diff options
| -rw-r--r-- | fs/direct-io.c | 21 |
1 files changed, 12 insertions, 9 deletions
diff --git a/fs/direct-io.c b/fs/direct-io.c index 848044af7e16..27f3e787faca 100644 --- a/fs/direct-io.c +++ b/fs/direct-io.c @@ -1155,15 +1155,16 @@ direct_io_worker(int rw, struct kiocb *iocb, struct inode *inode, * For writes, i_mutex is not held on entry; it is never taken. * * DIO_LOCKING (simple locking for regular files) - * For writes we are called under i_mutex and return with i_mutex held, even though - * it is internally dropped. + * For writes we are called under i_mutex and return with i_mutex held, even + * though it is internally dropped. * For reads, i_mutex is not held on entry, but it is taken and dropped before * returning. * * DIO_OWN_LOCKING (filesystem provides synchronisation and handling of * uninitialised data, allowing parallel direct readers and writers) * For writes we are called without i_mutex, return without it, never touch it. - * For reads, i_mutex is held on entry and will be released before returning. + * For reads we are called under i_mutex and return with i_mutex held, even + * though it may be internally dropped. * * Additional i_alloc_sem locking requirements described inline below. */ @@ -1182,7 +1183,8 @@ __blockdev_direct_IO(int rw, struct kiocb *iocb, struct inode *inode, ssize_t retval = -EINVAL; loff_t end = offset; struct dio *dio; - int reader_with_isem = (rw == READ && dio_lock_type == DIO_OWN_LOCKING); + int release_i_mutex = 0; + int acquire_i_mutex = 0; if (rw & WRITE) current->flags |= PF_SYNCWRITE; @@ -1225,7 +1227,6 @@ __blockdev_direct_IO(int rw, struct kiocb *iocb, struct inode *inode, * writers need to grab i_alloc_sem only (i_mutex is already held) * For regular files using DIO_OWN_LOCKING, * neither readers nor writers take any locks here - * (i_mutex is already held and release for writers here) */ dio->lock_type = dio_lock_type; if (dio_lock_type != DIO_NO_LOCKING) { @@ -1236,7 +1237,7 @@ __blockdev_direct_IO(int rw, struct kiocb *iocb, struct inode *inode, mapping = iocb->ki_filp->f_mapping; if (dio_lock_type != DIO_OWN_LOCKING) { mutex_lock(&inode->i_mutex); - reader_with_isem = 1; + release_i_mutex = 1; } retval = filemap_write_and_wait_range(mapping, offset, @@ -1248,7 +1249,7 @@ __blockdev_direct_IO(int rw, struct kiocb *iocb, struct inode *inode, if (dio_lock_type == DIO_OWN_LOCKING) { mutex_unlock(&inode->i_mutex); - reader_with_isem = 0; + acquire_i_mutex = 1; } } @@ -1269,11 +1270,13 @@ __blockdev_direct_IO(int rw, struct kiocb *iocb, struct inode *inode, nr_segs, blkbits, get_blocks, end_io, dio); if (rw == READ && dio_lock_type == DIO_LOCKING) - reader_with_isem = 0; + release_i_mutex = 0; out: - if (reader_with_isem) + if (release_i_mutex) mutex_unlock(&inode->i_mutex); + else if (acquire_i_mutex) + mutex_lock(&inode->i_mutex); if (rw & WRITE) current->flags &= ~PF_SYNCWRITE; return retval; |