[PATCH 3/6] ext4: rework partial cluster handling to use lblk more consistently

[Eric Whitney <enwlinux@xxxxxxxxx>]

Working in the logical block space where possible when manipulating
partial clusters makes the code easier to understand.  It also offers
the opportunity for efficiency improvements, both in this patch and
those that follow.

Signed-off-by: Eric Whitney <enwlinux@xxxxxxxxx>
---
 fs/ext4/extents.c | 20 +++++++++-----------
 1 file changed, 9 insertions(+), 11 deletions(-)

diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c
index 0c52218fb171..793a9437be9f 100644
--- a/fs/ext4/extents.c
+++ b/fs/ext4/extents.c
@@ -2505,7 +2505,7 @@ static int ext4_remove_blocks(handle_t *handle, struct inode *inode,
 	 */
 	last_pblk = ext4_ext_pblock(ex) + ee_len - 1;
 	if (partial->state != none &&
-	    partial->pclu != EXT4_B2C(sbi, last_pblk)) {
+		EXT4_B2C(sbi, partial->lblk) != EXT4_B2C(sbi, to)) {
 		if (partial->state == free)
 			free_partial_cluster(handle, inode, partial);
 		partial->state = none;
@@ -2547,7 +2547,8 @@ static int ext4_remove_blocks(handle_t *handle, struct inode *inode,
 	ext4_free_blocks(handle, inode, NULL, pblk, num, flags);
 
 	/* reset the partial cluster if we've freed past it */
-	if (partial->state != none && partial->pclu != EXT4_B2C(sbi, pblk))
+	if (partial->state != none &&
+	    EXT4_B2C(sbi, partial->lblk) != EXT4_B2C(sbi, from))
 		partial->state = none;
 
 	/*
@@ -2597,11 +2598,10 @@ ext4_ext_rm_leaf(handle_t *handle, struct inode *inode,
 	struct ext4_extent_header *eh;
 	ext4_lblk_t a, b;
 	unsigned num;
-	ext4_lblk_t ex_ee_block;
+	ext4_lblk_t ex_ee_block, lblk;
 	unsigned short ex_ee_len;
 	unsigned unwritten = 0;
 	struct ext4_extent *ex;
-	ext4_fsblk_t pblk;
 
 	/* the header must be checked already in ext4_ext_remove_space() */
 	ext_debug(inode, "truncate since %u in leaf to %u\n", start, end);
@@ -2649,8 +2649,7 @@ ext4_ext_rm_leaf(handle_t *handle, struct inode *inode,
 			 * be just to the left.
 			 */
 			if (sbi->s_cluster_ratio > 1) {
-				pblk = ext4_ext_pblock(ex);
-				partial->pclu = EXT4_B2C(sbi, pblk);
+				partial->lblk = ex_ee_block;
 				partial->state = keep;
 			}
 			ex--;
@@ -2767,8 +2766,8 @@ ext4_ext_rm_leaf(handle_t *handle, struct inode *inode,
 	 * to be removed but might be shared with the partial cluster.
 	 */
 	if (partial->state == free && ex >= EXT_FIRST_EXTENT(eh)) {
-		pblk = ext4_ext_pblock(ex) + ex_ee_len - 1;
-		if (partial->pclu != EXT4_B2C(sbi, pblk))
+		lblk = ex_ee_block + ex_ee_len - 1;
+		if (EXT4_B2C(sbi, partial->lblk) != EXT4_B2C(sbi, lblk))
 			free_partial_cluster(handle, inode, partial);
 		partial->state = none;
 	}
@@ -2878,8 +2877,7 @@ int ext4_ext_remove_space(struct inode *inode, ext4_lblk_t start,
 			 * in use to avoid freeing it when removing blocks.
 			 */
 			if (sbi->s_cluster_ratio > 1) {
-				pblk = ext4_ext_pblock(ex) + end - ee_block + 1;
-				partial.pclu = EXT4_B2C(sbi, pblk);
+				partial.lblk = end + 1;
 				partial.state = keep;
 			}
 
@@ -2912,7 +2910,7 @@ int ext4_ext_remove_space(struct inode *inode, ext4_lblk_t start,
 			if (err < 0)
 				goto out;
 			if (pblk) {
-				partial.pclu = EXT4_B2C(sbi, pblk);
+				partial.lblk = lblk;
 				partial.state = keep;
 			}
 		}
-- 
2.30.2