[kernel/f19] Fix btrfs balance/scrub issue (rhbz 1011714)

[Josh Boyer]

commit 42ae5788199cf1c02c0fc97963a24f935bb7cdaf
Author: Josh Boyer <jwboyer at fedoraproject.org>
Date:   Wed Oct 16 13:50:26 2013 -0400

    Fix btrfs balance/scrub issue (rhbz 1011714)

 ...relocate-csums-properly-with-prealloc-ext.patch |   60 ++++++++++++++++++++
 kernel.spec                                        |   11 +++-
 2 files changed, 70 insertions(+), 1 deletions(-)
---
diff --git a/btrfs-relocate-csums-properly-with-prealloc-ext.patch b/btrfs-relocate-csums-properly-with-prealloc-ext.patch
new file mode 100644
index 0000000..e103f70
--- /dev/null
+++ b/btrfs-relocate-csums-properly-with-prealloc-ext.patch
@@ -0,0 +1,60 @@
+A user reported a problem where they were getting csum errors when running a
+balance and running systemd's journal.  This is because systemd is awesome and
+fallocate()'s its log space and writes into it.  Unfortunately we assume that
+when we read in all the csums for an extent that they are sequential starting at
+the bytenr we care about.  This obviously isn't the case for prealloc extents,
+where we could have written to the middle of the prealloc extent only, which
+means the csum would be for the bytenr in the middle of our range and not the
+front of our range.  Fix this by offsetting the new bytenr we are logging to
+based on the original bytenr the csum was for.  With this patch I no longer see
+the csum errors I was seeing.  Thanks,
+
+Cc: stable at xxxxxxxxxxxxxxx
+Reported-by: Chris Murphy <lists at xxxxxxxxxxxxxxxxx>
+Signed-off-by: Josef Bacik <jbacik at xxxxxxxxxxxx>
+---
+ fs/btrfs/relocation.c | 18 +++++++++++++++---
+ 1 file changed, 15 insertions(+), 3 deletions(-)
+
+diff --git a/fs/btrfs/relocation.c b/fs/btrfs/relocation.c
+index 5ca7ea9..b7afeaa 100644
+--- a/fs/btrfs/relocation.c
++++ b/fs/btrfs/relocation.c
+@@ -4472,6 +4472,7 @@ int btrfs_reloc_clone_csums(struct inode *inode, u64 file_pos, u64 len)
+ 	struct btrfs_root *root = BTRFS_I(inode)->root;
+ 	int ret;
+ 	u64 disk_bytenr;
++	u64 new_bytenr;
+ 	LIST_HEAD(list);
+ 
+ 	ordered = btrfs_lookup_ordered_extent(inode, file_pos);
+@@ -4483,13 +4484,24 @@ int btrfs_reloc_clone_csums(struct inode *inode, u64 file_pos, u64 len)
+ 	if (ret)
+ 		goto out;
+ 
+-	disk_bytenr = ordered->start;
+ 	while (!list_empty(&list)) {
+ 		sums = list_entry(list.next, struct btrfs_ordered_sum, list);
+ 		list_del_init(&sums->list);
+ 
+-		sums->bytenr = disk_bytenr;
+-		disk_bytenr += sums->len;
++		/*
++		 * We need to offset the new_bytenr based on where the csum is.
++		 * We need to do this because we will read in entire prealloc
++		 * extents but we may have written to say the middle of the
++		 * prealloc extent, so we need to make sure the csum goes with
++		 * the right disk offset.
++		 *
++		 * We can do this because the data reloc inode refers strictly
++		 * to the on disk bytes, so we don't have to worry about
++		 * disk_len vs real len like with real inodes since it's all
++		 * disk length.
++		 */
++		new_bytenr = ordered->start + (sums->bytenr - disk_bytenr);
++		sums->bytenr = new_bytenr;
+ 
+ 		btrfs_add_ordered_sum(inode, ordered, sums);
+ 	}
+-- 
+1.8.3.1
diff --git a/kernel.spec b/kernel.spec
index c83454a..57b9ed9 100644
--- a/kernel.spec
+++ b/kernel.spec
@@ -62,7 +62,7 @@ Summary: The Linux kernel
 # For non-released -rc kernels, this will be appended after the rcX and
 # gitX tags, so a 3 here would become part of release "0.rcX.gitX.3"
 #
-%global baserelease 200
+%global baserelease 201
 %global fedora_build %{baserelease}
 
 # base_sublevel is the kernel version we're starting with and patching
@@ -767,6 +767,9 @@ Patch25129: cpupower-Fix-segfault-due-to-incorrect-getopt_long-a.patch
 #rhbz 1010679
 Patch25130: fix-radeon-sound.patch
 
+#rhbz 1011714
+Patch25131: btrfs-relocate-csums-properly-with-prealloc-ext.patch
+
 # END OF PATCH DEFINITIONS
 
 %endif
@@ -1482,6 +1485,9 @@ ApplyPatch cpupower-Fix-segfault-due-to-incorrect-getopt_long-a.patch
 #rhbz 1010679
 ApplyPatch fix-radeon-sound.patch
 
+#rhbz 1011714
+ApplyPatch btrfs-relocate-csums-properly-with-prealloc-ext.patch
+
 # END OF PATCH APPLICATIONS
 
 %endif
@@ -2294,6 +2300,9 @@ fi
 # and build.
 
 %changelog
+* Wed Oct 16 2013 Josh Boyer <jwboyer at fedoraproject.org> 
+- Fix btrfs balance/scrub issue (rhbz 1011714)
+
 * Tue Oct 15 2013 Josh Boyer <jwboyer at fedoraproject.org>
 - Fix regression in radeon sound (rhbz 1010679)