On Thu, Feb 06, 2020 at 02:26:30PM +0900, Damien Le Moal wrote:
> zonefs is a very simple file system exposing each zone of a zoned block
> device as a file. Unlike a regular file system with zoned block device
> support (e.g. f2fs), zonefs does not hide the sequential write
> constraint of zoned block devices to the user. Files representing
> sequential write zones of the device must be written sequentially
> starting from the end of the file (append only writes).
....
> + if (flags & IOMAP_WRITE)
> + length = zi->i_max_size - offset;
> + else
> + length = min(length, isize - offset);
> + mutex_unlock(&zi->i_truncate_mutex);
> +
> + iomap->offset = offset & (~sbi->s_blocksize_mask);
> + iomap->length = ((offset + length + sbi->s_blocksize_mask) &
> + (~sbi->s_blocksize_mask)) - iomap->offset;
iomap->length = __ALIGN_MASK(offset + length, sbi->s_blocksize_mask) -
iomap->offset;
or it could just use ALIGN(..., sb->s_blocksize) and not need
pre-calculation of the mask value...
> +static ssize_t zonefs_file_dio_write(struct kiocb *iocb, struct iov_iter *from)
> +{
> + struct inode *inode = file_inode(iocb->ki_filp);
> + struct zonefs_sb_info *sbi = ZONEFS_SB(inode->i_sb);
> + struct zonefs_inode_info *zi = ZONEFS_I(inode);
> + size_t count;
> + ssize_t ret;
> +
> + /*
> + * For async direct IOs to sequential zone files, ignore IOCB_NOWAIT
> + * as this can cause write reordering (e.g. the first aio gets EAGAIN
> + * on the inode lock but the second goes through but is now unaligned).
> + */
> + if (zi->i_ztype == ZONEFS_ZTYPE_SEQ && !is_sync_kiocb(iocb)
> + && (iocb->ki_flags & IOCB_NOWAIT))
> + iocb->ki_flags &= ~IOCB_NOWAIT;
Hmmm. I'm wondering if it would be better to return -EOPNOTSUPP here
so that the application knows it can't do non-blocking write AIO to
this file.
Everything else looks OK to me.
Cheers,
Dave.
--
Dave Chinner
david@xxxxxxxxxxxxx
