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btrfs: kill the RCU protection for fs_info->space_info 

We have this thing wrapped in an RCU lock, but it's really not needed.
We create all the space_info's on mount, and we destroy them on unmount.
The list never changes and we're protected from messing with it by the
normal mount/umount path, so kill the RCU stuff around it.

Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
This commit is contained in:
Josef Bacik 2020-09-01 17:40:37 -04:00 committed by David Sterba
parent 7269ddd2f6
commit 7280490500
4 changed files with 9 additions and 36 deletions
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16
fs/btrfs/block-group.c
View File

@ -2031,8 +2031,7 @@ int btrfs_read_block_groups(struct btrfs_fs_info *info)
btrfs_release_path(path);
}
rcu_read_lock();
list_for_each_entry_rcu(space_info, &info->space_info, list) {
list_for_each_entry(space_info, &info->space_info, list) {
if (!(btrfs_get_alloc_profile(info, space_info->flags) &
(BTRFS_BLOCK_GROUP_RAID10 |
BTRFS_BLOCK_GROUP_RAID1_MASK |
@ -2052,7 +2051,6 @@ int btrfs_read_block_groups(struct btrfs_fs_info *info)
list)
inc_block_group_ro(cache, 1);
}
rcu_read_unlock();
btrfs_init_global_block_rsv(info);
ret = check_chunk_block_group_mappings(info);
@ -3007,12 +3005,10 @@ static void force_metadata_allocation(struct btrfs_fs_info *info)
struct list_head *head = &info->space_info;
struct btrfs_space_info *found;
rcu_read_lock();
list_for_each_entry_rcu(found, head, list) {
list_for_each_entry(found, head, list) {
if (found->flags & BTRFS_BLOCK_GROUP_METADATA)
found->force_alloc = CHUNK_ALLOC_FORCE;
}
rcu_read_unlock();
}
static int should_alloc_chunk(struct btrfs_fs_info *fs_info,
@ -3343,14 +3339,6 @@ int btrfs_free_block_groups(struct btrfs_fs_info *info)
}
spin_unlock(&info->block_group_cache_lock);
/*
* Now that all the block groups are freed, go through and free all the
* space_info structs. This is only called during the final stages of
* unmount, and so we know nobody is using them. We call
* synchronize_rcu() once before we start, just to be on the safe side.
*/
synchronize_rcu();
btrfs_release_global_block_rsv(info);
while (!list_empty(&info->space_info)) {

10
fs/btrfs/ioctl.c
View File

@ -3475,15 +3475,12 @@ static long btrfs_ioctl_space_info(struct btrfs_fs_info *fs_info,
struct btrfs_space_info *tmp;
info = NULL;
rcu_read_lock();
list_for_each_entry_rcu(tmp, &fs_info->space_info,
list) {
list_for_each_entry(tmp, &fs_info->space_info, list) {
if (tmp->flags == types[i]) {
info = tmp;
break;
}
}
rcu_read_unlock();
if (!info)
continue;
@ -3531,15 +3528,12 @@ static long btrfs_ioctl_space_info(struct btrfs_fs_info *fs_info,
break;
info = NULL;
rcu_read_lock();
list_for_each_entry_rcu(tmp, &fs_info->space_info,
list) {
list_for_each_entry(tmp, &fs_info->space_info, list) {
if (tmp->flags == types[i]) {
info = tmp;
break;
}
}
rcu_read_unlock();
if (!info)
continue;

14
fs/btrfs/space-info.c
View File

@ -175,10 +175,8 @@ void btrfs_clear_space_info_full(struct btrfs_fs_info *info)
struct list_head *head = &info->space_info;
struct btrfs_space_info *found;
rcu_read_lock();
list_for_each_entry_rcu(found, head, list)
list_for_each_entry(found, head, list)
found->full = 0;
rcu_read_unlock();
}
static int create_space_info(struct btrfs_fs_info *info, u64 flags)
@ -213,7 +211,7 @@ static int create_space_info(struct btrfs_fs_info *info, u64 flags)
if (ret)
return ret;
list_add_rcu(&space_info->list, &info->space_info);
list_add(&space_info->list, &info->space_info);
if (flags & BTRFS_BLOCK_GROUP_DATA)
info->data_sinfo = space_info;
@ -290,14 +288,10 @@ struct btrfs_space_info *btrfs_find_space_info(struct btrfs_fs_info *info,
flags &= BTRFS_BLOCK_GROUP_TYPE_MASK;
rcu_read_lock();
list_for_each_entry_rcu(found, head, list) {
if (found->flags & flags) {
rcu_read_unlock();
list_for_each_entry(found, head, list) {
if (found->flags & flags)
return found;
}
}
rcu_read_unlock();
return NULL;
}

5
fs/btrfs/super.c
View File

@ -2164,8 +2164,7 @@ static int btrfs_statfs(struct dentry *dentry, struct kstatfs *buf)
u64 thresh = 0;
int mixed = 0;
rcu_read_lock();
list_for_each_entry_rcu(found, &fs_info->space_info, list) {
list_for_each_entry(found, &fs_info->space_info, list) {
if (found->flags & BTRFS_BLOCK_GROUP_DATA) {
int i;
@ -2194,8 +2193,6 @@ static int btrfs_statfs(struct dentry *dentry, struct kstatfs *buf)
total_used += found->disk_used;
}
rcu_read_unlock();
buf->f_blocks = div_u64(btrfs_super_total_bytes(disk_super), factor);
buf->f_blocks >>= bits;
buf->f_bfree = buf->f_blocks - (div_u64(total_used, factor) >> bits);