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(-)
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;
}
--
2.30.0On 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 -- Jan Kara <jack@suse.com> SUSE Labs, CR
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! -- Best wishes Kemeng Shi
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 }
--
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests
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!
--
Best wishes
Kemeng Shi
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
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