room to hide from me ...) So is this the call by which i can reserve a cdrom device file inode before i call i_size_write() ? If so, shouldn't the comment in fs.h be "... (normally inode_lock) ..." ? Have a nice day :) Thomas