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[PATCH RESEND] erofs: use Z_EROFS_LCLUSTER_TYPE_MAX to simplify switches

Hongzhen Luo posted 1 patch 1 year ago
There is a newer version of this series
fs/erofs/zmap.c | 59 ++++++++++++++++++-------------------------------
1 file changed, 22 insertions(+), 37 deletions(-)
[PATCH RESEND] erofs: use Z_EROFS_LCLUSTER_TYPE_MAX to simplify switches
Posted by Hongzhen Luo 1 year ago 
There's no need to enumerate each type.  No logic changes.

Signed-off-by: Hongzhen Luo <hongzhen@linux.alibaba.com>
---
 fs/erofs/zmap.c | 59 ++++++++++++++++++-------------------------------
 1 file changed, 22 insertions(+), 37 deletions(-)

diff --git a/fs/erofs/zmap.c b/fs/erofs/zmap.c
index 689437e99a5a..0ee78413bfd5 100644
--- a/fs/erofs/zmap.c
+++ b/fs/erofs/zmap.c
@@ -265,24 +265,20 @@ static int z_erofs_extent_lookback(struct z_erofs_maprecorder *m,
 		if (err)
 			return err;
 
-		switch (m->type) {
-		case Z_EROFS_LCLUSTER_TYPE_NONHEAD:
+		if (m->type == Z_EROFS_LCLUSTER_TYPE_NONHEAD) {
 			lookback_distance = m->delta[0];
 			if (!lookback_distance)
 				goto err_bogus;
 			continue;
-		case Z_EROFS_LCLUSTER_TYPE_PLAIN:
-		case Z_EROFS_LCLUSTER_TYPE_HEAD1:
-		case Z_EROFS_LCLUSTER_TYPE_HEAD2:
+		} else if (m->type < Z_EROFS_LCLUSTER_TYPE_MAX) {
 			m->headtype = m->type;
 			m->map->m_la = (lcn << lclusterbits) | m->clusterofs;
 			return 0;
-		default:
-			erofs_err(sb, "unknown type %u @ lcn %lu of nid %llu",
-				  m->type, lcn, vi->nid);
-			DBG_BUGON(1);
-			return -EOPNOTSUPP;
 		}
+		erofs_err(sb, "unknown type %u @ lcn %lu of nid %llu",
+			  m->type, lcn, vi->nid);
+		DBG_BUGON(1);
+		return -EOPNOTSUPP;
 	}
 err_bogus:
 	erofs_err(sb, "bogus lookback distance %u @ lcn %lu of nid %llu",
@@ -329,35 +325,28 @@ static int z_erofs_get_extent_compressedlen(struct z_erofs_maprecorder *m,
 	DBG_BUGON(lcn == initial_lcn &&
 		  m->type == Z_EROFS_LCLUSTER_TYPE_NONHEAD);
 
-	switch (m->type) {
-	case Z_EROFS_LCLUSTER_TYPE_PLAIN:
-	case Z_EROFS_LCLUSTER_TYPE_HEAD1:
-	case Z_EROFS_LCLUSTER_TYPE_HEAD2:
+	if (m->type == Z_EROFS_LCLUSTER_TYPE_NONHEAD) {
+		if (m->delta[0] != 1) {
+			erofs_err(sb, "bogus CBLKCNT @ lcn %lu of nid %llu", lcn, vi->nid);
+			DBG_BUGON(1);
+			return -EFSCORRUPTED;
+		}
+		if (m->compressedblks)
+			goto out;
+	} else if (m->type < Z_EROFS_LCLUSTER_TYPE_MAX) {
 		/*
 		 * if the 1st NONHEAD lcluster is actually PLAIN or HEAD type
 		 * rather than CBLKCNT, it's a 1 block-sized pcluster.
 		 */
 		m->compressedblks = 1;
-		break;
-	case Z_EROFS_LCLUSTER_TYPE_NONHEAD:
-		if (m->delta[0] != 1)
-			goto err_bonus_cblkcnt;
-		if (m->compressedblks)
-			break;
-		fallthrough;
-	default:
-		erofs_err(sb, "cannot found CBLKCNT @ lcn %lu of nid %llu", lcn,
-			  vi->nid);
-		DBG_BUGON(1);
-		return -EFSCORRUPTED;
+		goto out;
 	}
+	erofs_err(sb, "cannot found CBLKCNT @ lcn %lu of nid %llu", lcn, vi->nid);
+	DBG_BUGON(1);
+	return -EFSCORRUPTED;
 out:
 	m->map->m_plen = erofs_pos(sb, m->compressedblks);
 	return 0;
-err_bonus_cblkcnt:
-	erofs_err(sb, "bogus CBLKCNT @ lcn %lu of nid %llu", lcn, vi->nid);
-	DBG_BUGON(1);
-	return -EFSCORRUPTED;
 }
 
 static int z_erofs_get_extent_decompressedlen(struct z_erofs_maprecorder *m)
@@ -386,9 +375,7 @@ static int z_erofs_get_extent_decompressedlen(struct z_erofs_maprecorder *m)
 				m->delta[1] = 1;
 				DBG_BUGON(1);
 			}
-		} else if (m->type == Z_EROFS_LCLUSTER_TYPE_PLAIN ||
-			   m->type == Z_EROFS_LCLUSTER_TYPE_HEAD1 ||
-			   m->type == Z_EROFS_LCLUSTER_TYPE_HEAD2) {
+		} else if (m->type < Z_EROFS_LCLUSTER_TYPE_MAX) {
 			if (lcn != headlcn)
 				break;	/* ends at the next HEAD lcluster */
 			m->delta[1] = 1;
@@ -452,8 +439,7 @@ static int z_erofs_do_map_blocks(struct inode *inode,
 		}
 		/* m.lcn should be >= 1 if endoff < m.clusterofs */
 		if (!m.lcn) {
-			erofs_err(inode->i_sb,
-				  "invalid logical cluster 0 at nid %llu",
+			erofs_err(inode->i_sb, "invalid logical cluster 0 at nid %llu",
 				  vi->nid);
 			err = -EFSCORRUPTED;
 			goto unmap_out;
@@ -469,8 +455,7 @@ static int z_erofs_do_map_blocks(struct inode *inode,
 			goto unmap_out;
 		break;
 	default:
-		erofs_err(inode->i_sb,
-			  "unknown type %u @ offset %llu of nid %llu",
+		erofs_err(inode->i_sb, "unknown type %u @ offset %llu of nid %llu",
 			  m.type, ofs, vi->nid);
 		err = -EOPNOTSUPP;
 		goto unmap_out;
-- 
2.43.5
Re: [PATCH RESEND] erofs: use Z_EROFS_LCLUSTER_TYPE_MAX to simplify switches
Posted by Hongbo Li 1 year ago 

On 2025/2/7 14:41, Hongzhen Luo wrote:
> There's no need to enumerate each type.  No logic changes.
> 
> Signed-off-by: Hongzhen Luo <hongzhen@linux.alibaba.com>
> ---
>   fs/erofs/zmap.c | 59 ++++++++++++++++++-------------------------------
>   1 file changed, 22 insertions(+), 37 deletions(-)
> 
> diff --git a/fs/erofs/zmap.c b/fs/erofs/zmap.c
> index 689437e99a5a..0ee78413bfd5 100644
> --- a/fs/erofs/zmap.c
> +++ b/fs/erofs/zmap.c
> @@ -265,24 +265,20 @@ static int z_erofs_extent_lookback(struct z_erofs_maprecorder *m,
>   		if (err)
>   			return err;
>   
> -		switch (m->type) {
> -		case Z_EROFS_LCLUSTER_TYPE_NONHEAD:
> +		if (m->type == Z_EROFS_LCLUSTER_TYPE_NONHEAD) {
>   			lookback_distance = m->delta[0];
>   			if (!lookback_distance)
>   				goto err_bogus;
>   			continue;
> -		case Z_EROFS_LCLUSTER_TYPE_PLAIN:
> -		case Z_EROFS_LCLUSTER_TYPE_HEAD1:
> -		case Z_EROFS_LCLUSTER_TYPE_HEAD2:
> +		} else if (m->type < Z_EROFS_LCLUSTER_TYPE_MAX) {
>   			m->headtype = m->type;
>   			m->map->m_la = (lcn << lclusterbits) | m->clusterofs;
>   			return 0;
> -		default:
> -			erofs_err(sb, "unknown type %u @ lcn %lu of nid %llu",
> -				  m->type, lcn, vi->nid);
> -			DBG_BUGON(1);
> -			return -EOPNOTSUPP;
>   		}
> +		erofs_err(sb, "unknown type %u @ lcn %lu of nid %llu",
> +			  m->type, lcn, vi->nid);
> +		DBG_BUGON(1);
> +		return -EOPNOTSUPP;

May be it would be easier to understand if you put the exception branch 
at the beginning. Such as:

if (m->type >= Z_EROFS_LCLUSTER_TYPE_MAX) {
   // return -EOPNOTSUPP;
}

if (m->type == Z_EROFS_LCLUSTER_TYPE_NONHEAD) {
   // do something
}

// do something for other cases..

This is also useful for other places. :)

Thanks,
Hongbo

>   	}
>   err_bogus:
>   	erofs_err(sb, "bogus lookback distance %u @ lcn %lu of nid %llu",
> @@ -329,35 +325,28 @@ static int z_erofs_get_extent_compressedlen(struct z_erofs_maprecorder *m,
>   	DBG_BUGON(lcn == initial_lcn &&
>   		  m->type == Z_EROFS_LCLUSTER_TYPE_NONHEAD);
>   
> -	switch (m->type) {
> -	case Z_EROFS_LCLUSTER_TYPE_PLAIN:
> -	case Z_EROFS_LCLUSTER_TYPE_HEAD1:
> -	case Z_EROFS_LCLUSTER_TYPE_HEAD2:
> +	if (m->type == Z_EROFS_LCLUSTER_TYPE_NONHEAD) {
> +		if (m->delta[0] != 1) {
> +			erofs_err(sb, "bogus CBLKCNT @ lcn %lu of nid %llu", lcn, vi->nid);
> +			DBG_BUGON(1);
> +			return -EFSCORRUPTED;
> +		}
> +		if (m->compressedblks)
> +			goto out;
> +	} else if (m->type < Z_EROFS_LCLUSTER_TYPE_MAX) {
>   		/*
>   		 * if the 1st NONHEAD lcluster is actually PLAIN or HEAD type
>   		 * rather than CBLKCNT, it's a 1 block-sized pcluster.
>   		 */
>   		m->compressedblks = 1;
> -		break;
> -	case Z_EROFS_LCLUSTER_TYPE_NONHEAD:
> -		if (m->delta[0] != 1)
> -			goto err_bonus_cblkcnt;
> -		if (m->compressedblks)
> -			break;
> -		fallthrough;
> -	default:
> -		erofs_err(sb, "cannot found CBLKCNT @ lcn %lu of nid %llu", lcn,
> -			  vi->nid);
> -		DBG_BUGON(1);
> -		return -EFSCORRUPTED;
> +		goto out;
>   	}
> +	erofs_err(sb, "cannot found CBLKCNT @ lcn %lu of nid %llu", lcn, vi->nid);
> +	DBG_BUGON(1);
> +	return -EFSCORRUPTED;
>   out:
>   	m->map->m_plen = erofs_pos(sb, m->compressedblks);
>   	return 0;
> -err_bonus_cblkcnt:
> -	erofs_err(sb, "bogus CBLKCNT @ lcn %lu of nid %llu", lcn, vi->nid);
> -	DBG_BUGON(1);
> -	return -EFSCORRUPTED;
>   }
>   
>   static int z_erofs_get_extent_decompressedlen(struct z_erofs_maprecorder *m)
> @@ -386,9 +375,7 @@ static int z_erofs_get_extent_decompressedlen(struct z_erofs_maprecorder *m)
>   				m->delta[1] = 1;
>   				DBG_BUGON(1);
>   			}
> -		} else if (m->type == Z_EROFS_LCLUSTER_TYPE_PLAIN ||
> -			   m->type == Z_EROFS_LCLUSTER_TYPE_HEAD1 ||
> -			   m->type == Z_EROFS_LCLUSTER_TYPE_HEAD2) {
> +		} else if (m->type < Z_EROFS_LCLUSTER_TYPE_MAX) {
>   			if (lcn != headlcn)
>   				break;	/* ends at the next HEAD lcluster */
>   			m->delta[1] = 1;
> @@ -452,8 +439,7 @@ static int z_erofs_do_map_blocks(struct inode *inode,
>   		}
>   		/* m.lcn should be >= 1 if endoff < m.clusterofs */
>   		if (!m.lcn) {
> -			erofs_err(inode->i_sb,
> -				  "invalid logical cluster 0 at nid %llu",
> +			erofs_err(inode->i_sb, "invalid logical cluster 0 at nid %llu",
>   				  vi->nid);
>   			err = -EFSCORRUPTED;
>   			goto unmap_out;
> @@ -469,8 +455,7 @@ static int z_erofs_do_map_blocks(struct inode *inode,
>   			goto unmap_out;
>   		break;
>   	default:
> -		erofs_err(inode->i_sb,
> -			  "unknown type %u @ offset %llu of nid %llu",
> +		erofs_err(inode->i_sb, "unknown type %u @ offset %llu of nid %llu",
>   			  m.type, ofs, vi->nid);
>   		err = -EOPNOTSUPP;
>   		goto unmap_out;

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