On Tue, 2020-03-10 at 19:34 +0800, Yan, Zheng wrote:
> Returns 0 if caps were not able to be acquired (yet), 1 if succeed,
> or a negative error code. There are 3 speical error codes:
>
> -EAGAIN: need to sleep but non-blocking is specified
> -EFBIG: ask caller to call check_max_size() and try again.
> -ESTALE: ask caller to call ceph_renew_caps() and try again.
>
> Signed-off-by: "Yan, Zheng" <zyan@xxxxxxxxxx>
> ---
> fs/ceph/caps.c | 25 ++++++++++++++-----------
> 1 file changed, 14 insertions(+), 11 deletions(-)
>
> diff --git a/fs/ceph/caps.c b/fs/ceph/caps.c
> index 342a32c74c64..804f4c65251a 100644
> --- a/fs/ceph/caps.c
> +++ b/fs/ceph/caps.c
> @@ -2530,10 +2530,11 @@ void ceph_take_cap_refs(struct ceph_inode_info *ci, int got,
> * Note that caller is responsible for ensuring max_size increases are
> * requested from the MDS.
> *
> - * Returns 0 if caps were not able to be acquired (yet), a 1 if they were,
> - * or a negative error code.
> - *
> - * FIXME: how does a 0 return differ from -EAGAIN?
> + * Returns 0 if caps were not able to be acquired (yet), 1 if succeed,
> + * or a negative error code. There are 3 speical error codes:
> + * -EAGAIN: need to sleep but non-blocking is specified
> + * -EFBIG: ask caller to call check_max_size() and try again.
> + * -ESTALE: ask caller to call ceph_renew_caps() and try again.
> */
> enum {
> /* first 8 bits are reserved for CEPH_FILE_MODE_FOO */
> @@ -2581,7 +2582,7 @@ static int try_get_cap_refs(struct inode *inode, int need, int want,
> dout("get_cap_refs %p endoff %llu > maxsize %llu\n",
> inode, endoff, ci->i_max_size);
> if (endoff > ci->i_requested_max_size)
> - ret = -EAGAIN;
> + ret = -EFBIG;
> goto out_unlock;
> }
> /*
> @@ -2743,7 +2744,10 @@ int ceph_try_get_caps(struct inode *inode, int need, int want,
> flags |= NON_BLOCKING;
>
> ret = try_get_cap_refs(inode, need, want, 0, flags, got);
> - return ret == -EAGAIN ? 0 : ret;
> + /* three special error codes */
> + if (ret == -EAGAIN || ret == -EFBIG || ret == -EAGAIN)
> + ret = 0;
> + return ret;
> }
>
> /*
> @@ -2771,17 +2775,12 @@ int ceph_get_caps(struct file *filp, int need, int want,
> flags = get_used_fmode(need | want);
>
> while (true) {
> - if (endoff > 0)
> - check_max_size(inode, endoff);
> -
> flags &= CEPH_FILE_MODE_MASK;
> if (atomic_read(&fi->num_locks))
> flags |= CHECK_FILELOCK;
> _got = 0;
> ret = try_get_cap_refs(inode, need, want, endoff,
> flags, &_got);
> - if (ret == -EAGAIN)
> - continue;
Ok, so I guess we don't expect to see this error here since we didn't
set NON_BLOCKING. The error returns from try_get_cap_refs are pretty
complex, and I worry a little about future changes subtly breaking some
of these assumptions.
Maybe a WARN_ON_ONCE(ret == -EAGAIN) here would be good?
> if (!ret) {
> struct ceph_mds_client *mdsc = fsc->mdsc;
> struct cap_wait cw;
> @@ -2829,6 +2828,10 @@ int ceph_get_caps(struct file *filp, int need, int want,
> }
>
> if (ret < 0) {
> + if (ret == -EFBIG) {
> + check_max_size(inode, endoff);
> + continue;
> + }
> if (ret == -ESTALE) {
> /* session was killed, try renew caps */
> ret = ceph_renew_caps(inode, flags);
--
Jeff Layton <jlayton@xxxxxxxxxx>
