> On Nov 10, 2017, at 5:37 PM, Joshua Watt <jpewhacker@xxxxxxxxx> wrote:
>
> Specifying the serverfailed mount option causes all subsequent RPC tasks
> that are queued to fail with -EIO instead of timing out. For example, if
> a server has disappeared, the sequence:
>
> mount -o remount,serverfailed
> umount -f
>
> will ensure that all pending I/O requests are cancelled, and any new
> requests will also fail. In the event that the server returns, the flag
> can be removed with a remount:
>
> mount -o remount,noserverfailed
>
> Although bringing the server back may result in a loss of data
Hi Joshua, interesting work!
A couple of things I'm wondering:
1. Does this also change the serverfailed setting on submounts
(ie mounts that the kernel did when traversing an NFSv4 referral or
when going from the server's pseudofs into a real fs). These need
to be unmounted first before the parent mount can be unmounted,
and in the latter case they would all be backed by the same stuck
NFS server.
2. If there is a hanging sync(2), does the umount -f unstick it?
That seems relevant for Neil's "make shutdown reliable" use case.
I would like a stuck NFS mount not to result in local file system
corruption, if possible, during a hard shutdown.
> Signed-off-by: Joshua Watt <JPEWhacker@xxxxxxxxx>
> ---
> fs/nfs/inode.c | 6 ++++++
> fs/nfs/super.c | 30 +++++++++++++++++++++++++-----
> include/uapi/linux/nfs_mount.h | 1 +
> 3 files changed, 32 insertions(+), 5 deletions(-)
>
> diff --git a/fs/nfs/inode.c b/fs/nfs/inode.c
> index 134d9f560240..55b7cd40508d 100644
> --- a/fs/nfs/inode.c
> +++ b/fs/nfs/inode.c
> @@ -723,6 +723,12 @@ static void nfs_readdirplus_parent_cache_hit(struct dentry *dentry)
>
> static bool nfs_need_revalidate_inode(struct inode *inode)
> {
> + /* If the server has failed, it is not going to respond, so don't try
> + * and revalidated (otherwise, the serverfailed flag can't be cleared by
> + * a remount)
> + */
> + if (NFS_SERVER(inode)->flags & NFS_MOUNT_SERVERFAILED)
> + return false;
> if (NFS_I(inode)->cache_validity &
> (NFS_INO_INVALID_ATTR|NFS_INO_INVALID_LABEL))
> return true;
> diff --git a/fs/nfs/super.c b/fs/nfs/super.c
> index 777a0cc22704..bca38e1cdd85 100644
> --- a/fs/nfs/super.c
> +++ b/fs/nfs/super.c
> @@ -90,6 +90,7 @@ enum {
> Opt_resvport, Opt_noresvport,
> Opt_fscache, Opt_nofscache,
> Opt_migration, Opt_nomigration,
> + Opt_serverfailed, Opt_noserverfailed,
>
> /* Mount options that take integer arguments */
> Opt_port,
> @@ -151,6 +152,8 @@ static const match_table_t nfs_mount_option_tokens = {
> { Opt_nofscache, "nofsc" },
> { Opt_migration, "migration" },
> { Opt_nomigration, "nomigration" },
> + { Opt_serverfailed, "serverfailed" },
> + { Opt_noserverfailed, "noserverfailed" },
>
> { Opt_port, "port=%s" },
> { Opt_rsize, "rsize=%s" },
> @@ -637,6 +640,7 @@ static void nfs_show_mount_options(struct seq_file *m, struct nfs_server *nfss,
> { NFS_MOUNT_NORDIRPLUS, ",nordirplus", "" },
> { NFS_MOUNT_UNSHARED, ",nosharecache", "" },
> { NFS_MOUNT_NORESVPORT, ",noresvport", "" },
> + { NFS_MOUNT_SERVERFAILED, ",serverfailed", "" },
> { 0, NULL, NULL }
> };
> const struct proc_nfs_info *nfs_infop;
> @@ -1330,6 +1334,11 @@ static int nfs_parse_mount_options(char *raw,
> case Opt_nomigration:
> mnt->options &= ~NFS_OPTION_MIGRATION;
> break;
> + case Opt_serverfailed:
> + case Opt_noserverfailed:
> + set_flag(mnt, NFS_MOUNT_SERVERFAILED,
> + token == Opt_serverfailed);
> + break;
>
> /*
> * options that take numeric values
> @@ -2192,6 +2201,8 @@ static int nfs_validate_text_mount_data(void *options,
> return -EINVAL;
> }
>
> +#define NFS_REMOUNT_CHANGE_FLAGS (NFS_MOUNT_SERVERFAILED)
> +
> #define NFS_REMOUNT_CMP_FLAGMASK ~(NFS_MOUNT_INTR \
> | NFS_MOUNT_SECURE \
> | NFS_MOUNT_TCP \
> @@ -2200,7 +2211,8 @@ static int nfs_validate_text_mount_data(void *options,
> | NFS_MOUNT_NONLM \
> | NFS_MOUNT_BROKEN_SUID \
> | NFS_MOUNT_STRICTLOCK \
> - | NFS_MOUNT_LEGACY_INTERFACE)
> + | NFS_MOUNT_LEGACY_INTERFACE \
> + | NFS_REMOUNT_CHANGE_FLAGS)
>
> #define NFS_MOUNT_CMP_FLAGMASK (NFS_REMOUNT_CMP_FLAGMASK & \
> ~(NFS_MOUNT_UNSHARED | NFS_MOUNT_NORESVPORT))
> @@ -2209,12 +2221,15 @@ static int
> nfs_compare_and_set_remount_data(struct nfs_server *nfss,
> struct nfs_parsed_mount_data *data)
> {
> + int changed_flags_mask = data->flags_mask & NFS_REMOUNT_CHANGE_FLAGS;
> + struct rpc_clnt *cl = nfss->client;
> +
> if ((data->flags ^ nfss->flags) & NFS_REMOUNT_CMP_FLAGMASK ||
> data->rsize != nfss->rsize ||
> data->wsize != nfss->wsize ||
> data->version != nfss->nfs_client->rpc_ops->version ||
> data->minorversion != nfss->nfs_client->cl_minorversion ||
> - !nfs_auth_info_match(&data->auth_info, nfss->client->cl_auth->au_flavor) ||
> + !nfs_auth_info_match(&data->auth_info, cl->cl_auth->au_flavor) ||
> data->acregmin != nfss->acregmin / HZ ||
> data->acregmax != nfss->acregmax / HZ ||
> data->acdirmin != nfss->acdirmin / HZ ||
> @@ -2225,13 +2240,16 @@ nfs_compare_and_set_remount_data(struct nfs_server *nfss,
> (struct sockaddr *)&nfss->nfs_client->cl_addr))
> return -EINVAL;
>
> - if (data->retrans != nfss->client->cl_timeout->to_retries ||
> - data->timeo != (10U * nfss->client->cl_timeout->to_initval / HZ)) {
> + /* Update flags */
> + nfss->flags = (nfss->flags & ~changed_flags_mask) |
> + (data->flags & changed_flags_mask);
> +
> + if (data->retrans != cl->cl_timeout->to_retries ||
> + data->timeo != (10U * cl->cl_timeout->to_initval / HZ)) {
> /* Note that this will affect all mounts from the same server,
> * that use the same protocol. The timeouts are always forced
> * to be the same.
> */
> - struct rpc_clnt *cl = nfss->client;
> if (cl->cl_timeout != &cl->cl_timeout_default)
> memcpy(&cl->cl_timeout_default, cl->cl_timeout,
> sizeof(struct rpc_timeout));
> @@ -2239,6 +2257,8 @@ nfs_compare_and_set_remount_data(struct nfs_server *nfss,
> cl->cl_timeout_default.to_initval = data->timeo * HZ / 10U;
> }
>
> + cl->cl_kill_new_tasks = !!(nfss->flags & NFS_MOUNT_SERVERFAILED);
> +
> return 0;
> }
>
> diff --git a/include/uapi/linux/nfs_mount.h b/include/uapi/linux/nfs_mount.h
> index e44e00616ab5..8ad931cdca20 100644
> --- a/include/uapi/linux/nfs_mount.h
> +++ b/include/uapi/linux/nfs_mount.h
> @@ -74,5 +74,6 @@ struct nfs_mount_data {
>
> #define NFS_MOUNT_LOCAL_FLOCK 0x100000
> #define NFS_MOUNT_LOCAL_FCNTL 0x200000
> +#define NFS_MOUNT_SERVERFAILED 0x400000
>
> #endif
> --
> 2.13.6
>
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--
Chuck Lever
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