lightnvm: pblk: support packed metadata

pblk performs recovery of open lines by storing the LBA in the per LBA
metadata field. Recovery therefore only works for drives that has this
field.

This patch adds support for packed metadata, which store l2p mapping
for open lines in last sector of every write unit and enables drives
without per IO metadata to recover open lines.

After this patch, drives with OOB size <16B will use packed metadata
and metadata size larger than16B will continue to use the device per
IO metadata.

Reviewed-by: Javier González <javier@cnexlabs.com>
Signed-off-by: Igor Konopko <igor.j.konopko@intel.com>
Signed-off-by: Matias Bjørling <mb@lightnvm.io>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

1 files changed, 33 insertions, 5 deletions

diff --git a/drivers/lightnvm/pblk-init.c b/drivers/lightnvm/pblk-init.c
index e8055b796381..f9a3e47b6a93 100644
--- a/drivers/lightnvm/pblk-init.c
+++ b/drivers/lightnvm/pblk-init.c
@@ -399,6 +399,7 @@ static int pblk_core_init(struct pblk *pblk)
         pblk->nr_flush_rst = 0;
 
         pblk->min_write_pgs = geo->ws_opt;
+        pblk->min_write_pgs_data = pblk->min_write_pgs;
         max_write_ppas = pblk->min_write_pgs * geo->all_luns;
         pblk->max_write_pgs = min_t(int, max_write_ppas, NVM_MAX_VLBA);
         pblk->max_write_pgs = min_t(int, pblk->max_write_pgs,
@@ -406,9 +407,35 @@ static int pblk_core_init(struct pblk *pblk)
         pblk_set_sec_per_write(pblk, pblk->min_write_pgs);
 
         pblk->oob_meta_size = geo->sos;
-        if (pblk->oob_meta_size < sizeof(struct pblk_sec_meta)) {
-                pblk_err(pblk, "Unsupported metadata size\n");
-                return -EINVAL;
+        if (!pblk_is_oob_meta_supported(pblk)) {
+                /* For drives which does not have OOB metadata feature
+                 * in order to support recovery feature we need to use
+                 * so called packed metadata. Packed metada will store
+                 * the same information as OOB metadata (l2p table mapping,
+                 * but in the form of the single page at the end of
+                 * every write request.
+                 */
+                if (pblk->min_write_pgs
+                        * sizeof(struct pblk_sec_meta) > PAGE_SIZE) {
+                        /* We want to keep all the packed metadata on single
+                         * page per write requests. So we need to ensure that
+                         * it will fit.
+                         *
+                         * This is more like sanity check, since there is
+                         * no device with such a big minimal write size
+                         * (above 1 metabytes).
+                         */
+                        pblk_err(pblk, "Not supported min write size\n");
+                        return -EINVAL;
+                }
+                /* For packed meta approach we do some simplification.
+                 * On read path we always issue requests which size
+                 * equal to max_write_pgs, with all pages filled with
+                 * user payload except of last one page which will be
+                 * filled with packed metadata.
+                 */
+                pblk->max_write_pgs = pblk->min_write_pgs;
+                pblk->min_write_pgs_data = pblk->min_write_pgs - 1;
         }
 
         pblk->pad_dist = kcalloc(pblk->min_write_pgs - 1, sizeof(atomic64_t),
@@ -641,7 +668,7 @@ static int pblk_set_provision(struct pblk *pblk, int nr_free_chks)
         struct pblk_line_meta *lm = &pblk->lm;
         struct nvm_geo *geo = &dev->geo;
         sector_t provisioned;
-        int sec_meta, blk_meta;
+        int sec_meta, blk_meta, clba;
         int minimum;
 
         if (geo->op == NVM_TARGET_DEFAULT_OP)
@@ -682,7 +709,8 @@ static int pblk_set_provision(struct pblk *pblk, int nr_free_chks)
         sec_meta = (lm->smeta_sec + lm->emeta_sec[0]) * l_mg->nr_free_lines;
         blk_meta = DIV_ROUND_UP(sec_meta, geo->clba);
 
-        pblk->capacity = (provisioned - blk_meta) * geo->clba;
+        clba = (geo->clba / pblk->min_write_pgs) * pblk->min_write_pgs_data;
+        pblk->capacity = (provisioned - blk_meta) * clba;
 
         atomic_set(&pblk->rl.free_blocks, nr_free_chks);
         atomic_set(&pblk->rl.free_user_blocks, nr_free_chks);