On Mon, May 4, 2020 at 10:50 PM Lubos Dolezel <lubos@xxxxxxxxxxxx> wrote:
>
> Hello,
>
> overlayfs doesn't work well with the fanotify mechanism.
>
> Fanotify first probes for the required buffer size for the file handle,
> but overlayfs currently bails out without passing the size back.
>
> That results in errors in the kernel log, such as:
>
> [527944.485384] overlayfs: failed to encode file handle (/, err=-75, buflen=0, len=29, type=1)
> [527944.485386] fanotify: failed to encode fid (fsid=ae521e68.a434d95f, type=255, bytes=0, err=-2)
>
> Lubos
Hi Lubos,
Thank you for the fix.
Please leave greeting (Hello) and this line outside of the commit message.
You may add extra notes for email after --- line
>
> Signed-off-by: Lubos Dolezel <lubos@xxxxxxxxxxxx>
After fixing below you may add for v2:
Reviewed-by: Amir Goldstein <amir73il@xxxxxxxxx>
> ---
> fs/overlayfs/export.c | 16 ++++++++--------
> 1 file changed, 8 insertions(+), 8 deletions(-)
>
> diff --git a/fs/overlayfs/export.c b/fs/overlayfs/export.c
> index 475c61f53..0068bf3a0 100644
> --- a/fs/overlayfs/export.c
> +++ b/fs/overlayfs/export.c
> @@ -231,12 +231,9 @@ static int ovl_dentry_to_fid(struct dentry *dentry, u32 *fid, int buflen)
> if (IS_ERR(fh))
> return PTR_ERR(fh);
>
> - err = -EOVERFLOW;
> len = OVL_FH_LEN(fh);
> - if (len > buflen)
> - goto fail;
in pr_warn_ratelimited() under fail label, all printed values after 'err' are
now irrelevant for the warning. please remove them.
> -
> - memcpy(fid, fh, len);
> + if (buflen >= len)
> + memcpy(fid, fh, len);
> err = len;
>
> out:
> @@ -255,6 +252,7 @@ static int ovl_encode_fh(struct inode *inode, u32 *fid, int *max_len,
> {
> struct dentry *dentry;
> int bytes = *max_len << 2;
> + int bytes_used;
Please use these variable names instead to make code clearer:
int bytes, buflen = *max_len << 2;
BTW, do you plan to backport this patch to stable kernel 5.4?
Because this patch will not apply cleanly, but we should fix this in stable.
Thanks,
Amir.
