Advance seqnum in create and destroy local_slice_mapping

dm-sflc/src/lite/discard.c

@@ -31,13 +31,13 @@ void sflite_discard_work_fn(struct work_struct *work)
 	unsigned long flags;
 	u32 lsi = sio->lsi;
 	u32 psi;
+	int err = 0;
 
 	/* Mutual exclusion with FLUSHes */
 	if (down_read_interruptible(&svol->posmap.flush_lock)) {
 		orig_bio->bi_status = BLK_STS_IOERR;
 		goto unlock;
 	}
-
 	/* Lock the position map */
 	spin_lock_irqsave(&svol->posmap.lock, flags);
 
@@ -52,7 +52,7 @@ void sflite_discard_work_fn(struct work_struct *work)
 	}
 
 	/* Unmap the slice */
-	sflite_destroy_local_slice_mapping(svol, lsi);
+	err = sflite_destroy_local_slice_mapping(svol, lsi);
 
 unlock:
 	/* Unlock */
@@ -63,7 +63,7 @@ unlock:
 	/* WARNING: it is crucial that the original bio is terminated here and never 
 	   reaches the block device, otherwise the effect of a TRIM on the block device 
 	   would be obvious, and likely to break plausible deniability */
-	orig_bio->bi_status = BLK_STS_OK;
+	orig_bio->bi_status = errno_to_blk_status(err);
 	bio_endio(orig_bio);
 	return;
 }

dm-sflc/src/lite/flush.c

@@ -314,7 +314,7 @@ int sflite_flush_posmap(struct sflite_volume *svol, struct bio *orig_bio, gfp_t
 	 * If some CWBs failed, we return an error (then failing the upper-layer
 	 * bio in the caller, if there is one), but that doesn't mean aborting
 	 * entirely, because we can still mark some blocks as clean.
-	 * Here, we need to lock. */
+	 * Here, we need to lock again. */
 	down_write(&svol->posmap.flush_lock);	// Not killable, for simplicity
 	err = mark_posmap_blocks_clean(svol);
 	bitmap_clear(svol->posmap.cwb_error, 0, nblocks);

dm-sflc/src/lite/posmap.c

@@ -64,6 +64,7 @@ static int __peek_next_free_psi(struct sflite_device *sdev, u32 *psi)
 static void __create_local_slice_mapping(struct sflite_volume *svol, u32 lsi, u32 psi, bool set_dirty)
 {
 	struct sflite_device *sdev = svol->sdev;
+	u32 block = lsi/SFLITE_PSIS_PER_BLOCK;
 
 	/* Grab it from the device (NOCHECK whether PSI is taken already, or OOB) */
 	__set_bit(psi, sdev->occupation_bitmap);
@@ -78,7 +79,8 @@ static void __create_local_slice_mapping(struct sflite_volume *svol, u32 lsi, u3
 	svol->posmap.entries[lsi] = psi;
 	svol->posmap.nr_mapped_slices++;
 	if (likely(set_dirty)) {
-		__set_bit(lsi/SFLITE_PSIS_PER_BLOCK, svol->posmap.dirty);
+		__set_bit(block, svol->posmap.dirty);
+		svol->posmap.seqnum[block] += 1;	// Wrap around, no problem
 	}
 
 	return;
@@ -91,6 +93,7 @@ static void __create_local_slice_mapping(struct sflite_volume *svol, u32 lsi, u3
 int sflite_create_local_slice_mapping(struct sflite_volume *svol, u32 lsi, u32 *psi)
 {
 	struct sflite_device *sdev = svol->sdev;
+	u32 block = lsi/SFLITE_PSIS_PER_BLOCK;
 	int err;
 
 	/* Bounds check TODO redundant? */
@@ -99,6 +102,11 @@ int sflite_create_local_slice_mapping(struct sflite_volume *svol, u32 lsi, u32 *
 	/* Check LSI is unmapped TODO redundant? */
 	if (unlikely(svol->posmap.entries[lsi] != SFLITE_PSI_INVALID))
 		return -EINVAL;
+	/* Overwhelmingly unlikely: needs 16384 create/destroy on the same
+	 * posmap block while a FLUSH is pending. */
+	if (unlikely(test_bit(block, svol->posmap.flush_pending) &&
+	   (svol->posmap.seqnum[block] + 1 == svol->posmap.snap_seqnum[block])))
+		return -EAGAIN;
 
 	/* Create mapping */
 	err = __peek_next_free_psi(sdev, psi);
@@ -115,10 +123,17 @@ int sflite_create_local_slice_mapping(struct sflite_volume *svol, u32 lsi, u32 *
  */
 int sflite_destroy_local_slice_mapping(struct sflite_volume *svol, u32 lsi)
 {
+	u32 block = lsi/SFLITE_PSIS_PER_BLOCK;
+
 	/* Bounds check */
 	if (unlikely(lsi >= svol->sdev->tot_slices)) {
 		return -EINVAL;
 	}
+	/* Overwhelmingly unlikely: needs 16384 create/destroy on the same
+	 * posmap block while a FLUSH is pending. */
+	if (unlikely(test_bit(block, svol->posmap.flush_pending) &&
+	   (svol->posmap.seqnum[block] + 1 == svol->posmap.snap_seqnum[block])))
+		return -EAGAIN;
 
 	/* Unassign the PSI */
 	svol->posmap.entries[lsi] = SFLITE_PSI_INVALID;
@@ -131,7 +146,8 @@ int sflite_destroy_local_slice_mapping(struct sflite_volume *svol, u32 lsi)
 	   requiring reload/close-open? */
 
 	/* Set the dirty bit in position map */
-	__set_bit(lsi/SFLITE_PSIS_PER_BLOCK, svol->posmap.dirty);
+	__set_bit(block, svol->posmap.dirty);
+	svol->posmap.seqnum[block] += 1;	// Wrap around, no problem
 
 	return 0;
 }

dm-sflc/src/lite/read.c

@@ -107,7 +107,7 @@ static void sflite_decrypt_work_fn(struct work_struct *work)
 	struct bio *orig_bio = io->orig_bio;
 	struct bio *phys_bio = io->phys_bio;
 	struct bio_vec bvl = bio_iovec(orig_bio);
-	int err;
+	int err = 0;
 
 	/* If physical bio failed, then fail-fast */
 	if (unlikely(phys_bio->bi_status != BLK_STS_OK)) {

dm-sflc/src/lite/write.c

@@ -42,7 +42,7 @@ void sflite_write_work_fn(struct work_struct *work)
 	u32 block_offset = io->block_offset;
 	u32 psi;
 	unsigned long flags;
-	int err;
+	int err = 0;
 
 	// Catch FUA-tagged request early: unsupported TODO improve and support - BUG: this causes a bug, comment out for now
 	//if (orig_bio->bi_opf & REQ_FUA) {
@@ -68,12 +68,12 @@ void sflite_write_work_fn(struct work_struct *work)
 		err = sflite_create_local_slice_mapping(svol, lsi, &psi);
 		spin_unlock(&sdev->slices_lock);
 		if (unlikely(err)){
-			DMERR("Could not create slice mapping; error %d", err);
+			DMWARN("Could not create slice mapping; error %d", err);
 			/* Unlock */
 			spin_unlock_irqrestore(&svol->posmap.lock, flags);
 			up_read(&svol->posmap.flush_lock);
 			/* End of critical section: fail bio */
-			orig_bio->bi_status = BLK_STS_IOERR;
+			orig_bio->bi_status = errno_to_blk_status(err);
 			goto endio;
 		}
 	}