Hi Greg,
This was not marked for stable but seems it should be in stable.
Please apply to your queue of 4.14-stable.
--
Regards
Sudip
>From 6424105f11028f62bf0f6ef78df95d37e45647ec Mon Sep 17 00:00:00 2001
From: Filipe Manana <fdmanana@xxxxxxxx>
Date: Mon, 26 Mar 2018 23:59:00 +0100
Subject: [PATCH] Btrfs: fix fsync after hole punching when using no-holes feature
commit 4ee3fad34a9cc2cf33303dfbd0cf554248651c86 upstream
When we have the no-holes mode enabled and fsync a file after punching a
hole in it, we can end up not logging the whole hole range in the log tree.
This happens if the file has extent items that span more than one leaf and
we punch a hole that covers a range that starts in a leaf but does not go
beyond the offset of the first extent in the next leaf.
Example:
$ mkfs.btrfs -f -O no-holes -n 65536 /dev/sdb
$ mount /dev/sdb /mnt
$ for ((i = 0; i <= 831; i++)); do
offset=$((i * 2 * 256 * 1024))
xfs_io -f -c "pwrite -S 0xab -b 256K $offset 256K" \
/mnt/foobar >/dev/null
done
$ sync
# We now have 2 leafs in our filesystem fs tree, the first leaf has an
# item corresponding the extent at file offset 216530944 and the second
# leaf has a first item corresponding to the extent at offset 217055232.
# Now we punch a hole that partially covers the range of the extent at
# offset 216530944 but does go beyond the offset 217055232.
$ xfs_io -c "fpunch $((216530944 + 128 * 1024 - 4000)) 256K" /mnt/foobar
$ xfs_io -c "fsync" /mnt/foobar
<power fail>
# mount to replay the log
$ mount /dev/sdb /mnt
# Before this patch, only the subrange [216658016, 216662016[ (length of
# 4000 bytes) was logged, leaving an incorrect file layout after log
# replay.
Fix this by checking if there is a hole between the last extent item that
we processed and the first extent item in the next leaf, and if there is
one, log an explicit hole extent item.
Fixes: 16e7549f045d ("Btrfs: incompatible format change to remove hole extents")
Signed-off-by: Filipe Manana <fdmanana@xxxxxxxx>
Signed-off-by: David Sterba <dsterba@xxxxxxxx>
Signed-off-by: Sudip Mukherjee <sudipm.mukherjee@xxxxxxxxx>
---
fs/btrfs/tree-log.c | 30 ++++++++++++++++++++++++++++++
1 file changed, 30 insertions(+)
diff --git a/fs/btrfs/tree-log.c b/fs/btrfs/tree-log.c
index e1b4a59485df..3ecff6dd85f1 100644
--- a/fs/btrfs/tree-log.c
+++ b/fs/btrfs/tree-log.c
@@ -3959,6 +3959,36 @@ static noinline int copy_items(struct btrfs_trans_handle *trans,
break;
*last_extent = extent_end;
}
+
+ /*
+ * Check if there is a hole between the last extent found in our leaf
+ * and the first extent in the next leaf. If there is one, we need to
+ * log an explicit hole so that at replay time we can punch the hole.
+ */
+ if (ret == 0 &&
+ key.objectid == btrfs_ino(inode) &&
+ key.type == BTRFS_EXTENT_DATA_KEY &&
+ i == btrfs_header_nritems(src_path->nodes[0])) {
+ ret = btrfs_next_leaf(inode->root, src_path);
+ need_find_last_extent = true;
+ if (ret > 0) {
+ ret = 0;
+ } else if (ret == 0) {
+ btrfs_item_key_to_cpu(src_path->nodes[0], &key,
+ src_path->slots[0]);
+ if (key.objectid == btrfs_ino(inode) &&
+ key.type == BTRFS_EXTENT_DATA_KEY &&
+ *last_extent < key.offset) {
+ const u64 len = key.offset - *last_extent;
+
+ ret = btrfs_insert_file_extent(trans, log,
+ btrfs_ino(inode),
+ *last_extent, 0,
+ 0, len, 0, len,
+ 0, 0, 0);
+ }
+ }
+ }
/*
* Need to let the callers know we dropped the path so they should
* re-search.
--
2.11.0
