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[PATCHv2, 00/41] ext4: support of huge pages

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  [PATCHv2, 00/41] ext4: support of huge pages "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> - 2016-08-12 21:00 +0200
    [PATCHv2 03/41] radix-tree: Add radix_tree_join "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> - 2016-08-12 21:00 +0200
    [PATCHv2 02/41] radix tree test suite: Allow GFP_ATOMIC allocations to fail "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> - 2016-08-12 21:00 +0200
    Re: [PATCHv2, 00/41] ext4: support of huge pages Theodore Ts'o <tytso@mit.edu> - 2016-08-12 22:40 +0200
      Re: [PATCHv2, 00/41] ext4: support of huge pages "Kirill A. Shutemov" <kirill@shutemov.name> - 2016-08-13 01:30 +0200
    Re: [PATCHv2, 00/41] ext4: support of huge pages Andreas Dilger <adilger@dilger.ca> - 2016-08-14 10:30 +0200
      Re: [PATCHv2, 00/41] ext4: support of huge pages "Kirill A. Shutemov" <kirill@shutemov.name> - 2016-08-14 14:50 +0200

#1461415 — [PATCHv2, 00/41] ext4: support of huge pages

Here's stabilized version of my patchset which intended to bring huge pages
to ext4.

The basics are the same as with tmpfs[1] which is in Linus' tree now and
ext4 built on top of it. The main difference is that we need to handle
read out from and write-back to backing storage.

Head page links buffers for whole huge page. Dirty/writeback tracking
happens on per-hugepage level.

We read out whole huge page at once. It required bumping BIO_MAX_PAGES to
not less than HPAGE_PMD_NR. I defined BIO_MAX_PAGES to HPAGE_PMD_NR if
huge pagecache enabled.

On split_huge_page() we need to free buffers before splitting the page.
Page buffers takes additional pin on the page and can be a vector to mess
with the page during split. We want to avoid this.
If try_to_free_buffers() fails, split_huge_page() would return -EBUSY.

Readahead doesn't play with huge pages well: 128k max readahead window,
assumption on page size, PageReadahead() to track hit/miss.  I've got it
to allocate huge pages, but it doesn't provide any readahead as such.
I don't know how to do this right. It's not clear at this point if we
really need readahead with huge pages. I guess it's good enough for now.

Shadow entries ignored on allocation -- recently evicted page is not
promoted to active list. Not sure if current workingset logic is adequate
for huge pages. On eviction, we split the huge page and setup 4k shadow
entries as usual.

Unlike tmpfs, ext4 makes use of tags in radix-tree. The approach I used
for tmpfs -- 512 entries in radix-tree per-hugepages -- doesn't work well
if we want to have coherent view on tags. So the first 8 patches of the
patchset converts tmpfs to use multi-order entries in radix-tree.
The same infrastructure used for ext4.

Encryption doesn't handle huge pages yet. To avoid regressions we just
disable huge pages for the inode if it has EXT4_INODE_ENCRYPT.

With this version I don't see any xfstests regressions with huge pages enabled.
Patch with new configurations for xfstests-bld is below.

Tested with 4k, 1k, encryption and bigalloc. All with and without
huge=always. I think it's reasonable coverage.

The patchset is also in git:

git://git.kernel.org/pub/scm/linux/kernel/git/kas/linux.git hugeext4/v2

Please review and consider applying.

[1] http://lkml.kernel.org/r/1465222029-45942-1-git-send-email-kirill.shutemov@linux.intel.com

TODO:
  - readahead ?;
  - wire up madvise()/fadvise();
  - encryption with huge pages;
  - reclaim of file huge pages can be optimized -- split_huge_page() is not
    required for pages with backing storage;

Kirill A. Shutemov (34):
  mm, shmem: swich huge tmpfs to multi-order radix-tree entries
  Revert "radix-tree: implement radix_tree_maybe_preload_order()"
  page-flags: relax page flag policy for few flags
  mm, rmap: account file thp pages
  thp: try to free page's buffers before attempt split
  thp: handle write-protection faults for file THP
  truncate: make sure invalidate_mapping_pages() can discard huge pages
  filemap: allocate huge page in page_cache_read(), if allowed
  filemap: handle huge pages in do_generic_file_read()
  filemap: allocate huge page in pagecache_get_page(), if allowed
  filemap: handle huge pages in filemap_fdatawait_range()
  HACK: readahead: alloc huge pages, if allowed
  block: define BIO_MAX_PAGES to HPAGE_PMD_NR if huge page cache enabled
  mm: make write_cache_pages() work on huge pages
  thp: introduce hpage_size() and hpage_mask()
  thp: do not threat slab pages as huge in hpage_{nr_pages,size,mask}
  fs: make block_read_full_page() be able to read huge page
  fs: make block_write_{begin,end}() be able to handle huge pages
  fs: make block_page_mkwrite() aware about huge pages
  truncate: make truncate_inode_pages_range() aware about huge pages
  truncate: make invalidate_inode_pages2_range() aware about huge pages
  ext4: make ext4_mpage_readpages() hugepage-aware
  ext4: make ext4_writepage() work on huge pages
  ext4: handle huge pages in ext4_page_mkwrite()
  ext4: handle huge pages in __ext4_block_zero_page_range()
  ext4: make ext4_block_write_begin() aware about huge pages
  ext4: handle huge pages in ext4_da_write_end()
  ext4: make ext4_da_page_release_reservation() aware about huge pages
  ext4: handle writeback with huge pages
  ext4: make EXT4_IOC_MOVE_EXT work with huge pages
  ext4: fix SEEK_DATA/SEEK_HOLE for huge pages
  ext4: make fallocate() operations work with huge pages
  mm, fs, ext4: expand use of page_mapping() and page_to_pgoff()
  ext4, vfs: add huge= mount option

Matthew Wilcox (6):
  tools: Add WARN_ON_ONCE
  radix tree test suite: Allow GFP_ATOMIC allocations to fail
  radix-tree: Add radix_tree_join
  radix-tree: Add radix_tree_split
  radix-tree: Add radix_tree_split_preload()
  radix-tree: Handle multiorder entries being deleted by
    replace_clear_tags

Naoya Horiguchi (1):
  mm, hugetlb: switch hugetlbfs to multi-order radix-tree entries

 drivers/base/node.c                   |   6 +
 fs/buffer.c                           |  89 +++---
 fs/ext4/ext4.h                        |   5 +
 fs/ext4/extents.c                     |  10 +-
 fs/ext4/file.c                        |  18 +-
 fs/ext4/inode.c                       | 159 ++++++----
 fs/ext4/move_extent.c                 |  12 +-
 fs/ext4/page-io.c                     |  11 +-
 fs/ext4/readpage.c                    |  38 ++-
 fs/ext4/super.c                       |  26 ++
 fs/hugetlbfs/inode.c                  |  22 +-
 fs/proc/meminfo.c                     |   4 +
 fs/proc/task_mmu.c                    |   5 +-
 include/linux/bio.h                   |   4 +
 include/linux/buffer_head.h           |  10 +-
 include/linux/fs.h                    |   5 +
 include/linux/huge_mm.h               |  18 +-
 include/linux/mm.h                    |   1 +
 include/linux/mmzone.h                |   2 +
 include/linux/page-flags.h            |  12 +-
 include/linux/pagemap.h               |  32 +-
 include/linux/radix-tree.h            |  10 +-
 lib/radix-tree.c                      | 357 ++++++++++++++++-------
 mm/filemap.c                          | 529 ++++++++++++++++++++++++----------
 mm/huge_memory.c                      |  69 ++++-
 mm/hugetlb.c                          |  19 +-
 mm/khugepaged.c                       |  26 +-
 mm/memory.c                           |  15 +-
 mm/page-writeback.c                   |  19 +-
 mm/page_alloc.c                       |   5 +
 mm/readahead.c                        |  17 +-
 mm/rmap.c                             |  12 +-
 mm/shmem.c                            |  36 +--
 mm/truncate.c                         | 138 +++++++--
 mm/vmstat.c                           |   2 +
 tools/include/asm/bug.h               |  11 +
 tools/testing/radix-tree/Makefile     |   2 +-
 tools/testing/radix-tree/linux.c      |   7 +-
 tools/testing/radix-tree/linux/bug.h  |   2 +-
 tools/testing/radix-tree/linux/gfp.h  |  24 +-
 tools/testing/radix-tree/linux/slab.h |   5 -
 tools/testing/radix-tree/multiorder.c |  82 ++++++
 tools/testing/radix-tree/test.h       |   9 +
 43 files changed, 1373 insertions(+), 512 deletions(-)


------8<------

From f765119236c9963466cd39a1502653d8c1dde836 Mon Sep 17 00:00:00 2001
From: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Date: Fri, 12 Aug 2016 19:44:30 +0300
Subject: [PATCH] Add few more configurations to test ext4 with huge pages

Four new configurations: huge_4k, huge_1k, huge_bigalloc, huge_encrypt.

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
---
 kvm-xfstests/config                                      |  8 +++++---
 kvm-xfstests/kvm-xfstests                                |  2 +-
 .../test-appliance/files/root/fs/ext4/cfg/all.list       |  4 ++++
 .../test-appliance/files/root/fs/ext4/cfg/huge_1k        |  6 ++++++
 .../test-appliance/files/root/fs/ext4/cfg/huge_4k        |  6 ++++++
 .../test-appliance/files/root/fs/ext4/cfg/huge_bigalloc  | 14 ++++++++++++++
 .../files/root/fs/ext4/cfg/huge_bigalloc.exclude         |  7 +++++++
 .../test-appliance/files/root/fs/ext4/cfg/huge_encrypt   |  5 +++++
 .../files/root/fs/ext4/cfg/huge_encrypt.exclude          | 16 ++++++++++++++++
 kvm-xfstests/test-appliance/gen-image                    |  4 ++--
 kvm-xfstests/util/parse_cli                              |  1 +
 11 files changed, 67 insertions(+), 6 deletions(-)
 create mode 100644 kvm-xfstests/test-appliance/files/root/fs/ext4/cfg/huge_1k
 create mode 100644 kvm-xfstests/test-appliance/files/root/fs/ext4/cfg/huge_4k
 create mode 100644 kvm-xfstests/test-appliance/files/root/fs/ext4/cfg/huge_bigalloc
 create mode 100644 kvm-xfstests/test-appliance/files/root/fs/ext4/cfg/huge_bigalloc.exclude
 create mode 100644 kvm-xfstests/test-appliance/files/root/fs/ext4/cfg/huge_encrypt
 create mode 100644 kvm-xfstests/test-appliance/files/root/fs/ext4/cfg/huge_encrypt.exclude

diff --git a/kvm-xfstests/config b/kvm-xfstests/config
index e135f08872cb..11d513b71fbc 100644
--- a/kvm-xfstests/config
+++ b/kvm-xfstests/config
@@ -2,10 +2,12 @@
 # Customize these or put new values in ~/.config/kvm-xfstests or config.custom
 #
 #QEMU=/usr/local/bin/qemu-system-x86_64
-QEMU=/usr/bin/kvm
-KERNEL=/u1/ext4/arch/x86/boot/bzImage
+#QEMU=/usr/bin/kvm
+QEMU=/home/kas/opt/qemu/bin/qemu-system-x86_64
+KERNEL=/home/kas/var/linus/arch/x86/boot/bzImage
 NR_CPU=2
-MEM=2048
+MEM=16384
+#MEM=2048
 CONFIG_DIR=$HOME/.config
 
 PRIMARY_FSTYPE="ext4"
diff --git a/kvm-xfstests/kvm-xfstests b/kvm-xfstests/kvm-xfstests
index c7ac2b40cfb6..25e2c04c67d1 100755
--- a/kvm-xfstests/kvm-xfstests
+++ b/kvm-xfstests/kvm-xfstests
@@ -79,7 +79,7 @@ fi
 chmod 400 "$VDH"
 
 $NO_ACTION $IONICE $QEMU -boot order=c $NET \
-	-machine type=pc,accel=kvm:tcg \
+	-machine type=q35,accel=kvm:tcg \
 	-drive file=$ROOT_FS,if=virtio$SNAPSHOT \
 	-drive file=$VDB,cache=none,if=virtio,format=raw \
 	-drive file=$VDC,cache=none,if=virtio,format=raw \
diff --git a/kvm-xfstests/test-appliance/files/root/fs/ext4/cfg/all.list b/kvm-xfstests/test-appliance/files/root/fs/ext4/cfg/all.list
index 7ec37f4bafaa..14a8e72d2e6e 100644
--- a/kvm-xfstests/test-appliance/files/root/fs/ext4/cfg/all.list
+++ b/kvm-xfstests/test-appliance/files/root/fs/ext4/cfg/all.list
@@ -9,3 +9,7 @@ dioread_nolock
 data_journal
 bigalloc
 bigalloc_1k
+huge_4k
+huge_1k
+huge_bigalloc
+huge_encrypt
diff --git a/kvm-xfstests/test-appliance/files/root/fs/ext4/cfg/huge_1k b/kvm-xfstests/test-appliance/files/root/fs/ext4/cfg/huge_1k
new file mode 100644
index 000000000000..209c76a8a6c1
--- /dev/null
+++ b/kvm-xfstests/test-appliance/files/root/fs/ext4/cfg/huge_1k
@@ -0,0 +1,6 @@
+export FS=ext4
+export TEST_DEV=$SM_TST_DEV
+export TEST_DIR=$SM_TST_MNT
+export MKFS_OPTIONS="-q -b 1024"
+export EXT_MOUNT_OPTIONS="huge=always"
+TESTNAME="Ext4 1k block with huge pages"
diff --git a/kvm-xfstests/test-appliance/files/root/fs/ext4/cfg/huge_4k b/kvm-xfstests/test-appliance/files/root/fs/ext4/cfg/huge_4k
new file mode 100644
index 000000000000..bae901cb2bab
--- /dev/null
+++ b/kvm-xfstests/test-appliance/files/root/fs/ext4/cfg/huge_4k
@@ -0,0 +1,6 @@
+export FS=ext4
+export TEST_DEV=$PRI_TST_DEV
+export TEST_DIR=$PRI_TST_MNT
+export MKFS_OPTIONS="-q"
+export EXT_MOUNT_OPTIONS="huge=always"
+TESTNAME="Ext4 4k block with huge pages"
diff --git a/kvm-xfstests/test-appliance/files/root/fs/ext4/cfg/huge_bigalloc b/kvm-xfstests/test-appliance/files/root/fs/ext4/cfg/huge_bigalloc
new file mode 100644
index 000000000000..b3d87562bce6
--- /dev/null
+++ b/kvm-xfstests/test-appliance/files/root/fs/ext4/cfg/huge_bigalloc
@@ -0,0 +1,14 @@
+SIZE=large
+export MKFS_OPTIONS="-O bigalloc"
+export EXT_MOUNT_OPTIONS="huge=always"
+
+# Until we can teach xfstests the difference between cluster size and
+# block size, avoid collapse_range, insert_range, and zero_range since
+# these will fail due the fact that these operations require
+# cluster-aligned ranges.
+export FSX_AVOID="-C -I -z"
+export FSSTRESS_AVOID="-f collapse=0 -f insert=0 -f zero=0"
+export XFS_IO_AVOID="fcollapse finsert zero"
+
+TESTNAME="Ext4 4k block w/bigalloc"
+
diff --git a/kvm-xfstests/test-appliance/files/root/fs/ext4/cfg/huge_bigalloc.exclude b/kvm-xfstests/test-appliance/files/root/fs/ext4/cfg/huge_bigalloc.exclude
new file mode 100644
index 000000000000..bd779be99518
--- /dev/null
+++ b/kvm-xfstests/test-appliance/files/root/fs/ext4/cfg/huge_bigalloc.exclude
@@ -0,0 +1,7 @@
+# bigalloc does not support on-line defrag
+ext4/301
+ext4/302
+ext4/303
+ext4/304
+ext4/307
+ext4/308
diff --git a/kvm-xfstests/test-appliance/files/root/fs/ext4/cfg/huge_encrypt b/kvm-xfstests/test-appliance/files/root/fs/ext4/cfg/huge_encrypt
new file mode 100644
index 000000000000..29f058ba937d
--- /dev/null
+++ b/kvm-xfstests/test-appliance/files/root/fs/ext4/cfg/huge_encrypt
@@ -0,0 +1,5 @@
+SIZE=small
+export MKFS_OPTIONS=""
+export EXT_MOUNT_OPTIONS="test_dummy_encryption,huge=always"
+REQUIRE_FEATURE=encryption
+TESTNAME="Ext4 encryption"
diff --git a/kvm-xfstests/test-appliance/files/root/fs/ext4/cfg/huge_encrypt.exclude b/kvm-xfstests/test-appliance/files/root/fs/ext4/cfg/huge_encrypt.exclude
new file mode 100644
index 000000000000..b91cc58b5aa3
--- /dev/null
+++ b/kvm-xfstests/test-appliance/files/root/fs/ext4/cfg/huge_encrypt.exclude
@@ -0,0 +1,16 @@
+ext4/004	# dump/restore doesn't handle quotas
+
+# encryption doesn't play well with quota
+generic/082
+generic/219
+generic/230
+generic/231
+generic/232
+generic/233
+generic/235
+generic/270
+
+# generic/204 tests ENOSPC handling; it doesn't correctly
+# anticipate the external extended attribute required when
+# using a 1k block size
+generic/204
diff --git a/kvm-xfstests/test-appliance/gen-image b/kvm-xfstests/test-appliance/gen-image
index 717166047cbf..62871af12e12 100755
--- a/kvm-xfstests/test-appliance/gen-image
+++ b/kvm-xfstests/test-appliance/gen-image
@@ -4,8 +4,8 @@
 
 SAVE_ARGS=("$@")
 
-SUITE=jessie
-MIRROR=http://mirrors.kernel.org/debian
+SUITE=testing
+MIRROR="http://linux-ftp.fi.intel.com/pub/mirrors/debian"
 DIR=$(pwd)
 ROOTDIR=$DIR/rootdir
 #ARCH="--arch=i386"
diff --git a/kvm-xfstests/util/parse_cli b/kvm-xfstests/util/parse_cli
index 83400ea71985..ba64ce5df016 100644
--- a/kvm-xfstests/util/parse_cli
+++ b/kvm-xfstests/util/parse_cli
@@ -36,6 +36,7 @@ print_help ()
     echo "Common file system configurations are:"
     echo "	4k 1k ext3 nojournal ext3conv metacsum dioread_nolock "
     echo "	data_journal bigalloc bigalloc_1k inline"
+    echo "	huge_4k huge_1k huge_bigalloc huge_encrypt"
     echo ""
     echo "xfstest names have the form: ext4/NNN generic/NNN shared/NNN"
     echo ""
-- 
2.8.1

[toc] | [next] | [standalone]

#1461416 — [PATCHv2 03/41] radix-tree: Add radix_tree_join

From: Matthew Wilcox <willy@linux.intel.com>

This new function allows for the replacement of many smaller entries in
the radix tree with one larger multiorder entry.  From the point of view
of an RCU walker, they may see a mixture of the smaller entries and the
large entry during the same walk, but they will never see NULL for an
index which was populated before the join.

Signed-off-by: Matthew Wilcox <willy@linux.intel.com>
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
---
 include/linux/radix-tree.h            |   2 +
 lib/radix-tree.c                      | 159 +++++++++++++++++++++++++++-------
 tools/testing/radix-tree/multiorder.c |  32 +++++++
 3 files changed, 163 insertions(+), 30 deletions(-)

diff --git a/include/linux/radix-tree.h b/include/linux/radix-tree.h
index 4c45105dece3..75ae4648d13d 100644
--- a/include/linux/radix-tree.h
+++ b/include/linux/radix-tree.h
@@ -319,6 +319,8 @@ static inline void radix_tree_preload_end(void)
 	preempt_enable();
 }
 
+int radix_tree_join(struct radix_tree_root *, unsigned long index,
+			unsigned new_order, void *);
 /**
  * struct radix_tree_iter - radix tree iterator state
  *
diff --git a/lib/radix-tree.c b/lib/radix-tree.c
index 61b8fb529cef..00830dd77086 100644
--- a/lib/radix-tree.c
+++ b/lib/radix-tree.c
@@ -314,18 +314,14 @@ static void radix_tree_node_rcu_free(struct rcu_head *head)
 {
 	struct radix_tree_node *node =
 			container_of(head, struct radix_tree_node, rcu_head);
-	int i;
 
 	/*
-	 * must only free zeroed nodes into the slab. radix_tree_shrink
-	 * can leave us with a non-NULL entry in the first slot, so clear
-	 * that here to make sure.
+	 * Must only free zeroed nodes into the slab.  We can be left with
+	 * non-NULL entries by radix_tree_free_nodes, so clear the entries
+	 * and tags here.
 	 */
-	for (i = 0; i < RADIX_TREE_MAX_TAGS; i++)
-		tag_clear(node, i, 0);
-
-	node->slots[0] = NULL;
-	node->count = 0;
+	memset(node->slots, 0, sizeof(node->slots));
+	memset(node->tags, 0, sizeof(node->tags));
 
 	kmem_cache_free(radix_tree_node_cachep, node);
 }
@@ -557,14 +553,14 @@ int __radix_tree_create(struct radix_tree_root *root, unsigned long index,
 	shift = radix_tree_load_root(root, &child, &maxindex);
 
 	/* Make sure the tree is high enough.  */
+	if (order > 0 && max == ((1UL << order) - 1))
+		max++;
 	if (max > maxindex) {
 		int error = radix_tree_extend(root, max, shift);
 		if (error < 0)
 			return error;
 		shift = error;
 		child = root->rnode;
-		if (order == shift)
-			shift += RADIX_TREE_MAP_SHIFT;
 	}
 
 	while (shift > order) {
@@ -576,6 +572,7 @@ int __radix_tree_create(struct radix_tree_root *root, unsigned long index,
 				return -ENOMEM;
 			child->shift = shift;
 			child->offset = offset;
+			child->count = 0;
 			child->parent = node;
 			rcu_assign_pointer(*slot, node_to_entry(child));
 			if (node)
@@ -589,31 +586,113 @@ int __radix_tree_create(struct radix_tree_root *root, unsigned long index,
 		slot = &node->slots[offset];
 	}
 
+	if (nodep)
+		*nodep = node;
+	if (slotp)
+		*slotp = slot;
+	return 0;
+}
+
 #ifdef CONFIG_RADIX_TREE_MULTIORDER
-	/* Insert pointers to the canonical entry */
-	if (order > shift) {
-		unsigned i, n = 1 << (order - shift);
+/*
+ * Free any nodes below this node.  The tree is presumed to not need
+ * shrinking, and any user data in the tree is presumed to not need a
+ * destructor called on it.  If we need to add a destructor, we can
+ * add that functionality later.  Note that we may not clear tags or
+ * slots from the tree as an RCU walker may still have a pointer into
+ * this subtree.  We could replace the entries with RADIX_TREE_RETRY,
+ * but we'll still have to clear those in rcu_free.
+ */
+static void radix_tree_free_nodes(struct radix_tree_node *node)
+{
+	unsigned offset = 0;
+	struct radix_tree_node *child = entry_to_node(node);
+
+	for (;;) {
+		void *entry = child->slots[offset];
+		if (radix_tree_is_internal_node(entry) &&
+					!is_sibling_entry(child, entry)) {
+			child = entry_to_node(entry);
+			offset = 0;
+			continue;
+		}
+		offset++;
+		while (offset == RADIX_TREE_MAP_SIZE) {
+			struct radix_tree_node *old = child;
+			offset = child->offset + 1;
+			child = child->parent;
+			radix_tree_node_free(old);
+			if (old == entry_to_node(node))
+				return;
+		}
+	}
+}
+
+static inline int insert_entries(struct radix_tree_node *node, void **slot,
+				void *ptr, unsigned order, bool replace)
+{
+	struct radix_tree_node *child;
+	unsigned i, n, tag, offset, tags = 0;
+
+	if (node) {
+		n = 1 << (order - node->shift);
+		offset = get_slot_offset(node, slot);
+	} else {
+		n = 1;
+		offset = 0;
+	}
+
+	if (n > 1) {
 		offset = offset & ~(n - 1);
 		slot = &node->slots[offset];
-		child = node_to_entry(slot);
-		for (i = 0; i < n; i++) {
-			if (slot[i])
+	}
+	child = node_to_entry(slot);
+
+	for (i = 0; i < n; i++) {
+		if (slot[i]) {
+			if (replace) {
+				node->count--;
+				for (tag = 0; tag < RADIX_TREE_MAX_TAGS; tag++)
+					if (tag_get(node, tag, offset + i))
+						tags |= 1 << tag;
+			} else
 				return -EEXIST;
 		}
+	}
 
-		for (i = 1; i < n; i++) {
+	for (i = 0; i < n; i++) {
+		struct radix_tree_node *old = slot[i];
+		if (i) {
 			rcu_assign_pointer(slot[i], child);
-			node->count++;
+			for (tag = 0; tag < RADIX_TREE_MAX_TAGS; tag++)
+				if (tags & (1 << tag))
+					tag_clear(node, tag, offset + i);
+		} else {
+			rcu_assign_pointer(slot[i], ptr);
+			for (tag = 0; tag < RADIX_TREE_MAX_TAGS; tag++)
+				if (tags & (1 << tag))
+					tag_set(node, tag, offset);
 		}
+		if (radix_tree_is_internal_node(old) &&
+					!is_sibling_entry(node, old))
+			radix_tree_free_nodes(old);
 	}
-#endif
-
-	if (nodep)
-		*nodep = node;
-	if (slotp)
-		*slotp = slot;
-	return 0;
+	if (node)
+		node->count += n;
+	return n;
+}
+#else
+static inline int insert_entries(struct radix_tree_node *node, void **slot,
+				void *ptr, unsigned order, bool replace)
+{
+	if (*slot)
+		return -EEXIST;
+	rcu_assign_pointer(*slot, ptr);
+	if (node)
+		node->count++;
+	return 1;
 }
+#endif
 
 /**
  *	__radix_tree_insert    -    insert into a radix tree
@@ -636,13 +715,13 @@ int __radix_tree_insert(struct radix_tree_root *root, unsigned long index,
 	error = __radix_tree_create(root, index, order, &node, &slot);
 	if (error)
 		return error;
-	if (*slot != NULL)
-		return -EEXIST;
-	rcu_assign_pointer(*slot, item);
+
+	error = insert_entries(node, slot, item, order, false);
+	if (error < 0)
+		return error;
 
 	if (node) {
 		unsigned offset = get_slot_offset(node, slot);
-		node->count++;
 		BUG_ON(tag_get(node, 0, offset));
 		BUG_ON(tag_get(node, 1, offset));
 		BUG_ON(tag_get(node, 2, offset));
@@ -740,6 +819,26 @@ void *radix_tree_lookup(struct radix_tree_root *root, unsigned long index)
 }
 EXPORT_SYMBOL(radix_tree_lookup);
 
+#ifdef CONFIG_RADIX_TREE_MULTIORDER
+int radix_tree_join(struct radix_tree_root *root, unsigned long index,
+			unsigned order, void *item)
+{
+	struct radix_tree_node *node;
+	void **slot;
+	int error;
+
+	BUG_ON(radix_tree_is_internal_node(item));
+
+	error = __radix_tree_create(root, index, order, &node, &slot);
+	if (!error)
+		error = insert_entries(node, slot, item, order, true);
+	if (error > 0)
+		error = 0;
+
+	return error;
+}
+#endif
+
 /**
  *	radix_tree_tag_set - set a tag on a radix tree node
  *	@root:		radix tree root
diff --git a/tools/testing/radix-tree/multiorder.c b/tools/testing/radix-tree/multiorder.c
index 39d9b9568fe2..f917da164b00 100644
--- a/tools/testing/radix-tree/multiorder.c
+++ b/tools/testing/radix-tree/multiorder.c
@@ -317,6 +317,37 @@ void multiorder_tagged_iteration(void)
 	item_kill_tree(&tree);
 }
 
+static void __multiorder_join(unsigned long index,
+				unsigned order1, unsigned order2)
+{
+	unsigned long loc;
+	void *item, *item2 = item_create(index + 1);
+	RADIX_TREE(tree, GFP_KERNEL);
+
+	item_insert_order(&tree, index, order2);
+	item = radix_tree_lookup(&tree, index);
+	radix_tree_join(&tree, index + 1, order1, item2);
+	loc = radix_tree_locate_item(&tree, item);
+	if (loc == -1)
+		free(item);
+	item = radix_tree_lookup(&tree, index + 1);
+	assert(item == item2);
+	item_kill_tree(&tree);
+}
+
+static void multiorder_join(void)
+{
+	int i, j, idx;
+
+	for (idx = 0; idx < 1024; idx = idx * 2 + 3) {
+		for (i = 1; i < 15; i++) {
+			for (j = 0; j < i; j++) {
+				__multiorder_join(idx, i, j);
+			}
+		}
+	}
+}
+
 void multiorder_checks(void)
 {
 	int i;
@@ -334,4 +365,5 @@ void multiorder_checks(void)
 	multiorder_tag_tests();
 	multiorder_iteration();
 	multiorder_tagged_iteration();
+	multiorder_join();
 }
-- 
2.8.1

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#1461419 — [PATCHv2 02/41] radix tree test suite: Allow GFP_ATOMIC allocations to fail

From: Matthew Wilcox <willy@linux.intel.com>

In order to test the preload code, it is necessary to fail GFP_ATOMIC
allocations, which requires defining GFP_KERNEL and GFP_ATOMIC properly.
Remove the obsolete __GFP_WAIT and copy the definitions of the __GFP
flags which are used from the kernel include files.  We also need the
real definition of gfpflags_allow_blocking() to persuade the radix tree
to actually use its preallocated nodes.

Signed-off-by: Matthew Wilcox <willy@linux.intel.com>
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
---
 tools/testing/radix-tree/linux.c      |  7 ++++++-
 tools/testing/radix-tree/linux/gfp.h  | 24 ++++++++++++++++++++----
 tools/testing/radix-tree/linux/slab.h |  5 -----
 3 files changed, 26 insertions(+), 10 deletions(-)

diff --git a/tools/testing/radix-tree/linux.c b/tools/testing/radix-tree/linux.c
index 154823737b20..3cfb04e98e2f 100644
--- a/tools/testing/radix-tree/linux.c
+++ b/tools/testing/radix-tree/linux.c
@@ -33,7 +33,12 @@ mempool_t *mempool_create(int min_nr, mempool_alloc_t *alloc_fn,
 
 void *kmem_cache_alloc(struct kmem_cache *cachep, int flags)
 {
-	void *ret = malloc(cachep->size);
+	void *ret;
+
+	if (flags & __GFP_NOWARN)
+		return NULL;
+
+	ret = malloc(cachep->size);
 	if (cachep->ctor)
 		cachep->ctor(ret);
 	uatomic_inc(&nr_allocated);
diff --git a/tools/testing/radix-tree/linux/gfp.h b/tools/testing/radix-tree/linux/gfp.h
index 0e37f7a760eb..5b09b2ce6c33 100644
--- a/tools/testing/radix-tree/linux/gfp.h
+++ b/tools/testing/radix-tree/linux/gfp.h
@@ -1,10 +1,26 @@
 #ifndef _GFP_H
 #define _GFP_H
 
-#define __GFP_BITS_SHIFT 22
+#define __GFP_BITS_SHIFT 26
 #define __GFP_BITS_MASK ((gfp_t)((1 << __GFP_BITS_SHIFT) - 1))
-#define __GFP_WAIT 1
-#define __GFP_ACCOUNT 0
-#define __GFP_NOWARN 0
+
+#define __GFP_HIGH		0x20u
+#define __GFP_IO		0x40u
+#define __GFP_FS		0x80u
+#define __GFP_NOWARN		0x200u
+#define __GFP_ATOMIC		0x80000u
+#define __GFP_ACCOUNT		0x100000u
+#define __GFP_DIRECT_RECLAIM	0x400000u
+#define __GFP_KSWAPD_RECLAIM	0x2000000u
+
+#define __GFP_RECLAIM		(__GFP_DIRECT_RECLAIM|__GFP_KSWAPD_RECLAIM)
+
+#define GFP_ATOMIC		(__GFP_HIGH|__GFP_ATOMIC|__GFP_KSWAPD_RECLAIM)
+#define GFP_KERNEL		(__GFP_RECLAIM | __GFP_IO | __GFP_FS)
+
+static inline bool gfpflags_allow_blocking(const gfp_t gfp_flags)
+{
+	return !!(gfp_flags & __GFP_DIRECT_RECLAIM);
+}
 
 #endif
diff --git a/tools/testing/radix-tree/linux/slab.h b/tools/testing/radix-tree/linux/slab.h
index 6d5a34770fd4..452e2bf502e3 100644
--- a/tools/testing/radix-tree/linux/slab.h
+++ b/tools/testing/radix-tree/linux/slab.h
@@ -7,11 +7,6 @@
 #define SLAB_PANIC 2
 #define SLAB_RECLAIM_ACCOUNT    0x00020000UL            /* Objects are reclaimable */
 
-static inline int gfpflags_allow_blocking(gfp_t mask)
-{
-	return 1;
-}
-
 struct kmem_cache {
 	int size;
 	void (*ctor)(void *);
-- 
2.8.1

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#1461449

On Fri, Aug 12, 2016 at 09:37:43PM +0300, Kirill A. Shutemov wrote:
> Here's stabilized version of my patchset which intended to bring huge pages
> to ext4.

So this patch is more about mm level changes than it is about the file
system, and I didn't see any comments from the linux-mm peanut gallery
(unless the linux-ext4 list got removed from the cc list, or some such).

I haven't had time to take a close look at the ext4 changes, and I'll
try to carve out some time to do that --- but has anyone from the mm
side of the world taken a look at these patches?

Thanks,

						- Ted

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#1461510

On Fri, Aug 12, 2016 at 04:34:40PM -0400, Theodore Ts'o wrote:
> On Fri, Aug 12, 2016 at 09:37:43PM +0300, Kirill A. Shutemov wrote:
> > Here's stabilized version of my patchset which intended to bring huge pages
> > to ext4.
> 
> So this patch is more about mm level changes than it is about the file
> system, and I didn't see any comments from the linux-mm peanut gallery
> (unless the linux-ext4 list got removed from the cc list, or some such).
> 
> I haven't had time to take a close look at the ext4 changes, and I'll
> try to carve out some time to do that

I would appreciate it.

> --- but has anyone from the mm
> side of the world taken a look at these patches?

Not yet. I had hard time obtaining review on similar-sized patchsets
before :-/

-- 
 Kirill A. Shutemov

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#1461682

[Multipart message — attachments visible in raw view] — view raw

On Aug 12, 2016, at 12:37 PM, Kirill A. Shutemov <kirill.shutemov@linux.intel.com> wrote:
> 
> Here's stabilized version of my patchset which intended to bring huge pages
> to ext4.
> 
> The basics are the same as with tmpfs[1] which is in Linus' tree now and
> ext4 built on top of it. The main difference is that we need to handle
> read out from and write-back to backing storage.
> 
> Head page links buffers for whole huge page. Dirty/writeback tracking
> happens on per-hugepage level.
> 
> We read out whole huge page at once. It required bumping BIO_MAX_PAGES to
> not less than HPAGE_PMD_NR. I defined BIO_MAX_PAGES to HPAGE_PMD_NR if
> huge pagecache enabled.
> 
> On split_huge_page() we need to free buffers before splitting the page.
> Page buffers takes additional pin on the page and can be a vector to mess
> with the page during split. We want to avoid this.
> If try_to_free_buffers() fails, split_huge_page() would return -EBUSY.
> 
> Readahead doesn't play with huge pages well: 128k max readahead window,
> assumption on page size, PageReadahead() to track hit/miss.  I've got it
> to allocate huge pages, but it doesn't provide any readahead as such.
> I don't know how to do this right. It's not clear at this point if we
> really need readahead with huge pages. I guess it's good enough for now.

Typically read-ahead is a loss if you are able to get large allocations on
disk, since you can get at least seek_rate * chunk_size throughput from the
disks even with random IO at that size.  With 1MB allocations and 7200 RPM drives this works out to be about 150MB/s, which is close to the throughput
of these drive already.

Cheers, Andreas

> Shadow entries ignored on allocation -- recently evicted page is not
> promoted to active list. Not sure if current workingset logic is adequate
> for huge pages. On eviction, we split the huge page and setup 4k shadow
> entries as usual.
> 
> Unlike tmpfs, ext4 makes use of tags in radix-tree. The approach I used
> for tmpfs -- 512 entries in radix-tree per-hugepages -- doesn't work well
> if we want to have coherent view on tags. So the first 8 patches of the
> patchset converts tmpfs to use multi-order entries in radix-tree.
> The same infrastructure used for ext4.
> 
> Encryption doesn't handle huge pages yet. To avoid regressions we just
> disable huge pages for the inode if it has EXT4_INODE_ENCRYPT.
> 
> With this version I don't see any xfstests regressions with huge pages enabled.
> Patch with new configurations for xfstests-bld is below.
> 
> Tested with 4k, 1k, encryption and bigalloc. All with and without
> huge=always. I think it's reasonable coverage.
> 
> The patchset is also in git:
> 
> git://git.kernel.org/pub/scm/linux/kernel/git/kas/linux.git hugeext4/v2
> 
> Please review and consider applying.
> 
> [1] http://lkml.kernel.org/r/1465222029-45942-1-git-send-email-kirill.shutemov@linux.intel.com

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#1462117

On Sun, Aug 14, 2016 at 01:20:12AM -0600, Andreas Dilger wrote:
> On Aug 12, 2016, at 12:37 PM, Kirill A. Shutemov <kirill.shutemov@linux.intel.com> wrote:
> > 
> > Here's stabilized version of my patchset which intended to bring huge pages
> > to ext4.
> > 
> > The basics are the same as with tmpfs[1] which is in Linus' tree now and
> > ext4 built on top of it. The main difference is that we need to handle
> > read out from and write-back to backing storage.
> > 
> > Head page links buffers for whole huge page. Dirty/writeback tracking
> > happens on per-hugepage level.
> > 
> > We read out whole huge page at once. It required bumping BIO_MAX_PAGES to
> > not less than HPAGE_PMD_NR. I defined BIO_MAX_PAGES to HPAGE_PMD_NR if
> > huge pagecache enabled.
> > 
> > On split_huge_page() we need to free buffers before splitting the page.
> > Page buffers takes additional pin on the page and can be a vector to mess
> > with the page during split. We want to avoid this.
> > If try_to_free_buffers() fails, split_huge_page() would return -EBUSY.
> > 
> > Readahead doesn't play with huge pages well: 128k max readahead window,
> > assumption on page size, PageReadahead() to track hit/miss.  I've got it
> > to allocate huge pages, but it doesn't provide any readahead as such.
> > I don't know how to do this right. It's not clear at this point if we
> > really need readahead with huge pages. I guess it's good enough for now.
> 
> Typically read-ahead is a loss if you are able to get large allocations on
> disk, since you can get at least seek_rate * chunk_size throughput from the
> disks even with random IO at that size.  With 1MB allocations and 7200
> RPM drives this works out to be about 150MB/s, which is close to the
> throughput of these drive already.

I'm more worried about not about throughput, but latancy spikes once we
cross huge page boundaries. We can get cache miss where we had hit with
small pages.

-- 
 Kirill A. Shutemov

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