On Tue, 12 Dec 2006 16:18:32 +0300 Dmitriy Monakhov <[EMAIL PROTECTED]> wrote:
> >> but according to filemaps locking rules: mm/filemap.c:77 > >> .. > >> * ->i_mutex (generic_file_buffered_write) > >> * ->mmap_sem (fault_in_pages_readable->do_page_fault) > >> .. > >> I'm confused a litle bit, where is the truth? > > > > xfs_write() calls generic_file_direct_write() without taking i_mutex for > > O_DIRECT writes. > Yes, but my quastion is about __generic_file_aio_write_nolock(). > As i understand _nolock sufix means that i_mutex was already locked > by caller, am i right ? Nope. It just means that __generic_file_aio_write_nolock() doesn't take the lock. We don't assume or require that the caller took it. For example the raw driver calls generic_file_aio_write_nolock() without taking i_mutex. Raw isn't relevant to the problem (although ocfs2 might be). But we cannot assume that all callers have taken i_mutex, I think. I guess we can make that a rule (document it, add BUG_ON(!mutex_is_locked(..)) if it isn't a blockdev) if needs be. After really checking that this matches reality for all callers. It's important, too - if we have an unprotected i_size_write() then the seqlock can get out of sync due to a race and then i_size_read() locks up the kernel. - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
