[PATCH v6 3/9] ext4: Refactor code in ext4_mb_normalize_request() and ext4_mb_use_preallocated()

Ojaswin Mujoo posted 9 patches 2 years, 5 months ago
[PATCH v6 3/9] ext4: Refactor code in ext4_mb_normalize_request() and ext4_mb_use_preallocated()
Posted by Ojaswin Mujoo 2 years, 5 months ago
Change some variable names to be more consistent and
refactor some of the code to make it easier to read.

There are no functional changes in this patch

Signed-off-by: Ojaswin Mujoo <ojaswin@linux.ibm.com>
Reviewed-by: Ritesh Harjani (IBM) <ritesh.list@gmail.com>
Reviewed-by: Jan Kara <jack@suse.cz>
---
 fs/ext4/mballoc.c | 96 ++++++++++++++++++++++++-----------------------
 1 file changed, 49 insertions(+), 47 deletions(-)

diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c
index 18b65e53abbb..a1429d5a1197 100644
--- a/fs/ext4/mballoc.c
+++ b/fs/ext4/mballoc.c
@@ -3994,7 +3994,8 @@ ext4_mb_normalize_request(struct ext4_allocation_context *ac,
 	loff_t orig_size __maybe_unused;
 	ext4_lblk_t start;
 	struct ext4_inode_info *ei = EXT4_I(ac->ac_inode);
-	struct ext4_prealloc_space *pa;
+	struct ext4_prealloc_space *tmp_pa;
+	ext4_lblk_t tmp_pa_start, tmp_pa_end;
 
 	/* do normalize only data requests, metadata requests
 	   do not need preallocation */
@@ -4097,54 +4098,52 @@ ext4_mb_normalize_request(struct ext4_allocation_context *ac,
 
 	/* check we don't cross already preallocated blocks */
 	rcu_read_lock();
-	list_for_each_entry_rcu(pa, &ei->i_prealloc_list, pa_inode_list) {
-		ext4_lblk_t pa_end;
-
-		if (pa->pa_deleted)
+	list_for_each_entry_rcu(tmp_pa, &ei->i_prealloc_list, pa_inode_list) {
+		if (tmp_pa->pa_deleted)
 			continue;
-		spin_lock(&pa->pa_lock);
-		if (pa->pa_deleted) {
-			spin_unlock(&pa->pa_lock);
+		spin_lock(&tmp_pa->pa_lock);
+		if (tmp_pa->pa_deleted) {
+			spin_unlock(&tmp_pa->pa_lock);
 			continue;
 		}
 
-		pa_end = pa->pa_lstart + EXT4_C2B(sbi, pa->pa_len);
+		tmp_pa_start = tmp_pa->pa_lstart;
+		tmp_pa_end = tmp_pa->pa_lstart + EXT4_C2B(sbi, tmp_pa->pa_len);
 
 		/* PA must not overlap original request */
-		BUG_ON(!(ac->ac_o_ex.fe_logical >= pa_end ||
-			ac->ac_o_ex.fe_logical < pa->pa_lstart));
+		BUG_ON(!(ac->ac_o_ex.fe_logical >= tmp_pa_end ||
+			ac->ac_o_ex.fe_logical < tmp_pa_start));
 
 		/* skip PAs this normalized request doesn't overlap with */
-		if (pa->pa_lstart >= end || pa_end <= start) {
-			spin_unlock(&pa->pa_lock);
+		if (tmp_pa_start >= end || tmp_pa_end <= start) {
+			spin_unlock(&tmp_pa->pa_lock);
 			continue;
 		}
-		BUG_ON(pa->pa_lstart <= start && pa_end >= end);
+		BUG_ON(tmp_pa_start <= start && tmp_pa_end >= end);
 
 		/* adjust start or end to be adjacent to this pa */
-		if (pa_end <= ac->ac_o_ex.fe_logical) {
-			BUG_ON(pa_end < start);
-			start = pa_end;
-		} else if (pa->pa_lstart > ac->ac_o_ex.fe_logical) {
-			BUG_ON(pa->pa_lstart > end);
-			end = pa->pa_lstart;
+		if (tmp_pa_end <= ac->ac_o_ex.fe_logical) {
+			BUG_ON(tmp_pa_end < start);
+			start = tmp_pa_end;
+		} else if (tmp_pa_start > ac->ac_o_ex.fe_logical) {
+			BUG_ON(tmp_pa_start > end);
+			end = tmp_pa_start;
 		}
-		spin_unlock(&pa->pa_lock);
+		spin_unlock(&tmp_pa->pa_lock);
 	}
 	rcu_read_unlock();
 	size = end - start;
 
 	/* XXX: extra loop to check we really don't overlap preallocations */
 	rcu_read_lock();
-	list_for_each_entry_rcu(pa, &ei->i_prealloc_list, pa_inode_list) {
-		ext4_lblk_t pa_end;
-
-		spin_lock(&pa->pa_lock);
-		if (pa->pa_deleted == 0) {
-			pa_end = pa->pa_lstart + EXT4_C2B(sbi, pa->pa_len);
-			BUG_ON(!(start >= pa_end || end <= pa->pa_lstart));
+	list_for_each_entry_rcu(tmp_pa, &ei->i_prealloc_list, pa_inode_list) {
+		spin_lock(&tmp_pa->pa_lock);
+		if (tmp_pa->pa_deleted == 0) {
+			tmp_pa_start = tmp_pa->pa_lstart;
+			tmp_pa_end = tmp_pa->pa_lstart + EXT4_C2B(sbi, tmp_pa->pa_len);
+			BUG_ON(!(start >= tmp_pa_end || end <= tmp_pa_start));
 		}
-		spin_unlock(&pa->pa_lock);
+		spin_unlock(&tmp_pa->pa_lock);
 	}
 	rcu_read_unlock();
 
@@ -4358,7 +4357,8 @@ ext4_mb_use_preallocated(struct ext4_allocation_context *ac)
 	int order, i;
 	struct ext4_inode_info *ei = EXT4_I(ac->ac_inode);
 	struct ext4_locality_group *lg;
-	struct ext4_prealloc_space *pa, *cpa = NULL;
+	struct ext4_prealloc_space *tmp_pa, *cpa = NULL;
+	ext4_lblk_t tmp_pa_start, tmp_pa_end;
 	ext4_fsblk_t goal_block;
 
 	/* only data can be preallocated */
@@ -4367,18 +4367,20 @@ ext4_mb_use_preallocated(struct ext4_allocation_context *ac)
 
 	/* first, try per-file preallocation */
 	rcu_read_lock();
-	list_for_each_entry_rcu(pa, &ei->i_prealloc_list, pa_inode_list) {
+	list_for_each_entry_rcu(tmp_pa, &ei->i_prealloc_list, pa_inode_list) {
 
 		/* all fields in this condition don't change,
 		 * so we can skip locking for them */
-		if (ac->ac_o_ex.fe_logical < pa->pa_lstart ||
-		    ac->ac_o_ex.fe_logical >= (pa->pa_lstart +
-					       EXT4_C2B(sbi, pa->pa_len)))
+		tmp_pa_start = tmp_pa->pa_lstart;
+		tmp_pa_end = tmp_pa->pa_lstart + EXT4_C2B(sbi, tmp_pa->pa_len);
+
+		if (ac->ac_o_ex.fe_logical < tmp_pa_start ||
+		    ac->ac_o_ex.fe_logical >= tmp_pa_end)
 			continue;
 
 		/* non-extent files can't have physical blocks past 2^32 */
 		if (!(ext4_test_inode_flag(ac->ac_inode, EXT4_INODE_EXTENTS)) &&
-		    (pa->pa_pstart + EXT4_C2B(sbi, pa->pa_len) >
+		    (tmp_pa->pa_pstart + EXT4_C2B(sbi, tmp_pa->pa_len) >
 		     EXT4_MAX_BLOCK_FILE_PHYS)) {
 			/*
 			 * Since PAs don't overlap, we won't find any
@@ -4388,16 +4390,16 @@ ext4_mb_use_preallocated(struct ext4_allocation_context *ac)
 		}
 
 		/* found preallocated blocks, use them */
-		spin_lock(&pa->pa_lock);
-		if (pa->pa_deleted == 0 && pa->pa_free) {
-			atomic_inc(&pa->pa_count);
-			ext4_mb_use_inode_pa(ac, pa);
-			spin_unlock(&pa->pa_lock);
+		spin_lock(&tmp_pa->pa_lock);
+		if (tmp_pa->pa_deleted == 0 && tmp_pa->pa_free) {
+			atomic_inc(&tmp_pa->pa_count);
+			ext4_mb_use_inode_pa(ac, tmp_pa);
+			spin_unlock(&tmp_pa->pa_lock);
 			ac->ac_criteria = 10;
 			rcu_read_unlock();
 			return true;
 		}
-		spin_unlock(&pa->pa_lock);
+		spin_unlock(&tmp_pa->pa_lock);
 	}
 	rcu_read_unlock();
 
@@ -4421,16 +4423,16 @@ ext4_mb_use_preallocated(struct ext4_allocation_context *ac)
 	 */
 	for (i = order; i < PREALLOC_TB_SIZE; i++) {
 		rcu_read_lock();
-		list_for_each_entry_rcu(pa, &lg->lg_prealloc_list[i],
+		list_for_each_entry_rcu(tmp_pa, &lg->lg_prealloc_list[i],
 					pa_inode_list) {
-			spin_lock(&pa->pa_lock);
-			if (pa->pa_deleted == 0 &&
-					pa->pa_free >= ac->ac_o_ex.fe_len) {
+			spin_lock(&tmp_pa->pa_lock);
+			if (tmp_pa->pa_deleted == 0 &&
+					tmp_pa->pa_free >= ac->ac_o_ex.fe_len) {
 
 				cpa = ext4_mb_check_group_pa(goal_block,
-								pa, cpa);
+								tmp_pa, cpa);
 			}
-			spin_unlock(&pa->pa_lock);
+			spin_unlock(&tmp_pa->pa_lock);
 		}
 		rcu_read_unlock();
 	}
-- 
2.31.1