64 lines
2.5 KiB
Diff
64 lines
2.5 KiB
Diff
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From 4577b014d1bc3db386da3246f625888fc48083a9 Mon Sep 17 00:00:00 2001
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From: Josef Bacik <jbacik@fusionio.com>
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Date: Fri, 27 Sep 2013 13:33:09 +0000
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Subject: Btrfs: relocate csums properly with prealloc extents
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A user reported a problem where they were getting csum errors when running a
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balance and running systemd's journal. This is because systemd is awesome and
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fallocate()'s its log space and writes into it. Unfortunately we assume that
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when we read in all the csums for an extent that they are sequential starting at
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the bytenr we care about. This obviously isn't the case for prealloc extents,
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where we could have written to the middle of the prealloc extent only, which
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means the csum would be for the bytenr in the middle of our range and not the
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front of our range. Fix this by offsetting the new bytenr we are logging to
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based on the original bytenr the csum was for. With this patch I no longer see
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the csum errors I was seeing. Thanks,
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Cc: stable@vger.kernel.org
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Reported-by: Chris Murphy <lists@colorremedies.com>
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Signed-off-by: Josef Bacik <jbacik@fusionio.com>
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Signed-off-by: Chris Mason <chris.mason@fusionio.com>
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---
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diff --git a/fs/btrfs/relocation.c b/fs/btrfs/relocation.c
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index dec4f5a..0359eec 100644
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--- a/fs/btrfs/relocation.c
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+++ b/fs/btrfs/relocation.c
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@@ -4472,6 +4472,7 @@ int btrfs_reloc_clone_csums(struct inode *inode, u64 file_pos, u64 len)
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struct btrfs_root *root = BTRFS_I(inode)->root;
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int ret;
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u64 disk_bytenr;
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+ u64 new_bytenr;
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LIST_HEAD(list);
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ordered = btrfs_lookup_ordered_extent(inode, file_pos);
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@@ -4483,13 +4484,24 @@ int btrfs_reloc_clone_csums(struct inode *inode, u64 file_pos, u64 len)
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if (ret)
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goto out;
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- disk_bytenr = ordered->start;
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while (!list_empty(&list)) {
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sums = list_entry(list.next, struct btrfs_ordered_sum, list);
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list_del_init(&sums->list);
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- sums->bytenr = disk_bytenr;
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- disk_bytenr += sums->len;
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+ /*
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+ * We need to offset the new_bytenr based on where the csum is.
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+ * We need to do this because we will read in entire prealloc
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+ * extents but we may have written to say the middle of the
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+ * prealloc extent, so we need to make sure the csum goes with
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+ * the right disk offset.
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+ *
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+ * We can do this because the data reloc inode refers strictly
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+ * to the on disk bytes, so we don't have to worry about
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+ * disk_len vs real len like with real inodes since it's all
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+ * disk length.
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+ */
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+ new_bytenr = ordered->start + (sums->bytenr - disk_bytenr);
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+ sums->bytenr = new_bytenr;
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btrfs_add_ordered_sum(inode, ordered, sums);
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}
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--
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