* Does "i_mutex" in comments mean inode_lock() in code ?
@ 2020-08-18 7:02 Thomas Schmitt
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From: Thomas Schmitt @ 2020-08-18 7:02 UTC (permalink / raw)
To: kernelnewbies
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
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