[Ocfs2-devel] [PATCH 1/1] Ocfs2: Optimize punching-hole codes v4.

[Ocfs2-devel] [PATCH 1/1] Ocfs2: Optimize punching-hole codes v4.

[Tristan Ye]

Changes from v3 to v4:

1. Fix a bug when crossing extent blocks.

2. Fix a bug when hole exists in the beginning of an extent block.

3. Apply tao's comments.

V4 patch has survived with fill_verify_holes testcase in ocfs2-test,
it also passed my manual sanity check and stress tests with enormous
extent records, besides, more corner testcases succeeded than v3.

Currently punching hole on a file with 3+ extent tree depth was
really a performance disaster, it even caused several hours to
go, though we may not hit this in real life with such a huge extent
number.

One simple way to improve the performance is quite straightforward,
by learning the logic of truncating codes, means we'd punch hole from
hole_end to hole_start, which reduce the overhead of btree operation
in a significant way, such as tree rotation and moving.

Following is the testing result when punching hole from 0 to file end
in bytes, on a 1G file, 1G file consists of 256k extent records, each record
cover 4k data(just one cluster, clustersize is 4k):

===========================================================================
 * Former punching-hole mechanism:
===========================================================================

   I waited 1 hour for its completion, unfortunately it's still ongoing.

===========================================================================
 * Patched punching-hode mechanism:
===========================================================================

   real	0m2.518s
   user	0m0.000s
   sys	0m2.445s

That means we've gained up to 1000 times improvement on performance in this
case, whee! It's fairly cool. and it looks like that performance gain will
be raising when extent records grow.

The patch was based on my former 2 patches, which were about truncating
codes optimization and fixup to handle CoW on punching hole.

Signed-off-by: Tristan Ye <tristan.ye@oracle.com>
---
 fs/ocfs2/file.c |  233 ++++++++++++++++++++++++++++++++++++++++++++++++-------
 1 files changed, 206 insertions(+), 27 deletions(-)

diff --git a/fs/ocfs2/file.c b/fs/ocfs2/file.c
index db2e0c9..75e087f 100644
--- a/fs/ocfs2/file.c
+++ b/fs/ocfs2/file.c
@@ -1423,18 +1423,154 @@ out:
 	return ret;
 }
 
+static void ocfs2_find_rec(struct ocfs2_extent_list *el,
+			   struct ocfs2_extent_rec **rec_found,
+			   u32 *pos)
+{
+	int i, found = 0;
+	struct ocfs2_extent_rec *rec = NULL;
+
+	for (i = le16_to_cpu(el->l_next_free_rec) - 1; i >= 0; i--) {
+
+		rec = &el->l_recs[i];
+
+		if (le32_to_cpu(rec->e_cpos) <= *pos) {
+			found = 1;
+			break;
+		}
+	}
+
+	if (!found)
+		*rec_found = NULL;
+	else
+		*rec_found = &el->l_recs[i];
+}
+
+/*
+ * Hepler to find the rightmost record which contains 'pos' cpos,
+ * skip the holes if any, also adjust the 'pos' accordingly.
+ */
+static void ocfs2_find_rec_with_holes(struct ocfs2_extent_list *el,
+				      struct ocfs2_extent_rec **rec_found,
+				      u32 *pos)
+{
+	int i, found = 0;
+	u32 range;
+	struct ocfs2_extent_rec *rec = NULL;
+
+	for (i = le16_to_cpu(el->l_next_free_rec) - 1; i >= 0; i--) {
+
+		rec = &el->l_recs[i];
+		range = le32_to_cpu(rec->e_cpos) +
+				ocfs2_rec_clusters(el, rec);
+
+		if (le32_to_cpu(rec->e_cpos) < *pos) {
+			/*
+			 * Skip a hole.
+			 */
+			if (range < *pos)
+				*pos = range;
+
+			found = 1;
+			break;
+		}
+
+		/*
+		 * Simply jump to previous record if the pos is
+		 * the start of a record.
+		 */
+		if (le32_to_cpu(rec->e_cpos) == *pos) {
+			i--;
+			/*
+			 * The rec we're looking for is in previous
+			 * extent block.
+			 */
+			if (i < 0)
+				break;
+
+			rec = &el->l_recs[i];
+			range = le32_to_cpu(rec->e_cpos) +
+					ocfs2_rec_clusters(el, rec);
+			/*
+			 * Skip a hole.
+			 */
+			if (range < *pos)
+				*pos = range;
+
+			found = 1;
+			break;
+		}
+	}
+
+	if (!found)
+		*rec_found = NULL;
+	else
+		*rec_found = &el->l_recs[i];
+}
+
+/*
+ * Helper to calculate the punching pos and length in one run, we handle the
+ * following three cases in order:
+ *
+ * - remove the entire record
+ * - remove a partial record
+ * - no record needs to be removed (hole-punching completed)
+*/
+static void ocfs2_calc_trunc_pos(struct inode *inode,
+				 struct ocfs2_extent_list *el,
+				 struct ocfs2_extent_rec *rec,
+				 u32 trunc_start, u32 *trunc_cpos,
+				 u32 *trunc_len, u32 *trunc_end,
+				 u64 *blkno, int *done)
+{
+	int ret = 0;
+	u32 coff, range;
+
+	range = le32_to_cpu(rec->e_cpos) + ocfs2_rec_clusters(el, rec);
+
+	if (le32_to_cpu(rec->e_cpos) >= trunc_start) {
+		*trunc_cpos = le32_to_cpu(rec->e_cpos);
+		*trunc_len = *trunc_end - le32_to_cpu(rec->e_cpos);
+		*blkno = le64_to_cpu(rec->e_blkno);
+		*trunc_end = le32_to_cpu(rec->e_cpos);
+	} else if (range > trunc_start) {
+		*trunc_cpos = trunc_start;
+		*trunc_len = range - trunc_start;
+		coff = trunc_start - le32_to_cpu(rec->e_cpos);
+		*blkno = le64_to_cpu(rec->e_blkno) +
+				ocfs2_clusters_to_blocks(inode->i_sb, coff);
+		*trunc_end = trunc_start;
+	} else {
+		/*
+		 * It may have two following possibilities:
+		 *
+		 * - last record has been removed
+		 * - trunc_start was within a hole
+		 *
+		 * both two cases mean the completion of hole punching.
+		 */
+		ret = 1;
+	}
+
+	*done = ret;
+}
+
 static int ocfs2_remove_inode_range(struct inode *inode,
 				    struct buffer_head *di_bh, u64 byte_start,
 				    u64 byte_len)
 {
-	int ret = 0, flags = 0;
-	u32 trunc_start, trunc_len, cpos, phys_cpos, alloc_size;
+	int ret = 0, flags = 0, done = 0;
+	u32 trunc_start, trunc_len, trunc_end, trunc_cpos, phys_cpos;
+	u32 cluster_within_list;
 	struct ocfs2_super *osb = OCFS2_SB(inode->i_sb);
 	struct ocfs2_cached_dealloc_ctxt dealloc;
 	struct address_space *mapping = inode->i_mapping;
 	struct ocfs2_extent_tree et;
+	struct ocfs2_path *path = NULL;
+	struct ocfs2_extent_list *el = NULL;
+	struct ocfs2_extent_rec *rec = NULL;
 	struct ocfs2_dinode *di = (struct ocfs2_dinode *)di_bh->b_data;
-	u64 refcount_loc = le64_to_cpu(di->i_refcount_loc);
+	u64 blkno, refcount_loc = le64_to_cpu(di->i_refcount_loc);
 
 	ocfs2_init_dinode_extent_tree(&et, INODE_CACHE(inode), di_bh);
 	ocfs2_init_dealloc_ctxt(&dealloc);
@@ -1482,16 +1618,13 @@ static int ocfs2_remove_inode_range(struct inode *inode,
 	}
 
 	trunc_start = ocfs2_clusters_for_bytes(osb->sb, byte_start);
-	trunc_len = (byte_start + byte_len) >> osb->s_clustersize_bits;
-	if (trunc_len >= trunc_start)
-		trunc_len -= trunc_start;
-	else
-		trunc_len = 0;
+	trunc_end = (byte_start + byte_len) >> osb->s_clustersize_bits;
+	cluster_within_list = trunc_end;
 
-	mlog(0, "Inode: %llu, start: %llu, len: %llu, cstart: %u, clen: %u\n",
+	mlog(0, "Inode: %llu, start: %llu, len: %llu, cstart: %u, cend: %u\n",
 	     (unsigned long long)OCFS2_I(inode)->ip_blkno,
 	     (unsigned long long)byte_start,
-	     (unsigned long long)byte_len, trunc_start, trunc_len);
+	     (unsigned long long)byte_len, trunc_start, trunc_end);
 
 	ret = ocfs2_zero_partial_clusters(inode, byte_start, byte_len);
 	if (ret) {
@@ -1499,32 +1632,78 @@ static int ocfs2_remove_inode_range(struct inode *inode,
 		goto out;
 	}
 
-	cpos = trunc_start;
-	while (trunc_len) {
-		ret = ocfs2_get_clusters(inode, cpos, &phys_cpos,
-					 &alloc_size, &flags);
+	path = ocfs2_new_path_from_et(&et);
+	if (!path) {
+		ret = -ENOMEM;
+		mlog_errno(ret);
+		goto out;
+	}
+
+	while (trunc_end > 0) {
+		/*
+		 * Unlike truncate codes, here we want to find a path which
+		 * contains (trunc_end - 1) cpos, and then trunc_end will be
+		 * decreased after each removal of a record range.
+		 *
+		 * Why not using trunc_end to search the path?
+		 * The reason is simple, think about the situation of crossing
+		 * the extent block, we need to find the adjacent block by
+		 * decreasing one cluster, otherwise, it will run into a loop.
+		 */
+		ret = ocfs2_find_path(INODE_CACHE(inode), path,
+				      cluster_within_list);
 		if (ret) {
 			mlog_errno(ret);
 			goto out;
 		}
 
-		if (alloc_size > trunc_len)
-			alloc_size = trunc_len;
+		el = path_leaf_el(path);
 
-		/* Only do work for non-holes */
-		if (phys_cpos != 0) {
-			ret = ocfs2_remove_btree_range(inode, &et, cpos,
-						       phys_cpos, alloc_size,
-						       &dealloc, refcount_loc,
-						       flags);
-			if (ret) {
-				mlog_errno(ret);
-				goto out;
+		ocfs2_find_rec_with_holes(el, &rec, &trunc_end);
+		/*
+		 * Need to go to previous extent block.
+		 */
+		if (!rec) {
+			if (path->p_tree_depth == 0)
+				break;
+			else {
+				el = path->p_node[path->p_tree_depth - 1].el;
+				ocfs2_find_rec(el, &rec, &trunc_end);
+				if (!rec)
+					break;
+				if (le32_to_cpu(rec->e_cpos)) {
+					trunc_end = le32_to_cpu(rec->e_cpos);
+					cluster_within_list = trunc_end - 1;
+				} else
+					break;
 			}
+
+			ocfs2_reinit_path(path, 1);
+			continue;
 		}
 
-		cpos += alloc_size;
-		trunc_len -= alloc_size;
+		ocfs2_calc_trunc_pos(inode, el, rec, trunc_start, &trunc_cpos,
+				     &trunc_len, &trunc_end, &blkno, &done);
+		if (done)
+			break;
+
+		flags = rec->e_flags;
+		phys_cpos = ocfs2_blocks_to_clusters(inode->i_sb, blkno);
+
+		ret = ocfs2_remove_btree_range(inode, &et, trunc_cpos,
+					       phys_cpos, trunc_len, &dealloc,
+					       refcount_loc, flags);
+		if (ret < 0) {
+			mlog_errno(ret);
+			goto out;
+		}
+
+		if (trunc_end > 0)
+			cluster_within_list = trunc_end - 1;
+		else
+			break;
+
+		ocfs2_reinit_path(path, 1);
 	}
 
 	ocfs2_truncate_cluster_pages(inode, byte_start, byte_len);
-- 
1.5.5

[Ocfs2-devel] [PATCH 1/1] Ocfs2: Optimize punching-hole codes v4.

[Tao Ma]

Hi Tristan,
Tristan Ye wrote:
> Changes from v3 to v4:
>
> 1. Fix a bug when crossing extent blocks.
>
> 2. Fix a bug when hole exists in the beginning of an extent block.
>
> 3. Apply tao's comments.
>
>
> Signed-off-by: Tristan Ye <tristan.ye@oracle.com>
> ---
>  fs/ocfs2/file.c |  233 ++++++++++++++++++++++++++++++++++++++++++++++++-------
>  1 files changed, 206 insertions(+), 27 deletions(-)
>
> diff --git a/fs/ocfs2/file.c b/fs/ocfs2/file.c
> index db2e0c9..75e087f 100644
> --- a/fs/ocfs2/file.c
> +++ b/fs/ocfs2/file.c
> @@ -1423,18 +1423,154 @@ out:
>  	return ret;
>  }
>  
> +static void ocfs2_find_rec(struct ocfs2_extent_list *el,
> +			   struct ocfs2_extent_rec **rec_found,
> +			   u32 *pos)
> +{
> +	int i, found = 0;
> +	struct ocfs2_extent_rec *rec = NULL;
> +
> +	for (i = le16_to_cpu(el->l_next_free_rec) - 1; i >= 0; i--) {
> +
> +		rec = &el->l_recs[i];
> +
> +		if (le32_to_cpu(rec->e_cpos) <= *pos) {
> +			found = 1;
> +			break;
> +		}
> +	}
> +
> +	if (!found)
> +		*rec_found = NULL;
> +	else
> +		*rec_found = &el->l_recs[i];
> +}
>   
This function never returns pos now. So why you want to pass a *pos?
another issue is that now it seems that you only want to returns a rec?
then why not change this function to
static int ocfs2_find_rec(struct ocfs2_extent_list *el, u32 pos)
and after the loop, just return i. So if i>=0, you find it, if i < 0, no 
rec is found. Looks more natural?
> +
> +/*
> + * Hepler to find the rightmost record which contains 'pos' cpos,
> + * skip the holes if any, also adjust the 'pos' accordingly.
> + */
> +static void ocfs2_find_rec_with_holes(struct ocfs2_extent_list *el,
> +				      struct ocfs2_extent_rec **rec_found,
> +				      u32 *pos)
> +{
> +	int i, found = 0;
> +	u32 range;
> +	struct ocfs2_extent_rec *rec = NULL;
> +
> +	for (i = le16_to_cpu(el->l_next_free_rec) - 1; i >= 0; i--) {
> +
> +		rec = &el->l_recs[i];
> +		range = le32_to_cpu(rec->e_cpos) +
> +				ocfs2_rec_clusters(el, rec);
> +
> +		if (le32_to_cpu(rec->e_cpos) < *pos) {
> +			/*
> +			 * Skip a hole.
> +			 */
> +			if (range < *pos)
> +				*pos = range;
> +
> +			found = 1;
> +			break;
> +		}
> +
> +		/*
> +		 * Simply jump to previous record if the pos is
> +		 * the start of a record.
> +		 */
> +		if (le32_to_cpu(rec->e_cpos) == *pos) {
> +			i--;
> +			/*
> +			 * The rec we're looking for is in previous
> +			 * extent block.
> +			 */
> +			if (i < 0)
> +				break;
> +
> +			rec = &el->l_recs[i];
> +			range = le32_to_cpu(rec->e_cpos) +
> +					ocfs2_rec_clusters(el, rec);
> +			/*
> +			 * Skip a hole.
> +			 */
> +			if (range < *pos)
> +				*pos = range;
>   
As I have said in the previous e-mail, no matter whether there is a hole 
or not, we should set *pos = range since
it will be the next 'end' we punch. And it looks more readable.
> +
> +			found = 1;
> +			break;
> +		}
> +	}
> +
> +	if (!found)
> +		*rec_found = NULL;
> +	else
> +		*rec_found = &el->l_recs[i];
>   
And the same for this function you can just return 'i' and I guess this 
function and the previous one can be integrated
into just one.
> +}
> +
> +/*
> + * Helper to calculate the punching pos and length in one run, we handle the
> + * following three cases in order:
> + *
> + * - remove the entire record
> + * - remove a partial record
> + * - no record needs to be removed (hole-punching completed)
> +*/
> +static void ocfs2_calc_trunc_pos(struct inode *inode,
> +				 struct ocfs2_extent_list *el,
> +				 struct ocfs2_extent_rec *rec,
> +				 u32 trunc_start, u32 *trunc_cpos,
> +				 u32 *trunc_len, u32 *trunc_end,
> +				 u64 *blkno, int *done)
> +{
> +	int ret = 0;
> +	u32 coff, range;
> +
> +	range = le32_to_cpu(rec->e_cpos) + ocfs2_rec_clusters(el, rec);
> +
> +	if (le32_to_cpu(rec->e_cpos) >= trunc_start) {
> +		*trunc_cpos = le32_to_cpu(rec->e_cpos);
> +		*trunc_len = *trunc_end - le32_to_cpu(rec->e_cpos);
> +		*blkno = le64_to_cpu(rec->e_blkno);
> +		*trunc_end = le32_to_cpu(rec->e_cpos);
> +	} else if (range > trunc_start) {
> +		*trunc_cpos = trunc_start;
> +		*trunc_len = range - trunc_start;
> +		coff = trunc_start - le32_to_cpu(rec->e_cpos);
> +		*blkno = le64_to_cpu(rec->e_blkno) +
> +				ocfs2_clusters_to_blocks(inode->i_sb, coff);
> +		*trunc_end = trunc_start;
> +	} else {
> +		/*
> +		 * It may have two following possibilities:
> +		 *
> +		 * - last record has been removed
> +		 * - trunc_start was within a hole
> +		 *
> +		 * both two cases mean the completion of hole punching.
> +		 */
> +		ret = 1;
> +	}
> +
> +	*done = ret;
> +}
> +
>  static int ocfs2_remove_inode_range(struct inode *inode,
>  				    struct buffer_head *di_bh, u64 byte_start,
>  				    u64 byte_len)
>  {
> -	int ret = 0, flags = 0;
> -	u32 trunc_start, trunc_len, cpos, phys_cpos, alloc_size;
> +	int ret = 0, flags = 0, done = 0;
> +	u32 trunc_start, trunc_len, trunc_end, trunc_cpos, phys_cpos;
> +	u32 cluster_within_list;
>  	struct ocfs2_super *osb = OCFS2_SB(inode->i_sb);
>  	struct ocfs2_cached_dealloc_ctxt dealloc;
>  	struct address_space *mapping = inode->i_mapping;
>  	struct ocfs2_extent_tree et;
> +	struct ocfs2_path *path = NULL;
> +	struct ocfs2_extent_list *el = NULL;
> +	struct ocfs2_extent_rec *rec = NULL;
>  	struct ocfs2_dinode *di = (struct ocfs2_dinode *)di_bh->b_data;
> -	u64 refcount_loc = le64_to_cpu(di->i_refcount_loc);
> +	u64 blkno, refcount_loc = le64_to_cpu(di->i_refcount_loc);
>  
>  	ocfs2_init_dinode_extent_tree(&et, INODE_CACHE(inode), di_bh);
>  	ocfs2_init_dealloc_ctxt(&dealloc);
> @@ -1482,16 +1618,13 @@ static int ocfs2_remove_inode_range(struct inode *inode,
>  	}
>  
>  	trunc_start = ocfs2_clusters_for_bytes(osb->sb, byte_start);
> -	trunc_len = (byte_start + byte_len) >> osb->s_clustersize_bits;
> -	if (trunc_len >= trunc_start)
> -		trunc_len -= trunc_start;
> -	else
> -		trunc_len = 0;
> +	trunc_end = (byte_start + byte_len) >> osb->s_clustersize_bits;
> +	cluster_within_list = trunc_end;
>  
> -	mlog(0, "Inode: %llu, start: %llu, len: %llu, cstart: %u, clen: %u\n",
> +	mlog(0, "Inode: %llu, start: %llu, len: %llu, cstart: %u, cend: %u\n",
>  	     (unsigned long long)OCFS2_I(inode)->ip_blkno,
>  	     (unsigned long long)byte_start,
> -	     (unsigned long long)byte_len, trunc_start, trunc_len);
> +	     (unsigned long long)byte_len, trunc_start, trunc_end);
>  
>  	ret = ocfs2_zero_partial_clusters(inode, byte_start, byte_len);
>  	if (ret) {
> @@ -1499,32 +1632,78 @@ static int ocfs2_remove_inode_range(struct inode *inode,
>  		goto out;
>  	}
>  
> -	cpos = trunc_start;
> -	while (trunc_len) {
> -		ret = ocfs2_get_clusters(inode, cpos, &phys_cpos,
> -					 &alloc_size, &flags);
> +	path = ocfs2_new_path_from_et(&et);
> +	if (!path) {
> +		ret = -ENOMEM;
> +		mlog_errno(ret);
> +		goto out;
> +	}
> +
> +	while (trunc_end > 0) {
>   
I think we have a consensus to change this check somehow?
> +		/*
> +		 * Unlike truncate codes, here we want to find a path which
> +		 * contains (trunc_end - 1) cpos, and then trunc_end will be
> +		 * decreased after each removal of a record range.
> +		 *
> +		 * Why not using trunc_end to search the path?
> +		 * The reason is simple, think about the situation of crossing
> +		 * the extent block, we need to find the adjacent block by
> +		 * decreasing one cluster, otherwise, it will run into a loop.
> +		 */
> +		ret = ocfs2_find_path(INODE_CACHE(inode), path,
> +				      cluster_within_list);
>  		if (ret) {
>  			mlog_errno(ret);
>  			goto out;
>  		}
>  
> -		if (alloc_size > trunc_len)
> -			alloc_size = trunc_len;
> +		el = path_leaf_el(path);
>  
> -		/* Only do work for non-holes */
> -		if (phys_cpos != 0) {
> -			ret = ocfs2_remove_btree_range(inode, &et, cpos,
> -						       phys_cpos, alloc_size,
> -						       &dealloc, refcount_loc,
> -						       flags);
> -			if (ret) {
> -				mlog_errno(ret);
> -				goto out;
> +		ocfs2_find_rec_with_holes(el, &rec, &trunc_end);
> +		/*
> +		 * Need to go to previous extent block.
> +		 */
> +		if (!rec) {
> +			if (path->p_tree_depth == 0)
> +				break;
> +			else {
> +				el = path->p_node[path->p_tree_depth - 1].el;
> +				ocfs2_find_rec(el, &rec, &trunc_end);
> +				if (!rec)
> +					break;
> +				if (le32_to_cpu(rec->e_cpos)) {
> +					trunc_end = le32_to_cpu(rec->e_cpos);
> +					cluster_within_list = trunc_end - 1;
> +				} else
> +					break;
>  			}
>   
oh, I really see what you are going to do here. It is really buggy. What 
if the tree_depth=2, and the branch
extent block with 'tree_depth-1' is also recs[0] in the tree_depth 
extent block? you can't find 'rec' and break.
Actually there is already a function. ;)  Check 
ocfs2_find_cpos_for_left_leaf for detail.

> +
> +			ocfs2_reinit_path(path, 1);
> +			continue;
>  		}
>  
> -		cpos += alloc_size;
> -		trunc_len -= alloc_size;
> +		ocfs2_calc_trunc_pos(inode, el, rec, trunc_start, &trunc_cpos,
> +				     &trunc_len, &trunc_end, &blkno, &done);
> +		if (done)
> +			break;
> +
> +		flags = rec->e_flags;
> +		phys_cpos = ocfs2_blocks_to_clusters(inode->i_sb, blkno);
> +
> +		ret = ocfs2_remove_btree_range(inode, &et, trunc_cpos,
> +					       phys_cpos, trunc_len, &dealloc,
> +					       refcount_loc, flags);
> +		if (ret < 0) {
> +			mlog_errno(ret);
> +			goto out;
> +		}
> +
> +		if (trunc_end > 0)
> +			cluster_within_list = trunc_end - 1;
> +		else
> +			break;
> +
> +		ocfs2_reinit_path(path, 1);
>  	}
>  
>  	ocfs2_truncate_cluster_pages(inode, byte_start, byte_len);
>   
Regards,
Tao

[Ocfs2-devel] [PATCH 1/1] Ocfs2: Optimize punching-hole codes v4.

[tristan]

Tao,

Thanks a lot for your quick review;)

Tao Ma wrote:
> Hi Tristan,
> Tristan Ye wrote:
>> Changes from v3 to v4:
>>
>> 1. Fix a bug when crossing extent blocks.
>>
>> 2. Fix a bug when hole exists in the beginning of an extent block.
>>
>> 3. Apply tao's comments.
>>
>>
>> Signed-off-by: Tristan Ye <tristan.ye@oracle.com>
>> ---
>>  fs/ocfs2/file.c |  233 
>> ++++++++++++++++++++++++++++++++++++++++++++++++-------
>>  1 files changed, 206 insertions(+), 27 deletions(-)
>>
>> diff --git a/fs/ocfs2/file.c b/fs/ocfs2/file.c
>> index db2e0c9..75e087f 100644
>> --- a/fs/ocfs2/file.c
>> +++ b/fs/ocfs2/file.c
>> @@ -1423,18 +1423,154 @@ out:
>>      return ret;
>>  }
>>  
>> +static void ocfs2_find_rec(struct ocfs2_extent_list *el,
>> +               struct ocfs2_extent_rec **rec_found,
>> +               u32 *pos)
>> +{
>> +    int i, found = 0;
>> +    struct ocfs2_extent_rec *rec = NULL;
>> +
>> +    for (i = le16_to_cpu(el->l_next_free_rec) - 1; i >= 0; i--) {
>> +
>> +        rec = &el->l_recs[i];
>> +
>> +        if (le32_to_cpu(rec->e_cpos) <= *pos) {
>> +            found = 1;
>> +            break;
>> +        }
>> +    }
>> +
>> +    if (!found)
>> +        *rec_found = NULL;
>> +    else
>> +        *rec_found = &el->l_recs[i];
>> +}
>>   
> This function never returns pos now. So why you want to pass a *pos?
> another issue is that now it seems that you only want to returns a rec?
> then why not change this function to
> static int ocfs2_find_rec(struct ocfs2_extent_list *el, u32 pos)

Yes, it's confusing to use *pos, thanks for pointing this out.

> and after the loop, just return i. So if i>=0, you find it, if i < 0, 
> no rec is found. Looks more natural?

I think returning  a meaty record would be more straightforward.

>> +
>> +/*
>> + * Hepler to find the rightmost record which contains 'pos' cpos,
>> + * skip the holes if any, also adjust the 'pos' accordingly.
>> + */
>> +static void ocfs2_find_rec_with_holes(struct ocfs2_extent_list *el,
>> +                      struct ocfs2_extent_rec **rec_found,
>> +                      u32 *pos)
>> +{
>> +    int i, found = 0;
>> +    u32 range;
>> +    struct ocfs2_extent_rec *rec = NULL;
>> +
>> +    for (i = le16_to_cpu(el->l_next_free_rec) - 1; i >= 0; i--) {
>> +
>> +        rec = &el->l_recs[i];
>> +        range = le32_to_cpu(rec->e_cpos) +
>> +                ocfs2_rec_clusters(el, rec);
>> +
>> +        if (le32_to_cpu(rec->e_cpos) < *pos) {
>> +            /*
>> +             * Skip a hole.
>> +             */
>> +            if (range < *pos)
>> +                *pos = range;
>> +
>> +            found = 1;
>> +            break;
>> +        }
>> +
>> +        /*
>> +         * Simply jump to previous record if the pos is
>> +         * the start of a record.
>> +         */
>> +        if (le32_to_cpu(rec->e_cpos) == *pos) {
>> +            i--;
>> +            /*
>> +             * The rec we're looking for is in previous
>> +             * extent block.
>> +             */
>> +            if (i < 0)
>> +                break;
>> +
>> +            rec = &el->l_recs[i];
>> +            range = le32_to_cpu(rec->e_cpos) +
>> +                    ocfs2_rec_clusters(el, rec);
>> +            /*
>> +             * Skip a hole.
>> +             */
>> +            if (range < *pos)
>> +                *pos = range;
>>   
> As I have said in the previous e-mail, no matter whether there is a 
> hole or not, we should set *pos = range since
> it will be the next 'end' we punch. And it looks more readable.
>> +
>> +            found = 1;
>> +            break;
>> +        }
>> +    }
>> +
>> +    if (!found)
>> +        *rec_found = NULL;
>> +    else
>> +        *rec_found = &el->l_recs[i];
>>   
> And the same for this function you can just return 'i' and I guess 
> this function and the previous one can be integrated
> into just one.

I don't think so, second function handles the hole and adjust the pos 
accordingly, while second one only simply search the rec.

>> +}
>> +
>> +/*
>> + * Helper to calculate the punching pos and length in one run, we 
>> handle the
>> + * following three cases in order:
>> + *
>> + * - remove the entire record
>> + * - remove a partial record
>> + * - no record needs to be removed (hole-punching completed)
>> +*/
>> +static void ocfs2_calc_trunc_pos(struct inode *inode,
>> +                 struct ocfs2_extent_list *el,
>> +                 struct ocfs2_extent_rec *rec,
>> +                 u32 trunc_start, u32 *trunc_cpos,
>> +                 u32 *trunc_len, u32 *trunc_end,
>> +                 u64 *blkno, int *done)
>> +{
>> +    int ret = 0;
>> +    u32 coff, range;
>> +
>> +    range = le32_to_cpu(rec->e_cpos) + ocfs2_rec_clusters(el, rec);
>> +
>> +    if (le32_to_cpu(rec->e_cpos) >= trunc_start) {
>> +        *trunc_cpos = le32_to_cpu(rec->e_cpos);
>> +        *trunc_len = *trunc_end - le32_to_cpu(rec->e_cpos);
>> +        *blkno = le64_to_cpu(rec->e_blkno);
>> +        *trunc_end = le32_to_cpu(rec->e_cpos);
>> +    } else if (range > trunc_start) {
>> +        *trunc_cpos = trunc_start;
>> +        *trunc_len = range - trunc_start;
>> +        coff = trunc_start - le32_to_cpu(rec->e_cpos);
>> +        *blkno = le64_to_cpu(rec->e_blkno) +
>> +                ocfs2_clusters_to_blocks(inode->i_sb, coff);
>> +        *trunc_end = trunc_start;
>> +    } else {
>> +        /*
>> +         * It may have two following possibilities:
>> +         *
>> +         * - last record has been removed
>> +         * - trunc_start was within a hole
>> +         *
>> +         * both two cases mean the completion of hole punching.
>> +         */
>> +        ret = 1;
>> +    }
>> +
>> +    *done = ret;
>> +}
>> +
>>  static int ocfs2_remove_inode_range(struct inode *inode,
>>                      struct buffer_head *di_bh, u64 byte_start,
>>                      u64 byte_len)
>>  {
>> -    int ret = 0, flags = 0;
>> -    u32 trunc_start, trunc_len, cpos, phys_cpos, alloc_size;
>> +    int ret = 0, flags = 0, done = 0;
>> +    u32 trunc_start, trunc_len, trunc_end, trunc_cpos, phys_cpos;
>> +    u32 cluster_within_list;
>>      struct ocfs2_super *osb = OCFS2_SB(inode->i_sb);
>>      struct ocfs2_cached_dealloc_ctxt dealloc;
>>      struct address_space *mapping = inode->i_mapping;
>>      struct ocfs2_extent_tree et;
>> +    struct ocfs2_path *path = NULL;
>> +    struct ocfs2_extent_list *el = NULL;
>> +    struct ocfs2_extent_rec *rec = NULL;
>>      struct ocfs2_dinode *di = (struct ocfs2_dinode *)di_bh->b_data;
>> -    u64 refcount_loc = le64_to_cpu(di->i_refcount_loc);
>> +    u64 blkno, refcount_loc = le64_to_cpu(di->i_refcount_loc);
>>  
>>      ocfs2_init_dinode_extent_tree(&et, INODE_CACHE(inode), di_bh);
>>      ocfs2_init_dealloc_ctxt(&dealloc);
>> @@ -1482,16 +1618,13 @@ static int ocfs2_remove_inode_range(struct 
>> inode *inode,
>>      }
>>  
>>      trunc_start = ocfs2_clusters_for_bytes(osb->sb, byte_start);
>> -    trunc_len = (byte_start + byte_len) >> osb->s_clustersize_bits;
>> -    if (trunc_len >= trunc_start)
>> -        trunc_len -= trunc_start;
>> -    else
>> -        trunc_len = 0;
>> +    trunc_end = (byte_start + byte_len) >> osb->s_clustersize_bits;
>> +    cluster_within_list = trunc_end;
>>  
>> -    mlog(0, "Inode: %llu, start: %llu, len: %llu, cstart: %u, clen: 
>> %u\n",
>> +    mlog(0, "Inode: %llu, start: %llu, len: %llu, cstart: %u, cend: 
>> %u\n",
>>           (unsigned long long)OCFS2_I(inode)->ip_blkno,
>>           (unsigned long long)byte_start,
>> -         (unsigned long long)byte_len, trunc_start, trunc_len);
>> +         (unsigned long long)byte_len, trunc_start, trunc_end);
>>  
>>      ret = ocfs2_zero_partial_clusters(inode, byte_start, byte_len);
>>      if (ret) {
>> @@ -1499,32 +1632,78 @@ static int ocfs2_remove_inode_range(struct 
>> inode *inode,
>>          goto out;
>>      }
>>  
>> -    cpos = trunc_start;
>> -    while (trunc_len) {
>> -        ret = ocfs2_get_clusters(inode, cpos, &phys_cpos,
>> -                     &alloc_size, &flags);
>> +    path = ocfs2_new_path_from_et(&et);
>> +    if (!path) {
>> +        ret = -ENOMEM;
>> +        mlog_errno(ret);
>> +        goto out;
>> +    }
>> +
>> +    while (trunc_end > 0) {
>>   
> I think we have a consensus to change this check somehow?

Oh, that's correct, I hate to be a moron to forget updating this...


>> +        /*
>> +         * Unlike truncate codes, here we want to find a path which
>> +         * contains (trunc_end - 1) cpos, and then trunc_end will be
>> +         * decreased after each removal of a record range.
>> +         *
>> +         * Why not using trunc_end to search the path?
>> +         * The reason is simple, think about the situation of crossing
>> +         * the extent block, we need to find the adjacent block by
>> +         * decreasing one cluster, otherwise, it will run into a loop.
>> +         */
>> +        ret = ocfs2_find_path(INODE_CACHE(inode), path,
>> +                      cluster_within_list);
>>          if (ret) {
>>              mlog_errno(ret);
>>              goto out;
>>          }
>>  
>> -        if (alloc_size > trunc_len)
>> -            alloc_size = trunc_len;
>> +        el = path_leaf_el(path);
>>  
>> -        /* Only do work for non-holes */
>> -        if (phys_cpos != 0) {
>> -            ret = ocfs2_remove_btree_range(inode, &et, cpos,
>> -                               phys_cpos, alloc_size,
>> -                               &dealloc, refcount_loc,
>> -                               flags);
>> -            if (ret) {
>> -                mlog_errno(ret);
>> -                goto out;
>> +        ocfs2_find_rec_with_holes(el, &rec, &trunc_end);
>> +        /*
>> +         * Need to go to previous extent block.
>> +         */
>> +        if (!rec) {
>> +            if (path->p_tree_depth == 0)
>> +                break;
>> +            else {
>> +                el = path->p_node[path->p_tree_depth - 1].el;
>> +                ocfs2_find_rec(el, &rec, &trunc_end);
>> +                if (!rec)
>> +                    break;
>> +                if (le32_to_cpu(rec->e_cpos)) {
>> +                    trunc_end = le32_to_cpu(rec->e_cpos);
>> +                    cluster_within_list = trunc_end - 1;
>> +                } else
>> +                    break;
>>              }
>>   
> oh, I really see what you are going to do here. It is really buggy. 
> What if the tree_depth=2, and the branch
> extent block with 'tree_depth-1' is also recs[0] in the tree_depth 
> extent block? you can't find 'rec' and break.
> Actually there is already a function. ;)  Check 
> ocfs2_find_cpos_for_left_leaf for detail.

Sorry, I can't get your idea clearly, what did you mean 'the branch
extent block with 'tree_depth-1' is also recs[0] in the tree_depth 
extent block?', how does that matter? why can't I find the 'rec' here?

Per my understanding, when we found the hole before first rec in leaf 
extent block, we need to go back to its father extent block through path 
where no hole existed for sure. and we definitely find the rec there.

>
>> +
>> +            ocfs2_reinit_path(path, 1);
>> +            continue;
>>          }
>>  
>> -        cpos += alloc_size;
>> -        trunc_len -= alloc_size;
>> +        ocfs2_calc_trunc_pos(inode, el, rec, trunc_start, &trunc_cpos,
>> +                     &trunc_len, &trunc_end, &blkno, &done);
>> +        if (done)
>> +            break;
>> +
>> +        flags = rec->e_flags;
>> +        phys_cpos = ocfs2_blocks_to_clusters(inode->i_sb, blkno);
>> +
>> +        ret = ocfs2_remove_btree_range(inode, &et, trunc_cpos,
>> +                           phys_cpos, trunc_len, &dealloc,
>> +                           refcount_loc, flags);
>> +        if (ret < 0) {
>> +            mlog_errno(ret);
>> +            goto out;
>> +        }
>> +
>> +        if (trunc_end > 0)
>> +            cluster_within_list = trunc_end - 1;
>> +        else
>> +            break;
>> +
>> +        ocfs2_reinit_path(path, 1);
>>      }
>>  
>>      ocfs2_truncate_cluster_pages(inode, byte_start, byte_len);
>>   
> Regards,
> Tao

[Ocfs2-devel] [PATCH 1/1] Ocfs2: Optimize punching-hole codes v4.

[tristan]

Tao Ma wrote:
> Hi Tristan,
> Tristan Ye wrote:
>> Changes from v3 to v4:
>>
>> 1. Fix a bug when crossing extent blocks.
>>
>> 2. Fix a bug when hole exists in the beginning of an extent block.
>>
>> 3. Apply tao's comments.
>>
>>
>> Signed-off-by: Tristan Ye <tristan.ye@oracle.com>
>> ---
>>  fs/ocfs2/file.c |  233 
>> ++++++++++++++++++++++++++++++++++++++++++++++++-------
>>  1 files changed, 206 insertions(+), 27 deletions(-)
>>
>> diff --git a/fs/ocfs2/file.c b/fs/ocfs2/file.c
>> index db2e0c9..75e087f 100644
>> --- a/fs/ocfs2/file.c
>> +++ b/fs/ocfs2/file.c
>> @@ -1423,18 +1423,154 @@ out:
>>      return ret;
>>  }
>>  
>> +static void ocfs2_find_rec(struct ocfs2_extent_list *el,
>> +               struct ocfs2_extent_rec **rec_found,
>> +               u32 *pos)
>> +{
>> +    int i, found = 0;
>> +    struct ocfs2_extent_rec *rec = NULL;
>> +
>> +    for (i = le16_to_cpu(el->l_next_free_rec) - 1; i >= 0; i--) {
>> +
>> +        rec = &el->l_recs[i];
>> +
>> +        if (le32_to_cpu(rec->e_cpos) <= *pos) {
>> +            found = 1;
>> +            break;
>> +        }
>> +    }
>> +
>> +    if (!found)
>> +        *rec_found = NULL;
>> +    else
>> +        *rec_found = &el->l_recs[i];
>> +}
>>   
> This function never returns pos now. So why you want to pass a *pos?
> another issue is that now it seems that you only want to returns a rec?
> then why not change this function to
> static int ocfs2_find_rec(struct ocfs2_extent_list *el, u32 pos)
> and after the loop, just return i. So if i>=0, you find it, if i < 0, 
> no rec is found. Looks more natural?
>> +
>> +/*
>> + * Hepler to find the rightmost record which contains 'pos' cpos,
>> + * skip the holes if any, also adjust the 'pos' accordingly.
>> + */
>> +static void ocfs2_find_rec_with_holes(struct ocfs2_extent_list *el,
>> +                      struct ocfs2_extent_rec **rec_found,
>> +                      u32 *pos)
>> +{
>> +    int i, found = 0;
>> +    u32 range;
>> +    struct ocfs2_extent_rec *rec = NULL;
>> +
>> +    for (i = le16_to_cpu(el->l_next_free_rec) - 1; i >= 0; i--) {
>> +
>> +        rec = &el->l_recs[i];
>> +        range = le32_to_cpu(rec->e_cpos) +
>> +                ocfs2_rec_clusters(el, rec);
>> +
>> +        if (le32_to_cpu(rec->e_cpos) < *pos) {
>> +            /*
>> +             * Skip a hole.
>> +             */
>> +            if (range < *pos)
>> +                *pos = range;
>> +
>> +            found = 1;
>> +            break;
>> +        }
>> +
>> +        /*
>> +         * Simply jump to previous record if the pos is
>> +         * the start of a record.
>> +         */
>> +        if (le32_to_cpu(rec->e_cpos) == *pos) {
>> +            i--;
>> +            /*
>> +             * The rec we're looking for is in previous
>> +             * extent block.
>> +             */
>> +            if (i < 0)
>> +                break;
>> +
>> +            rec = &el->l_recs[i];
>> +            range = le32_to_cpu(rec->e_cpos) +
>> +                    ocfs2_rec_clusters(el, rec);
>> +            /*
>> +             * Skip a hole.
>> +             */
>> +            if (range < *pos)
>> +                *pos = range;
>>   
> As I have said in the previous e-mail, no matter whether there is a 
> hole or not, we should set *pos = range since
> it will be the next 'end' we punch. And it looks more readable.

Yes, we definitely set *pos = range for next punch, but it's not here, 
we do this in ocfs2_calc_trunc_pos;)

This func only find the desired record, and skip the hole if any, then 
accordingly update the pos. therefore, I'm afraid that such judgement is 
necessary, in the normal case range should be equal to pos,  while 
'range < *pos' mean hole existed, we just need to skip, doing this 
beforehand is beneficial for ocfs2_calc_trunc_pos().




>> +
>> +            found = 1;
>> +            break;
>> +        }
>> +    }
>> +
>> +    if (!found)
>> +        *rec_found = NULL;
>> +    else
>> +        *rec_found = &el->l_recs[i];
>>   
> And the same for this function you can just return 'i' and I guess 
> this function and the previous one can be integrated
> into just one.
>> +}
>> +
>> +/*
>> + * Helper to calculate the punching pos and length in one run, we 
>> handle the
>> + * following three cases in order:
>> + *
>> + * - remove the entire record
>> + * - remove a partial record
>> + * - no record needs to be removed (hole-punching completed)
>> +*/
>> +static void ocfs2_calc_trunc_pos(struct inode *inode,
>> +                 struct ocfs2_extent_list *el,
>> +                 struct ocfs2_extent_rec *rec,
>> +                 u32 trunc_start, u32 *trunc_cpos,
>> +                 u32 *trunc_len, u32 *trunc_end,
>> +                 u64 *blkno, int *done)
>> +{
>> +    int ret = 0;
>> +    u32 coff, range;
>> +
>> +    range = le32_to_cpu(rec->e_cpos) + ocfs2_rec_clusters(el, rec);
>> +
>> +    if (le32_to_cpu(rec->e_cpos) >= trunc_start) {
>> +        *trunc_cpos = le32_to_cpu(rec->e_cpos);
>> +        *trunc_len = *trunc_end - le32_to_cpu(rec->e_cpos);
>> +        *blkno = le64_to_cpu(rec->e_blkno);
>> +        *trunc_end = le32_to_cpu(rec->e_cpos);
>> +    } else if (range > trunc_start) {
>> +        *trunc_cpos = trunc_start;
>> +        *trunc_len = range - trunc_start;
>> +        coff = trunc_start - le32_to_cpu(rec->e_cpos);
>> +        *blkno = le64_to_cpu(rec->e_blkno) +
>> +                ocfs2_clusters_to_blocks(inode->i_sb, coff);
>> +        *trunc_end = trunc_start;
>> +    } else {
>> +        /*
>> +         * It may have two following possibilities:
>> +         *
>> +         * - last record has been removed
>> +         * - trunc_start was within a hole
>> +         *
>> +         * both two cases mean the completion of hole punching.
>> +         */
>> +        ret = 1;
>> +    }
>> +
>> +    *done = ret;
>> +}
>> +
>>  static int ocfs2_remove_inode_range(struct inode *inode,
>>                      struct buffer_head *di_bh, u64 byte_start,
>>                      u64 byte_len)
>>  {
>> -    int ret = 0, flags = 0;
>> -    u32 trunc_start, trunc_len, cpos, phys_cpos, alloc_size;
>> +    int ret = 0, flags = 0, done = 0;
>> +    u32 trunc_start, trunc_len, trunc_end, trunc_cpos, phys_cpos;
>> +    u32 cluster_within_list;
>>      struct ocfs2_super *osb = OCFS2_SB(inode->i_sb);
>>      struct ocfs2_cached_dealloc_ctxt dealloc;
>>      struct address_space *mapping = inode->i_mapping;
>>      struct ocfs2_extent_tree et;
>> +    struct ocfs2_path *path = NULL;
>> +    struct ocfs2_extent_list *el = NULL;
>> +    struct ocfs2_extent_rec *rec = NULL;
>>      struct ocfs2_dinode *di = (struct ocfs2_dinode *)di_bh->b_data;
>> -    u64 refcount_loc = le64_to_cpu(di->i_refcount_loc);
>> +    u64 blkno, refcount_loc = le64_to_cpu(di->i_refcount_loc);
>>  
>>      ocfs2_init_dinode_extent_tree(&et, INODE_CACHE(inode), di_bh);
>>      ocfs2_init_dealloc_ctxt(&dealloc);
>> @@ -1482,16 +1618,13 @@ static int ocfs2_remove_inode_range(struct 
>> inode *inode,
>>      }
>>  
>>      trunc_start = ocfs2_clusters_for_bytes(osb->sb, byte_start);
>> -    trunc_len = (byte_start + byte_len) >> osb->s_clustersize_bits;
>> -    if (trunc_len >= trunc_start)
>> -        trunc_len -= trunc_start;
>> -    else
>> -        trunc_len = 0;
>> +    trunc_end = (byte_start + byte_len) >> osb->s_clustersize_bits;
>> +    cluster_within_list = trunc_end;
>>  
>> -    mlog(0, "Inode: %llu, start: %llu, len: %llu, cstart: %u, clen: 
>> %u\n",
>> +    mlog(0, "Inode: %llu, start: %llu, len: %llu, cstart: %u, cend: 
>> %u\n",
>>           (unsigned long long)OCFS2_I(inode)->ip_blkno,
>>           (unsigned long long)byte_start,
>> -         (unsigned long long)byte_len, trunc_start, trunc_len);
>> +         (unsigned long long)byte_len, trunc_start, trunc_end);
>>  
>>      ret = ocfs2_zero_partial_clusters(inode, byte_start, byte_len);
>>      if (ret) {
>> @@ -1499,32 +1632,78 @@ static int ocfs2_remove_inode_range(struct 
>> inode *inode,
>>          goto out;
>>      }
>>  
>> -    cpos = trunc_start;
>> -    while (trunc_len) {
>> -        ret = ocfs2_get_clusters(inode, cpos, &phys_cpos,
>> -                     &alloc_size, &flags);
>> +    path = ocfs2_new_path_from_et(&et);
>> +    if (!path) {
>> +        ret = -ENOMEM;
>> +        mlog_errno(ret);
>> +        goto out;
>> +    }
>> +
>> +    while (trunc_end > 0) {
>>   
> I think we have a consensus to change this check somehow?
>> +        /*
>> +         * Unlike truncate codes, here we want to find a path which
>> +         * contains (trunc_end - 1) cpos, and then trunc_end will be
>> +         * decreased after each removal of a record range.
>> +         *
>> +         * Why not using trunc_end to search the path?
>> +         * The reason is simple, think about the situation of crossing
>> +         * the extent block, we need to find the adjacent block by
>> +         * decreasing one cluster, otherwise, it will run into a loop.
>> +         */
>> +        ret = ocfs2_find_path(INODE_CACHE(inode), path,
>> +                      cluster_within_list);
>>          if (ret) {
>>              mlog_errno(ret);
>>              goto out;
>>          }
>>  
>> -        if (alloc_size > trunc_len)
>> -            alloc_size = trunc_len;
>> +        el = path_leaf_el(path);
>>  
>> -        /* Only do work for non-holes */
>> -        if (phys_cpos != 0) {
>> -            ret = ocfs2_remove_btree_range(inode, &et, cpos,
>> -                               phys_cpos, alloc_size,
>> -                               &dealloc, refcount_loc,
>> -                               flags);
>> -            if (ret) {
>> -                mlog_errno(ret);
>> -                goto out;
>> +        ocfs2_find_rec_with_holes(el, &rec, &trunc_end);
>> +        /*
>> +         * Need to go to previous extent block.
>> +         */
>> +        if (!rec) {
>> +            if (path->p_tree_depth == 0)
>> +                break;
>> +            else {
>> +                el = path->p_node[path->p_tree_depth - 1].el;
>> +                ocfs2_find_rec(el, &rec, &trunc_end);
>> +                if (!rec)
>> +                    break;
>> +                if (le32_to_cpu(rec->e_cpos)) {
>> +                    trunc_end = le32_to_cpu(rec->e_cpos);
>> +                    cluster_within_list = trunc_end - 1;
>> +                } else
>> +                    break;
>>              }
>>   
> oh, I really see what you are going to do here. It is really buggy. 
> What if the tree_depth=2, and the branch
> extent block with 'tree_depth-1' is also recs[0] in the tree_depth 
> extent block? you can't find 'rec' and break.
> Actually there is already a function. ;)  Check 
> ocfs2_find_cpos_for_left_leaf for detail.
>
>> +
>> +            ocfs2_reinit_path(path, 1);
>> +            continue;
>>          }
>>  
>> -        cpos += alloc_size;
>> -        trunc_len -= alloc_size;
>> +        ocfs2_calc_trunc_pos(inode, el, rec, trunc_start, &trunc_cpos,
>> +                     &trunc_len, &trunc_end, &blkno, &done);
>> +        if (done)
>> +            break;
>> +
>> +        flags = rec->e_flags;
>> +        phys_cpos = ocfs2_blocks_to_clusters(inode->i_sb, blkno);
>> +
>> +        ret = ocfs2_remove_btree_range(inode, &et, trunc_cpos,
>> +                           phys_cpos, trunc_len, &dealloc,
>> +                           refcount_loc, flags);
>> +        if (ret < 0) {
>> +            mlog_errno(ret);
>> +            goto out;
>> +        }
>> +
>> +        if (trunc_end > 0)
>> +            cluster_within_list = trunc_end - 1;
>> +        else
>> +            break;
>> +
>> +        ocfs2_reinit_path(path, 1);
>>      }
>>  
>>      ocfs2_truncate_cluster_pages(inode, byte_start, byte_len);
>>   
> Regards,
> Tao

[Ocfs2-devel] [PATCH 1/1] Ocfs2: Optimize punching-hole codes v4.

[Tao Ma]

Hi Tristan,

tristan wrote:
> Tao,
> 
> Thanks a lot for your quick review;)
> 
> Tao Ma wrote:
>> Hi Tristan,
>> Tristan Ye wrote:
>>> Changes from v3 to v4:
>>>
>>> 1. Fix a bug when crossing extent blocks.
>>>
>>> 2. Fix a bug when hole exists in the beginning of an extent block.
>>>
>>> 3. Apply tao's comments.
>>>
>>>
>>> Signed-off-by: Tristan Ye <tristan.ye@oracle.com>
>>> ---
>>>  fs/ocfs2/file.c |  233 
>>> ++++++++++++++++++++++++++++++++++++++++++++++++-------
>>>  1 files changed, 206 insertions(+), 27 deletions(-)
>>>
>>> diff --git a/fs/ocfs2/file.c b/fs/ocfs2/file.c
>>> index db2e0c9..75e087f 100644
>>> --- a/fs/ocfs2/file.c
>>> +++ b/fs/ocfs2/file.c
>>> @@ -1423,18 +1423,154 @@ out:
>>>      return ret;
>>>  }
>>>  
>>> +static void ocfs2_find_rec(struct ocfs2_extent_list *el,
>>> +               struct ocfs2_extent_rec **rec_found,
>>> +               u32 *pos)
>>> +{
>>> +    int i, found = 0;
>>> +    struct ocfs2_extent_rec *rec = NULL;
>>> +
>>> +    for (i = le16_to_cpu(el->l_next_free_rec) - 1; i >= 0; i--) {
>>> +
>>> +        rec = &el->l_recs[i];
>>> +
>>> +        if (le32_to_cpu(rec->e_cpos) <= *pos) {
>>> +            found = 1;
>>> +            break;
>>> +        }
>>> +    }
>>> +
>>> +    if (!found)
>>> +        *rec_found = NULL;
>>> +    else
>>> +        *rec_found = &el->l_recs[i];
>>> +}
>>>   
>> This function never returns pos now. So why you want to pass a *pos?
>> another issue is that now it seems that you only want to returns a rec?
>> then why not change this function to
>> static int ocfs2_find_rec(struct ocfs2_extent_list *el, u32 pos)
> 
> Yes, it's confusing to use *pos, thanks for pointing this out.
> 
>> and after the loop, just return i. So if i>=0, you find it, if i < 0, 
>> no rec is found. Looks more natural?
> 
> I think returning  a meaty record would be more straightforward.
why? actually as I have said below, these 2 functions ocfs2_find_rec and 
ocfs2_find_rec_with_holes can be integrated into one function named 
ocfs2_find_rec or whatever. You are too nervous about holes actually.
So
static int ocfs2_find_rec(struct ocfs2_extent_list *el, u32 pos)
{
	int i;
	struct ocfs2_extent_rec *rec = NULL;

	for (i = le16_to_cpu(el->l_next_free_rec) - 1; i >= 0; i--) {
		rec = &el->l_recs[i];

		if (le32_to_cpu(rec->e_cpos) < pos)
			break;
	}

	return i;
}

And in the caller, you do(only the schema here):
	i = ocfs2_find_rec(el, pos);
	if (i > 0) {
		/* ok, we have to remove some clusters somehow. */
		rec = &el->l_recs[i];
		range = le32_to_cpu(rec->e_cpos) +
			ocfs2_rec_clusters(el, rec);
		range = min(range, pos);

		ocfs2_calc_trunc_pos();
		ocfs2_remove_btree_range();
		/* Finished the work or we still have some more recs to punch. */
		if (trunc_start == trunc_end) /* I don't know whether this check is 
right or not. */
			break;
		i--;
	}

	if (i < 0) {
		/* ok, get to the next block, some calculation to find 		new pos. */
		continue;
	} else
		cpos = le32_to_cpu(rec->e_cpos) +
			ocfs2_rec_clusters(el, rec);	

See the both functions looks more clean now.
And your function ocfs2_find_rec_with_holes is a little complicated and 
so many comments to say why we want to do this.
> 
>>> +
>>> +/*
>>> + * Hepler to find the rightmost record which contains 'pos' cpos,
>>> + * skip the holes if any, also adjust the 'pos' accordingly.
>>> + */
>>> +static void ocfs2_find_rec_with_holes(struct ocfs2_extent_list *el,
>>> +                      struct ocfs2_extent_rec **rec_found,
>>> +                      u32 *pos)
>>> +{
>>> +    int i, found = 0;
>>> +    u32 range;
>>> +    struct ocfs2_extent_rec *rec = NULL;
>>> +
>>> +    for (i = le16_to_cpu(el->l_next_free_rec) - 1; i >= 0; i--) {
>>> +
>>> +        rec = &el->l_recs[i];
>>> +        range = le32_to_cpu(rec->e_cpos) +
>>> +                ocfs2_rec_clusters(el, rec);
>>> +
>>> +        if (le32_to_cpu(rec->e_cpos) < *pos) {
>>> +            /*
>>> +             * Skip a hole.
>>> +             */
>>> +            if (range < *pos)
>>> +                *pos = range;
>>> +
>>> +            found = 1;
>>> +            break;
>>> +        }
>>> +
>>> +        /*
>>> +         * Simply jump to previous record if the pos is
>>> +         * the start of a record.
>>> +         */
>>> +        if (le32_to_cpu(rec->e_cpos) == *pos) {
>>> +            i--;
>>> +            /*
>>> +             * The rec we're looking for is in previous
>>> +             * extent block.
>>> +             */
>>> +            if (i < 0)
>>> +                break;
>>> +
>>> +            rec = &el->l_recs[i];
>>> +            range = le32_to_cpu(rec->e_cpos) +
>>> +                    ocfs2_rec_clusters(el, rec);
>>> +            /*
>>> +             * Skip a hole.
>>> +             */
>>> +            if (range < *pos)
>>> +                *pos = range;
>>>   
>> As I have said in the previous e-mail, no matter whether there is a 
>> hole or not, we should set *pos = range since
>> it will be the next 'end' we punch. And it looks more readable.
>>> +
>>> +            found = 1;
>>> +            break;
>>> +        }
>>> +    }
>>> +
>>> +    if (!found)
>>> +        *rec_found = NULL;
>>> +    else
>>> +        *rec_found = &el->l_recs[i];
>>>   
>> And the same for this function you can just return 'i' and I guess 
>> this function and the previous one can be integrated
>> into just one.
> 
> I don't think so, second function handles the hole and adjust the pos 
> accordingly, while second one only simply search the rec.
> 
>>> +}
>>> +
>>> +/*
>>> + * Helper to calculate the punching pos and length in one run, we 
>>> handle the
>>> + * following three cases in order:
>>> + *
>>> + * - remove the entire record
>>> + * - remove a partial record
>>> + * - no record needs to be removed (hole-punching completed)
>>> +*/
>>> +static void ocfs2_calc_trunc_pos(struct inode *inode,
>>> +                 struct ocfs2_extent_list *el,
>>> +                 struct ocfs2_extent_rec *rec,
>>> +                 u32 trunc_start, u32 *trunc_cpos,
>>> +                 u32 *trunc_len, u32 *trunc_end,
>>> +                 u64 *blkno, int *done)
>>> +{
>>> +    int ret = 0;
>>> +    u32 coff, range;
>>> +
>>> +    range = le32_to_cpu(rec->e_cpos) + ocfs2_rec_clusters(el, rec);
>>> +
>>> +    if (le32_to_cpu(rec->e_cpos) >= trunc_start) {
>>> +        *trunc_cpos = le32_to_cpu(rec->e_cpos);
>>> +        *trunc_len = *trunc_end - le32_to_cpu(rec->e_cpos);
>>> +        *blkno = le64_to_cpu(rec->e_blkno);
>>> +        *trunc_end = le32_to_cpu(rec->e_cpos);
>>> +    } else if (range > trunc_start) {
>>> +        *trunc_cpos = trunc_start;
>>> +        *trunc_len = range - trunc_start;
>>> +        coff = trunc_start - le32_to_cpu(rec->e_cpos);
>>> +        *blkno = le64_to_cpu(rec->e_blkno) +
>>> +                ocfs2_clusters_to_blocks(inode->i_sb, coff);
>>> +        *trunc_end = trunc_start;
>>> +    } else {
>>> +        /*
>>> +         * It may have two following possibilities:
>>> +         *
>>> +         * - last record has been removed
>>> +         * - trunc_start was within a hole
>>> +         *
>>> +         * both two cases mean the completion of hole punching.
>>> +         */
>>> +        ret = 1;
>>> +    }
>>> +
>>> +    *done = ret;
>>> +}
>>> +
>>>  static int ocfs2_remove_inode_range(struct inode *inode,
>>>                      struct buffer_head *di_bh, u64 byte_start,
>>>                      u64 byte_len)
>>>  {
>>> -    int ret = 0, flags = 0;
>>> -    u32 trunc_start, trunc_len, cpos, phys_cpos, alloc_size;
>>> +    int ret = 0, flags = 0, done = 0;
>>> +    u32 trunc_start, trunc_len, trunc_end, trunc_cpos, phys_cpos;
>>> +    u32 cluster_within_list;
>>>      struct ocfs2_super *osb = OCFS2_SB(inode->i_sb);
>>>      struct ocfs2_cached_dealloc_ctxt dealloc;
>>>      struct address_space *mapping = inode->i_mapping;
>>>      struct ocfs2_extent_tree et;
>>> +    struct ocfs2_path *path = NULL;
>>> +    struct ocfs2_extent_list *el = NULL;
>>> +    struct ocfs2_extent_rec *rec = NULL;
>>>      struct ocfs2_dinode *di = (struct ocfs2_dinode *)di_bh->b_data;
>>> -    u64 refcount_loc = le64_to_cpu(di->i_refcount_loc);
>>> +    u64 blkno, refcount_loc = le64_to_cpu(di->i_refcount_loc);
>>>  
>>>      ocfs2_init_dinode_extent_tree(&et, INODE_CACHE(inode), di_bh);
>>>      ocfs2_init_dealloc_ctxt(&dealloc);
>>> @@ -1482,16 +1618,13 @@ static int ocfs2_remove_inode_range(struct 
>>> inode *inode,
>>>      }
>>>  
>>>      trunc_start = ocfs2_clusters_for_bytes(osb->sb, byte_start);
>>> -    trunc_len = (byte_start + byte_len) >> osb->s_clustersize_bits;
>>> -    if (trunc_len >= trunc_start)
>>> -        trunc_len -= trunc_start;
>>> -    else
>>> -        trunc_len = 0;
>>> +    trunc_end = (byte_start + byte_len) >> osb->s_clustersize_bits;
>>> +    cluster_within_list = trunc_end;
>>>  
>>> -    mlog(0, "Inode: %llu, start: %llu, len: %llu, cstart: %u, clen: 
>>> %u\n",
>>> +    mlog(0, "Inode: %llu, start: %llu, len: %llu, cstart: %u, cend: 
>>> %u\n",
>>>           (unsigned long long)OCFS2_I(inode)->ip_blkno,
>>>           (unsigned long long)byte_start,
>>> -         (unsigned long long)byte_len, trunc_start, trunc_len);
>>> +         (unsigned long long)byte_len, trunc_start, trunc_end);
>>>  
>>>      ret = ocfs2_zero_partial_clusters(inode, byte_start, byte_len);
>>>      if (ret) {
>>> @@ -1499,32 +1632,78 @@ static int ocfs2_remove_inode_range(struct 
>>> inode *inode,
>>>          goto out;
>>>      }
>>>  
>>> -    cpos = trunc_start;
>>> -    while (trunc_len) {
>>> -        ret = ocfs2_get_clusters(inode, cpos, &phys_cpos,
>>> -                     &alloc_size, &flags);
>>> +    path = ocfs2_new_path_from_et(&et);
>>> +    if (!path) {
>>> +        ret = -ENOMEM;
>>> +        mlog_errno(ret);
>>> +        goto out;
>>> +    }
>>> +
>>> +    while (trunc_end > 0) {
>>>   
>> I think we have a consensus to change this check somehow?
> 
> Oh, that's correct, I hate to be a moron to forget updating this...
> 
> 
>>> +        /*
>>> +         * Unlike truncate codes, here we want to find a path which
>>> +         * contains (trunc_end - 1) cpos, and then trunc_end will be
>>> +         * decreased after each removal of a record range.
>>> +         *
>>> +         * Why not using trunc_end to search the path?
>>> +         * The reason is simple, think about the situation of crossing
>>> +         * the extent block, we need to find the adjacent block by
>>> +         * decreasing one cluster, otherwise, it will run into a loop.
>>> +         */
>>> +        ret = ocfs2_find_path(INODE_CACHE(inode), path,
>>> +                      cluster_within_list);
>>>          if (ret) {
>>>              mlog_errno(ret);
>>>              goto out;
>>>          }
>>>  
>>> -        if (alloc_size > trunc_len)
>>> -            alloc_size = trunc_len;
>>> +        el = path_leaf_el(path);
>>>  
>>> -        /* Only do work for non-holes */
>>> -        if (phys_cpos != 0) {
>>> -            ret = ocfs2_remove_btree_range(inode, &et, cpos,
>>> -                               phys_cpos, alloc_size,
>>> -                               &dealloc, refcount_loc,
>>> -                               flags);
>>> -            if (ret) {
>>> -                mlog_errno(ret);
>>> -                goto out;
>>> +        ocfs2_find_rec_with_holes(el, &rec, &trunc_end);
>>> +        /*
>>> +         * Need to go to previous extent block.
>>> +         */
>>> +        if (!rec) {
>>> +            if (path->p_tree_depth == 0)
>>> +                break;
>>> +            else {
>>> +                el = path->p_node[path->p_tree_depth - 1].el;
>>> +                ocfs2_find_rec(el, &rec, &trunc_end);
>>> +                if (!rec)
>>> +                    break;
>>> +                if (le32_to_cpu(rec->e_cpos)) {
>>> +                    trunc_end = le32_to_cpu(rec->e_cpos);
>>> +                    cluster_within_list = trunc_end - 1;
>>> +                } else
>>> +                    break;
>>>              }
>>>   
>> oh, I really see what you are going to do here. It is really buggy. 
>> What if the tree_depth=2, and the branch
>> extent block with 'tree_depth-1' is also recs[0] in the tree_depth 
>> extent block? you can't find 'rec' and break.
>> Actually there is already a function. ;)  Check 
>> ocfs2_find_cpos_for_left_leaf for detail.
> 
> Sorry, I can't get your idea clearly, what did you mean 'the branch
> extent block with 'tree_depth-1' is also recs[0] in the tree_depth 
> extent block?', how does that matter? why can't I find the 'rec' here?
> 
> Per my understanding, when we found the hole before first rec in leaf 
> extent block, we need to go back to its father extent block through path 
> where no hole existed for sure. and we definitely find the rec there.
Check ocfs2_find_cpos_for_left_leaf. It has done what you want already.

Regards,
Tao

[Ocfs2-devel] [PATCH 1/1] Ocfs2: Optimize punching-hole codes v4.

[tristan]

Tao Ma wrote:
> Hi Tristan,
>
> tristan wrote:
>> Tao,
>>
>> Thanks a lot for your quick review;)
>>
>> Tao Ma wrote:
>>> Hi Tristan,
>>> Tristan Ye wrote:
>>>> Changes from v3 to v4:
>>>>
>>>> 1. Fix a bug when crossing extent blocks.
>>>>
>>>> 2. Fix a bug when hole exists in the beginning of an extent block.
>>>>
>>>> 3. Apply tao's comments.
>>>>
>>>>
>>>> Signed-off-by: Tristan Ye <tristan.ye@oracle.com>
>>>> ---
>>>>  fs/ocfs2/file.c |  233 
>>>> ++++++++++++++++++++++++++++++++++++++++++++++++-------
>>>>  1 files changed, 206 insertions(+), 27 deletions(-)
>>>>
>>>> diff --git a/fs/ocfs2/file.c b/fs/ocfs2/file.c
>>>> index db2e0c9..75e087f 100644
>>>> --- a/fs/ocfs2/file.c
>>>> +++ b/fs/ocfs2/file.c
>>>> @@ -1423,18 +1423,154 @@ out:
>>>>      return ret;
>>>>  }
>>>>  
>>>> +static void ocfs2_find_rec(struct ocfs2_extent_list *el,
>>>> +               struct ocfs2_extent_rec **rec_found,
>>>> +               u32 *pos)
>>>> +{
>>>> +    int i, found = 0;
>>>> +    struct ocfs2_extent_rec *rec = NULL;
>>>> +
>>>> +    for (i = le16_to_cpu(el->l_next_free_rec) - 1; i >= 0; i--) {
>>>> +
>>>> +        rec = &el->l_recs[i];
>>>> +
>>>> +        if (le32_to_cpu(rec->e_cpos) <= *pos) {
>>>> +            found = 1;
>>>> +            break;
>>>> +        }
>>>> +    }
>>>> +
>>>> +    if (!found)
>>>> +        *rec_found = NULL;
>>>> +    else
>>>> +        *rec_found = &el->l_recs[i];
>>>> +}
>>>>   
>>> This function never returns pos now. So why you want to pass a *pos?
>>> another issue is that now it seems that you only want to returns a rec?
>>> then why not change this function to
>>> static int ocfs2_find_rec(struct ocfs2_extent_list *el, u32 pos)
>>
>> Yes, it's confusing to use *pos, thanks for pointing this out.
>>
>>> and after the loop, just return i. So if i>=0, you find it, if i < 
>>> 0, no rec is found. Looks more natural?
>>
>> I think returning  a meaty record would be more straightforward.
> why? actually as I have said below, these 2 functions ocfs2_find_rec 
> and ocfs2_find_rec_with_holes can be integrated into one function 
> named ocfs2_find_rec or whatever. You are too nervous about holes 
> actually.

Hole still needs to be handled, while I may over-treat this  a little bit.

I'll try to merge the 2 funcs into one.
> So
> static int ocfs2_find_rec(struct ocfs2_extent_list *el, u32 pos)
> {
>     int i;
>     struct ocfs2_extent_rec *rec = NULL;
>
>     for (i = le16_to_cpu(el->l_next_free_rec) - 1; i >= 0; i--) {
>         rec = &el->l_recs[i];
>
>         if (le32_to_cpu(rec->e_cpos) < pos)
>             break;
>     }
>
>     return i;
> }

Not enough,

cases about 'we didn't find a rec' and 'we find rec[0]' both return i=0;

>
> And in the caller, you do(only the schema here):
>     i = ocfs2_find_rec(el, pos);
>     if (i > 0) {
>         /* ok, we have to remove some clusters somehow. */
>         rec = &el->l_recs[i];
>         range = le32_to_cpu(rec->e_cpos) +
>             ocfs2_rec_clusters(el, rec);
>         range = min(range, pos);
>
>         ocfs2_calc_trunc_pos();
>         ocfs2_remove_btree_range();
>         /* Finished the work or we still have some more recs to punch. */
>         if (trunc_start == trunc_end) /* I don't know whether this 
> check is right or not. */
>             break;
>         i--;
>     }
>
>     if (i < 0) {
>         /* ok, get to the next block, some calculation to find         
> new pos. */
>         continue;
>     } else
>         cpos = le32_to_cpu(rec->e_cpos) +
>             ocfs2_rec_clusters(el, rec);   
>
> See the both functions looks more clean now.
> And your function ocfs2_find_rec_with_holes is a little complicated 
> and so many comments to say why we want to do this.

Yes, it's a little bit complicated and obscure, you're right, I may move 
the hole-handling logic to ocfs2_calc_trunc_pos(), while 
ocfs2_find_rec() only do the searching job only, which simply the 
process and make the logic more straightforward.

>>
>>>> +
>>>> +/*
>>>> + * Hepler to find the rightmost record which contains 'pos' cpos,
>>>> + * skip the holes if any, also adjust the 'pos' accordingly.
>>>> + */
>>>> +static void ocfs2_find_rec_with_holes(struct ocfs2_extent_list *el,
>>>> +                      struct ocfs2_extent_rec **rec_found,
>>>> +                      u32 *pos)
>>>> +{
>>>> +    int i, found = 0;
>>>> +    u32 range;
>>>> +    struct ocfs2_extent_rec *rec = NULL;
>>>> +
>>>> +    for (i = le16_to_cpu(el->l_next_free_rec) - 1; i >= 0; i--) {
>>>> +
>>>> +        rec = &el->l_recs[i];
>>>> +        range = le32_to_cpu(rec->e_cpos) +
>>>> +                ocfs2_rec_clusters(el, rec);
>>>> +
>>>> +        if (le32_to_cpu(rec->e_cpos) < *pos) {
>>>> +            /*
>>>> +             * Skip a hole.
>>>> +             */
>>>> +            if (range < *pos)
>>>> +                *pos = range;
>>>> +
>>>> +            found = 1;
>>>> +            break;
>>>> +        }
>>>> +
>>>> +        /*
>>>> +         * Simply jump to previous record if the pos is
>>>> +         * the start of a record.
>>>> +         */
>>>> +        if (le32_to_cpu(rec->e_cpos) == *pos) {
>>>> +            i--;
>>>> +            /*
>>>> +             * The rec we're looking for is in previous
>>>> +             * extent block.
>>>> +             */
>>>> +            if (i < 0)
>>>> +                break;
>>>> +
>>>> +            rec = &el->l_recs[i];
>>>> +            range = le32_to_cpu(rec->e_cpos) +
>>>> +                    ocfs2_rec_clusters(el, rec);
>>>> +            /*
>>>> +             * Skip a hole.
>>>> +             */
>>>> +            if (range < *pos)
>>>> +                *pos = range;
>>>>   
>>> As I have said in the previous e-mail, no matter whether there is a 
>>> hole or not, we should set *pos = range since
>>> it will be the next 'end' we punch. And it looks more readable.
>>>> +
>>>> +            found = 1;
>>>> +            break;
>>>> +        }
>>>> +    }
>>>> +
>>>> +    if (!found)
>>>> +        *rec_found = NULL;
>>>> +    else
>>>> +        *rec_found = &el->l_recs[i];
>>>>   
>>> And the same for this function you can just return 'i' and I guess 
>>> this function and the previous one can be integrated
>>> into just one.
>>
>> I don't think so, second function handles the hole and adjust the pos 
>> accordingly, while second one only simply search the rec.
>>
>>>> +}
>>>> +
>>>> +/*
>>>> + * Helper to calculate the punching pos and length in one run, we 
>>>> handle the
>>>> + * following three cases in order:
>>>> + *
>>>> + * - remove the entire record
>>>> + * - remove a partial record
>>>> + * - no record needs to be removed (hole-punching completed)
>>>> +*/
>>>> +static void ocfs2_calc_trunc_pos(struct inode *inode,
>>>> +                 struct ocfs2_extent_list *el,
>>>> +                 struct ocfs2_extent_rec *rec,
>>>> +                 u32 trunc_start, u32 *trunc_cpos,
>>>> +                 u32 *trunc_len, u32 *trunc_end,
>>>> +                 u64 *blkno, int *done)
>>>> +{
>>>> +    int ret = 0;
>>>> +    u32 coff, range;
>>>> +
>>>> +    range = le32_to_cpu(rec->e_cpos) + ocfs2_rec_clusters(el, rec);
>>>> +
>>>> +    if (le32_to_cpu(rec->e_cpos) >= trunc_start) {
>>>> +        *trunc_cpos = le32_to_cpu(rec->e_cpos);
>>>> +        *trunc_len = *trunc_end - le32_to_cpu(rec->e_cpos);
>>>> +        *blkno = le64_to_cpu(rec->e_blkno);
>>>> +        *trunc_end = le32_to_cpu(rec->e_cpos);
>>>> +    } else if (range > trunc_start) {
>>>> +        *trunc_cpos = trunc_start;
>>>> +        *trunc_len = range - trunc_start;
>>>> +        coff = trunc_start - le32_to_cpu(rec->e_cpos);
>>>> +        *blkno = le64_to_cpu(rec->e_blkno) +
>>>> +                ocfs2_clusters_to_blocks(inode->i_sb, coff);
>>>> +        *trunc_end = trunc_start;
>>>> +    } else {
>>>> +        /*
>>>> +         * It may have two following possibilities:
>>>> +         *
>>>> +         * - last record has been removed
>>>> +         * - trunc_start was within a hole
>>>> +         *
>>>> +         * both two cases mean the completion of hole punching.
>>>> +         */
>>>> +        ret = 1;
>>>> +    }
>>>> +
>>>> +    *done = ret;
>>>> +}
>>>> +
>>>>  static int ocfs2_remove_inode_range(struct inode *inode,
>>>>                      struct buffer_head *di_bh, u64 byte_start,
>>>>                      u64 byte_len)
>>>>  {
>>>> -    int ret = 0, flags = 0;
>>>> -    u32 trunc_start, trunc_len, cpos, phys_cpos, alloc_size;
>>>> +    int ret = 0, flags = 0, done = 0;
>>>> +    u32 trunc_start, trunc_len, trunc_end, trunc_cpos, phys_cpos;
>>>> +    u32 cluster_within_list;
>>>>      struct ocfs2_super *osb = OCFS2_SB(inode->i_sb);
>>>>      struct ocfs2_cached_dealloc_ctxt dealloc;
>>>>      struct address_space *mapping = inode->i_mapping;
>>>>      struct ocfs2_extent_tree et;
>>>> +    struct ocfs2_path *path = NULL;
>>>> +    struct ocfs2_extent_list *el = NULL;
>>>> +    struct ocfs2_extent_rec *rec = NULL;
>>>>      struct ocfs2_dinode *di = (struct ocfs2_dinode *)di_bh->b_data;
>>>> -    u64 refcount_loc = le64_to_cpu(di->i_refcount_loc);
>>>> +    u64 blkno, refcount_loc = le64_to_cpu(di->i_refcount_loc);
>>>>  
>>>>      ocfs2_init_dinode_extent_tree(&et, INODE_CACHE(inode), di_bh);
>>>>      ocfs2_init_dealloc_ctxt(&dealloc);
>>>> @@ -1482,16 +1618,13 @@ static int ocfs2_remove_inode_range(struct 
>>>> inode *inode,
>>>>      }
>>>>  
>>>>      trunc_start = ocfs2_clusters_for_bytes(osb->sb, byte_start);
>>>> -    trunc_len = (byte_start + byte_len) >> osb->s_clustersize_bits;
>>>> -    if (trunc_len >= trunc_start)
>>>> -        trunc_len -= trunc_start;
>>>> -    else
>>>> -        trunc_len = 0;
>>>> +    trunc_end = (byte_start + byte_len) >> osb->s_clustersize_bits;
>>>> +    cluster_within_list = trunc_end;
>>>>  
>>>> -    mlog(0, "Inode: %llu, start: %llu, len: %llu, cstart: %u, 
>>>> clen: %u\n",
>>>> +    mlog(0, "Inode: %llu, start: %llu, len: %llu, cstart: %u, 
>>>> cend: %u\n",
>>>>           (unsigned long long)OCFS2_I(inode)->ip_blkno,
>>>>           (unsigned long long)byte_start,
>>>> -         (unsigned long long)byte_len, trunc_start, trunc_len);
>>>> +         (unsigned long long)byte_len, trunc_start, trunc_end);
>>>>  
>>>>      ret = ocfs2_zero_partial_clusters(inode, byte_start, byte_len);
>>>>      if (ret) {
>>>> @@ -1499,32 +1632,78 @@ static int ocfs2_remove_inode_range(struct 
>>>> inode *inode,
>>>>          goto out;
>>>>      }
>>>>  
>>>> -    cpos = trunc_start;
>>>> -    while (trunc_len) {
>>>> -        ret = ocfs2_get_clusters(inode, cpos, &phys_cpos,
>>>> -                     &alloc_size, &flags);
>>>> +    path = ocfs2_new_path_from_et(&et);
>>>> +    if (!path) {
>>>> +        ret = -ENOMEM;
>>>> +        mlog_errno(ret);
>>>> +        goto out;
>>>> +    }
>>>> +
>>>> +    while (trunc_end > 0) {
>>>>   
>>> I think we have a consensus to change this check somehow?
>>
>> Oh, that's correct, I hate to be a moron to forget updating this...
>>
>>
>>>> +        /*
>>>> +         * Unlike truncate codes, here we want to find a path which
>>>> +         * contains (trunc_end - 1) cpos, and then trunc_end will be
>>>> +         * decreased after each removal of a record range.
>>>> +         *
>>>> +         * Why not using trunc_end to search the path?
>>>> +         * The reason is simple, think about the situation of 
>>>> crossing
>>>> +         * the extent block, we need to find the adjacent block by
>>>> +         * decreasing one cluster, otherwise, it will run into a 
>>>> loop.
>>>> +         */
>>>> +        ret = ocfs2_find_path(INODE_CACHE(inode), path,
>>>> +                      cluster_within_list);
>>>>          if (ret) {
>>>>              mlog_errno(ret);
>>>>              goto out;
>>>>          }
>>>>  
>>>> -        if (alloc_size > trunc_len)
>>>> -            alloc_size = trunc_len;
>>>> +        el = path_leaf_el(path);
>>>>  
>>>> -        /* Only do work for non-holes */
>>>> -        if (phys_cpos != 0) {
>>>> -            ret = ocfs2_remove_btree_range(inode, &et, cpos,
>>>> -                               phys_cpos, alloc_size,
>>>> -                               &dealloc, refcount_loc,
>>>> -                               flags);
>>>> -            if (ret) {
>>>> -                mlog_errno(ret);
>>>> -                goto out;
>>>> +        ocfs2_find_rec_with_holes(el, &rec, &trunc_end);
>>>> +        /*
>>>> +         * Need to go to previous extent block.
>>>> +         */
>>>> +        if (!rec) {
>>>> +            if (path->p_tree_depth == 0)
>>>> +                break;
>>>> +            else {
>>>> +                el = path->p_node[path->p_tree_depth - 1].el;
>>>> +                ocfs2_find_rec(el, &rec, &trunc_end);
>>>> +                if (!rec)
>>>> +                    break;
>>>> +                if (le32_to_cpu(rec->e_cpos)) {
>>>> +                    trunc_end = le32_to_cpu(rec->e_cpos);
>>>> +                    cluster_within_list = trunc_end - 1;
>>>> +                } else
>>>> +                    break;
>>>>              }
>>>>   
>>> oh, I really see what you are going to do here. It is really buggy. 
>>> What if the tree_depth=2, and the branch
>>> extent block with 'tree_depth-1' is also recs[0] in the tree_depth 
>>> extent block? you can't find 'rec' and break.
>>> Actually there is already a function. ;)  Check 
>>> ocfs2_find_cpos_for_left_leaf for detail.
>>
>> Sorry, I can't get your idea clearly, what did you mean 'the branch
>> extent block with 'tree_depth-1' is also recs[0] in the tree_depth 
>> extent block?', how does that matter? why can't I find the 'rec' here?
>>
>> Per my understanding, when we found the hole before first rec in leaf 
>> extent block, we need to go back to its father extent block through 
>> path where no hole existed for sure. and we definitely find the rec 
>> there.
> Check ocfs2_find_cpos_for_left_leaf. It has done what you want already.
>
> Regards,
> Tao
>

[Ocfs2-devel] [PATCH 1/1] Ocfs2: Optimize punching-hole codes v4.

[Tao Ma]

tristan wrote:
> Tao Ma wrote:
>> Hi Tristan,
>>
>> tristan wrote:
>>> Tao,
>>>
>>> Thanks a lot for your quick review;)
>>>
>>> Tao Ma wrote:
>>>> Hi Tristan,
>>>> Tristan Ye wrote:
>>>>> Changes from v3 to v4:
>>>>>
>>>>> 1. Fix a bug when crossing extent blocks.
>>>>>
>>>>> 2. Fix a bug when hole exists in the beginning of an extent block.
>>>>>
>>>>> 3. Apply tao's comments.
>>>>>
>>>>>
>>>>> Signed-off-by: Tristan Ye <tristan.ye@oracle.com>
>>>>> ---
>>>>>  fs/ocfs2/file.c |  233 
>>>>> ++++++++++++++++++++++++++++++++++++++++++++++++-------
>>>>>  1 files changed, 206 insertions(+), 27 deletions(-)
>>>>>
>>>>> diff --git a/fs/ocfs2/file.c b/fs/ocfs2/file.c
>>>>> index db2e0c9..75e087f 100644
>>>>> --- a/fs/ocfs2/file.c
>>>>> +++ b/fs/ocfs2/file.c
>>>>> @@ -1423,18 +1423,154 @@ out:
>>>>>      return ret;
>>>>>  }
>>>>>  
>>>>> +static void ocfs2_find_rec(struct ocfs2_extent_list *el,
>>>>> +               struct ocfs2_extent_rec **rec_found,
>>>>> +               u32 *pos)
>>>>> +{
>>>>> +    int i, found = 0;
>>>>> +    struct ocfs2_extent_rec *rec = NULL;
>>>>> +
>>>>> +    for (i = le16_to_cpu(el->l_next_free_rec) - 1; i >= 0; i--) {
>>>>> +
>>>>> +        rec = &el->l_recs[i];
>>>>> +
>>>>> +        if (le32_to_cpu(rec->e_cpos) <= *pos) {
>>>>> +            found = 1;
>>>>> +            break;
>>>>> +        }
>>>>> +    }
>>>>> +
>>>>> +    if (!found)
>>>>> +        *rec_found = NULL;
>>>>> +    else
>>>>> +        *rec_found = &el->l_recs[i];
>>>>> +}
>>>>>   
>>>> This function never returns pos now. So why you want to pass a *pos?
>>>> another issue is that now it seems that you only want to returns a rec?
>>>> then why not change this function to
>>>> static int ocfs2_find_rec(struct ocfs2_extent_list *el, u32 pos)
>>>
>>> Yes, it's confusing to use *pos, thanks for pointing this out.
>>>
>>>> and after the loop, just return i. So if i>=0, you find it, if i < 
>>>> 0, no rec is found. Looks more natural?
>>>
>>> I think returning  a meaty record would be more straightforward.
>> why? actually as I have said below, these 2 functions ocfs2_find_rec 
>> and ocfs2_find_rec_with_holes can be integrated into one function 
>> named ocfs2_find_rec or whatever. You are too nervous about holes 
>> actually.
> 
> Hole still needs to be handled, while I may over-treat this  a little bit.
> 
> I'll try to merge the 2 funcs into one.
>> So
>> static int ocfs2_find_rec(struct ocfs2_extent_list *el, u32 pos)
>> {
>>     int i;
>>     struct ocfs2_extent_rec *rec = NULL;
>>
>>     for (i = le16_to_cpu(el->l_next_free_rec) - 1; i >= 0; i--) {
>>         rec = &el->l_recs[i];
>>
>>         if (le32_to_cpu(rec->e_cpos) < pos)
>>             break;
>>     }
>>
>>     return i;
>> }
> 
> Not enough,
> 
> cases about 'we didn't find a rec' and 'we find rec[0]' both return i=0;
what do you mean? If we can't find a rec, i will be set to -1, so we 
will return '-1'. It is the rule of 'for'.

Regards,
Tao