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[94.245.46.61]) by smtp.gmail.com with ESMTPSA id v8sm464263lfq.177.2021.12.15.11.40.26 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 15 Dec 2021 11:40:27 -0800 (PST) From: Uladzislau Rezki X-Google-Original-From: Uladzislau Rezki Date: Wed, 15 Dec 2021 20:40:25 +0100 To: Theodore Ts'o , linux-ext4@vger.kernel.org Cc: LKML , RCU , "Paul E . McKenney" , Michal Hocko , Andrew Morton , Daniel Axtens , Frederic Weisbecker , Neeraj Upadhyay , Joel Fernandes , Peter Zijlstra , Thomas Gleixner , "Theodore Y . Ts'o" , Sebastian Andrzej Siewior , Oleksiy Avramchenko Subject: Re: [PATCH RESEND] ext4: Replace ext4_kvfree_array_rcu() by kvfree_rcu() API Message-ID: References: <20211215111845.2514-1-urezki@gmail.com> <20211215111845.2514-2-urezki@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20211215111845.2514-2-urezki@gmail.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Dec 15, 2021 at 12:18:38PM +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. > > TO: "Theodore Ts'o" > TO: linux-ext4@vger.kernel.org > Signed-off-by: Uladzislau Rezki (Sony) > --- > 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 404dd50856e5..7e8ff3ac2beb 100644 > --- a/fs/ext4/ext4.h > +++ b/fs/ext4/ext4.h > @@ -3089,7 +3089,6 @@ 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 215b7068f548..b0469f7a5c55 100644 > --- a/fs/ext4/mballoc.c > +++ b/fs/ext4/mballoc.c > @@ -3109,7 +3109,7 @@ 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(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 b63cb88ccdae..ac6aa037aaab 100644 > --- a/fs/ext4/resize.c > +++ b/fs/ext4/resize.c > @@ -17,33 +17,6 @@ > > #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); > @@ -906,7 +879,7 @@ 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(o_group_desc); > > lock_buffer(EXT4_SB(sb)->s_sbh); > le16_add_cpu(&es->s_reserved_gdt_blocks, -1); > @@ -969,7 +942,7 @@ 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(o_group_desc); > return err; > } > > diff --git a/fs/ext4/super.c b/fs/ext4/super.c > index 111b0498a232..3942cd271a00 100644 > --- a/fs/ext4/super.c > +++ b/fs/ext4/super.c > @@ -2759,7 +2759,7 @@ 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(old_groups); > return 0; > } > > -- > 2.30.2 > + "Theodore Ts'o" + linux-ext4@vger.kernel.org -- Vlad Rezki