Hi Satoru and all,
I think there maybe a leftover issue.
That is if we don't set label, in default it will output a blank line.
Steps to reproduce:
# mkfs.btrfs -f /dev/sdb
# mount /dev/sdb
# cat /sys/fs/btrfs/<uuid>/label -->an extra line will be outputed.
This is because in btrfs_label_show(), we did something like this directly:
return snprintf(buf, PAGE_SIZE, "%s\n", fs_info->super_copy->label);
Maybe we can have a check whether label is NULL before we output?
otherwise,the
extra blank line is outputed, IMO this is not so nice thing!
Thanks,
Wang
On 07/01/2014 01:22 PM, Satoru Takeuchi wrote:
> Although Anand once sent the following two patches,
>
> - [PATCH 1/2 v4] btrfs: label should not contain return char
> - [PATCH 2/2 v4] btrfs: usage error should not be logged into system log
>
> only the latter patch was merged to mason/for-linus and 3.16-rc3
> as 402a0f4 (by accident?). It results in that the former patch can't
> be cleanly applied to 3.16-rc3.
>
> I fixed this problem, wrote a reproducer, and tested it.
>
> Test Result:
> 3.16-rc3 w/o this patch: fail
> 3.16-rc3 w/ this patch: pass
>
>
>
> Subject: [PATCH v5] btrfs: label should not contain return char
>
> From: Anand Jain <Anand.Jain@xxxxxxxxxx>
>
> generally if you use
> echo "test" > /sys/fs/btrfs/<fsid>/label
> it would introduce return char at the end and it can not
> be part of the label. The correct command is
> echo -n "test" > /sys/fs/btrfs/<fsid>/label
>
> This patch will check for this user error
>
> reproducer.sh:
> ===============================================================================
> #!/bin/bash
>
> TEST_DEV=/dev/vdb
> TEST_DIR=/home/sat/mnt
>
> umount /home/sat/mnt
>
> mkfs.btrfs -f $TEST_DEV
> UUID=$(btrfs fi show $TEST_DEV | head -1 | sed -e 's/.*uuid: \([-0-9a-z]*\)$/\1/')
> mount $TEST_DEV $TEST_DIR
> LABELFILE=/sys/fs/btrfs/$UUID/label
>
> echo testlabel >$LABELFILE
> LINES="$(cat $LABELFILE | wc -l | awk '{print $1}')"
>
> RET=1
> if [ $LINES -eq 1 ] ; then
> echo '[PASS] Trailing \n is removed correctly.' >&2
> RET=0
> else
> echo '[FAIL] Trailing \n still exists.' >&2
> fi
>
> exit $RET
> ===============================================================================
>
> Signed-off-by: Anand Jain <Anand.Jain@xxxxxxxxxx>
> Signed-off-by: Satoru Takeuchi <takeuchi_satoru@xxxxxxxxxxxxxx>
> Reviewed-by: Satoru Takeuchi <takeuchi_satoru@xxxxxxxxxxxxxx>
> Tested-by: Satoru Takeuchi <takeuchi_satoru@xxxxxxxxxxxxxx>
> ---
> v5: tweak to be able to apply on the top of 402a0f4.
> add test program.
> v4: used memcpy and memset. Thanks David again
> v3: accepts review comments. Thanks David and Eric again
> v2: accepts review comments. Thanks Eric and Roman
>
> ---
> fs/btrfs/sysfs.c | 12 ++++++++++--
> 1 file changed, 10 insertions(+), 2 deletions(-)
>
> diff --git a/fs/btrfs/sysfs.c b/fs/btrfs/sysfs.c
> index df39458..dcae61a 100644
> --- a/fs/btrfs/sysfs.c
> +++ b/fs/btrfs/sysfs.c
> @@ -374,8 +374,15 @@ static ssize_t btrfs_label_store(struct kobject *kobj,
> struct btrfs_trans_handle *trans;
> struct btrfs_root *root = fs_info->fs_root;
> int ret;
> + size_t p_len;
>
> - if (len >= BTRFS_LABEL_SIZE)
> + /*
> + * p_len is the len until the first occurrence of either
> + * '\n' or '\0'
> + */
> + p_len = strcspn(buf, "\n");
> +
> + if (p_len >= BTRFS_LABEL_SIZE)
> return -EINVAL;
>
> trans = btrfs_start_transaction(root, 0);
> @@ -383,7 +390,8 @@ static ssize_t btrfs_label_store(struct kobject *kobj,
> return PTR_ERR(trans);
>
> spin_lock(&root->fs_info->super_lock);
> - strcpy(fs_info->super_copy->label, buf);
> + memset(fs_info->super_copy->label, 0, BTRFS_LABEL_SIZE);
> + memcpy(fs_info->super_copy->label, buf, p_len);
> spin_unlock(&root->fs_info->super_lock);
> ret = btrfs_commit_transaction(trans, root);
>
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