On Fri, Feb 6, 2015 at 8:42 AM, Zhaolei <zhaolei@xxxxxxxxxxxxxx> wrote:
> From: Zhao Lei <zhaolei@xxxxxxxxxxxxxx>
>
> Btrfs will report NO_SPACE when we create and remove files for several times:
> 1: Create a single-dev btrfs fs with default option
> 2: Write a file into it to take up most fs space
> 3: Delete above file
> 4: Wait about 100s to let chunk removed
> 5: goto 2
>
> Script is like following:
> #!/bin/bash
>
> # Recommend 1.2G space, too large disk will make test slow
> DEV="/dev/sda16"
> MNT="/mnt/tmp"
>
> dev_size="$(lsblk -bn -o SIZE "$DEV")" || exit 2
> file_size_m=$((dev_size * 75 / 100 / 1024 / 1024))
>
> echo "Loop write ${file_size_m}M file on $((dev_size / 1024 / 1024))M dev"
>
> for ((i = 0; i < 10; i++)); do umount "$MNT" 2>/dev/null; done
> echo "mkfs $DEV"
> mkfs.btrfs -f "$DEV" >/dev/null || exit 2
> echo "mount $DEV $MNT"
> mount "$DEV" "$MNT" || exit 2
>
> for ((loop_i = 0; loop_i < 20; loop_i++)); do
> echo
> echo "loop $loop_i"
>
> echo "dd file..."
> cmd=(dd if=/dev/zero of="$MNT"/file0 bs=1M count="$file_size_m")
> "${cmd[@]}" 2>/dev/null || {
> # NO_SPACE error triggered
> echo "dd failed: ${cmd[*]}"
> exit 1
> }
>
> echo "rm file..."
> rm -f "$MNT"/file0 || exit 2
>
> for ((i = 0; i < 10; i++)); do
> df "$MNT" | tail -1
> sleep 10
> done
> done
>
> Reason:
> When we get a free space segment with pending_extent in
> find_free_dev_extent(), we need bypass pending_extent segment in
> front and continue to use free space segment in tail.
> But current code ignored whole dev_extent, and cause NO_SPACE in
> some case.
>
> Fix:
> Adjust hole_size to real free space value instead of 0 in
> find_free_dev_extent().
>
> Reported-by: Tsutomu Itoh <t-itoh@xxxxxxxxxxxxxx>
>
> Signed-off-by: Zhao Lei <zhaolei@xxxxxxxxxxxxxx>
This was already fixed by Forrest recently. See:
https://patchwork.kernel.org/patch/5776231/
> ---
> fs/btrfs/volumes.c | 8 ++++++--
> 1 file changed, 6 insertions(+), 2 deletions(-)
>
> diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
> index 5cd0930..0cc9422 100644
> --- a/fs/btrfs/volumes.c
> +++ b/fs/btrfs/volumes.c
> @@ -1194,8 +1194,12 @@ again:
> */
> if (contains_pending_extent(trans, device,
> &search_start,
> - hole_size))
> - hole_size = 0;
> + hole_size)) {
> + if (search_start > key.offset)
> + hole_size = 0;
> + else
> + hole_size = key.offset - search_start;
> + }
>
> if (hole_size > max_hole_size) {
> max_hole_start = search_start;
> --
> 1.8.5.1
>
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Unreasonable men adapt the world to themselves.
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