raid5-ppl: support disk hot add/remove with PPL

Add a function to modify the log by removing an rdev when a drive fails
or adding when a spare/replacement is activated as a raid member.

Removing a disk just clears the child log rdev pointer. No new stripes
will be accepted for this child log in ppl_write_stripe() and running io
units will be processed without writing PPL to the device.

Adding a disk sets the child log rdev pointer and writes an empty PPL
header.

Signed-off-by: Artur Paszkiewicz <artur.paszkiewicz@intel.com>
Signed-off-by: Shaohua Li <shli@fb.com>

1 files changed, 44 insertions, 1 deletions

diff --git a/drivers/md/raid5-ppl.c b/drivers/md/raid5-ppl.c
index d336c024eef9..4af420f4d8c0 100644
--- a/drivers/md/raid5-ppl.c
+++ b/drivers/md/raid5-ppl.c
@@ -400,6 +400,13 @@ static void ppl_submit_iounit(struct ppl_io_unit *io)
         struct stripe_head *sh;
         int i;
 
+        bio->bi_private = io;
+
+        if (!log->rdev || test_bit(Faulty, &log->rdev->flags)) {
+                ppl_log_endio(bio);
+                return;
+        }
+
         for (i = 0; i < io->entries_count; i++) {
                 struct ppl_header_entry *e = &pplhdr->entries[i];
 
@@ -415,7 +422,6 @@ static void ppl_submit_iounit(struct ppl_io_unit *io)
         pplhdr->entries_count = cpu_to_le32(io->entries_count);
         pplhdr->checksum = cpu_to_le32(~crc32c_le(~0, pplhdr, PPL_HEADER_SIZE));
 
-        bio->bi_private = io;
         bio->bi_end_io = ppl_log_endio;
         bio->bi_opf = REQ_OP_WRITE | REQ_FUA;
         bio->bi_bdev = log->rdev->bdev;
@@ -1190,3 +1196,40 @@ err:
         __ppl_exit_log(ppl_conf);
         return ret;
 }
+
+int ppl_modify_log(struct r5conf *conf, struct md_rdev *rdev, bool add)
+{
+        struct ppl_conf *ppl_conf = conf->log_private;
+        struct ppl_log *log;
+        int ret = 0;
+        char b[BDEVNAME_SIZE];
+
+        if (!rdev)
+                return -EINVAL;
+
+        pr_debug("%s: disk: %d operation: %s dev: %s\n",
+                 __func__, rdev->raid_disk, add ? "add" : "remove",
+                 bdevname(rdev->bdev, b));
+
+        if (rdev->raid_disk < 0)
+                return 0;
+
+        if (rdev->raid_disk >= ppl_conf->count)
+                return -ENODEV;
+
+        log = &ppl_conf->child_logs[rdev->raid_disk];
+
+        mutex_lock(&log->io_mutex);
+        if (add) {
+                ret = ppl_validate_rdev(rdev);
+                if (!ret) {
+                        log->rdev = rdev;
+                        ret = ppl_write_empty_header(log);
+                }
+        } else {
+                log->rdev = NULL;
+        }
+        mutex_unlock(&log->io_mutex);
+
+        return ret;
+}