Messages in this thread | | | Date | Wed, 26 Jul 2023 09:17:59 +0800 | Subject | Re: [PATCH v2 1/3] ext4: add two helper functions extent_logical_end() and pa_logical_end() | From | Baokun Li <> |
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On 2023/7/26 1:29, Ritesh Harjani (IBM) wrote: > Baokun Li <libaokun1@huawei.com> writes: > >> When we use lstart + len to calculate the end of free extent or prealloc >> space, it may exceed the maximum value of 4294967295(0xffffffff) supported >> by ext4_lblk_t and cause overflow, which may lead to various problems. >> >> Therefore, we add two helper functions, extent_logical_end() and >> pa_logical_end(), to limit the type of end to loff_t, and also convert >> lstart to loff_t for calculation to avoid overflow. > Sure. extent_logical_end() is not as bad after dropping the third param. > Thanks for addressing review comments and identifying overflow issues :) > > Looks good to me. Feel free to add: > > Reviewed-by: Ritesh Harjani (IBM) <ritesh.list@gmail.com> > Thank you very much for your patient review! 😊 >> Signed-off-by: Baokun Li <libaokun1@huawei.com> >> --- >> fs/ext4/mballoc.c | 9 +++------ >> fs/ext4/mballoc.h | 14 ++++++++++++++ >> 2 files changed, 17 insertions(+), 6 deletions(-) >> >> diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c >> index 21b903fe546e..4cb13b3e41b3 100644 >> --- a/fs/ext4/mballoc.c >> +++ b/fs/ext4/mballoc.c >> @@ -4432,7 +4432,7 @@ ext4_mb_normalize_request(struct ext4_allocation_context *ac, >> >> /* first, let's learn actual file size >> * given current request is allocated */ >> - size = ac->ac_o_ex.fe_logical + EXT4_C2B(sbi, ac->ac_o_ex.fe_len); >> + size = extent_logical_end(sbi, &ac->ac_o_ex); >> size = size << bsbits; >> if (size < i_size_read(ac->ac_inode)) >> size = i_size_read(ac->ac_inode); >> @@ -4766,7 +4766,6 @@ ext4_mb_use_preallocated(struct ext4_allocation_context *ac) >> struct ext4_inode_info *ei = EXT4_I(ac->ac_inode); >> struct ext4_locality_group *lg; >> struct ext4_prealloc_space *tmp_pa = NULL, *cpa = NULL; >> - loff_t tmp_pa_end; >> struct rb_node *iter; >> ext4_fsblk_t goal_block; >> >> @@ -4862,9 +4861,7 @@ ext4_mb_use_preallocated(struct ext4_allocation_context *ac) >> * pa can possibly satisfy the request hence check if it overlaps >> * original logical start and stop searching if it doesn't. >> */ >> - tmp_pa_end = (loff_t)tmp_pa->pa_lstart + EXT4_C2B(sbi, tmp_pa->pa_len); >> - >> - if (ac->ac_o_ex.fe_logical >= tmp_pa_end) { >> + if (ac->ac_o_ex.fe_logical >= pa_logical_end(sbi, tmp_pa)) { >> spin_unlock(&tmp_pa->pa_lock); >> goto try_group_pa; >> } >> @@ -5769,7 +5766,7 @@ static void ext4_mb_group_or_file(struct ext4_allocation_context *ac) >> >> group_pa_eligible = sbi->s_mb_group_prealloc > 0; >> inode_pa_eligible = true; >> - size = ac->ac_o_ex.fe_logical + EXT4_C2B(sbi, ac->ac_o_ex.fe_len); >> + size = extent_logical_end(sbi, &ac->ac_o_ex); >> isize = (i_size_read(ac->ac_inode) + ac->ac_sb->s_blocksize - 1) >> >> bsbits; >> >> diff --git a/fs/ext4/mballoc.h b/fs/ext4/mballoc.h >> index df6b5e7c2274..d7aeb5da7d86 100644 >> --- a/fs/ext4/mballoc.h >> +++ b/fs/ext4/mballoc.h >> @@ -233,6 +233,20 @@ static inline ext4_fsblk_t ext4_grp_offs_to_block(struct super_block *sb, >> (fex->fe_start << EXT4_SB(sb)->s_cluster_bits); >> } >> >> +static inline loff_t extent_logical_end(struct ext4_sb_info *sbi, >> + struct ext4_free_extent *fex) >> +{ >> + /* Use loff_t to avoid end exceeding ext4_lblk_t max. */ >> + return (loff_t)fex->fe_logical + EXT4_C2B(sbi, fex->fe_len); >> +} >> + >> +static inline loff_t pa_logical_end(struct ext4_sb_info *sbi, >> + struct ext4_prealloc_space *pa) >> +{ >> + /* Use loff_t to avoid end exceeding ext4_lblk_t max. */ >> + return (loff_t)pa->pa_lstart + EXT4_C2B(sbi, pa->pa_len); >> +} >> + >> typedef int (*ext4_mballoc_query_range_fn)( >> struct super_block *sb, >> ext4_group_t agno, >> -- >> 2.31.1 Cheers! -- With Best Regards, Baokun Li .
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