Commit 7762f5a0 authored Oct 17, 2006 by Miklos Szeredi Committed by Linus Torvalds Oct 17, 2006

[PATCH] document i_size_write locking rules



Unless someone reads the documentation for write_seqcount_{begin,end} it is
not obvious, that i_size_write() needs locking.  Especially, that lack of such
locking can result in a system hang.

Signed-off-by: Miklos Szeredi <miklos@szeredi.hu>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

parent 9ffbb916

include/linux/fs.h

+5 −1

Original line number	Diff line number	Diff line
		@@ -656,7 +656,11 @@ static inline loff_t i_size_read(struct inode *inode)
		#endif
		}


		/*
		* 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.
		*/
		static inline void i_size_write(struct inode *inode, loff_t i_size)
		{
		#if BITS_PER_LONG==32 && defined(CONFIG_SMP)