Re: [PATCH 6/8] Fix btrfs/098 to work on non-4k block sized filesystems

Filipe Manana
2015-12-10T17:27:35Z

On Mon, Nov 30, 2015 at 10:17 AM, Chandan Rajendra
<chandan@linux.vnet.ibm.com> wrote:
> This commit makes use of the new _filter_xfs_io_blocks_modified filtering
> function to print information in terms of file blocks rather than file
> offset.
>
> Signed-off-by: Chandan Rajendra <chandan@linux.vnet.ibm.com>
Reviewed-by: Filipe Manana <fdmanana@suse.com>

Thanks!

> ---
> tests/btrfs/098 | 67 +++++++++++++++++++++++++++++------------------------
> tests/btrfs/098.out | 27 ++++++++++++++++-----
> 2 files changed, 58 insertions(+), 36 deletions(-)
>
> diff --git a/tests/btrfs/098 b/tests/btrfs/098
> index 8aef119..49f6d16 100755
> --- a/tests/btrfs/098
> +++ b/tests/btrfs/098
> @@ -58,43 +58,50 @@ _scratch_mkfs >>$seqres.full 2>&1
> _init_flakey
> _mount_flakey
>
> -# Create our test file with a single 100K extent starting at file offset 800K.
> -# We fsync the file here to make the fsync log tree gets a single csum item that
> -# covers the whole 100K extent, which causes the second fsync, done after the
> -# cloning operation below, to not leave in the log tree two csum items covering
> -# two sub-ranges ([0, 20K[ and [20K, 100K[)) of our extent.
> -$XFS_IO_PROG -f -c "pwrite -S 0xaa 800K 100K" \
> +BLOCK_SIZE=$(get_block_size $SCRATCH_MNT)
> +
> +# Create our test file with a single 25 block extent starting at file offset
> +# mapped by 200th block We fsync the file here to make the fsync log tree get a
> +# single csum item that covers the whole 25 block extent, which causes the
> +# second fsync, done after the cloning operation below, to not leave in the log
> +# tree two csum items covering two block sub-ranges ([0, 5[ and [5, 25[)) of our
> +# extent.
> +$XFS_IO_PROG -f -c "pwrite -S 0xaa $((200 * $BLOCK_SIZE)) $((25 * $BLOCK_SIZE))" \
> -c "fsync" \
> - $SCRATCH_MNT/foo | _filter_xfs_io
> + $SCRATCH_MNT/foo | _filter_xfs_io_blocks_modified
> +
>
> -# Now clone part of our extent into file offset 400K. This adds a file extent
> -# item to our inode's metadata that points to the 100K extent we created before,
> -# using a data offset of 20K and a data length of 20K, so that it refers to
> -# the sub-range [20K, 40K[ of our original extent.
> -$CLONER_PROG -s $((800 * 1024 + 20 * 1024)) -d $((400 * 1024)) \
> - -l $((20 * 1024)) $SCRATCH_MNT/foo $SCRATCH_MNT/foo
> +# Now clone part of our extent into file offset mapped by 100th block. This adds
> +# a file extent item to our inode's metadata that points to the 25 block extent
> +# we created before, using a data offset of 5 blocks and a data length of 5
> +# blocks, so that it refers to the block sub-range [5, 10[ of our original
> +# extent.
> +$CLONER_PROG -s $(((200 * $BLOCK_SIZE) + (5 * $BLOCK_SIZE))) \
> + -d $((100 * $BLOCK_SIZE)) -l $((5 * $BLOCK_SIZE)) \
> + $SCRATCH_MNT/foo $SCRATCH_MNT/foo
>
> # Now fsync our file to make sure the extent cloning is durably persisted. This
> # fsync will not add a second csum item to the log tree containing the checksums
> -# for the blocks in the sub-range [20K, 40K[ of our extent, because there was
> +# for the blocks in the block sub-range [5, 10[ of our extent, because there was
> # already a csum item in the log tree covering the whole extent, added by the
> # first fsync we did before.
> $XFS_IO_PROG -c "fsync" $SCRATCH_MNT/foo
>
> -echo "File digest before power failure:"
> -md5sum $SCRATCH_MNT/foo | _filter_scratch
> +echo "File contents before power failure:"
> +od -t x1 $SCRATCH_MNT/foo | _filter_od
>
> # The fsync log replay first processes the file extent item corresponding to the
> -# file offset 400K (the one which refers to the [20K, 40K[ sub-range of our 100K
> -# extent) and then processes the file extent item for file offset 800K. It used
> -# to happen that when processing the later, it erroneously left in the csum tree
> -# 2 csum items that overlapped each other, 1 for the sub-range [20K, 40K[ and 1
> -# for the whole range of our extent. This introduced a problem where subsequent
> -# lookups for the checksums of blocks within the range [40K, 100K[ of our extent
> -# would not find anything because lookups in the csum tree ended up looking only
> -# at the smaller csum item, the one covering the subrange [20K, 40K[. This made
> -# read requests assume an expected checksum with a value of 0 for those blocks,
> -# which caused checksum verification failure when the read operations finished.
> +# file offset mapped by 100th block (the one which refers to the [5, 10[ block
> +# sub-range of our 25 block extent) and then processes the file extent item for
> +# file offset mapped by 200th block. It used to happen that when processing the
> +# later, it erroneously left in the csum tree 2 csum items that overlapped each
> +# other, 1 for the block sub-range [5, 10[ and 1 for the whole range of our
> +# extent. This introduced a problem where subsequent lookups for the checksums
> +# of blocks within the block range [10, 25[ of our extent would not find
> +# anything because lookups in the csum tree ended up looking only at the smaller
> +# csum item, the one covering the block subrange [5, 10[. This made read
> +# requests assume an expected checksum with a value of 0 for those blocks, which
> +# caused checksum verification failure when the read operations finished.
> # However those checksum failure did not result in read requests returning an
> # error to user space (like -EIO for e.g.) because the expected checksum value
> # had the special value 0, and in that case btrfs set all bytes of the
> @@ -106,10 +113,10 @@ md5sum $SCRATCH_MNT/foo | _filter_scratch
> #
> _flakey_drop_and_remount
>
> -echo "File digest after log replay:"
> -# Must match the same digest he had after cloning the extent and before the
> -# power failure happened.
> -md5sum $SCRATCH_MNT/foo | _filter_scratch
> +echo "File contents after log replay:"
> +# Must match the file contents we had after cloning the extent and before
> +# the power failure happened.
> +od -t x1 $SCRATCH_MNT/foo | _filter_od
>
> _unmount_flakey
>
> diff --git a/tests/btrfs/098.out b/tests/btrfs/098.out
> index 3aa0772..98a96de 100644
> --- a/tests/btrfs/098.out
> +++ b/tests/btrfs/098.out
> @@ -1,7 +1,22 @@
> QA output created by 098
> -wrote 102400/102400 bytes at offset 819200
> -XXX Bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
> -File digest before power failure:
> -39b386375971248740ed8651d5a2ed9f SCRATCH_MNT/foo
> -File digest after log replay:
> -39b386375971248740ed8651d5a2ed9f SCRATCH_MNT/foo
> +Blocks modified: [200 - 224]
> +File contents before power failure:
> +0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
> +*
> +144 aa aa aa aa aa aa aa aa aa aa aa aa aa aa aa aa
> +*
> +151 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
> +*
> +310 aa aa aa aa aa aa aa aa aa aa aa aa aa aa aa aa
> +*
> +341
> +File contents after log replay:
> +0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
> +*
> +144 aa aa aa aa aa aa aa aa aa aa aa aa aa aa aa aa
> +*
> +151 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
> +*
> +310 aa aa aa aa aa aa aa aa aa aa aa aa aa aa aa aa
> +*
> +341
> --
> 2.1.0
>

--
Filipe David Manana,

"Reasonable men adapt themselves to the world.
Unreasonable men adapt the world to themselves.
That's why all progress depends on unreasonable men."