On 2/27/18 4:44 AM, Yang Joseph wrote:
> xfs_repair should not touch non-xfs mountpoints in platform_check_mount().
> If non-xfs mountpoints can be filtered out, the dead fuse mountpoint can
> never block our xfs_repair. The following patch can fix my problem and not
> add dangerous option to xfs_repair.
I don't think this is a safe solution. For example:
# mkfs.ext4 /dev/sdb1
# mount /dev/sdb1 /mnt/test
Old behavior:
# xfs_repair /dev/sdb1
xfs_repair: /dev/sdb1 contains a mounted filesystem
New behavior with your patch:
# repair/xfs_repair /dev/sdb1
xfs_repair: cannot open /dev/sdb1: Device or resource busy
With your patch, if we explicitly ask xfs_repair to repair a non-xfs
filesystem which is mounted, it will get past all of the checks and
try to open the device O_EXCL - which should fail if the device is
mounted, but I'm guessing your fuse case would now simply hang here
instead.
Worse, other utilities aren't so graceful.
Old:
# xfs_copy /dev/sdb2 /dev/sdb1
xfs_copy: a filesystem is mounted on target device "/dev/sdb1".
xfs_copy cannot copy to mounted filesystems. Aborting
New:
copy/xfs_copy /dev/sdb2 /dev/sdb1
0% ... 10% ... 20% ... 30% ... 40% ... 50% ... 60% ... 70% ... 80% ... 90% ... 100%
All copies completed.
(now we've just written over a mounted, writable ext4 filesystem)
(Anyone want to investigate whether every device open in xfsprogs should
be O_EXCL?)
Also, in general:
When sending a patch to the list, please prefix the subject with
[PATCH] to make it obvious; patches also require a Signed-off-by:
line similar to:
Signed-off-by: Yang Joseph <joseph.yang@xxxxxxxxxxxx>
The Signed-off-by: tag indicates that the signer was involved in the
development of the patch.
It essentially states that you are the author of this work and you have
the right to submit it for inclusion in this project.
Thanks,
-Eric
> thx,
>
> Yang Honggang
>
> -------------------------new patch----------------------
> diff --git a/libxfs/linux.c b/libxfs/linux.c
> index 0bace3e..6ad24ce 100644
> --- a/libxfs/linux.c
> +++ b/libxfs/linux.c
> @@ -44,6 +44,7 @@ static int max_block_alignment;
> #endif
>
> #define PROC_MOUNTED "/proc/mounts"
> +#define MNTTYPE_XFS "xfs"
indentation should be consistent with the string above; the whole
patch is whitespace-mangled and won't apply.
>
> /*
> * Check if the filesystem is mounted. Be verbose if asked, and
> @@ -78,6 +79,9 @@ platform_check_mount(char *name, char *block, struct stat *s, int flags)
> return 1;
> }
> while ((mnt = getmntent(f)) != NULL) {
> + /* filter out non xfs mountpoint */
> + if (strncmp(mnt->mnt_type, MNTTYPE_XFS, strlen(mnt->mnt_type)))
> + continue;
> if (stat(mnt->mnt_dir, &mst) < 0)
> continue;
> if (mst.st_dev != s->st_rdev)
> -------------------------new patch end-----------------
>
> On 02/25/2018 06:04 AM, Dave Chinner wrote:
>> On Sat, Feb 24, 2018 at 11:56:44AM -0600, Eric Sandeen wrote:
>>> On 2/24/18 5:23 AM, Yang Joseph wrote:
>>>> hello,
>>>>
>>>> Before the repair process, xfs_repair will check if user specified device already
>>>> has a writable mountpoint. And it will stat all the mountpoints of the system. If there
>>>> is a dead mountpoint, this checking will be blocked and xfs_repair will enter 'D' state.
>> So why is the mount point dead?
>>
>> That kinda means that the filesystem is still mounted, but something
>> has hung somewhere and the filesystem may still have active
>> references to the underlying device and be doing stuff that is
>> modifying the filesystem....
>>
>> And if the device is still busy, then you aren't going to be able to
>> mount the repaired device, anyway, because the block device is still
>> busy...
>>
>>> That sounds like a bug worth fixing, but I am much
>>> less excited about adding options which could do serious damage
>>> to a filesystem.
>> TO me it sounds like something that should be fixed by a reboot, not
>> by adding dangerous options to xfs_repair...
>>
>> Cheers,
>>
>> Dave.
>
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