On Wed, 2016-05-11 at 06:21 -0400, Jeff Layton wrote:
> If we get back something like NFS4ERR_OLD_STATEID, that will be
> translated into -EAGAIN, and the do/while loop in send_layoutget
> will drive the call again.
>
> This is not quite what we want, I think. An error like that is a
> sign that something has changed. That something could have been a
> concurrent LAYOUTGET that would give us a usable lseg.
>
> Lift the retry logic into pnfs_update_layout instead. That allows
> us to redo the layout search, and may spare us from having to issue
> an RPC.
>
> Signed-off-by: Jeff Layton <jeff.layton@xxxxxxxxxxxxxxx>
> ---
> fs/nfs/pnfs.c | 67 ++++++++++++++++++++++++++++++-----------------------------
> 1 file changed, 34 insertions(+), 33 deletions(-)
>
> diff --git a/fs/nfs/pnfs.c b/fs/nfs/pnfs.c
> index 5f6ed295acb5..ed3ab3e81f38 100644
> --- a/fs/nfs/pnfs.c
> +++ b/fs/nfs/pnfs.c
> @@ -839,7 +839,6 @@ send_layoutget(struct pnfs_layout_hdr *lo,
> struct inode *ino = lo->plh_inode;
> struct nfs_server *server = NFS_SERVER(ino);
> struct nfs4_layoutget *lgp;
> - struct pnfs_layout_segment *lseg;
> loff_t i_size;
>
> dprintk("--> %s\n", __func__);
> @@ -849,42 +848,30 @@ send_layoutget(struct pnfs_layout_hdr *lo,
> * store in lseg. If we race with a concurrent seqid morphing
> * op, then re-send the LAYOUTGET.
> */
> - do {
> - lgp = kzalloc(sizeof(*lgp), gfp_flags);
> - if (lgp == NULL)
> - return NULL;
> -
Just spotted this bug. The above should return ERR_PTR(-ENOMEM). Fixed
in my nfs-4.7 branch.
> - i_size = i_size_read(ino);
> -
> - lgp->args.minlength = PAGE_SIZE;
> - if (lgp->args.minlength > range->length)
> - lgp->args.minlength = range->length;
> - if (range->iomode == IOMODE_READ) {
> - if (range->offset >= i_size)
> - lgp->args.minlength = 0;
> - else if (i_size - range->offset < lgp->args.minlength)
> - lgp->args.minlength = i_size - range->offset;
> - }
> - lgp->args.maxcount = PNFS_LAYOUT_MAXSIZE;
> - pnfs_copy_range(&lgp->args.range, range);
> - lgp->args.type = server->pnfs_curr_ld->id;
> - lgp->args.inode = ino;
> - lgp->args.ctx = get_nfs_open_context(ctx);
> - lgp->gfp_flags = gfp_flags;
> - lgp->cred = lo->plh_lc_cred;
> + lgp = kzalloc(sizeof(*lgp), gfp_flags);
> + if (lgp == NULL)
> + return NULL;
>
> - lseg = nfs4_proc_layoutget(lgp, gfp_flags);
> - } while (lseg == ERR_PTR(-EAGAIN));
> + i_size = i_size_read(ino);
>
> - if (IS_ERR(lseg)) {
> - if (!nfs_error_is_fatal(PTR_ERR(lseg)))
> - lseg = NULL;
> - } else {
> - pnfs_layout_clear_fail_bit(lo,
> - pnfs_iomode_to_fail_bit(range->iomode));
> + lgp->args.minlength = PAGE_SIZE;
> + if (lgp->args.minlength > range->length)
> + lgp->args.minlength = range->length;
> + if (range->iomode == IOMODE_READ) {
> + if (range->offset >= i_size)
> + lgp->args.minlength = 0;
> + else if (i_size - range->offset < lgp->args.minlength)
> + lgp->args.minlength = i_size - range->offset;
> }
> + lgp->args.maxcount = PNFS_LAYOUT_MAXSIZE;
> + pnfs_copy_range(&lgp->args.range, range);
> + lgp->args.type = server->pnfs_curr_ld->id;
> + lgp->args.inode = ino;
> + lgp->args.ctx = get_nfs_open_context(ctx);
> + lgp->gfp_flags = gfp_flags;
> + lgp->cred = lo->plh_lc_cred;
>
> - return lseg;
> + return nfs4_proc_layoutget(lgp, gfp_flags);
> }
>
> static void pnfs_clear_layoutcommit(struct inode *inode,
> @@ -1646,6 +1633,20 @@ lookup_again:
> arg.length = PAGE_ALIGN(arg.length);
>
> lseg = send_layoutget(lo, ctx, &arg, gfp_flags);
> + if (IS_ERR(lseg)) {
> + if (lseg == ERR_PTR(-EAGAIN)) {
> + if (first)
> + pnfs_clear_first_layoutget(lo);
> + pnfs_put_layout_hdr(lo);
> + goto lookup_again;
> + }
> +
> + if (!nfs_error_is_fatal(PTR_ERR(lseg)))
> + lseg = NULL;
> + } else {
> + pnfs_layout_clear_fail_bit(lo, pnfs_iomode_to_fail_bit(iomode));
> + }
> +
> atomic_dec(&lo->plh_outstanding);
> trace_pnfs_update_layout(ino, pos, count, iomode, lo,
> PNFS_UPDATE_LAYOUT_SEND_LAYOUTGET);
--
Jeff Layton <jlayton@xxxxxxxxxxxxxxx>
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