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| author | Naohiro Aota <naohiro.aota@wdc.com> | 2024-02-02 13:23:28 +0900 |
|---|---|---|
| committer | David Sterba <dsterba@suse.com> | 2024-03-04 16:24:47 +0100 |
| commit | 4dc4a3be6cc4ef0a04785124afb0bd4fd06298ff (patch) | |
| tree | 025f6217aab3402a67451979fb1d9466d0a873d8 /fs/btrfs/sysfs.c | |
| parent | e383e158ed1b6abc2d2d3e6736d77a46393f80fa (diff) | |
| download | linux-4dc4a3be6cc4ef0a04785124afb0bd4fd06298ff.tar.gz linux-4dc4a3be6cc4ef0a04785124afb0bd4fd06298ff.tar.bz2 linux-4dc4a3be6cc4ef0a04785124afb0bd4fd06298ff.zip | |
btrfs: use READ/WRITE_ONCE for fs_devices->read_policy
Since we can read/modify the value from the sysfs interface concurrently,
it would be better to protect it from compiler optimizations.
Currently, there is only one read policy BTRFS_READ_POLICY_PID available,
so no actual problem can happen now. This is a preparation for the future
expansion.
Reviewed-by: Anand Jain <anand.jain@oracle.com>
Signed-off-by: Naohiro Aota <naohiro.aota@wdc.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Diffstat (limited to 'fs/btrfs/sysfs.c')
| -rw-r--r-- | fs/btrfs/sysfs.c | 7 |
1 files changed, 4 insertions, 3 deletions
diff --git a/fs/btrfs/sysfs.c b/fs/btrfs/sysfs.c index 84c05246ffd8..21586ecc35bf 100644 --- a/fs/btrfs/sysfs.c +++ b/fs/btrfs/sysfs.c @@ -1228,11 +1228,12 @@ static ssize_t btrfs_read_policy_show(struct kobject *kobj, struct kobj_attribute *a, char *buf) { struct btrfs_fs_devices *fs_devices = to_fs_devs(kobj); + const enum btrfs_read_policy policy = READ_ONCE(fs_devices->read_policy); ssize_t ret = 0; int i; for (i = 0; i < BTRFS_NR_READ_POLICY; i++) { - if (fs_devices->read_policy == i) + if (policy == i) ret += sysfs_emit_at(buf, ret, "%s[%s]", (ret == 0 ? "" : " "), btrfs_read_policy_name[i]); @@ -1256,8 +1257,8 @@ static ssize_t btrfs_read_policy_store(struct kobject *kobj, for (i = 0; i < BTRFS_NR_READ_POLICY; i++) { if (sysfs_streq(buf, btrfs_read_policy_name[i])) { - if (i != fs_devices->read_policy) { - fs_devices->read_policy = i; + if (i != READ_ONCE(fs_devices->read_policy)) { + WRITE_ONCE(fs_devices->read_policy, i); btrfs_info(fs_devices->fs_info, "read policy set to '%s'", btrfs_read_policy_name[i]); |