3453d5708b
A 'false retry' in NFSv4.1 occurs when the client attempts to transmit a new RPC call using a slot+sequence number combination that references an already cached one. Currently, the Linux NFS client will do this if a user process interrupts an RPC call that is in progress. The problem with doing so is that we defeat the main mechanism used by the server to differentiate between a new call and a replayed one. Even if the server is able to perfectly cache the arguments of the old call, it cannot know if the client intended to replay or send a new call. The obvious fix is to bump the sequence number pre-emptively if an RPC call is interrupted, but in order to deal with the corner cases where the interrupted call is not actually received and processed by the server, we need to interpret the error NFS4ERR_SEQ_MISORDERED as a sign that we need to either wait or locate a correct sequence number that lies between the value we sent, and the last value that was acked by a SEQUENCE call on that slot. Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com> Tested-by: Jason Tibbitts <tibbs@math.uh.edu>
185 lines
5.2 KiB
C
185 lines
5.2 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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/*
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* fs/nfs/nfs4session.h
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*
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* Copyright (c) 2012 Trond Myklebust <Trond.Myklebust@netapp.com>
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*
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*/
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#ifndef __LINUX_FS_NFS_NFS4SESSION_H
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#define __LINUX_FS_NFS_NFS4SESSION_H
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/* maximum number of slots to use */
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#define NFS4_DEF_SLOT_TABLE_SIZE (64U)
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#define NFS4_DEF_CB_SLOT_TABLE_SIZE (1U)
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#define NFS4_MAX_SLOT_TABLE (1024U)
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#define NFS4_NO_SLOT ((u32)-1)
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#if IS_ENABLED(CONFIG_NFS_V4)
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/* Sessions slot seqid */
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struct nfs4_slot {
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struct nfs4_slot_table *table;
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struct nfs4_slot *next;
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unsigned long generation;
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u32 slot_nr;
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u32 seq_nr;
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u32 seq_nr_last_acked;
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u32 seq_nr_highest_sent;
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unsigned int privileged : 1,
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seq_done : 1;
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};
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/* Sessions */
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enum nfs4_slot_tbl_state {
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NFS4_SLOT_TBL_DRAINING,
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};
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#define SLOT_TABLE_SZ DIV_ROUND_UP(NFS4_MAX_SLOT_TABLE, 8*sizeof(long))
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struct nfs4_slot_table {
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struct nfs4_session *session; /* Parent session */
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struct nfs4_slot *slots; /* seqid per slot */
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unsigned long used_slots[SLOT_TABLE_SZ]; /* used/unused bitmap */
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spinlock_t slot_tbl_lock;
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struct rpc_wait_queue slot_tbl_waitq; /* allocators may wait here */
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wait_queue_head_t slot_waitq; /* Completion wait on slot */
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u32 max_slots; /* # slots in table */
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u32 max_slotid; /* Max allowed slotid value */
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u32 highest_used_slotid; /* sent to server on each SEQ.
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* op for dynamic resizing */
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u32 target_highest_slotid; /* Server max_slot target */
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u32 server_highest_slotid; /* Server highest slotid */
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s32 d_target_highest_slotid; /* Derivative */
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s32 d2_target_highest_slotid; /* 2nd derivative */
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unsigned long generation; /* Generation counter for
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target_highest_slotid */
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struct completion complete;
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unsigned long slot_tbl_state;
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};
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/*
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* Session related parameters
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*/
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struct nfs4_session {
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struct nfs4_sessionid sess_id;
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u32 flags;
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unsigned long session_state;
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u32 hash_alg;
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u32 ssv_len;
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/* The fore and back channel */
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struct nfs4_channel_attrs fc_attrs;
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struct nfs4_slot_table fc_slot_table;
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struct nfs4_channel_attrs bc_attrs;
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struct nfs4_slot_table bc_slot_table;
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struct nfs_client *clp;
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};
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enum nfs4_session_state {
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NFS4_SESSION_INITING,
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NFS4_SESSION_ESTABLISHED,
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};
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extern int nfs4_setup_slot_table(struct nfs4_slot_table *tbl,
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unsigned int max_reqs, const char *queue);
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extern void nfs4_shutdown_slot_table(struct nfs4_slot_table *tbl);
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extern struct nfs4_slot *nfs4_alloc_slot(struct nfs4_slot_table *tbl);
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extern struct nfs4_slot *nfs4_lookup_slot(struct nfs4_slot_table *tbl, u32 slotid);
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extern int nfs4_slot_wait_on_seqid(struct nfs4_slot_table *tbl,
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u32 slotid, u32 seq_nr,
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unsigned long timeout);
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extern bool nfs4_try_to_lock_slot(struct nfs4_slot_table *tbl, struct nfs4_slot *slot);
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extern void nfs4_free_slot(struct nfs4_slot_table *tbl, struct nfs4_slot *slot);
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extern void nfs4_slot_tbl_drain_complete(struct nfs4_slot_table *tbl);
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bool nfs41_wake_and_assign_slot(struct nfs4_slot_table *tbl,
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struct nfs4_slot *slot);
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void nfs41_wake_slot_table(struct nfs4_slot_table *tbl);
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static inline bool nfs4_slot_tbl_draining(struct nfs4_slot_table *tbl)
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{
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return !!test_bit(NFS4_SLOT_TBL_DRAINING, &tbl->slot_tbl_state);
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}
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static inline bool nfs4_test_locked_slot(const struct nfs4_slot_table *tbl,
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u32 slotid)
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{
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return !!test_bit(slotid, tbl->used_slots);
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}
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static inline struct nfs4_session *nfs4_get_session(const struct nfs_client *clp)
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{
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return clp->cl_session;
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}
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#if defined(CONFIG_NFS_V4_1)
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extern void nfs41_set_target_slotid(struct nfs4_slot_table *tbl,
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u32 target_highest_slotid);
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extern void nfs41_update_target_slotid(struct nfs4_slot_table *tbl,
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struct nfs4_slot *slot,
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struct nfs4_sequence_res *res);
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extern int nfs4_setup_session_slot_tables(struct nfs4_session *ses);
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extern struct nfs4_session *nfs4_alloc_session(struct nfs_client *clp);
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extern void nfs4_destroy_session(struct nfs4_session *session);
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extern int nfs4_init_session(struct nfs_client *clp);
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extern int nfs4_init_ds_session(struct nfs_client *, unsigned long);
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/*
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* Determine if sessions are in use.
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*/
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static inline int nfs4_has_session(const struct nfs_client *clp)
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{
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if (clp->cl_session)
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return 1;
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return 0;
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}
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static inline int nfs4_has_persistent_session(const struct nfs_client *clp)
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{
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if (nfs4_has_session(clp))
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return (clp->cl_session->flags & SESSION4_PERSIST);
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return 0;
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}
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static inline void nfs4_copy_sessionid(struct nfs4_sessionid *dst,
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const struct nfs4_sessionid *src)
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{
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memcpy(dst->data, src->data, NFS4_MAX_SESSIONID_LEN);
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}
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#ifdef CONFIG_CRC32
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/*
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* nfs_session_id_hash - calculate the crc32 hash for the session id
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* @session - pointer to session
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*/
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#define nfs_session_id_hash(sess_id) \
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(~crc32_le(0xFFFFFFFF, &(sess_id)->data[0], sizeof((sess_id)->data)))
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#else
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#define nfs_session_id_hash(session) (0)
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#endif
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#else /* defined(CONFIG_NFS_V4_1) */
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static inline int nfs4_init_session(struct nfs_client *clp)
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{
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return 0;
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}
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/*
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* Determine if sessions are in use.
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*/
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static inline int nfs4_has_session(const struct nfs_client *clp)
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{
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return 0;
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}
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static inline int nfs4_has_persistent_session(const struct nfs_client *clp)
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{
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return 0;
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}
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#define nfs_session_id_hash(session) (0)
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#endif /* defined(CONFIG_NFS_V4_1) */
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#endif /* IS_ENABLED(CONFIG_NFS_V4) */
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#endif /* __LINUX_FS_NFS_NFS4SESSION_H */
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