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Subject[PATCH RESEND] ext4: Replace ext4_kvfree_array_rcu() by kvfree_rcu() API
Date
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" <tytso@mit.edu>
TO: linux-ext4@vger.kernel.org
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(-)

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
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