On Mon 24-07-23 20:10:57, Baokun Li wrote: > 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. > > Signed-off-by: Baokun Li <libaokun1@xxxxxxxxxx> Looks good to me. Feel free to add: Reviewed-by: Jan Kara <jack@xxxxxxx> Honza > --- > 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 > -- Jan Kara <jack@xxxxxxxx> SUSE Labs, CR