diff options
Diffstat (limited to 'fs/direct-io.c')
| -rw-r--r-- | fs/direct-io.c | 25 |
1 files changed, 13 insertions, 12 deletions
diff --git a/fs/direct-io.c b/fs/direct-io.c index 354cbdbc14b..0a073c7125a 100644 --- a/fs/direct-io.c +++ b/fs/direct-io.c @@ -297,8 +297,7 @@ static ssize_t dio_complete(struct dio *dio, loff_t offset, ssize_t ret, bool is aio_complete(dio->iocb, ret, 0); } - if (dio->flags & DIO_LOCKING) - inode_dio_done(dio->inode); + inode_dio_done(dio->inode); return ret; } @@ -1185,14 +1184,16 @@ direct_io_worker(int rw, struct kiocb *iocb, struct inode *inode, * For writes this function is called under i_mutex and returns with * i_mutex held, for reads, i_mutex is not held on entry, but it is * taken and dropped again before returning. - * The i_dio_count counter keeps track of the number of outstanding - * direct I/O requests, and truncate waits for it to reach zero. - * New references to i_dio_count must only be grabbed with i_mutex - * held. - * * - if the flags value does NOT contain DIO_LOCKING we don't use any * internal locking but rather rely on the filesystem to synchronize * direct I/O reads/writes versus each other and truncate. + * + * To help with locking against truncate we incremented the i_dio_count + * counter before starting direct I/O, and decrement it once we are done. + * Truncate can wait for it to reach zero to provide exclusion. It is + * expected that filesystem provide exclusion between new direct I/O + * and truncates. For DIO_LOCKING filesystems this is done by i_mutex, + * but other filesystems need to take care of this on their own. */ ssize_t __blockdev_direct_IO(int rw, struct kiocb *iocb, struct inode *inode, @@ -1270,14 +1271,14 @@ __blockdev_direct_IO(int rw, struct kiocb *iocb, struct inode *inode, goto out; } } - - /* - * Will be decremented at I/O completion time. - */ - atomic_inc(&inode->i_dio_count); } /* + * Will be decremented at I/O completion time. + */ + atomic_inc(&inode->i_dio_count); + + /* * For file extending writes updating i_size before data * writeouts complete can expose uninitialized blocks. So * even for AIO, we need to wait for i/o to complete before |