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Message-ID: <202302222219.u328sqfs-lkp@intel.com>
Date: Wed, 22 Feb 2023 18:13:55 +0300
From: Dan Carpenter <error27@...il.com>
To: oe-kbuild@...ts.linux.dev, Kemeng Shi <shikemeng@...weicloud.com>,
tytso@....edu, adilger.kernel@...ger.ca
Cc: lkp@...el.com, oe-kbuild-all@...ts.linux.dev,
linux-ext4@...r.kernel.org, linux-kernel@...r.kernel.org,
shikemeng@...weicloud.com
Subject: Re: [PATCH 7/7] ext4: improve inode table blocks counting in
ext4_num_overhead_clusters
Hi Kemeng,
https://git-scm.com/docs/git-format-patch#_base_tree_information]
url: https://github.com/intel-lab-lkp/linux/commits/Kemeng-Shi/ext4-properly-handle-error-of-ext4_init_block_bitmap-in-ext4_read_block_bitmap_nowait/20230221-115830
base: https://git.kernel.org/pub/scm/linux/kernel/git/tytso/ext4.git dev
patch link: https://lore.kernel.org/r/20230221115919.1918161-8-shikemeng%40huaweicloud.com
patch subject: [PATCH 7/7] ext4: improve inode table blocks counting in ext4_num_overhead_clusters
config: riscv-randconfig-m031-20230219 (https://download.01.org/0day-ci/archive/20230222/202302222219.u328sqfs-lkp@intel.com/config)
compiler: riscv32-linux-gcc (GCC) 12.1.0
If you fix the issue, kindly add following tag where applicable
| Reported-by: kernel test robot <lkp@...el.com>
| Reported-by: Dan Carpenter <error27@...il.com>
| Link: https://lore.kernel.org/r/202302222219.u328sqfs-lkp@intel.com/
New smatch warnings:
fs/ext4/balloc.c:153 ext4_num_overhead_clusters() error: uninitialized symbol 'block_cluster'.
vim +/block_cluster +153 fs/ext4/balloc.c
c197855ea14175 Stephen Hemminger 2014-05-12 87 static unsigned ext4_num_overhead_clusters(struct super_block *sb,
e187c6588d6ef3 Theodore Ts'o 2009-02-06 88 ext4_group_t block_group,
e187c6588d6ef3 Theodore Ts'o 2009-02-06 89 struct ext4_group_desc *gdp)
0bf7e8379ce7e0 Jose R. Santos 2008-06-03 90 {
2b59a2fd93873a Kemeng Shi 2023-02-21 91 unsigned base_clusters, num_clusters;
2b59a2fd93873a Kemeng Shi 2023-02-21 92 int block_cluster, inode_cluster;
2b59a2fd93873a Kemeng Shi 2023-02-21 93 int itbl_cluster_start = -1, itbl_cluster_end = -1;
d5b8f31007a937 Theodore Ts'o 2011-09-09 94 ext4_fsblk_t start = ext4_group_first_block_no(sb, block_group);
2b59a2fd93873a Kemeng Shi 2023-02-21 95 ext4_fsblk_t end = start + EXT4_BLOCKS_PER_GROUP(sb) - 1;
2b59a2fd93873a Kemeng Shi 2023-02-21 96 ext4_fsblk_t itbl_blk_start, itbl_blk_end;
0bf7e8379ce7e0 Jose R. Santos 2008-06-03 97 struct ext4_sb_info *sbi = EXT4_SB(sb);
0bf7e8379ce7e0 Jose R. Santos 2008-06-03 98
d5b8f31007a937 Theodore Ts'o 2011-09-09 99 /* This is the number of clusters used by the superblock,
d5b8f31007a937 Theodore Ts'o 2011-09-09 100 * block group descriptors, and reserved block group
d5b8f31007a937 Theodore Ts'o 2011-09-09 101 * descriptor blocks */
2b59a2fd93873a Kemeng Shi 2023-02-21 102 base_clusters = ext4_num_base_meta_clusters(sb, block_group);
2b59a2fd93873a Kemeng Shi 2023-02-21 103 num_clusters = base_clusters;
2b59a2fd93873a Kemeng Shi 2023-02-21 104
2b59a2fd93873a Kemeng Shi 2023-02-21 105 /*
2b59a2fd93873a Kemeng Shi 2023-02-21 106 * Account and record inode table clusters if any cluster
2b59a2fd93873a Kemeng Shi 2023-02-21 107 * is in the block group, or inode table cluster range is
2b59a2fd93873a Kemeng Shi 2023-02-21 108 * [-1, -1] and won't overlap with block/inode bitmap cluster
2b59a2fd93873a Kemeng Shi 2023-02-21 109 * accounted below.
2b59a2fd93873a Kemeng Shi 2023-02-21 110 */
2b59a2fd93873a Kemeng Shi 2023-02-21 111 itbl_blk_start = ext4_inode_table(sb, gdp);
2b59a2fd93873a Kemeng Shi 2023-02-21 112 itbl_blk_end = itbl_blk_start + sbi->s_itb_per_group - 1;
2b59a2fd93873a Kemeng Shi 2023-02-21 113 if (itbl_blk_start <= end && itbl_blk_end >= start) {
2b59a2fd93873a Kemeng Shi 2023-02-21 114 itbl_blk_start = itbl_blk_start >= start ?
2b59a2fd93873a Kemeng Shi 2023-02-21 115 itbl_blk_start : start;
2b59a2fd93873a Kemeng Shi 2023-02-21 116 itbl_blk_end = itbl_blk_end <= end ?
2b59a2fd93873a Kemeng Shi 2023-02-21 117 itbl_blk_end : end;
2b59a2fd93873a Kemeng Shi 2023-02-21 118
2b59a2fd93873a Kemeng Shi 2023-02-21 119 itbl_cluster_start = EXT4_B2C(sbi, itbl_blk_start - start);
2b59a2fd93873a Kemeng Shi 2023-02-21 120 itbl_cluster_end = EXT4_B2C(sbi, itbl_blk_end - start);
2b59a2fd93873a Kemeng Shi 2023-02-21 121
2b59a2fd93873a Kemeng Shi 2023-02-21 122 num_clusters += itbl_cluster_end - itbl_cluster_start + 1;
2b59a2fd93873a Kemeng Shi 2023-02-21 123 /* check if border cluster is overlapped */
2b59a2fd93873a Kemeng Shi 2023-02-21 124 if (itbl_cluster_start == base_clusters - 1)
2b59a2fd93873a Kemeng Shi 2023-02-21 125 num_clusters--;
2b59a2fd93873a Kemeng Shi 2023-02-21 126 }
0bf7e8379ce7e0 Jose R. Santos 2008-06-03 127
d5b8f31007a937 Theodore Ts'o 2011-09-09 128 /*
2b59a2fd93873a Kemeng Shi 2023-02-21 129 * For the allocation bitmaps, we first need to check to see
2b59a2fd93873a Kemeng Shi 2023-02-21 130 * if the block is in the block group. If it is, then check
2b59a2fd93873a Kemeng Shi 2023-02-21 131 * to see if the cluster is already accounted for in the clusters
2b59a2fd93873a Kemeng Shi 2023-02-21 132 * used for the base metadata cluster and inode tables cluster.
d5b8f31007a937 Theodore Ts'o 2011-09-09 133 * Normally all of these blocks are contiguous, so the special
d5b8f31007a937 Theodore Ts'o 2011-09-09 134 * case handling shouldn't be necessary except for *very*
d5b8f31007a937 Theodore Ts'o 2011-09-09 135 * unusual file system layouts.
d5b8f31007a937 Theodore Ts'o 2011-09-09 136 */
d5b8f31007a937 Theodore Ts'o 2011-09-09 137 if (ext4_block_in_group(sb, ext4_block_bitmap(sb, gdp), block_group)) {
b0dd6b70f0fda1 Theodore Ts'o 2012-06-07 138 block_cluster = EXT4_B2C(sbi,
b0dd6b70f0fda1 Theodore Ts'o 2012-06-07 139 ext4_block_bitmap(sb, gdp) - start);
2b59a2fd93873a Kemeng Shi 2023-02-21 140 if (block_cluster >= base_clusters &&
2b59a2fd93873a Kemeng Shi 2023-02-21 141 (block_cluster < itbl_cluster_start ||
2b59a2fd93873a Kemeng Shi 2023-02-21 142 block_cluster > itbl_cluster_end))
d5b8f31007a937 Theodore Ts'o 2011-09-09 143 num_clusters++;
d5b8f31007a937 Theodore Ts'o 2011-09-09 144 }
d5b8f31007a937 Theodore Ts'o 2011-09-09 145
d5b8f31007a937 Theodore Ts'o 2011-09-09 146 if (ext4_block_in_group(sb, ext4_inode_bitmap(sb, gdp), block_group)) {
These two conditions are exactly the same so I don't see why they can't
be combined into one condition. I have read the comment, but I guess I
don't understand ext4 well enough to really understand it.
d5b8f31007a937 Theodore Ts'o 2011-09-09 147 inode_cluster = EXT4_B2C(sbi,
b0dd6b70f0fda1 Theodore Ts'o 2012-06-07 148 ext4_inode_bitmap(sb, gdp) - start);
2b59a2fd93873a Kemeng Shi 2023-02-21 149 /*
2b59a2fd93873a Kemeng Shi 2023-02-21 150 * Additional check if inode bitmap is in just accounted
2b59a2fd93873a Kemeng Shi 2023-02-21 151 * block_cluster
2b59a2fd93873a Kemeng Shi 2023-02-21 152 */
2b59a2fd93873a Kemeng Shi 2023-02-21 @153 if (inode_cluster != block_cluster &&
So this seems like a false positive to me. But the code is puzzling for
a human or for a static checker.
2b59a2fd93873a Kemeng Shi 2023-02-21 154 inode_cluster >= base_clusters &&
2b59a2fd93873a Kemeng Shi 2023-02-21 155 (inode_cluster < itbl_cluster_start ||
2b59a2fd93873a Kemeng Shi 2023-02-21 156 inode_cluster > itbl_cluster_end))
d5b8f31007a937 Theodore Ts'o 2011-09-09 157 num_clusters++;
0bf7e8379ce7e0 Jose R. Santos 2008-06-03 158 }
d5b8f31007a937 Theodore Ts'o 2011-09-09 159
d5b8f31007a937 Theodore Ts'o 2011-09-09 160 return num_clusters;
0bf7e8379ce7e0 Jose R. Santos 2008-06-03 161 }
--
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