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Message-ID: <20240823061824.3323522-4-lizetao1@huawei.com>
Date: Fri, 23 Aug 2024 14:18:24 +0800
From: Li Zetao <lizetao1@...wei.com>
To: <tytso@....edu>, <adilger.kernel@...ger.ca>
CC: <lizetao1@...wei.com>, <linux-ext4@...r.kernel.org>
Subject: [PATCH -next 3/3] ext4: Use scoped()/scoped_guard() to drop rcu_read_lock()/unlock pair
A rcu_read_lock() and rcu_read_unlock() pair can be replaced by a
scope-based resource management function scoped(rcu) or scoped_guard(rcu)
which can make the code more readable and safer. In some functions, we
can remove the goto label which will release the lock, and return from
function directly.
Signed-off-by: Li Zetao <lizetao1@...wei.com>
---
fs/ext4/block_validity.c | 27 +++++++++++++--------------
fs/ext4/ext4.h | 3 +--
fs/ext4/inode.c | 3 +--
fs/ext4/mballoc.c | 37 ++++++++++++++++---------------------
fs/ext4/resize.c | 20 ++++++++++----------
fs/ext4/super.c | 26 +++++++++++---------------
6 files changed, 52 insertions(+), 64 deletions(-)
diff --git a/fs/ext4/block_validity.c b/fs/ext4/block_validity.c
index 87ee3a17bd29..962ee95017fd 100644
--- a/fs/ext4/block_validity.c
+++ b/fs/ext4/block_validity.c
@@ -130,17 +130,17 @@ static void debug_print_tree(struct ext4_sb_info *sbi)
int first = 1;
printk(KERN_INFO "System zones: ");
- rcu_read_lock();
- system_blks = rcu_dereference(sbi->s_system_blks);
- node = rb_first(&system_blks->root);
- while (node) {
- entry = rb_entry(node, struct ext4_system_zone, node);
- printk(KERN_CONT "%s%llu-%llu", first ? "" : ", ",
- entry->start_blk, entry->start_blk + entry->count - 1);
- first = 0;
- node = rb_next(node);
+ scoped_guard(rcu) {
+ system_blks = rcu_dereference(sbi->s_system_blks);
+ node = rb_first(&system_blks->root);
+ while (node) {
+ entry = rb_entry(node, struct ext4_system_zone, node);
+ printk(KERN_CONT "%s%llu-%llu", first ? "" : ", ",
+ entry->start_blk, entry->start_blk + entry->count - 1);
+ first = 0;
+ node = rb_next(node);
+ }
}
- rcu_read_unlock();
printk(KERN_CONT "\n");
}
@@ -311,10 +311,10 @@ int ext4_sb_block_valid(struct super_block *sb, struct inode *inode,
* when doing a remount which inverse current "[no]block_validity"
* mount option.
*/
- rcu_read_lock();
+ guard(rcu)();
system_blks = rcu_dereference(sbi->s_system_blks);
if (system_blks == NULL)
- goto out_rcu;
+ return ret;
n = system_blks->root.rb_node;
while (n) {
@@ -330,8 +330,7 @@ int ext4_sb_block_valid(struct super_block *sb, struct inode *inode,
break;
}
}
-out_rcu:
- rcu_read_unlock();
+
return ret;
}
diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
index 92a5e2d29599..13402929c757 100644
--- a/fs/ext4/ext4.h
+++ b/fs/ext4/ext4.h
@@ -1809,9 +1809,8 @@ static inline int ext4_valid_inum(struct super_block *sb, unsigned long ino)
#define sbi_array_rcu_deref(sbi, field, index) \
({ \
typeof(*((sbi)->field)) _v; \
- rcu_read_lock(); \
+ guard(rcu)(); \
_v = ((typeof(_v)*)rcu_dereference((sbi)->field))[index]; \
- rcu_read_unlock(); \
_v; \
})
diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index 2c978d8ff3ba..1172b43dcc18 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -5099,14 +5099,13 @@ static void ext4_update_other_inodes_time(struct super_block *sb,
* (assuming 4k blocks and 256 byte inodes) is (n*16 + 1).
*/
ino = ((orig_ino - 1) & ~(inodes_per_block - 1)) + 1;
- rcu_read_lock();
+ guard(rcu)();
for (i = 0; i < inodes_per_block; i++, ino++, buf += inode_size) {
if (ino == orig_ino)
continue;
__ext4_update_other_inode_time(sb, orig_ino, ino,
(struct ext4_inode *)buf);
}
- rcu_read_unlock();
}
/*
diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c
index e9bc4056ea94..905752a396c1 100644
--- a/fs/ext4/mballoc.c
+++ b/fs/ext4/mballoc.c
@@ -3291,12 +3291,12 @@ int ext4_mb_alloc_groupinfo(struct super_block *sb, ext4_group_t ngroups)
ext4_msg(sb, KERN_ERR, "can't allocate buddy meta group");
return -ENOMEM;
}
- rcu_read_lock();
- old_groupinfo = rcu_dereference(sbi->s_group_info);
- if (old_groupinfo)
- memcpy(new_groupinfo, old_groupinfo,
- sbi->s_group_info_size * sizeof(*sbi->s_group_info));
- rcu_read_unlock();
+ scoped_guard(rcu) {
+ old_groupinfo = rcu_dereference(sbi->s_group_info);
+ if (old_groupinfo)
+ memcpy(new_groupinfo, old_groupinfo,
+ sbi->s_group_info_size * sizeof(*sbi->s_group_info));
+ }
rcu_assign_pointer(sbi->s_group_info, new_groupinfo);
sbi->s_group_info_size = size / sizeof(*sbi->s_group_info);
if (old_groupinfo)
@@ -3331,9 +3331,8 @@ int ext4_mb_add_groupinfo(struct super_block *sb, ext4_group_t group,
"for a buddy group");
return -ENOMEM;
}
- rcu_read_lock();
+ guard(rcu)();
rcu_dereference(sbi->s_group_info)[idx] = meta_group_info;
- rcu_read_unlock();
}
meta_group_info = sbi_array_rcu_deref(sbi, s_group_info, idx);
@@ -3377,11 +3376,10 @@ int ext4_mb_add_groupinfo(struct super_block *sb, ext4_group_t group,
if (group % EXT4_DESC_PER_BLOCK(sb) == 0) {
struct ext4_group_info ***group_info;
- rcu_read_lock();
+ guard(rcu)();
group_info = rcu_dereference(sbi->s_group_info);
kfree(group_info[idx]);
group_info[idx] = NULL;
- rcu_read_unlock();
}
return -ENOMEM;
} /* ext4_mb_add_groupinfo */
@@ -3462,16 +3460,15 @@ static int ext4_mb_init_backend(struct super_block *sb)
kmem_cache_free(cachep, grp);
}
i = sbi->s_group_info_size;
- rcu_read_lock();
- group_info = rcu_dereference(sbi->s_group_info);
- while (i-- > 0)
- kfree(group_info[i]);
- rcu_read_unlock();
+ scoped_guard(rcu) {
+ group_info = rcu_dereference(sbi->s_group_info);
+ while (i-- > 0)
+ kfree(group_info[i]);
+ }
iput(sbi->s_buddy_cache);
err_freesgi:
- rcu_read_lock();
+ guard(rcu)();
kvfree(rcu_dereference(sbi->s_group_info));
- rcu_read_unlock();
return -ENOMEM;
}
@@ -3789,12 +3786,11 @@ void ext4_mb_release(struct super_block *sb)
num_meta_group_infos = (ngroups +
EXT4_DESC_PER_BLOCK(sb) - 1) >>
EXT4_DESC_PER_BLOCK_BITS(sb);
- rcu_read_lock();
+ guard(rcu)();
group_info = rcu_dereference(sbi->s_group_info);
for (i = 0; i < num_meta_group_infos; i++)
kfree(group_info[i]);
kvfree(group_info);
- rcu_read_unlock();
}
kfree(sbi->s_mb_avg_fragment_size);
kfree(sbi->s_mb_avg_fragment_size_locks);
@@ -4946,7 +4942,7 @@ ext4_mb_use_preallocated(struct ext4_allocation_context *ac)
* minimal distance from the goal block.
*/
for (i = order; i < PREALLOC_TB_SIZE; i++) {
- rcu_read_lock();
+ guard(rcu)();
list_for_each_entry_rcu(tmp_pa, &lg->lg_prealloc_list[i],
pa_node.lg_list) {
spin_lock(&tmp_pa->pa_lock);
@@ -4958,7 +4954,6 @@ ext4_mb_use_preallocated(struct ext4_allocation_context *ac)
}
spin_unlock(&tmp_pa->pa_lock);
}
- rcu_read_unlock();
}
if (cpa) {
ext4_mb_use_group_pa(ac, cpa);
diff --git a/fs/ext4/resize.c b/fs/ext4/resize.c
index 0ba9837d65ca..a72e0b1f6435 100644
--- a/fs/ext4/resize.c
+++ b/fs/ext4/resize.c
@@ -920,11 +920,11 @@ static int add_new_gdb(handle_t *handle, struct inode *inode,
}
brelse(dind);
- rcu_read_lock();
- o_group_desc = rcu_dereference(EXT4_SB(sb)->s_group_desc);
- memcpy(n_group_desc, o_group_desc,
- EXT4_SB(sb)->s_gdb_count * sizeof(struct buffer_head *));
- rcu_read_unlock();
+ scoped_guard(rcu) {
+ o_group_desc = rcu_dereference(EXT4_SB(sb)->s_group_desc);
+ memcpy(n_group_desc, o_group_desc,
+ EXT4_SB(sb)->s_gdb_count * sizeof(struct buffer_head *));
+ }
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++;
@@ -980,11 +980,11 @@ static int add_new_gdb_meta_bg(struct super_block *sb,
return err;
}
- rcu_read_lock();
- o_group_desc = rcu_dereference(EXT4_SB(sb)->s_group_desc);
- memcpy(n_group_desc, o_group_desc,
- EXT4_SB(sb)->s_gdb_count * sizeof(struct buffer_head *));
- rcu_read_unlock();
+ scoped_guard(rcu) {
+ o_group_desc = rcu_dereference(EXT4_SB(sb)->s_group_desc);
+ memcpy(n_group_desc, o_group_desc,
+ EXT4_SB(sb)->s_gdb_count * sizeof(struct buffer_head *));
+ }
n_group_desc[gdb_num] = gdb_bh;
BUFFER_TRACE(gdb_bh, "get_write_access");
diff --git a/fs/ext4/super.c b/fs/ext4/super.c
index 5ae7bc36eb78..4826b1689c53 100644
--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -1249,12 +1249,11 @@ static void ext4_group_desc_free(struct ext4_sb_info *sbi)
struct buffer_head **group_desc;
int i;
- rcu_read_lock();
+ guard(rcu)();
group_desc = rcu_dereference(sbi->s_group_desc);
for (i = 0; i < sbi->s_gdb_count; i++)
brelse(group_desc[i]);
kvfree(group_desc);
- rcu_read_unlock();
}
static void ext4_flex_groups_free(struct ext4_sb_info *sbi)
@@ -1262,14 +1261,13 @@ static void ext4_flex_groups_free(struct ext4_sb_info *sbi)
struct flex_groups **flex_groups;
int i;
- rcu_read_lock();
+ guard(rcu)();
flex_groups = rcu_dereference(sbi->s_flex_groups);
if (flex_groups) {
for (i = 0; i < sbi->s_flex_groups_allocated; i++)
kvfree(flex_groups[i]);
kvfree(flex_groups);
}
- rcu_read_unlock();
}
static void ext4_put_super(struct super_block *sb)
@@ -2892,14 +2890,13 @@ static inline void ext4_show_quota_options(struct seq_file *seq,
seq_printf(seq, ",jqfmt=%s", fmtname);
}
- rcu_read_lock();
+ guard(rcu)();
usr_qf_name = rcu_dereference(sbi->s_qf_names[USRQUOTA]);
grp_qf_name = rcu_dereference(sbi->s_qf_names[GRPQUOTA]);
if (usr_qf_name)
seq_show_option(seq, "usrjquota", usr_qf_name);
if (grp_qf_name)
seq_show_option(seq, "grpjquota", grp_qf_name);
- rcu_read_unlock();
#endif
}
@@ -3140,13 +3137,13 @@ int ext4_alloc_flex_bg_array(struct super_block *sb, ext4_group_t ngroup)
return -ENOMEM;
}
}
- rcu_read_lock();
- old_groups = rcu_dereference(sbi->s_flex_groups);
- if (old_groups)
- memcpy(new_groups, old_groups,
- (sbi->s_flex_groups_allocated *
- sizeof(struct flex_groups *)));
- rcu_read_unlock();
+ scoped_guard(rcu) {
+ old_groups = rcu_dereference(sbi->s_flex_groups);
+ if (old_groups)
+ memcpy(new_groups, old_groups,
+ (sbi->s_flex_groups_allocated *
+ sizeof(struct flex_groups *)));
+ }
rcu_assign_pointer(sbi->s_flex_groups, new_groups);
sbi->s_flex_groups_allocated = size;
if (old_groups)
@@ -4851,9 +4848,8 @@ static int ext4_group_desc_init(struct super_block *sb,
sbi->s_gdb_count = i;
return PTR_ERR(bh);
}
- rcu_read_lock();
+ guard(rcu)();
rcu_dereference(sbi->s_group_desc)[i] = bh;
- rcu_read_unlock();
}
sbi->s_gdb_count = db_count;
if (!ext4_check_descriptors(sb, logical_sb_block, first_not_zeroed)) {
--
2.34.1
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