Message ID | 20230221115919.1918161-8-shikemeng@huaweicloud.com |
---|---|
State | Awaiting Upstream |
Headers | show |
Series | A few patches to improve ext4 balloc | expand |
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@intel.com> | Reported-by: Dan Carpenter <error27@gmail.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 }
on 2/22/2023 11:13 PM, Dan Carpenter wrote: > 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@intel.com> > | Reported-by: Dan Carpenter <error27@gmail.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 [...] > 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. These two conditions check two kinds of bitmap block: *block* bitmap block and *inode* bitmap block. For case that block bitmap in the block group while inode bitmap in a different group, there is a risk to access uninitialized block_cluster. I will fix this in next version, Thanks!
On Thu, Feb 23, 2023 at 09:31:54AM +0800, Kemeng Shi wrote: > > > on 2/22/2023 11:13 PM, Dan Carpenter wrote: > > 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@intel.com> > > | Reported-by: Dan Carpenter <error27@gmail.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 > [...] > > 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. > These two conditions check two kinds of bitmap block: *block* bitmap block > and *inode* bitmap block. Ah right. When I was reviewing this code, I copy and pasted the if conditions so they were exactly lined up with each other and I still didn't see the block vs inode difference until you pointed it out. :P Thanks! regards, dan carpenter
On Tue 21-02-23 19:59:19, Kemeng Shi wrote: > 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@huaweicloud.com> FWIW this is triggering Coverity warning: *** CID 1536792: Uninitialized variables (UNINIT) /fs/ext4/balloc.c: 153 in ext4_num_overhead_clusters() 147 inode_cluster = EXT4_B2C(sbi, 148 ext4_inode_bitmap(sb, gdp) - st 149 /* 150 * Additional check if inode bitmap is in just accounted 151 * block_cluster 152 */ >>> CID 1536792: Uninitialized variables (UNINIT) >>> Using uninitialized value "block_cluster". 153 if (inode_cluster != block_cluster && 154 inode_cluster >= base_clusters && 155 (inode_cluster < itbl_cluster_start || 156 inode_cluster > itbl_cluster_end)) 157 num_clusters++; 158 } which actually looks valid AFAICT. Honza
on 3/20/2023 8:44 PM, Jan Kara wrote: > On Tue 21-02-23 19:59:19, Kemeng Shi wrote: >> 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@huaweicloud.com> > > FWIW this is triggering Coverity warning: > > *** CID 1536792: Uninitialized variables (UNINIT) > /fs/ext4/balloc.c: 153 in ext4_num_overhead_clusters() > 147 inode_cluster = EXT4_B2C(sbi, > 148 ext4_inode_bitmap(sb, gdp) - st > 149 /* > 150 * Additional check if inode bitmap is in just accounted > 151 * block_cluster > 152 */ >>>> CID 1536792: Uninitialized variables (UNINIT) >>>> Using uninitialized value "block_cluster". > 153 if (inode_cluster != block_cluster && > 154 inode_cluster >= base_clusters && > 155 (inode_cluster < itbl_cluster_start || > 156 inode_cluster > itbl_cluster_end)) > 157 num_clusters++; > 158 } > > which actually looks valid AFAICT. Yes, there is a risk to access uninitialized block_cluster if block bitmap block and inode bitmap block are in different groups. Patch to fix is just sent. Thanks!
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; }
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@huaweicloud.com> --- fs/ext4/balloc.c | 90 +++++++++++++++++++++++++----------------------- 1 file changed, 47 insertions(+), 43 deletions(-)