Merge 4.4.230 into android-4.4-p

Changes in 4.4.230
	btrfs: cow_file_range() num_bytes and disk_num_bytes are same
	btrfs: fix data block group relocation failure due to concurrent scrub
	mm: fix swap cache node allocation mask
	EDAC/amd64: Read back the scrub rate PCI register on F15h
	mm/slub: fix stack overruns with SLUB_STATS
	usb: usbtest: fix missing kfree(dev->buf) in usbtest_disconnect
	kgdb: Avoid suspicious RCU usage warning
	crypto: af_alg - fix use-after-free in af_alg_accept() due to bh_lock_sock()
	sched/rt: Show the 'sched_rr_timeslice' SCHED_RR timeslice tuning knob in milliseconds
	hwmon: (max6697) Make sure the OVERT mask is set correctly
	hwmon: (acpi_power_meter) Fix potential memory leak in acpi_power_meter_add()
	virtio-blk: free vblk-vqs in error path of virtblk_probe()
	i2c: algo-pca: Add 0x78 as SCL stuck low status for PCA9665
	Revert "ALSA: usb-audio: Improve frames size computation"
	SMB3: Honor 'seal' flag for multiuser mounts
	SMB3: Honor persistent/resilient handle flags for multiuser mounts
	cifs: Fix the target file was deleted when rename failed.
	MIPS: Add missing EHB in mtc0 -> mfc0 sequence for DSPen
	netfilter: nf_conntrack_h323: lost .data_len definition for Q.931/ipv6
	Linux 4.4.230

Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>
Change-Id: I5402fcb3d8e16e5bf6bec2151354cb207b064e91

1 files changed, 26 insertions, 10 deletions

diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index 972475eeb2dd..b1125778b908 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -926,7 +926,7 @@ static noinline int cow_file_range(struct inode *inode,
 	u64 alloc_hint = 0;
 	u64 num_bytes;
 	unsigned long ram_size;
-	u64 disk_num_bytes;
+	u64 min_alloc_size;
 	u64 cur_alloc_size;
 	u64 blocksize = root->sectorsize;
 	struct btrfs_key ins;
@@ -942,7 +942,6 @@ static noinline int cow_file_range(struct inode *inode,
 
 	num_bytes = ALIGN(end - start + 1, blocksize);
 	num_bytes = max(blocksize,  num_bytes);
-	disk_num_bytes = num_bytes;
 
 	/* if this is a small write inside eof, kick off defrag */
 	if (num_bytes < 64 * 1024 &&
@@ -969,18 +968,33 @@ static noinline int cow_file_range(struct inode *inode,
 		}
 	}
 
-	BUG_ON(disk_num_bytes >
-	       btrfs_super_total_bytes(root->fs_info->super_copy));
+	BUG_ON(num_bytes > btrfs_super_total_bytes(root->fs_info->super_copy));
 
 	alloc_hint = get_extent_allocation_hint(inode, start, num_bytes);
 	btrfs_drop_extent_cache(inode, start, start + num_bytes - 1, 0);
 
-	while (disk_num_bytes > 0) {
+	/*
+	 * Relocation relies on the relocated extents to have exactly the same
+	 * size as the original extents. Normally writeback for relocation data
+	 * extents follows a NOCOW path because relocation preallocates the
+	 * extents. However, due to an operation such as scrub turning a block
+	 * group to RO mode, it may fallback to COW mode, so we must make sure
+	 * an extent allocated during COW has exactly the requested size and can
+	 * not be split into smaller extents, otherwise relocation breaks and
+	 * fails during the stage where it updates the bytenr of file extent
+	 * items.
+	 */
+	if (root->root_key.objectid == BTRFS_DATA_RELOC_TREE_OBJECTID)
+		min_alloc_size = num_bytes;
+	else
+		min_alloc_size = root->sectorsize;
+
+	while (num_bytes > 0) {
 		unsigned long op;
 
-		cur_alloc_size = disk_num_bytes;
+		cur_alloc_size = num_bytes;
 		ret = btrfs_reserve_extent(root, cur_alloc_size,
-					   root->sectorsize, 0, alloc_hint,
+					   min_alloc_size, 0, alloc_hint,
 					   &ins, 1, 1);
 		if (ret < 0)
 			goto out_unlock;
@@ -1033,7 +1047,7 @@ static noinline int cow_file_range(struct inode *inode,
 				goto out_drop_extent_cache;
 		}
 
-		if (disk_num_bytes < cur_alloc_size)
+		if (num_bytes < cur_alloc_size)
 			break;
 
 		/* we're not doing compressed IO, don't unlock the first
@@ -1050,8 +1064,10 @@ static noinline int cow_file_range(struct inode *inode,
 					     start + ram_size - 1, locked_page,
 					     EXTENT_LOCKED | EXTENT_DELALLOC,
 					     op);
-		disk_num_bytes -= cur_alloc_size;
-		num_bytes -= cur_alloc_size;
+		if (num_bytes < cur_alloc_size)
+			num_bytes = 0;
+		else
+			num_bytes -= cur_alloc_size;
 		alloc_hint = ins.objectid + ins.offset;
 		start += cur_alloc_size;
 	}