[Ocfs2-devel] [PATCH 4/4] ocfs2: do not use ocfs2_zero_extend during direct IO
Joseph Qi
joseph.qi at huawei.com
Thu Mar 26 02:25:42 PDT 2015
Hi Mark,
Could you please help review these 4 patches?
On 2015/2/25 17:35, Joseph Qi wrote:
> In ocfs2_direct_IO_write, we use ocfs2_zero_extend to zero allocated
> clusters in case of cluster not aligned. But ocfs2_zero_extend uses page
> cache, this may happen that it clears the data which blockdev_direct_IO
> has already witten.
> We should use blkdev_issue_zeroout instead of ocfs2_zero_extend
> during direct IO.
> So fix this issue by introducing ocfs2_direct_IO_zero_extend and
> ocfs2_direct_IO_extend_no_holes.
>
> Reported-by: Yiwen Jiang <jiangyiwen at huawei.com>
> Signed-off-by: Joseph Qi <joseph.qi at huawei.com>
> Tested-by: Yiwen Jiang <jiangyiwen at huawei.com>
> ---
> fs/ocfs2/aops.c | 138 ++++++++++++++++++++++++++++++++++++++++++++++++++++----
> 1 file changed, 130 insertions(+), 8 deletions(-)
>
> diff --git a/fs/ocfs2/aops.c b/fs/ocfs2/aops.c
> index 973a636..1b0463a 100644
> --- a/fs/ocfs2/aops.c
> +++ b/fs/ocfs2/aops.c
> @@ -663,6 +663,117 @@ static int ocfs2_is_overwrite(struct ocfs2_super *osb,
> return 0;
> }
>
> +static int ocfs2_direct_IO_zero_extend(struct ocfs2_super *osb,
> + struct inode *inode, loff_t offset,
> + u64 zero_len, int cluster_align)
> +{
> + u32 p_cpos = 0;
> + u32 v_cpos = ocfs2_bytes_to_clusters(osb->sb, i_size_read(inode));
> + unsigned int num_clusters = 0;
> + unsigned int ext_flags = 0;
> + int ret = 0;
> +
> + if (offset <= i_size_read(inode) || cluster_align)
> + return 0;
> +
> + ret = ocfs2_get_clusters(inode, v_cpos, &p_cpos, &num_clusters,
> + &ext_flags);
> + if (ret < 0) {
> + mlog_errno(ret);
> + return ret;
> + }
> +
> + if (p_cpos && !(ext_flags & OCFS2_EXT_UNWRITTEN)) {
> + u64 s = i_size_read(inode);
> + sector_t sector = (p_cpos << (osb->s_clustersize_bits - 9)) +
> + (do_div(s, osb->s_clustersize) >> 9);
> +
> + ret = blkdev_issue_zeroout(osb->sb->s_bdev, sector,
> + zero_len >> 9, GFP_NOFS, false);
> + if (ret < 0)
> + mlog_errno(ret);
> + }
> +
> + return ret;
> +}
> +
> +static int ocfs2_direct_IO_extend_no_holes(struct ocfs2_super *osb,
> + struct inode *inode, loff_t offset)
> +{
> + u64 zero_start, zero_len, total_zero_len;
> + u32 p_cpos = 0, clusters_to_add;
> + u32 v_cpos = ocfs2_bytes_to_clusters(osb->sb, i_size_read(inode));
> + unsigned int num_clusters = 0;
> + unsigned int ext_flags = 0;
> + u32 size_div, offset_div;
> + int ret = 0;
> +
> + {
> + u64 o = offset;
> + u64 s = i_size_read(inode);
> +
> + offset_div = do_div(o, osb->s_clustersize);
> + size_div = do_div(s, osb->s_clustersize);
> + }
> +
> + if (offset <= i_size_read(inode))
> + return 0;
> +
> + clusters_to_add = ocfs2_bytes_to_clusters(inode->i_sb, offset) -
> + ocfs2_bytes_to_clusters(inode->i_sb, i_size_read(inode));
> + total_zero_len = offset - i_size_read(inode);
> + if (clusters_to_add)
> + total_zero_len -= offset_div;
> +
> + /* Allocate clusters to fill out holes, and this is only needed
> + * when we add more than one clusters. Otherwise the cluster will
> + * be allocated during direct IO */
> + if (clusters_to_add > 1) {
> + ret = ocfs2_extend_allocation(inode,
> + OCFS2_I(inode)->ip_clusters,
> + clusters_to_add - 1, 0);
> + if (ret) {
> + mlog_errno(ret);
> + goto out;
> + }
> + }
> +
> + while (total_zero_len) {
> + ret = ocfs2_get_clusters(inode, v_cpos, &p_cpos, &num_clusters,
> + &ext_flags);
> + if (ret < 0) {
> + mlog_errno(ret);
> + goto out;
> + }
> +
> + zero_start = ocfs2_clusters_to_bytes(osb->sb, p_cpos) +
> + size_div;
> + zero_len = ocfs2_clusters_to_bytes(osb->sb, num_clusters) -
> + size_div;
> + zero_len = min(total_zero_len, zero_len);
> +
> + if (p_cpos && !(ext_flags & OCFS2_EXT_UNWRITTEN)) {
> + ret = blkdev_issue_zeroout(osb->sb->s_bdev,
> + zero_start >> 9, zero_len >> 9,
> + GFP_NOFS, false);
> + if (ret < 0) {
> + mlog_errno(ret);
> + goto out;
> + }
> + }
> +
> + total_zero_len -= zero_len;
> + v_cpos += ocfs2_bytes_to_clusters(osb->sb, zero_len + size_div);
> +
> + /* Only at first iteration can be cluster not aligned.
> + * So set size_div to 0 for the rest */
> + size_div = 0;
> + }
> +
> +out:
> + return ret;
> +}
> +
> static ssize_t ocfs2_direct_IO_write(struct kiocb *iocb,
> struct iov_iter *iter,
> loff_t offset)
> @@ -677,8 +788,8 @@ static ssize_t ocfs2_direct_IO_write(struct kiocb *iocb,
> struct buffer_head *di_bh = NULL;
> size_t count = iter->count;
> journal_t *journal = osb->journal->j_journal;
> - u32 zero_len;
> - int cluster_align;
> + u64 zero_len_head, zero_len_tail;
> + int cluster_align_head, cluster_align_tail;
> loff_t final_size = offset + count;
> int append_write = offset >= i_size_read(inode) ? 1 : 0;
> unsigned int num_clusters = 0;
> @@ -686,9 +797,16 @@ static ssize_t ocfs2_direct_IO_write(struct kiocb *iocb,
>
> {
> u64 o = offset;
> + u64 s = i_size_read(inode);
> +
> + zero_len_head = do_div(o, 1 << osb->s_clustersize_bits);
> + cluster_align_head = !zero_len_head;
>
> - zero_len = do_div(o, 1 << osb->s_clustersize_bits);
> - cluster_align = !zero_len;
> + zero_len_tail = osb->s_clustersize -
> + do_div(s, osb->s_clustersize);
> + if ((offset - i_size_read(inode)) < zero_len_tail)
> + zero_len_tail = offset - i_size_read(inode);
> + cluster_align_tail = !zero_len_tail;
> }
>
> /*
> @@ -712,10 +830,13 @@ static ssize_t ocfs2_direct_IO_write(struct kiocb *iocb,
> goto clean_orphan;
> }
>
> + /* zeroing out the previously allocated cluster tail
> + * that but not zeroed */
> if (ocfs2_sparse_alloc(OCFS2_SB(inode->i_sb)))
> - ret = ocfs2_zero_extend(inode, di_bh, offset);
> + ret = ocfs2_direct_IO_zero_extend(osb, inode, offset,
> + zero_len_tail, cluster_align_tail);
> else
> - ret = ocfs2_extend_no_holes(inode, di_bh, offset,
> + ret = ocfs2_direct_IO_extend_no_holes(osb, inode,
> offset);
> if (ret < 0) {
> mlog_errno(ret);
> @@ -768,7 +889,8 @@ static ssize_t ocfs2_direct_IO_write(struct kiocb *iocb,
> mlog_errno(ret);
> }
> } else if (written > 0 && append_write && !is_overwrite &&
> - !cluster_align) {
> + !cluster_align_head) {
> + /* zeroing out the allocated cluster head */
> u32 p_cpos = 0;
> u32 v_cpos = ocfs2_bytes_to_clusters(osb->sb, offset);
>
> @@ -790,7 +912,7 @@ static ssize_t ocfs2_direct_IO_write(struct kiocb *iocb,
>
> ret = blkdev_issue_zeroout(osb->sb->s_bdev,
> p_cpos << (osb->s_clustersize_bits - 9),
> - zero_len >> 9, GFP_NOFS, false);
> + zero_len_head >> 9, GFP_NOFS, false);
> if (ret < 0)
> mlog_errno(ret);
>
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