From 3d8cc17a0561dc4c037ede4886d7975009075d6d Mon Sep 17 00:00:00 2001 From: Anand Jain Date: Wed, 28 Oct 2020 21:14:47 +0800 Subject: [PATCH] btrfs: sysfs: add per-fs attribute for read policy Add /sys/fs/btrfs/UUID/read_policy attribute so that the read policy for the raid1, raid1c34 and raid10 can be tuned. When this attribute is read, it will show all available policies, with active policy in [ ]. The read_policy attribute can be written using one of the items listed in there. For example: $ cat /sys/fs/btrfs/UUID/read_policy [pid] $ echo pid > /sys/fs/btrfs/UUID/read_policy Reviewed-by: Josef Bacik Signed-off-by: Anand Jain Reviewed-by: David Sterba Signed-off-by: David Sterba --- fs/btrfs/sysfs.c | 49 +++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 49 insertions(+) diff --git a/fs/btrfs/sysfs.c b/fs/btrfs/sysfs.c index b2f653e..620fddf 100644 --- a/fs/btrfs/sysfs.c +++ b/fs/btrfs/sysfs.c @@ -907,6 +907,54 @@ static bool strmatch(const char *buffer, const char *string) return false; } +static const char * const btrfs_read_policy_name[] = { "pid" }; + +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); + ssize_t ret = 0; + int i; + + for (i = 0; i < BTRFS_NR_READ_POLICY; i++) { + if (fs_devices->read_policy == i) + ret += scnprintf(buf + ret, PAGE_SIZE - ret, "%s[%s]", + (ret == 0 ? "" : " "), + btrfs_read_policy_name[i]); + else + ret += scnprintf(buf + ret, PAGE_SIZE - ret, "%s%s", + (ret == 0 ? "" : " "), + btrfs_read_policy_name[i]); + } + + ret += scnprintf(buf + ret, PAGE_SIZE - ret, "\n"); + + return ret; +} + +static ssize_t btrfs_read_policy_store(struct kobject *kobj, + struct kobj_attribute *a, + const char *buf, size_t len) +{ + struct btrfs_fs_devices *fs_devices = to_fs_devs(kobj); + int i; + + for (i = 0; i < BTRFS_NR_READ_POLICY; i++) { + if (strmatch(buf, btrfs_read_policy_name[i])) { + if (i != fs_devices->read_policy) { + fs_devices->read_policy = i; + btrfs_info(fs_devices->fs_info, + "read policy set to '%s'", + btrfs_read_policy_name[i]); + } + return len; + } + } + + return -EINVAL; +} +BTRFS_ATTR_RW(, read_policy, btrfs_read_policy_show, btrfs_read_policy_store); + static const struct attribute *btrfs_attrs[] = { BTRFS_ATTR_PTR(, label), BTRFS_ATTR_PTR(, nodesize), @@ -917,6 +965,7 @@ static const struct attribute *btrfs_attrs[] = { BTRFS_ATTR_PTR(, checksum), BTRFS_ATTR_PTR(, exclusive_operation), BTRFS_ATTR_PTR(, generation), + BTRFS_ATTR_PTR(, read_policy), NULL, }; -- 2.7.4