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From:   Harshad Shirwadkar <harshadshirwadkar@gmail.com>
To:     linux-ext4@vger.kernel.org
Cc:     tytso@mit.edu, Harshad Shirwadkar <harshadshirwadkar@gmail.com>
Subject: [PATCH v4 1/8] ext2fs: add new APIs needed for fast commits
Date:   Thu, 21 Jan 2021 21:44:57 -0800
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From: Harshad Shirwadkar <harshadshirwadkar@gmail.com>

This patch adds the following new APIs:

Count the total number of blocks occupied by inode including
intermediate extent tree nodes.
extern errcode_t ext2fs_count_blocks(ext2_filsys fs, ext2_ino_t ino,
                                     struct ext2_inode *inode,
				     blk64_t *ret_count);

Convert ext3_extent to ext2fs_extent.
extern void ext2fs_convert_extent(struct ext2fs_extent *to,
                                       struct ext3_extent *from);

Signed-off-by: Harshad Shirwadkar <harshadshirwadkar@gmail.com>
---
 lib/ext2fs/ext2fs.h |  4 +++
 lib/ext2fs/extent.c | 64 +++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 68 insertions(+)

diff --git a/lib/ext2fs/ext2fs.h b/lib/ext2fs/ext2fs.h
index 7218fde9..7a25e0e5 100644
--- a/lib/ext2fs/ext2fs.h
+++ b/lib/ext2fs/ext2fs.h
@@ -1341,6 +1341,10 @@ extern errcode_t ext2fs_extent_fix_parents(ext2_extent_handle_t handle);
 extern size_t ext2fs_max_extent_depth(ext2_extent_handle_t handle);
 extern errcode_t ext2fs_fix_extents_checksums(ext2_filsys fs, ext2_ino_t ino,
 					      struct ext2_inode *inode);
+extern errcode_t ext2fs_count_blocks(ext2_filsys fs, ext2_ino_t ino,
+				     struct ext2_inode *inode, blk64_t *ret_count);
+extern errcode_t ext2fs_decode_extent(struct ext2fs_extent *to, void *from,
+				      int len);
 
 /* fallocate.c */
 #define EXT2_FALLOCATE_ZERO_BLOCKS	(0x1)
diff --git a/lib/ext2fs/extent.c b/lib/ext2fs/extent.c
index ac3dbfec..bde6b0f3 100644
--- a/lib/ext2fs/extent.c
+++ b/lib/ext2fs/extent.c
@@ -1785,6 +1785,70 @@ out:
 	return errcode;
 }
 
+errcode_t ext2fs_decode_extent(struct ext2fs_extent *to, void *addr, int len)
+{
+	struct ext3_extent *from = (struct ext3_extent *)addr;
+
+	if (len != sizeof(struct ext3_extent))
+		return EXT2_ET_INVALID_ARGUMENT;
+
+	to->e_pblk = ext2fs_le32_to_cpu(from->ee_start) +
+		((__u64) ext2fs_le16_to_cpu(from->ee_start_hi)
+			<< 32);
+	to->e_lblk = ext2fs_le32_to_cpu(from->ee_block);
+	to->e_len = ext2fs_le16_to_cpu(from->ee_len);
+	to->e_flags |= EXT2_EXTENT_FLAGS_LEAF;
+	if (to->e_len > EXT_INIT_MAX_LEN) {
+		to->e_len -= EXT_INIT_MAX_LEN;
+		to->e_flags |= EXT2_EXTENT_FLAGS_UNINIT;
+	}
+
+	return 0;
+}
+
+errcode_t ext2fs_count_blocks(ext2_filsys fs, ext2_ino_t ino,
+			      struct ext2_inode *inode, blk64_t *ret_count)
+{
+	ext2_extent_handle_t	handle;
+	struct ext2fs_extent	extent;
+	errcode_t		errcode;
+	int			i;
+	blk64_t			blkcount = 0;
+	blk64_t			*intermediate_nodes;
+
+	errcode = ext2fs_extent_open2(fs, ino, inode, &handle);
+	if (errcode)
+		goto out;
+
+	errcode = ext2fs_extent_get(handle, EXT2_EXTENT_ROOT, &extent);
+	if (errcode)
+		goto out;
+
+	ext2fs_get_array(handle->max_depth, sizeof(blk64_t),
+				&intermediate_nodes);
+	blkcount = handle->level;
+	while (!errcode) {
+		if (extent.e_flags & EXT2_EXTENT_FLAGS_LEAF) {
+			blkcount += extent.e_len;
+			for (i = 0; i < handle->level; i++) {
+				if (intermediate_nodes[i] !=
+					handle->path[i].end_blk) {
+					blkcount++;
+					intermediate_nodes[i] =
+						handle->path[i].end_blk;
+				}
+			}
+		}
+		errcode = ext2fs_extent_get(handle, EXT2_EXTENT_NEXT, &extent);
+	}
+	ext2fs_free_mem(&intermediate_nodes);
+out:
+	*ret_count = blkcount;
+	ext2fs_extent_free(handle);
+
+	return 0;
+}
+
 #ifdef DEBUG
 /*
  * Override debugfs's prompt
-- 
2.30.0.280.ga3ce27912f-goog