Messages in this thread | | | Date | Mon, 11 Dec 2006 22:36:30 -0800 | From | Andrew Morton <> | Subject | Re: [PATCH] incorrect error handling inside generic_file_direct_write |
| |
On Tue, 12 Dec 2006 12:22:14 +0300 Dmitriy Monakhov <dmonakhov@sw.ru> wrote:
> >> @@ -2041,6 +2041,14 @@ generic_file_direct_write(struct kiocb * > >> mark_inode_dirty(inode); > >> } > >> *ppos = end; > >> + } else if (written < 0) { > >> + loff_t isize = i_size_read(inode); > >> + /* > >> + * generic_file_direct_IO() may have instantiated a few blocks > >> + * outside i_size. Trim these off again. > >> + */ > >> + if (pos + count > isize) > >> + vmtruncate(inode, isize); > >> } > >> > > > > XFS (at least) can call generic_file_direct_write() with i_mutex not held. > How could it be ? > > from mm/filemap.c:2046 generic_file_direct_write() comment right after > place where i want to add vmtruncate() > /* > * Sync the fs metadata but not the minor inode changes and > * of course not the data as we did direct DMA for the IO. > * i_mutex is held, which protects generic_osync_inode() from > * livelocking. > */ > > > And vmtruncate() expects i_mutex to be held. > generic_file_direct_IO must called under i_mutex too > from mm/filemap.c:2388 > /* > * Called under i_mutex for writes to S_ISREG files. Returns -EIO if something > * went wrong during pagecache shootdown. > */ > static ssize_t > generic_file_direct_IO(int rw, struct kiocb *iocb, const struct iovec *iov,
yup, the comments are wrong.
> This means XFS generic_file_direct_write() call generic_file_direct_IO() without > i_mutex held too?
Think so. XFS uses blockdev_direct_IO_own_locking(). We'd need to check with the XFS guys regarding its precise operation and what needs to be done here.
> > > > I guess a suitable solution would be to push this problem back up to the > > callers: let them decide whether to run vmtruncate() and if so, to ensure > > that i_mutex is held. > > > > The existence of generic_file_aio_write_nolock() makes that rather messy > > though. - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
| |