Qu Wenruo @ 2026-02-24 15:07 +1030: > 在 2026/2/24 10:14, Miquel Sabaté Solà 写道: >> Commit 2932ba8d9c99 ("slab: Introduce kmalloc_obj() and family") >> introduced, among many others, the kzalloc_objs() helper, which has some >> benefits over kcalloc(). >> Cc: Kees Cook >> Signed-off-by: Miquel Sabaté Solà >> --- >> fs/btrfs/block-group.c | 2 +- >> fs/btrfs/raid56.c | 8 ++++---- >> fs/btrfs/tests/zoned-tests.c | 2 +- >> fs/btrfs/volumes.c | 6 ++---- >> fs/btrfs/zoned.c | 5 ++--- >> 5 files changed, 10 insertions(+), 13 deletions(-) >> diff --git a/fs/btrfs/block-group.c b/fs/btrfs/block-group.c >> index 37bea850b3f0..8d85b4707690 100644 >> --- a/fs/btrfs/block-group.c >> +++ b/fs/btrfs/block-group.c >> @@ -2239,7 +2239,7 @@ int btrfs_rmap_block(struct btrfs_fs_info *fs_info, u64 chunk_start, >> if (map->type & BTRFS_BLOCK_GROUP_RAID56_MASK) >> io_stripe_size = btrfs_stripe_nr_to_offset(nr_data_stripes(map)); >> - buf = kcalloc(map->num_stripes, sizeof(u64), GFP_NOFS); >> + buf = kzalloc_objs(*buf, map->num_stripes, GFP_NOFS); > > Not sure if we should use *buf for the type. > > I still remember we had some bugs related to incorrect type usage. Considering the type of 'buf' and how kzalloc_objs() will resolve the first argument '*buf', it should really just be equivalent to what was written before. > > Another thing is, we may not want to use the kzalloc version. > We don't want to waste CPU time just to zero out the content meanwhile we're > ensured to re-assign the contents. > > Thus kmalloc_objs() maybe better. Yes, having a second look at this function, it looks like kmalloc_objs() might just be enough. If you don't mind, I will add another commit in v2 translating kzalloc_objs() into kmalloc_objs() wherever I see we can do this from the ones I've touched. This way we can easily revert in case things go south :) > > Thanks, > Qu Thanks, Miquel > > >> if (!buf) { >> ret = -ENOMEM; >> goto out; >> diff --git a/fs/btrfs/raid56.c b/fs/btrfs/raid56.c >> index 02105d68accb..1ebfed8f0a0a 100644 >> --- a/fs/btrfs/raid56.c >> +++ b/fs/btrfs/raid56.c >> @@ -2110,8 +2110,8 @@ static int recover_sectors(struct btrfs_raid_bio *rbio) >> * @unmap_array stores copy of pointers that does not get reordered >> * during reconstruction so that kunmap_local works. >> */ >> - pointers = kcalloc(rbio->real_stripes, sizeof(void *), GFP_NOFS); >> - unmap_array = kcalloc(rbio->real_stripes, sizeof(void *), GFP_NOFS); >> + pointers = kzalloc_objs(*pointers, rbio->real_stripes, GFP_NOFS); >> + unmap_array = kzalloc_objs(*unmap_array, rbio->real_stripes, GFP_NOFS); >> if (!pointers || !unmap_array) { >> ret = -ENOMEM; >> goto out; >> @@ -2844,8 +2844,8 @@ static int recover_scrub_rbio(struct btrfs_raid_bio *rbio) >> * @unmap_array stores copy of pointers that does not get reordered >> * during reconstruction so that kunmap_local works. >> */ >> - pointers = kcalloc(rbio->real_stripes, sizeof(void *), GFP_NOFS); >> - unmap_array = kcalloc(rbio->real_stripes, sizeof(void *), GFP_NOFS); >> + pointers = kzalloc_objs(*pointers, rbio->real_stripes, GFP_NOFS); >> + unmap_array = kzalloc_objs(*unmap_array, rbio->real_stripes, GFP_NOFS); >> if (!pointers || !unmap_array) { >> ret = -ENOMEM; >> goto out; >> diff --git a/fs/btrfs/tests/zoned-tests.c b/fs/btrfs/tests/zoned-tests.c >> index da21c7aea31a..2bc3b14baa41 100644 >> --- a/fs/btrfs/tests/zoned-tests.c >> +++ b/fs/btrfs/tests/zoned-tests.c >> @@ -58,7 +58,7 @@ static int test_load_zone_info(struct btrfs_fs_info *fs_info, >> return -ENOMEM; >> } >> - zone_info = kcalloc(test->num_stripes, sizeof(*zone_info), GFP_KERNEL); >> + zone_info = kzalloc_objs(*zone_info, test->num_stripes, GFP_KERNEL); >> if (!zone_info) { >> test_err("cannot allocate zone info"); >> return -ENOMEM; >> diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c >> index e15e138c515b..c0cf8f7c5a8e 100644 >> --- a/fs/btrfs/volumes.c >> +++ b/fs/btrfs/volumes.c >> @@ -5499,8 +5499,7 @@ static int calc_one_profile_avail(struct btrfs_fs_info *fs_info, >> goto out; >> } >> - devices_info = kcalloc(fs_devices->rw_devices, sizeof(*devices_info), >> - GFP_NOFS); >> + devices_info = kzalloc_objs(*devices_info, fs_devices->rw_devices, GFP_NOFS); >> if (!devices_info) { >> ret = -ENOMEM; >> goto out; >> @@ -6067,8 +6066,7 @@ struct btrfs_block_group *btrfs_create_chunk(struct btrfs_trans_handle *trans, >> ctl.space_info = space_info; >> init_alloc_chunk_ctl(fs_devices, &ctl); >> - devices_info = kcalloc(fs_devices->rw_devices, sizeof(*devices_info), >> - GFP_NOFS); >> + devices_info = kzalloc_objs(*devices_info, fs_devices->rw_devices, GFP_NOFS); >> if (!devices_info) >> return ERR_PTR(-ENOMEM); >> diff --git a/fs/btrfs/zoned.c b/fs/btrfs/zoned.c >> index ab330ec957bc..851b0de7bed7 100644 >> --- a/fs/btrfs/zoned.c >> +++ b/fs/btrfs/zoned.c >> @@ -1697,8 +1697,7 @@ static int btrfs_load_block_group_raid10(struct btrfs_block_group *bg, >> return -EINVAL; >> } >> - raid0_allocs = kcalloc(map->num_stripes / map->sub_stripes, >> sizeof(*raid0_allocs), >> - GFP_NOFS); >> + raid0_allocs = kzalloc_objs(*raid0_allocs, map->num_stripes / map->sub_stripes, GFP_NOFS); >> if (!raid0_allocs) >> return -ENOMEM; >> @@ -1916,7 +1915,7 @@ int btrfs_load_block_group_zone_info(struct >> btrfs_block_group *cache, bool new) >> cache->physical_map = map; >> - zone_info = kcalloc(map->num_stripes, sizeof(*zone_info), GFP_NOFS); >> + zone_info = kzalloc_objs(*zone_info, map->num_stripes, GFP_NOFS); >> if (!zone_info) { >> ret = -ENOMEM; >> goto out;