[Devel] [PATCH rh7] ploop: Disable holes on io_direct raw images

[Kirill Tkhai]

The problem is raw images may have ploop1 snapshots
on top of them. When base image contains a hole and
there is a read bio covering both the hole and some
existing extent, a part of the bio must be zoroes,
while another part must go to existing extent.
Ploop driver stack does not support this.

In case of there is no a snapshot, we used to fallocate
a hole on-flight as workaround, but this works only
for R/W mounted ploop. So, we completely disable holes
there.

https://jira.sw.ru/browse/PSBM-101189

Signed-off-by: Kirill Tkhai <ktkhai at virtuozzo.com>
---
 drivers/block/ploop/fmt_raw.c       |    3 +
 drivers/block/ploop/io_direct_map.c |   71 -----------------------------------
 2 files changed, 4 insertions(+), 70 deletions(-)

diff --git a/drivers/block/ploop/fmt_raw.c b/drivers/block/ploop/fmt_raw.c
index 5b6821afa38a..da1f50465ff1 100644
--- a/drivers/block/ploop/fmt_raw.c
+++ b/drivers/block/ploop/fmt_raw.c
@@ -56,6 +56,9 @@ raw_open(struct ploop_delta * delta)
 	pos += (1 << (cluster_log + 9)) - 1;
 	delta->io.alloc_head = pos >> (cluster_log + 9);
 
+	if (delta->io.ops->id == PLOOP_IO_DIRECT)
+		set_bit(PLOOP_S_NO_FALLOC_DISCARD, &delta->plo->state);
+
 	/* no more allocations at all */
 	delta->flags |= PLOOP_FMT_PREALLOCATED;
 
diff --git a/drivers/block/ploop/io_direct_map.c b/drivers/block/ploop/io_direct_map.c
index 83b83027c013..a3f19d22e313 100644
--- a/drivers/block/ploop/io_direct_map.c
+++ b/drivers/block/ploop/io_direct_map.c
@@ -576,61 +576,6 @@ static int remove_extent_mapping(struct extent_map_tree *tree, struct extent_map
 	return ret;
 }
 
-static int fallocate_cluster(struct ploop_io *io, struct inode *inode,
-			     loff_t start_off, loff_t len, bool align)
-{
-	struct ploop_device *plo = io->plo;
-	struct file *file = io->files.file;
-	unsigned int clu_sz = cluster_size_in_bytes(plo);
-	struct fiemap_extent_info fieinfo;
-	struct fiemap_extent fi_extent;
-	loff_t start_clu = round_down(start_off, clu_sz);
-	int ret;
-
-	if (start_clu + clu_sz >= i_size_read(inode))
-		return -EINVAL;
-
-	if (test_bit(PLOOP_S_NO_FALLOC_DISCARD, &plo->state)) {
-		pr_err("a hole in image file detected (i_size=%llu off=%llu)",
-		       i_size_read(inode), start_off);
-		return -EINVAL;
-	}
-
-	fieinfo.fi_extents_start = &fi_extent;
-	fieinfo.fi_extents_max = 1;
-	fieinfo.fi_flags = 0;
-	fieinfo.fi_extents_mapped = 0;
-	fi_extent.fe_flags = 0;
-
-	if (!align)
-		goto not_align;
-
-	ret = inode->i_op->fiemap(inode, &fieinfo, start_clu, clu_sz);
-	if (ret)
-		goto out;
-
-	if (fieinfo.fi_extents_mapped == 0) {
-		start_off = start_clu;
-		len = clu_sz;
-	} else {
-not_align:
-		fi_extent.fe_flags = 0;
-		ret = inode->i_op->fiemap(inode, &fieinfo, start_off, len);
-		if (ret)
-			goto out;
-		if (fieinfo.fi_extents_mapped != 0) {
-			WARN_ON_ONCE(fi_extent.fe_logical <= start_off);
-			len = fi_extent.fe_logical - start_off;
-		}
-	}
-
-	ret = file->f_op->fallocate(file, FALLOC_FL_KEEP_SIZE, start_off, len);
-	if (!ret)
-		ret = io->ops->sync(io);
-out:
-	return ret;
-}
-
 static struct extent_map *__map_extent_bmap(struct ploop_io *io,
 				       struct address_space *mapping,
 				       sector_t start, sector_t len, gfp_t gfp_mask)
@@ -708,22 +653,8 @@ static struct extent_map *__map_extent_bmap(struct ploop_io *io,
 	}
 
 	if (fieinfo.fi_extents_mapped != 1) {
-		struct ploop_device *plo = io->plo;
 		ploop_extent_put(em);
-		/*
-		 * In case of io_direct we may support discards
-		 * in multi-delta case, since all allocated blocks
-		 * are added to extent tree. But we follow generic
-		 * way, and encode discarded blocks by zeroing
-		 * their indexes in maps (ploop1).
-		 */
-		if (!test_bit(PLOOP_MAP_IDENTICAL, &plo->map.flags))
-			return ERR_PTR(-ENOENT);
-
-		ret = fallocate_cluster(io, inode, start_off, len, align_to_clu);
-		if (!ret)
-			goto again;
-		return ERR_PTR(ret);
+		return ERR_PTR(-ENOENT);
 	}
 
 	em->start = fi_extent.fe_logical >> 9;