| Message ID | 6957a4896cc64a1ff44b712bb6723ada016d76b9.1497544265.git.dsterba@suse.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On 06/16/2017 12:49 AM, David Sterba wrote: > Add per-filesystem tunable to switch on/off the device barriers, > regardless of the actual device support. This is a debugging feature. > > The path to the sysfs file is /sys/fs/btrfs/UUID/force_dev_flush, > allowed values are 0 and 1. Default is 0. Anyway the flush command won't touch the device if its write through. So unless I am missing something, IMO we don't need something like this. ------------------- generic_make_request_checks(struct bio *bio) :: /* * Filter flush bio's early so that make_request based * drivers without flush support don't have to worry * about them. */ if (op_is_flush(bio->bi_opf) && !test_bit(QUEUE_FLAG_WC, &q->queue_flags)) { bio->bi_opf &= ~(REQ_PREFLUSH | REQ_FUA); if (!nr_sectors) { err = 0; goto end_io; } } ------------------- Thanks, Anand > Signed-off-by: David Sterba <dsterba@suse.com> > --- > fs/btrfs/sysfs.c | 47 +++++++++++++++++++++++++++++++++++++++++++++++ > 1 file changed, 47 insertions(+) > > diff --git a/fs/btrfs/sysfs.c b/fs/btrfs/sysfs.c > index c2d5f3580b4c..197d43911936 100644 > --- a/fs/btrfs/sysfs.c > +++ b/fs/btrfs/sysfs.c > @@ -487,12 +487,59 @@ static ssize_t quota_override_store(struct kobject *kobj, > > BTRFS_ATTR_RW(quota_override, quota_override_show, quota_override_store); > > +static ssize_t force_dev_flush_show(struct kobject *kobj, > + struct kobj_attribute *a, char *buf) > +{ > + struct btrfs_fs_info *fs_info = to_fs_info(kobj); > + int force; > + > + if (!fs_info) > + return -EPERM; > + > + force = !!(test_bit(BTRFS_FS_FORCE_DEV_FLUSH, &fs_info->flags)); > + return snprintf(buf, PAGE_SIZE, "%d\n", force); > +} > + > +static ssize_t force_dev_flush_store(struct kobject *kobj, > + struct kobj_attribute *a, > + const char *buf, size_t len) > +{ > + struct btrfs_fs_info *fs_info = to_fs_info(kobj); > + unsigned long force; > + int err; > + > + if (!fs_info) > + return -EPERM; > + > + if (!capable(CAP_SYS_ADMIN)) > + return -EPERM; > + > + err = kstrtoul(buf, 10, &force); > + if (err) > + return err; > + if (force > 1) > + return -EINVAL; > + > + if (force) { > + set_bit(BTRFS_FS_FORCE_DEV_FLUSH, &fs_info->flags); > + btrfs_info(fs_info, "Forced device flushes enabled"); > + } else { > + clear_bit(BTRFS_FS_FORCE_DEV_FLUSH, &fs_info->flags); > + btrfs_info(fs_info, "Forced device flushes disabled"); > + } > + > + return len; > +} > + > +BTRFS_ATTR_RW(force_dev_flush, force_dev_flush_show, force_dev_flush_store); > + > static const struct attribute *btrfs_attrs[] = { > BTRFS_ATTR_PTR(label), > BTRFS_ATTR_PTR(nodesize), > BTRFS_ATTR_PTR(sectorsize), > BTRFS_ATTR_PTR(clone_alignment), > BTRFS_ATTR_PTR(quota_override), > + BTRFS_ATTR_PTR(force_dev_flush), > NULL, > }; > > -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/fs/btrfs/sysfs.c b/fs/btrfs/sysfs.c index c2d5f3580b4c..197d43911936 100644 --- a/fs/btrfs/sysfs.c +++ b/fs/btrfs/sysfs.c @@ -487,12 +487,59 @@ static ssize_t quota_override_store(struct kobject *kobj, BTRFS_ATTR_RW(quota_override, quota_override_show, quota_override_store); +static ssize_t force_dev_flush_show(struct kobject *kobj, + struct kobj_attribute *a, char *buf) +{ + struct btrfs_fs_info *fs_info = to_fs_info(kobj); + int force; + + if (!fs_info) + return -EPERM; + + force = !!(test_bit(BTRFS_FS_FORCE_DEV_FLUSH, &fs_info->flags)); + return snprintf(buf, PAGE_SIZE, "%d\n", force); +} + +static ssize_t force_dev_flush_store(struct kobject *kobj, + struct kobj_attribute *a, + const char *buf, size_t len) +{ + struct btrfs_fs_info *fs_info = to_fs_info(kobj); + unsigned long force; + int err; + + if (!fs_info) + return -EPERM; + + if (!capable(CAP_SYS_ADMIN)) + return -EPERM; + + err = kstrtoul(buf, 10, &force); + if (err) + return err; + if (force > 1) + return -EINVAL; + + if (force) { + set_bit(BTRFS_FS_FORCE_DEV_FLUSH, &fs_info->flags); + btrfs_info(fs_info, "Forced device flushes enabled"); + } else { + clear_bit(BTRFS_FS_FORCE_DEV_FLUSH, &fs_info->flags); + btrfs_info(fs_info, "Forced device flushes disabled"); + } + + return len; +} + +BTRFS_ATTR_RW(force_dev_flush, force_dev_flush_show, force_dev_flush_store); + static const struct attribute *btrfs_attrs[] = { BTRFS_ATTR_PTR(label), BTRFS_ATTR_PTR(nodesize), BTRFS_ATTR_PTR(sectorsize), BTRFS_ATTR_PTR(clone_alignment), BTRFS_ATTR_PTR(quota_override), + BTRFS_ATTR_PTR(force_dev_flush), NULL, };
Add per-filesystem tunable to switch on/off the device barriers, regardless of the actual device support. This is a debugging feature. The path to the sysfs file is /sys/fs/btrfs/UUID/force_dev_flush, allowed values are 0 and 1. Default is 0. Signed-off-by: David Sterba <dsterba@suse.com> --- fs/btrfs/sysfs.c | 47 +++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 47 insertions(+)