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SubjectRe: [Ocfs2-devel] [PATCH v3 2/3] ocfs2: add ocfs2_overwrite_io function
Hi Gang,

On 2017/12/28 18:07, Gang He wrote:
> Add ocfs2_overwrite_io function, which is used to judge if
> overwrite allocated blocks, otherwise, the write will bring extra
> block allocation overhead.
>
> Signed-off-by: Gang He <ghe@suse.com>
> ---
> fs/ocfs2/extent_map.c | 45 +++++++++++++++++++++++++++++++++++++++++++++
> fs/ocfs2/extent_map.h | 3 +++
> 2 files changed, 48 insertions(+)
>
> diff --git a/fs/ocfs2/extent_map.c b/fs/ocfs2/extent_map.c
> index e4719e0..06cb964 100644
> --- a/fs/ocfs2/extent_map.c
> +++ b/fs/ocfs2/extent_map.c
> @@ -38,6 +38,7 @@
> #include "inode.h"
> #include "super.h"
> #include "symlink.h"
> +#include "aops.h"
> #include "ocfs2_trace.h"
>
> #include "buffer_head_io.h"
> @@ -832,6 +833,50 @@ int ocfs2_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo,
> return ret;
> }
>
> +/* Is IO overwriting allocated blocks? */
> +int ocfs2_overwrite_io(struct inode *inode, struct buffer_head *di_bh,
> + u64 map_start, u64 map_len)
Here can the type of 'map_start' is struct loff_t and map_len is struct size_t?

Thanks,
Alex
> +{
> + int ret = 0, is_last;
> + u32 mapping_end, cpos;
> + struct ocfs2_super *osb = OCFS2_SB(inode->i_sb);
> + struct ocfs2_extent_rec rec;
> +
> + if (OCFS2_I(inode)->ip_dyn_features & OCFS2_INLINE_DATA_FL) {
> + if (ocfs2_size_fits_inline_data(di_bh, map_start + map_len))
> + return ret;
> + else
> + return -EAGAIN;
> + }
> +
> + cpos = map_start >> osb->s_clustersize_bits;
> + mapping_end = ocfs2_clusters_for_bytes(inode->i_sb,
> + map_start + map_len);
> + is_last = 0;
> + while (cpos < mapping_end && !is_last) {
> + ret = ocfs2_get_clusters_nocache(inode, di_bh, cpos,
> + NULL, &rec, &is_last);
> + if (ret) {
> + mlog_errno(ret);
> + goto out;
> + }
> +
> + if (rec.e_blkno == 0ULL)
> + break;
> +
> + if (rec.e_flags & OCFS2_EXT_REFCOUNTED)
> + break;
> +
> + cpos = le32_to_cpu(rec.e_cpos) +
> + le16_to_cpu(rec.e_leaf_clusters);
> + }
> +
> + if (cpos < mapping_end)
> + ret = -EAGAIN;
> +out:
> + return ret;
> +}
> +
> int ocfs2_seek_data_hole_offset(struct file *file, loff_t *offset, int whence)
> {
> struct inode *inode = file->f_mapping->host;
> diff --git a/fs/ocfs2/extent_map.h b/fs/ocfs2/extent_map.h
> index 67ea57d..1057586 100644
> --- a/fs/ocfs2/extent_map.h
> +++ b/fs/ocfs2/extent_map.h
> @@ -53,6 +53,9 @@ int ocfs2_extent_map_get_blocks(struct inode *inode, u64 v_blkno, u64 *p_blkno,
> int ocfs2_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo,
> u64 map_start, u64 map_len);
>
> +int ocfs2_overwrite_io(struct inode *inode, struct buffer_head *di_bh,
> + u64 map_start, u64 map_len);
> +
> int ocfs2_seek_data_hole_offset(struct file *file, loff_t *offset, int origin);
>
> int ocfs2_xattr_get_clusters(struct inode *inode, u32 v_cluster,
>

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