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Message-Id: <20230221115919.1918161-8-shikemeng@huaweicloud.com>
Date: Tue, 21 Feb 2023 19:59:19 +0800
From: Kemeng Shi <shikemeng@...weicloud.com>
To: tytso@....edu, adilger.kernel@...ger.ca
Cc: linux-ext4@...r.kernel.org, linux-kernel@...r.kernel.org,
shikemeng@...weicloud.com
Subject: [PATCH 7/7] ext4: improve inode table blocks counting in ext4_num_overhead_clusters
As inode table blocks are contiguous, inode table blocks inside the
block_group can be represented as range [itbl_cluster_start,
itbl_cluster_last]. Then we can simply account inode table cluters and
check cluster overlap with [itbl_cluster_start, itbl_cluster_last] instead
of traverse each block of inode table.
By the way, this patch fixes code style problem of comment for
ext4_num_overhead_clusters.
Signed-off-by: Kemeng Shi <shikemeng@...weicloud.com>
---
fs/ext4/balloc.c | 90 +++++++++++++++++++++++++-----------------------
1 file changed, 47 insertions(+), 43 deletions(-)
diff --git a/fs/ext4/balloc.c b/fs/ext4/balloc.c
index dab46274d591..689edfed231a 100644
--- a/fs/ext4/balloc.c
+++ b/fs/ext4/balloc.c
@@ -80,32 +80,56 @@ static inline int ext4_block_in_group(struct super_block *sb,
return (actual_group == block_group) ? 1 : 0;
}
-/* Return the number of clusters used for file system metadata; this
+/*
+ * Return the number of clusters used for file system metadata; this
* represents the overhead needed by the file system.
*/
static unsigned ext4_num_overhead_clusters(struct super_block *sb,
ext4_group_t block_group,
struct ext4_group_desc *gdp)
{
- unsigned num_clusters;
- int block_cluster = -1, inode_cluster = -1, itbl_cluster = -1, i, c;
+ unsigned base_clusters, num_clusters;
+ int block_cluster, inode_cluster;
+ int itbl_cluster_start = -1, itbl_cluster_end = -1;
ext4_fsblk_t start = ext4_group_first_block_no(sb, block_group);
- ext4_fsblk_t itbl_blk;
+ ext4_fsblk_t end = start + EXT4_BLOCKS_PER_GROUP(sb) - 1;
+ ext4_fsblk_t itbl_blk_start, itbl_blk_end;
struct ext4_sb_info *sbi = EXT4_SB(sb);
/* This is the number of clusters used by the superblock,
* block group descriptors, and reserved block group
* descriptor blocks */
- num_clusters = ext4_num_base_meta_clusters(sb, block_group);
+ base_clusters = ext4_num_base_meta_clusters(sb, block_group);
+ num_clusters = base_clusters;
/*
- * For the allocation bitmaps and inode table, we first need
- * to check to see if the block is in the block group. If it
- * is, then check to see if the cluster is already accounted
- * for in the clusters used for the base metadata cluster, or
- * if we can increment the base metadata cluster to include
- * that block. Otherwise, we will have to track the cluster
- * used for the allocation bitmap or inode table explicitly.
+ * Account and record inode table clusters if any cluster
+ * is in the block group, or inode table cluster range is
+ * [-1, -1] and won't overlap with block/inode bitmap cluster
+ * accounted below.
+ */
+ itbl_blk_start = ext4_inode_table(sb, gdp);
+ itbl_blk_end = itbl_blk_start + sbi->s_itb_per_group - 1;
+ if (itbl_blk_start <= end && itbl_blk_end >= start) {
+ itbl_blk_start = itbl_blk_start >= start ?
+ itbl_blk_start : start;
+ itbl_blk_end = itbl_blk_end <= end ?
+ itbl_blk_end : end;
+
+ itbl_cluster_start = EXT4_B2C(sbi, itbl_blk_start - start);
+ itbl_cluster_end = EXT4_B2C(sbi, itbl_blk_end - start);
+
+ num_clusters += itbl_cluster_end - itbl_cluster_start + 1;
+ /* check if border cluster is overlapped */
+ if (itbl_cluster_start == base_clusters - 1)
+ num_clusters--;
+ }
+
+ /*
+ * For the allocation bitmaps, we first need to check to see
+ * if the block is in the block group. If it is, then check
+ * to see if the cluster is already accounted for in the clusters
+ * used for the base metadata cluster and inode tables cluster.
* Normally all of these blocks are contiguous, so the special
* case handling shouldn't be necessary except for *very*
* unusual file system layouts.
@@ -113,46 +137,26 @@ static unsigned ext4_num_overhead_clusters(struct super_block *sb,
if (ext4_block_in_group(sb, ext4_block_bitmap(sb, gdp), block_group)) {
block_cluster = EXT4_B2C(sbi,
ext4_block_bitmap(sb, gdp) - start);
- if (block_cluster < num_clusters)
- block_cluster = -1;
- else if (block_cluster == num_clusters) {
+ if (block_cluster >= base_clusters &&
+ (block_cluster < itbl_cluster_start ||
+ block_cluster > itbl_cluster_end))
num_clusters++;
- block_cluster = -1;
- }
}
if (ext4_block_in_group(sb, ext4_inode_bitmap(sb, gdp), block_group)) {
inode_cluster = EXT4_B2C(sbi,
ext4_inode_bitmap(sb, gdp) - start);
- if (inode_cluster < num_clusters)
- inode_cluster = -1;
- else if (inode_cluster == num_clusters) {
- num_clusters++;
- inode_cluster = -1;
- }
- }
-
- itbl_blk = ext4_inode_table(sb, gdp);
- for (i = 0; i < sbi->s_itb_per_group; i++) {
- if (ext4_block_in_group(sb, itbl_blk + i, block_group)) {
- c = EXT4_B2C(sbi, itbl_blk + i - start);
- if ((c < num_clusters) || (c == inode_cluster) ||
- (c == block_cluster) || (c == itbl_cluster))
- continue;
- if (c == num_clusters) {
- num_clusters++;
- continue;
- }
+ /*
+ * Additional check if inode bitmap is in just accounted
+ * block_cluster
+ */
+ if (inode_cluster != block_cluster &&
+ inode_cluster >= base_clusters &&
+ (inode_cluster < itbl_cluster_start ||
+ inode_cluster > itbl_cluster_end))
num_clusters++;
- itbl_cluster = c;
- }
}
- if (block_cluster != -1)
- num_clusters++;
- if (inode_cluster != -1)
- num_clusters++;
-
return num_clusters;
}
--
2.30.0
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