md: support updating bitmap parameters via sysfs.

A new attribute directory 'bitmap' in 'md' is created which
contains files for configuring the bitmap.
'location' identifies where the bitmap is, either 'none',
or 'file' or 'sector offset from metadata'.
Writing 'location' can create or remove a bitmap.
Adding a 'file' bitmap this way is not yet supported.
'chunksize' and 'time_base' must be set before 'location'
can be set.

'chunksize' can be set before creating a bitmap, but is
currently always over-ridden by the bitmap superblock.

'time_base' and 'backlog' can be updated at any time.


Signed-off-by: NeilBrown <neilb@suse.de>
Reviewed-by: Andre Noll <maan@systemlinux.org>

1 files changed, 205 insertions, 0 deletions

diff --git a/drivers/md/bitmap.c b/drivers/md/bitmap.c
index 958865445f06..24fff75b2191 100644
--- a/drivers/md/bitmap.c
+++ b/drivers/md/bitmap.c
@@ -510,6 +510,9 @@ void bitmap_update_sb(struct bitmap *bitmap)
                 bitmap->events_cleared = bitmap->mddev->events;
                 sb->events_cleared = cpu_to_le64(bitmap->events_cleared);
         }
+        /* Just in case these have been changed via sysfs: */
+        sb->daemon_sleep = cpu_to_le32(bitmap->mddev->bitmap_info.daemon_sleep/HZ);
+        sb->write_behind = cpu_to_le32(bitmap->mddev->bitmap_info.max_write_behind);
         kunmap_atomic(sb, KM_USER0);
         write_page(bitmap, bitmap->sb_page, 1);
 }
@@ -1714,6 +1717,208 @@ int bitmap_create(mddev_t *mddev)
         return err;
 }
 
+static ssize_t
+location_show(mddev_t *mddev, char *page)
+{
+        ssize_t len;
+        if (mddev->bitmap_info.file) {
+                len = sprintf(page, "file");
+        } else if (mddev->bitmap_info.offset) {
+                len = sprintf(page, "%+lld", (long long)mddev->bitmap_info.offset);
+        } else
+                len = sprintf(page, "none");
+        len += sprintf(page+len, "\n");
+        return len;
+}
+
+static ssize_t
+location_store(mddev_t *mddev, const char *buf, size_t len)
+{
+
+        if (mddev->pers) {
+                if (!mddev->pers->quiesce)
+                        return -EBUSY;
+                if (mddev->recovery || mddev->sync_thread)
+                        return -EBUSY;
+        }
+
+        if (mddev->bitmap || mddev->bitmap_info.file ||
+            mddev->bitmap_info.offset) {
+                /* bitmap already configured.  Only option is to clear it */
+                if (strncmp(buf, "none", 4) != 0)
+                        return -EBUSY;
+                if (mddev->pers) {
+                        mddev->pers->quiesce(mddev, 1);
+                        bitmap_destroy(mddev);
+                        mddev->pers->quiesce(mddev, 0);
+                }
+                mddev->bitmap_info.offset = 0;
+                if (mddev->bitmap_info.file) {
+                        struct file *f = mddev->bitmap_info.file;
+                        mddev->bitmap_info.file = NULL;
+                        restore_bitmap_write_access(f);
+                        fput(f);
+                }
+        } else {
+                /* No bitmap, OK to set a location */
+                long long offset;
+                if (strncmp(buf, "none", 4) == 0)
+                        /* nothing to be done */;
+                else if (strncmp(buf, "file:", 5) == 0) {
+                        /* Not supported yet */
+                        return -EINVAL;
+                } else {
+                        int rv;
+                        if (buf[0] == '+')
+                                rv = strict_strtoll(buf+1, 10, &offset);
+                        else
+                                rv = strict_strtoll(buf, 10, &offset);
+                        if (rv)
+                                return rv;
+                        if (offset == 0)
+                                return -EINVAL;
+                        if (mddev->major_version == 0 &&
+                            offset != mddev->bitmap_info.default_offset)
+                                return -EINVAL;
+                        mddev->bitmap_info.offset = offset;
+                        if (mddev->pers) {
+                                mddev->pers->quiesce(mddev, 1);
+                                rv = bitmap_create(mddev);
+                                if (rv) {
+                                        bitmap_destroy(mddev);
+                                        mddev->bitmap_info.offset = 0;
+                                }
+                                mddev->pers->quiesce(mddev, 0);
+                                if (rv)
+                                        return rv;
+                        }
+                }
+        }
+        if (!mddev->external) {
+                /* Ensure new bitmap info is stored in
+                 * metadata promptly.
+                 */
+                set_bit(MD_CHANGE_DEVS, &mddev->flags);
+                md_wakeup_thread(mddev->thread);
+        }
+        return len;
+}
+
+static struct md_sysfs_entry bitmap_location =
+__ATTR(location, S_IRUGO|S_IWUSR, location_show, location_store);
+
+static ssize_t
+timeout_show(mddev_t *mddev, char *page)
+{
+        ssize_t len;
+        unsigned long secs = mddev->bitmap_info.daemon_sleep / HZ;
+        unsigned long jifs = mddev->bitmap_info.daemon_sleep % HZ;
+        
+        len = sprintf(page, "%lu", secs);
+        if (jifs)
+                len += sprintf(page+len, ".%03u", jiffies_to_msecs(jifs));
+        len += sprintf(page+len, "\n");
+        return len;
+}
+
+static ssize_t
+timeout_store(mddev_t *mddev, const char *buf, size_t len)
+{
+        /* timeout can be set at any time */
+        unsigned long timeout;
+        int rv = strict_strtoul_scaled(buf, &timeout, 4);
+        if (rv)
+                return rv;
+
+        /* just to make sure we don't overflow... */
+        if (timeout >= LONG_MAX / HZ)
+                return -EINVAL;
+
+        timeout = timeout * HZ / 10000;
+
+        if (timeout >= MAX_SCHEDULE_TIMEOUT)
+                timeout = MAX_SCHEDULE_TIMEOUT-1;
+        if (timeout < 1)
+                timeout = 1;
+        mddev->bitmap_info.daemon_sleep = timeout;
+        if (mddev->thread) {
+                /* if thread->timeout is MAX_SCHEDULE_TIMEOUT, then
+                 * the bitmap is all clean and we don't need to
+                 * adjust the timeout right now
+                 */
+                if (mddev->thread->timeout < MAX_SCHEDULE_TIMEOUT) {
+                        mddev->thread->timeout = timeout;
+                        md_wakeup_thread(mddev->thread);
+                }
+        }
+        return len;
+}
+
+static struct md_sysfs_entry bitmap_timeout =
+__ATTR(time_base, S_IRUGO|S_IWUSR, timeout_show, timeout_store);
+
+static ssize_t
+backlog_show(mddev_t *mddev, char *page)
+{
+        return sprintf(page, "%lu\n", mddev->bitmap_info.max_write_behind);
+}
+
+static ssize_t
+backlog_store(mddev_t *mddev, const char *buf, size_t len)
+{
+        unsigned long backlog;
+        int rv = strict_strtoul(buf, 10, &backlog);
+        if (rv)
+                return rv;
+        if (backlog > COUNTER_MAX)
+                return -EINVAL;
+        mddev->bitmap_info.max_write_behind = backlog;
+        return len;
+}
+
+static struct md_sysfs_entry bitmap_backlog =
+__ATTR(backlog, S_IRUGO|S_IWUSR, backlog_show, backlog_store);
+
+static ssize_t
+chunksize_show(mddev_t *mddev, char *page)
+{
+        return sprintf(page, "%lu\n", mddev->bitmap_info.chunksize);
+}
+
+static ssize_t
+chunksize_store(mddev_t *mddev, const char *buf, size_t len)
+{
+        /* Can only be changed when no bitmap is active */
+        int rv;
+        unsigned long csize;
+        if (mddev->bitmap)
+                return -EBUSY;
+        rv = strict_strtoul(buf, 10, &csize);
+        if (rv)
+                return rv;
+        if (csize < 512 ||
+            !is_power_of_2(csize))
+                return -EINVAL;
+        mddev->bitmap_info.chunksize = csize;
+        return len;
+}
+
+static struct md_sysfs_entry bitmap_chunksize =
+__ATTR(chunksize, S_IRUGO|S_IWUSR, chunksize_show, chunksize_store);
+
+static struct attribute *md_bitmap_attrs[] = {
+        &bitmap_location.attr,
+        &bitmap_timeout.attr,
+        &bitmap_backlog.attr,
+        &bitmap_chunksize.attr,
+        NULL
+};
+struct attribute_group md_bitmap_group = {
+        .name = "bitmap",
+        .attrs = md_bitmap_attrs,
+};
+
+
 /* the bitmap API -- for raid personalities */
 EXPORT_SYMBOL(bitmap_startwrite);
 EXPORT_SYMBOL(bitmap_endwrite);