774d5f14ee
On a CB_RECALL the callback service thread flushes the inode using filemap_flush prior to scheduling the state manager thread to return the delegation. When pNFS is used and I/O has not yet gone to the data server servicing the inode, a LAYOUTGET can preceed the I/O. Unlike the async filemap_flush call, the LAYOUTGET must proceed to completion. If the state manager starts to recover data while the inode flush is sending the LAYOUTGET, a deadlock occurs as the callback service thread holds the single callback session slot until the flushing is done which blocks the state manager thread, and the state manager thread has set the session draining bit which puts the inode flush LAYOUTGET RPC to sleep on the forechannel slot table waitq. Separate the draining of the back channel from the draining of the fore channel by moving the NFS4_SESSION_DRAINING bit from session scope into the fore and back slot tables. Drain the back channel first allowing the LAYOUTGET call to proceed (and fail) so the callback service thread frees the callback slot. Then proceed with draining the forechannel. Signed-off-by: Andy Adamson <andros@netapp.com> Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
146 lines
3.9 KiB
C
146 lines
3.9 KiB
C
/*
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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 (16U)
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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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unsigned int interrupted : 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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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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/* Create session arguments */
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unsigned int fc_target_max_rqst_sz;
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unsigned int fc_target_max_resp_sz;
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};
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enum nfs4_session_state {
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NFS4_SESSION_INITING,
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};
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#if defined(CONFIG_NFS_V4_1)
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extern struct nfs4_slot *nfs4_alloc_slot(struct nfs4_slot_table *tbl);
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extern void nfs4_free_slot(struct nfs4_slot_table *tbl, struct nfs4_slot *slot);
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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_server *server);
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extern int nfs4_init_ds_session(struct nfs_client *, unsigned long);
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extern void nfs4_slot_tbl_drain_complete(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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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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/*
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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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#else /* defined(CONFIG_NFS_V4_1) */
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static inline int nfs4_init_session(struct nfs_server *server)
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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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#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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