On Mon, Feb 13, 2017 at 08:46:02PM -0600, Goldwyn Rodrigues wrote:
> From: Goldwyn Rodrigues <rgoldwyn@xxxxxxxx>
Please Cc the while series to all lists, otherwiwe it's impossible
to review the thing.
>
> If IOCB_NONBLOCKING is set:
> + Check if writing beyond end of file, if yes return EAGAIN
> - check if writing to a hole which does not have allocated
> file blocks.
> - Check if i_rwsem is immediately lockable in xfs_rw_ilock()
Why the + vs - above?
> -static inline void
> +static inline int
> xfs_rw_ilock(
This function has been removed a while ago.
>
> + if (iocb->ki_flags & IOCB_NONBLOCKING) {
> + struct xfs_bmbt_irec imap;
> + xfs_fileoff_t offset_fsb, end_fsb;
> + int nimaps = 1, ret = 0;
> + end_fsb = XFS_B_TO_FSB(ip->i_mount, iocb->ki_pos + count);
> + if (XFS_B_TO_FSB(ip->i_mount, i_size_read(inode)) < end_fsb)
> + return -EAGAIN;
Bogus check, XFS supports async write beyond EOF if the space is
preallocated.
> + /* Check if it is an unallocated hole */
> + offset_fsb = XFS_B_TO_FSBT(ip->i_mount, iocb->ki_pos);
> +
> + ret = xfs_bmapi_read(ip, offset_fsb, end_fsb - offset_fsb, &imap,
> + &nimaps, 0);
> + if (ret)
> + return ret;
> + if (!nimaps || imap.br_startblock == HOLESTARTBLOCK)
> + return -EAGAIN;
This would need the ilock. But extent list lookups are expensive,
so please don't add another one here. Just return when we hit the
first unallocated extent in xfs_bmapi_write - either a short write or
-EAGAIN if nothing has been written.
> error = xfs_break_layouts(inode, iolock, true);
> if (error)
> return error;
Additionally this can drop the iolock, so you might get a new
hole after it.
