linux-ext4 - Re: [PATCH v2] resize2fs: resize2fs disk hardlinks will be error

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Message-ID: <43391b1d-d58c-f954-e861-1176eac48443@huawei.com>
Date:   Thu, 24 Feb 2022 16:28:52 +0800
From:   zhanchengbin <zhanchengbin1@...wei.com>
To:     Theodore Ts'o <tytso@....edu>
CC:     <linux-ext4@...r.kernel.org>, <liuzhiqiang26@...wei.com>,
        linfeilong <linfeilong@...wei.com>
Subject: Re: [PATCH v2] resize2fs: resize2fs disk hardlinks will be error

friendly ping..

在 2022/1/4 22:23, zhanchengbin 写道:
> Resize2fs disk hardlinks which mounting after the same name as tmpfs
>   filesystem it will be error. The items in /proc/mounts are traversed,
> when you get to tmpfs,file!=mnt->mnt_fsname, therefore, the
> stat(mnt->mnt_fsname, &st_buf) branch is used, however, the values of
>   file_rdev and st_buf.st_rdev are the same. As a result, the system
> mistakenly considers that disk is mounted to /root/tmp. As a result
> , resize2fs fails.
> 
> example:
> dev_name="/dev/sdc" (ps: a disk in you self)
> mkdir /root/tmp
> mkdir /root/mnt
> mkfs.ext4 -F -b 1024 -E "resize=10000000" "${dev_name}" 32768
> mount -t tmpfs "${dev_name}" /root/tmp
> mount "${dev_name}" /root/mnt
> ln "${dev_name}" "${dev_name}"-ln
> resize2fs "${dev_name}"-ln 6G
> 
> Signed-off-by: zhanchengbin <zhanchengbin1@...wei.com>
> Signed-off-by: Zhiqiang Liu <liuzhiqiang26@...wei.com>
> 
> ---
>   lib/ext2fs/ismounted.c | 9 +++++++--
>   1 file changed, 7 insertions(+), 2 deletions(-)
> 
> diff --git a/lib/ext2fs/ismounted.c b/lib/ext2fs/ismounted.c
> index aee7d726..463a82a6 100644
> --- a/lib/ext2fs/ismounted.c
> +++ b/lib/ext2fs/ismounted.c
> @@ -98,6 +98,7 @@ static errcode_t check_mntent_file(const char 
> *mtab_file, const char *file,
>   {
>       struct mntent     *mnt;
>       struct stat    st_buf;
> +    struct stat    dir_st_buf;
>       errcode_t    retval = 0;
>       dev_t        file_dev=0, file_rdev=0;
>       ino_t        file_ino=0;
> @@ -144,8 +145,12 @@ static errcode_t check_mntent_file(const char 
> *mtab_file, const char *file,
>           if (stat(mnt->mnt_fsname, &st_buf) == 0) {
>               if (ext2fsP_is_disk_device(st_buf.st_mode)) {
>   #ifndef __GNU__
> -                if (file_rdev && (file_rdev == st_buf.st_rdev))
> -                    break;
> +                if (file_rdev && (file_rdev == st_buf.st_rdev)) {
> +                    if (stat(mnt->mnt_dir, &dir_st_buf) != 0)
> +                        continue;
> +                    if (file_rdev == dir_st_buf.st_dev)
> +                        break;
> +                }
>                   if (check_loop_mounted(mnt->mnt_fsname,
>                           st_buf.st_rdev, file_dev,
>                           file_ino) == 1)