Hi Changwei,
On 2017/12/18 20:06, Changwei Ge wrote:
> Before ocfs2 supporting allocating clusters while doing append-dio, all append
> dio will fall back to buffer io to allocate clusters firstly. Also, when it
> steps on a file hole, it will fall back to buffer io, too. But for current
> code, writing to file hole will leverage dio to allocate clusters. This is not
> right, since whether append-io is enabled tells the capability whether ocfs2
> can
> allocate space while doing dio.
> So introduce file hole check function back into ocfs2.
> Once ocfs2 is doing dio upon a file hole with append-dio disabled, it will
> fall
> back to buffer IO to allocate clusters.
>
1. Do you mean that filling hole can't go with dio when append-dio is disabled?
2. Is your checking-hole just for 'append-dio' or for 'all-common-dio'?
> Signed-off-by: Changwei Ge <ge.chang...@h3c.com>
> ---
> fs/ocfs2/aops.c | 44 ++++++++++++++++++++++++++++++++++++++++++--
> 1 file changed, 42 insertions(+), 2 deletions(-)
>
> diff --git a/fs/ocfs2/aops.c b/fs/ocfs2/aops.c
> index d151632..a982cf6 100644
> --- a/fs/ocfs2/aops.c
> +++ b/fs/ocfs2/aops.c
> @@ -2414,6 +2414,44 @@ static int ocfs2_dio_end_io(struct kiocb *iocb,
> return ret;
> }
>
> +/*
> + * Will look for holes and unwritten extents in the range starting at
> + * pos for count bytes (inclusive).
> + */
> +static int ocfs2_check_range_for_holes(struct inode *inode, loff_t pos,
> + size_t count)
> +{
> + int ret = 0;
> + unsigned int extent_flags;
> + u32 cpos, clusters, extent_len, phys_cpos;
> + struct super_block *sb = inode->i_sb;
> +
> + cpos = pos >> OCFS2_SB(sb)->s_clustersize_bits;
> + clusters = ocfs2_clusters_for_bytes(sb, pos + count) - cpos;
> +
> + while (clusters) {
> + ret = ocfs2_get_clusters(inode, cpos, &phys_cpos, &extent_len,
> + &extent_flags);
> + if (ret < 0) {
> + mlog_errno(ret);
> + goto out;
> + }
> +
> + if (phys_cpos == 0 || (extent_flags & OCFS2_EXT_UNWRITTEN)) {
> + ret = 1;
> + break;
> + }
> +
> + if (extent_len > clusters)
> + extent_len = clusters;
> +
> + clusters -= extent_len;
> + cpos += extent_len;
> + }
> +out:
> + return ret;
> +}
> +
> static ssize_t ocfs2_direct_IO(struct kiocb *iocb, struct iov_iter *iter)
> {
> struct file *file = iocb->ki_filp;
> @@ -2429,8 +2467,10 @@ static ssize_t ocfs2_direct_IO(struct kiocb *iocb,
> struct iov_iter *iter)
> return 0;
>
> /* Fallback to buffered I/O if we do not support append dio. */
> - if (iocb->ki_pos + iter->count > i_size_read(inode) &&
> - !ocfs2_supports_append_dio(osb))
> + if (!ocfs2_supports_append_dio(osb) &&
> + (iocb->ki_pos + iter->count > i_size_read(inode) ||
> + ocfs2_check_range_for_holes(inode, iocb->ki_pos,
> + iter->count)))
we should check error here, right?
thanks,
Jun
> return 0;
>
> if (iov_iter_rw(iter) == READ)
>
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