| Message ID | 20230317071558.335645-1-urezki@gmail.com |
|---|---|
| State | New |
| Headers | show |
| Series | [1/1] ext4: Replace ext4_kvfree_array_rcu() by kvfree_rcu_mightsleep() | expand |
On Fri, Mar 17, 2023 at 08:15:58AM +0100, Uladzislau Rezki (Sony) wrote: > The ext4_kvfree_array_rcu() function was introduced in order to > release some memory after a grace period during resizing of a > partition. An object that is freed does not contain any rcu_head > filed. > > To do so, it requires to allocate some extra memory for a special > structure that has an rcu_head filed and pointer one where a freed > memory is attached. Finally call_rcu() API is invoked. > > Since we have a single argument of kvfree_rcu() API, we can easily > replace all that tricky code by one single call that does the same > but in more efficient way. > > Cc: linux-ext4@vger.kernel.org > Cc: Lukas Czerner <lczerner@redhat.com> > Cc: Andreas Dilger <adilger.kernel@dilger.ca> > Signed-off-by: Uladzislau Rezki (Sony) <urezki@gmail.com> From an RCU perspective: Reviewed-by: Paul E. McKenney <paulmck@kernel.org> > --- > fs/ext4/ext4.h | 1 - > fs/ext4/mballoc.c | 2 +- > fs/ext4/resize.c | 31 ++----------------------------- > fs/ext4/super.c | 2 +- > 4 files changed, 4 insertions(+), 32 deletions(-) > > diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h > index 140e1eb300d1..e43d1a2d175e 100644 > --- a/fs/ext4/ext4.h > +++ b/fs/ext4/ext4.h > @@ -3057,7 +3057,6 @@ extern int ext4_generic_delete_entry(struct inode *dir, > extern bool ext4_empty_dir(struct inode *inode); > > /* resize.c */ > -extern void ext4_kvfree_array_rcu(void *to_free); > extern int ext4_group_add(struct super_block *sb, > struct ext4_new_group_data *input); > extern int ext4_group_extend(struct super_block *sb, > diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c > index 5b2ae37a8b80..96b4e3317640 100644 > --- a/fs/ext4/mballoc.c > +++ b/fs/ext4/mballoc.c > @@ -3055,7 +3055,7 @@ int ext4_mb_alloc_groupinfo(struct super_block *sb, ext4_group_t ngroups) > rcu_assign_pointer(sbi->s_group_info, new_groupinfo); > sbi->s_group_info_size = size / sizeof(*sbi->s_group_info); > if (old_groupinfo) > - ext4_kvfree_array_rcu(old_groupinfo); > + kvfree_rcu_mightsleep(old_groupinfo); > ext4_debug("allocated s_groupinfo array for %d meta_bg's\n", > sbi->s_group_info_size); > return 0; > diff --git a/fs/ext4/resize.c b/fs/ext4/resize.c > index 6b91443d6bf3..330b81f36e10 100644 > --- a/fs/ext4/resize.c > +++ b/fs/ext4/resize.c > @@ -18,33 +18,6 @@ > > #include "ext4_jbd2.h" > > -struct ext4_rcu_ptr { > - struct rcu_head rcu; > - void *ptr; > -}; > - > -static void ext4_rcu_ptr_callback(struct rcu_head *head) > -{ > - struct ext4_rcu_ptr *ptr; > - > - ptr = container_of(head, struct ext4_rcu_ptr, rcu); > - kvfree(ptr->ptr); > - kfree(ptr); > -} > - > -void ext4_kvfree_array_rcu(void *to_free) > -{ > - struct ext4_rcu_ptr *ptr = kzalloc(sizeof(*ptr), GFP_KERNEL); > - > - if (ptr) { > - ptr->ptr = to_free; > - call_rcu(&ptr->rcu, ext4_rcu_ptr_callback); > - return; > - } > - synchronize_rcu(); > - kvfree(to_free); > -} > - > int ext4_resize_begin(struct super_block *sb) > { > struct ext4_sb_info *sbi = EXT4_SB(sb); > @@ -931,7 +904,7 @@ static int add_new_gdb(handle_t *handle, struct inode *inode, > n_group_desc[gdb_num] = gdb_bh; > rcu_assign_pointer(EXT4_SB(sb)->s_group_desc, n_group_desc); > EXT4_SB(sb)->s_gdb_count++; > - ext4_kvfree_array_rcu(o_group_desc); > + kvfree_rcu_mightsleep(o_group_desc); > > lock_buffer(EXT4_SB(sb)->s_sbh); > le16_add_cpu(&es->s_reserved_gdt_blocks, -1); > @@ -994,7 +967,7 @@ static int add_new_gdb_meta_bg(struct super_block *sb, > > rcu_assign_pointer(EXT4_SB(sb)->s_group_desc, n_group_desc); > EXT4_SB(sb)->s_gdb_count++; > - ext4_kvfree_array_rcu(o_group_desc); > + kvfree_rcu_mightsleep(o_group_desc); > return err; > } > > diff --git a/fs/ext4/super.c b/fs/ext4/super.c > index 87aa23d047c9..34d802848d6d 100644 > --- a/fs/ext4/super.c > +++ b/fs/ext4/super.c > @@ -3108,7 +3108,7 @@ int ext4_alloc_flex_bg_array(struct super_block *sb, ext4_group_t ngroup) > rcu_assign_pointer(sbi->s_flex_groups, new_groups); > sbi->s_flex_groups_allocated = size; > if (old_groups) > - ext4_kvfree_array_rcu(old_groups); > + kvfree_rcu_mightsleep(old_groups); > return 0; > } > > -- > 2.30.2 >
On Fri, Mar 17, 2023 at 05:31:04PM -0700, Paul E. McKenney wrote: > On Fri, Mar 17, 2023 at 08:15:58AM +0100, Uladzislau Rezki (Sony) wrote: > > The ext4_kvfree_array_rcu() function was introduced in order to > > release some memory after a grace period during resizing of a > > partition. An object that is freed does not contain any rcu_head > > filed. > > > > To do so, it requires to allocate some extra memory for a special > > structure that has an rcu_head filed and pointer one where a freed > > memory is attached. Finally call_rcu() API is invoked. > > > > Since we have a single argument of kvfree_rcu() API, we can easily > > replace all that tricky code by one single call that does the same > > but in more efficient way. > > > > Cc: linux-ext4@vger.kernel.org > > Cc: Lukas Czerner <lczerner@redhat.com> > > Cc: Andreas Dilger <adilger.kernel@dilger.ca> > > Signed-off-by: Uladzislau Rezki (Sony) <urezki@gmail.com> > > From an RCU perspective: > > Reviewed-by: Paul E. McKenney <paulmck@kernel.org> > Thank you! -- Uladzislau Rezki
diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h index 140e1eb300d1..e43d1a2d175e 100644 --- a/fs/ext4/ext4.h +++ b/fs/ext4/ext4.h @@ -3057,7 +3057,6 @@ extern int ext4_generic_delete_entry(struct inode *dir, extern bool ext4_empty_dir(struct inode *inode); /* resize.c */ -extern void ext4_kvfree_array_rcu(void *to_free); extern int ext4_group_add(struct super_block *sb, struct ext4_new_group_data *input); extern int ext4_group_extend(struct super_block *sb, diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c index 5b2ae37a8b80..96b4e3317640 100644 --- a/fs/ext4/mballoc.c +++ b/fs/ext4/mballoc.c @@ -3055,7 +3055,7 @@ int ext4_mb_alloc_groupinfo(struct super_block *sb, ext4_group_t ngroups) rcu_assign_pointer(sbi->s_group_info, new_groupinfo); sbi->s_group_info_size = size / sizeof(*sbi->s_group_info); if (old_groupinfo) - ext4_kvfree_array_rcu(old_groupinfo); + kvfree_rcu_mightsleep(old_groupinfo); ext4_debug("allocated s_groupinfo array for %d meta_bg's\n", sbi->s_group_info_size); return 0; diff --git a/fs/ext4/resize.c b/fs/ext4/resize.c index 6b91443d6bf3..330b81f36e10 100644 --- a/fs/ext4/resize.c +++ b/fs/ext4/resize.c @@ -18,33 +18,6 @@ #include "ext4_jbd2.h" -struct ext4_rcu_ptr { - struct rcu_head rcu; - void *ptr; -}; - -static void ext4_rcu_ptr_callback(struct rcu_head *head) -{ - struct ext4_rcu_ptr *ptr; - - ptr = container_of(head, struct ext4_rcu_ptr, rcu); - kvfree(ptr->ptr); - kfree(ptr); -} - -void ext4_kvfree_array_rcu(void *to_free) -{ - struct ext4_rcu_ptr *ptr = kzalloc(sizeof(*ptr), GFP_KERNEL); - - if (ptr) { - ptr->ptr = to_free; - call_rcu(&ptr->rcu, ext4_rcu_ptr_callback); - return; - } - synchronize_rcu(); - kvfree(to_free); -} - int ext4_resize_begin(struct super_block *sb) { struct ext4_sb_info *sbi = EXT4_SB(sb); @@ -931,7 +904,7 @@ static int add_new_gdb(handle_t *handle, struct inode *inode, n_group_desc[gdb_num] = gdb_bh; rcu_assign_pointer(EXT4_SB(sb)->s_group_desc, n_group_desc); EXT4_SB(sb)->s_gdb_count++; - ext4_kvfree_array_rcu(o_group_desc); + kvfree_rcu_mightsleep(o_group_desc); lock_buffer(EXT4_SB(sb)->s_sbh); le16_add_cpu(&es->s_reserved_gdt_blocks, -1); @@ -994,7 +967,7 @@ static int add_new_gdb_meta_bg(struct super_block *sb, rcu_assign_pointer(EXT4_SB(sb)->s_group_desc, n_group_desc); EXT4_SB(sb)->s_gdb_count++; - ext4_kvfree_array_rcu(o_group_desc); + kvfree_rcu_mightsleep(o_group_desc); return err; } diff --git a/fs/ext4/super.c b/fs/ext4/super.c index 87aa23d047c9..34d802848d6d 100644 --- a/fs/ext4/super.c +++ b/fs/ext4/super.c @@ -3108,7 +3108,7 @@ int ext4_alloc_flex_bg_array(struct super_block *sb, ext4_group_t ngroup) rcu_assign_pointer(sbi->s_flex_groups, new_groups); sbi->s_flex_groups_allocated = size; if (old_groups) - ext4_kvfree_array_rcu(old_groups); + kvfree_rcu_mightsleep(old_groups); return 0; }
The ext4_kvfree_array_rcu() function was introduced in order to release some memory after a grace period during resizing of a partition. An object that is freed does not contain any rcu_head filed. To do so, it requires to allocate some extra memory for a special structure that has an rcu_head filed and pointer one where a freed memory is attached. Finally call_rcu() API is invoked. Since we have a single argument of kvfree_rcu() API, we can easily replace all that tricky code by one single call that does the same but in more efficient way. Cc: linux-ext4@vger.kernel.org Cc: Lukas Czerner <lczerner@redhat.com> Cc: Andreas Dilger <adilger.kernel@dilger.ca> Signed-off-by: Uladzislau Rezki (Sony) <urezki@gmail.com> --- fs/ext4/ext4.h | 1 - fs/ext4/mballoc.c | 2 +- fs/ext4/resize.c | 31 ++----------------------------- fs/ext4/super.c | 2 +- 4 files changed, 4 insertions(+), 32 deletions(-)