diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c index cf5d30a..91a2496 100644 --- a/fs/ext4/inode.c +++ b/fs/ext4/inode.c @@ -2927,10 +2927,10 @@ retry: * fall back to buffered IO. * * For holes, we fallocate those blocks, mark them as uninitialized - * If those blocks were preallocated, we mark sure they are splited, but + * If those blocks were preallocated, we mark sure they are split, but * still keep the range to write as uninitialized. * - * The unwrritten extents will be converted to written when DIO is completed. + * The unwritten extents will be converted to written when DIO is completed. * For async direct IO, since the IO may still pending when return, we * set up an end_io call back function, which will do the conversion * when async direct IO completed. @@ -2948,125 +2948,120 @@ static ssize_t ext4_ext_direct_IO(int rw, struct kiocb *iocb, struct inode *inode = file->f_mapping->host; ssize_t ret; size_t count = iov_length(iov, nr_segs); - + int overwrite = 0; + get_block_t *get_block_func = NULL; + int dio_flags = 0; loff_t final_size = offset + count; - if (rw == WRITE && final_size <= inode->i_size) { - int overwrite = 0; - get_block_t *get_block_func = NULL; - int dio_flags = 0; - BUG_ON(iocb->private == NULL); + /* Use the old path for reads and writes beyond i_size. */ + if (rw != WRITE || final_size > inode->i_size) + return ext4_ind_direct_IO(rw, iocb, iov, offset, nr_segs); - /* If we do a overwrite dio, i_mutex locking can be released */ - overwrite = *((int *)iocb->private); + BUG_ON(iocb->private == NULL); - if (overwrite) { - atomic_inc(&inode->i_dio_count); - down_read(&EXT4_I(inode)->i_data_sem); - mutex_unlock(&inode->i_mutex); - } + /* If we do a overwrite dio, i_mutex locking can be released */ + overwrite = *((int *)iocb->private); - /* - * We could direct write to holes and fallocate. - * - * Allocated blocks to fill the hole are marked as uninitialized - * to prevent parallel buffered read to expose the stale data - * before DIO complete the data IO. - * - * As to previously fallocated extents, ext4 get_block - * will just simply mark the buffer mapped but still - * keep the extents uninitialized. - * - * for non AIO case, we will convert those unwritten extents - * to written after return back from blockdev_direct_IO. - * - * for async DIO, the conversion needs to be defered when - * the IO is completed. The ext4 end_io callback function - * will be called to take care of the conversion work. - * Here for async case, we allocate an io_end structure to - * hook to the iocb. - */ - iocb->private = NULL; - ext4_inode_aio_set(inode, NULL); - if (!is_sync_kiocb(iocb)) { - ext4_io_end_t *io_end = - ext4_init_io_end(inode, GFP_NOFS); - if (!io_end) { - ret = -ENOMEM; - goto retake_lock; - } - io_end->flag |= EXT4_IO_END_DIRECT; - iocb->private = io_end; - /* - * we save the io structure for current async - * direct IO, so that later ext4_map_blocks() - * could flag the io structure whether there - * is a unwritten extents needs to be converted - * when IO is completed. - */ - ext4_inode_aio_set(inode, io_end); - } + if (overwrite) { + atomic_inc(&inode->i_dio_count); + down_read(&EXT4_I(inode)->i_data_sem); + mutex_unlock(&inode->i_mutex); + } - if (overwrite) { - get_block_func = ext4_get_block_write_nolock; - } else { - get_block_func = ext4_get_block_write; - dio_flags = DIO_LOCKING; + /* + * We could direct write to holes and fallocate. + * + * Allocated blocks to fill the hole are marked as + * uninitialized to prevent parallel buffered read to expose + * the stale data before DIO complete the data IO. + * + * As to previously fallocated extents, ext4 get_block will + * just simply mark the buffer mapped but still keep the + * extents uninitialized. + * + * For non AIO case, we will convert those unwritten extents + * to written after return back from blockdev_direct_IO. + * + * For async DIO, the conversion needs to be deferred when the + * IO is completed. The ext4 end_io callback function will be + * called to take care of the conversion work. Here for async + * case, we allocate an io_end structure to hook to the iocb. + */ + iocb->private = NULL; + ext4_inode_aio_set(inode, NULL); + if (!is_sync_kiocb(iocb)) { + ext4_io_end_t *io_end = ext4_init_io_end(inode, GFP_NOFS); + if (!io_end) { + ret = -ENOMEM; + goto retake_lock; } - ret = __blockdev_direct_IO(rw, iocb, inode, - inode->i_sb->s_bdev, iov, - offset, nr_segs, - get_block_func, - ext4_end_io_dio, - NULL, - dio_flags); - - if (iocb->private) - ext4_inode_aio_set(inode, NULL); + io_end->flag |= EXT4_IO_END_DIRECT; + iocb->private = io_end; /* - * The io_end structure takes a reference to the inode, - * that structure needs to be destroyed and the - * reference to the inode need to be dropped, when IO is - * complete, even with 0 byte write, or failed. - * - * In the successful AIO DIO case, the io_end structure will be - * desctroyed and the reference to the inode will be dropped - * after the end_io call back function is called. - * - * In the case there is 0 byte write, or error case, since - * VFS direct IO won't invoke the end_io call back function, - * we need to free the end_io structure here. + * we save the io structure for current async direct + * IO, so that later ext4_map_blocks() could flag the + * io structure whether there is a unwritten extents + * needs to be converted when IO is completed. */ - if (ret != -EIOCBQUEUED && ret <= 0 && iocb->private) { - ext4_free_io_end(iocb->private); - iocb->private = NULL; - } else if (ret > 0 && !overwrite && ext4_test_inode_state(inode, - EXT4_STATE_DIO_UNWRITTEN)) { - int err; - /* - * for non AIO case, since the IO is already - * completed, we could do the conversion right here - */ - err = ext4_convert_unwritten_extents(inode, - offset, ret); - if (err < 0) - ret = err; - ext4_clear_inode_state(inode, EXT4_STATE_DIO_UNWRITTEN); - } + ext4_inode_aio_set(inode, io_end); + } - retake_lock: - /* take i_mutex locking again if we do a ovewrite dio */ - if (overwrite) { - inode_dio_done(inode); - up_read(&EXT4_I(inode)->i_data_sem); - mutex_lock(&inode->i_mutex); - } + if (overwrite) { + get_block_func = ext4_get_block_write_nolock; + } else { + get_block_func = ext4_get_block_write; + dio_flags = DIO_LOCKING; + } + ret = __blockdev_direct_IO(rw, iocb, inode, + inode->i_sb->s_bdev, iov, + offset, nr_segs, + get_block_func, + ext4_end_io_dio, + NULL, + dio_flags); + + if (iocb->private) + ext4_inode_aio_set(inode, NULL); + /* + * The io_end structure takes a reference to the inode, that + * structure needs to be destroyed and the reference to the + * inode need to be dropped, when IO is complete, even with 0 + * byte write, or failed. + * + * In the successful AIO DIO case, the io_end structure will + * be destroyed and the reference to the inode will be dropped + * after the end_io call back function is called. + * + * In the case there is 0 byte write, or error case, since VFS + * direct IO won't invoke the end_io call back function, we + * need to free the end_io structure here. + */ + if (ret != -EIOCBQUEUED && ret <= 0 && iocb->private) { + ext4_free_io_end(iocb->private); + iocb->private = NULL; + } else if (ret > 0 && !overwrite && ext4_test_inode_state(inode, + EXT4_STATE_DIO_UNWRITTEN)) { + int err; + /* + * for non AIO case, since the IO is already + * completed, we could do the conversion right here + */ + err = ext4_convert_unwritten_extents(inode, + offset, ret); + if (err < 0) + ret = err; + ext4_clear_inode_state(inode, EXT4_STATE_DIO_UNWRITTEN); + } - return ret; +retake_lock: + /* take i_mutex locking again if we do a ovewrite dio */ + if (overwrite) { + inode_dio_done(inode); + up_read(&EXT4_I(inode)->i_data_sem); + mutex_lock(&inode->i_mutex); } - /* for write the the end of file case, we fall back to old way */ - return ext4_ind_direct_IO(rw, iocb, iov, offset, nr_segs); + return ret; } static ssize_t ext4_direct_IO(int rw, struct kiocb *iocb,