From patchwork Mon Nov 18 14:54:34 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jeff Layton X-Patchwork-Id: 13878719 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 2FC341A9B3C; Mon, 18 Nov 2024 14:54:55 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1731941696; cv=none; b=To/jSzXyySpdKJwBkKMh0uS1W3eOq7I8IAdn45rnJpPMRfpl0sOCM1ojHJ2XfcxQDYyBpZu9EXgzWZBs5DIMR6xRYJEHGbMxOUd55A7j5O1+/OvGAnzK6IsTxRwQur9a/R+3mnxyXaQYwEkH3KGXoaN7auG20t/f47MCVu693vo= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1731941696; c=relaxed/simple; bh=rOBgeTq6q/7XFpNzebRzGO4cYS25aQiP5lwa88anNo0=; h=From:Date:Subject:MIME-Version:Content-Type:Message-Id:To:Cc; b=YpCuis5O5gOCwfyfDc5xjGtf8u5WNusvGWYW6cQHyC3ZiROGQPdgZFnoaZJwXc+lWChEvr8lbqtqVK36Kny9eNVw0HzD37PJvF+q0awVW6KT8ZHPJbNoSdGS+F1BzwXuJ80GNCZpzD+9Xrfb8u/znvUEXsz7uzSf2oK88IVsHgg= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=g0+P6FgV; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="g0+P6FgV" Received: by smtp.kernel.org (Postfix) with ESMTPSA id E7458C4CECF; Mon, 18 Nov 2024 14:54:54 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1731941695; bh=rOBgeTq6q/7XFpNzebRzGO4cYS25aQiP5lwa88anNo0=; h=From:Date:Subject:To:Cc:From; b=g0+P6FgV5xheIdK/n/w2meOINBfilPlzGyMOULNNppEu/3/XP+8TYxxfas3KCkgHh lzAQTOJV7Rbx3KGSE9kekrFNh7JZ7sZx8XQcqBP1h/s5Koy2ZNZkT29yx4fJvQypae DOmffl+n5q1MiQnxGPWZ6h6DShQaXLZNnzwPG1kfaVwdAlaS5ml8tt+T8K3mNj7Ecj 4HRkh2ZTVKw11bLhekW6O0bXEse832NX95F1A7sj+vfcxA8JS00pCTqgNSNca0yZ/M JVXdJPtdi75AhrjlcsflBlYPOTiljY9t04QEUeQks53XaZvvBsWwc8DwZbW7wEO0NM iPRxXMUlEiAGw== From: Jeff Layton Date: Mon, 18 Nov 2024 09:54:34 -0500 Subject: [PATCH v5] nfsd: allow for up to 32 callback session slots Precedence: bulk X-Mailing-List: linux-nfs@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Message-Id: <20241118-bcwide-v5-1-e21f211f2543@kernel.org> X-B4-Tracking: v=1; b=H4sIAClVO2cC/2WPywrCMBBFf0WyNjKZJH248j/ERZNMNCitpFIV6 b+bFmkrXd7hnnuYD2spBmrZfvNhkbrQhqZOQW83zF6q+kw8uJQZAioBqLmxz+CIZ8blpEwmnUG WyvdIPrzGoeMp5UtoH018j7udGK6riU5w4A4BZE5aQWUPV4o13XZNPA+Tv37x1wfKdVWgKJ2FZ X9wdrj0lBOHXHAqQYDJyGvtVpxccBImTiafRedVWWFmlV5xauYEzH+p5FOF10gE3sDfX6e+779 HKi0gdQEAAA== X-Change-ID: 20241025-bcwide-6bd7e4b63db2 To: Chuck Lever , Neil Brown , Dai Ngo , Tom Talpey Cc: Olga Kornievskaia , linux-nfs@vger.kernel.org, linux-kernel@vger.kernel.org, Jeff Layton X-Mailer: b4 0.14.2 X-Developer-Signature: v=1; a=openpgp-sha256; l=14190; i=jlayton@kernel.org; h=from:subject:message-id; bh=rOBgeTq6q/7XFpNzebRzGO4cYS25aQiP5lwa88anNo0=; b=owEBbQKS/ZANAwAIAQAOaEEZVoIVAcsmYgBnO1U28fBaEFKT9isTkUr7jX6DLR9VtZEr/NCIQ nupZJH8d56JAjMEAAEIAB0WIQRLwNeyRHGyoYTq9dMADmhBGVaCFQUCZztVNgAKCRAADmhBGVaC FXe7EADJQmQF1EJe7lSD29EQ7hCH0gLflSqZDyEmAfRusNdFAAE1XwxiQfGz8fJCF7W1Rd5J33t w9FjCLr1uRm6aBQLXB0/h/jgvgQGKtXITHsRsKoGu3XYb7rSik+8R0BFMh1Ezx/WOf+lbedQ5Uo GQ8peErcBmkenlJ9Gk8m/KXCf8hQpraiQVMbGabR2Fs/QhI5iwLwY9pakZukkLjlNgbZbN7QIsa 06MpKZw4awqXUcdcRSKGQbr2/rV8Ik24wMZM0dV1aTy35+mnt/NJKiW7F4MHDsJ4ayFyosGv0OB 62Cx3mXY7A3XWWwc/gGPcx+95mtlyOpEYoq39NqG5rAcQueEqjG84hF4HYROFHyW2D0p9Mwz3OE QxNITr4AKziR3jD0Tnzi/ir/ETV4eUaf0ENbuzAcfITfYsuHAcbiBkpYZwvBNJZuTJdo+P+XFzE AAJGnwwAeoNgZzxr6RISA9LVUgzFhhAwif6usjlZFfLsT8lWECodavTsK3M//P+vfdm9zQOhaFC dhrQBPnnvdYCc7oz0dWCgsuNi9yltuxkgHmrZb7C0Uhb2GYdCz2rFM/AS0kfNZJn8yJFcg/YjPe zIZUb8pVpO3p3dHZcquOrWMBtZ+9HF0F+q5Yj+fdkX4fVcxHFX/+6reiGwaLc0rtxoDrFG7nxyw vdwYlUf7nKs/hHg== X-Developer-Key: i=jlayton@kernel.org; a=openpgp; fpr=4BC0D7B24471B2A184EAF5D3000E684119568215 nfsd currently only uses a single slot in the callback channel, which is proving to be a bottleneck in some cases. Widen the callback channel to a max of 32 slots (subject to the client's target_maxreqs value). Change the cb_holds_slot boolean to an integer that tracks the current slot number (with -1 meaning "unassigned"). Move the callback slot tracking info into the session. Add a new u32 that acts as a bitmap to track which slots are in use, and a u32 to track the latest callback target_slotid that the client reports. To protect the new fields, add a new per-session spinlock (the se_lock). Fix nfsd41_cb_get_slot to always search for the lowest slotid (using ffs()). Finally, convert the session->se_cb_seq_nr field into an array of ints and add the necessary handling to ensure that the seqids get reset when the slot table grows after shrinking. Signed-off-by: Jeff Layton --- A minor bugfix, and some comments, cleanup and symbol renaming. --- Changes in v5: - Fix off-by-one bug when initializing seqid array - Rename NFSD_BC_SLOT_TABLE_MAX to NFSD_BC_SLOT_TABLE_SIZE, and reframe it to be the size of the array instead of last index. - Comments around seqid reinitialization when the slot table grows - Link to v4: https://lore.kernel.org/r/20241105-bcwide-v4-1-48f52ee0fb0c@kernel.org Changes in v4: - Wait the correct way for slots to be freed. - Link to v3: https://lore.kernel.org/r/20241030-bcwide-v3-0-c2df49a26c45@kernel.org Changes in v3: - add patch to convert se_flags to single se_dead bool - fix off-by-one bug in handling of NFSD_BC_SLOT_TABLE_MAX - don't reject target highest slot value of 0 - Link to v2: https://lore.kernel.org/r/20241029-bcwide-v2-1-e9010b6ef55d@kernel.org Changes in v2: - take cl_lock when fetching fields from session to be encoded - use fls() instead of bespoke highest_unset_index() - rename variables in several functions with more descriptive names - clamp limit of for loop in update_cb_slot_table() - re-add missing rpc_wake_up_queued_task() call - fix slotid check in decode_cb_sequence4resok() - add new per-session spinlock --- fs/nfsd/nfs4callback.c | 118 ++++++++++++++++++++++++++++++++++++------------- fs/nfsd/nfs4state.c | 14 ++++-- fs/nfsd/state.h | 15 ++++--- fs/nfsd/trace.h | 2 +- 4 files changed, 109 insertions(+), 40 deletions(-) --- base-commit: f055a6cafaea151c2df2a75f31c3ecfaa8b90b9e change-id: 20241025-bcwide-6bd7e4b63db2 Best regards, diff --git a/fs/nfsd/nfs4callback.c b/fs/nfsd/nfs4callback.c index e38fa834b3d91333acf1425eb14c644e5d5f2601..0d1ebeaca14a40980d08e223cb6598e20c6ce21a 100644 --- a/fs/nfsd/nfs4callback.c +++ b/fs/nfsd/nfs4callback.c @@ -406,6 +406,19 @@ encode_cb_getattr4args(struct xdr_stream *xdr, struct nfs4_cb_compound_hdr *hdr, hdr->nops++; } +static u32 highest_slotid(struct nfsd4_session *ses) +{ + u32 idx; + + spin_lock(&ses->se_lock); + idx = fls(~ses->se_cb_slot_avail); + if (idx > 0) + --idx; + idx = max(idx, ses->se_cb_highest_slot); + spin_unlock(&ses->se_lock); + return idx; +} + /* * CB_SEQUENCE4args * @@ -432,15 +445,40 @@ static void encode_cb_sequence4args(struct xdr_stream *xdr, encode_sessionid4(xdr, session); p = xdr_reserve_space(xdr, 4 + 4 + 4 + 4 + 4); - *p++ = cpu_to_be32(session->se_cb_seq_nr); /* csa_sequenceid */ - *p++ = xdr_zero; /* csa_slotid */ - *p++ = xdr_zero; /* csa_highest_slotid */ + *p++ = cpu_to_be32(session->se_cb_seq_nr[cb->cb_held_slot]); /* csa_sequenceid */ + *p++ = cpu_to_be32(cb->cb_held_slot); /* csa_slotid */ + *p++ = cpu_to_be32(highest_slotid(session)); /* csa_highest_slotid */ *p++ = xdr_zero; /* csa_cachethis */ xdr_encode_empty_array(p); /* csa_referring_call_lists */ hdr->nops++; } +static void update_cb_slot_table(struct nfsd4_session *ses, u32 target) +{ + /* No need to do anything if nothing changed */ + if (likely(target == READ_ONCE(ses->se_cb_highest_slot))) + return; + + spin_lock(&ses->se_lock); + if (target > ses->se_cb_highest_slot) { + int i; + + target = min(target, NFSD_BC_SLOT_TABLE_SIZE - 1); + + /* + * Growing the slot table. Reset any new sequences to 1. + * + * NB: There is some debate about whether the RFC requires this, + * but the Linux client expects it. + */ + for (i = ses->se_cb_highest_slot + 1; i <= target; ++i) + ses->se_cb_seq_nr[i] = 1; + } + ses->se_cb_highest_slot = target; + spin_unlock(&ses->se_lock); +} + /* * CB_SEQUENCE4resok * @@ -468,7 +506,7 @@ static int decode_cb_sequence4resok(struct xdr_stream *xdr, struct nfsd4_session *session = cb->cb_clp->cl_cb_session; int status = -ESERVERFAULT; __be32 *p; - u32 dummy; + u32 seqid, slotid, target; /* * If the server returns different values for sessionID, slotID or @@ -484,21 +522,22 @@ static int decode_cb_sequence4resok(struct xdr_stream *xdr, } p += XDR_QUADLEN(NFS4_MAX_SESSIONID_LEN); - dummy = be32_to_cpup(p++); - if (dummy != session->se_cb_seq_nr) { + seqid = be32_to_cpup(p++); + if (seqid != session->se_cb_seq_nr[cb->cb_held_slot]) { dprintk("NFS: %s Invalid sequence number\n", __func__); goto out; } - dummy = be32_to_cpup(p++); - if (dummy != 0) { + slotid = be32_to_cpup(p++); + if (slotid != cb->cb_held_slot) { dprintk("NFS: %s Invalid slotid\n", __func__); goto out; } - /* - * FIXME: process highest slotid and target highest slotid - */ + p++; // ignore current highest slot value + + target = be32_to_cpup(p++); + update_cb_slot_table(session, target); status = 0; out: cb->cb_seq_status = status; @@ -1203,6 +1242,22 @@ void nfsd4_change_callback(struct nfs4_client *clp, struct nfs4_cb_conn *conn) spin_unlock(&clp->cl_lock); } +static int grab_slot(struct nfsd4_session *ses) +{ + int idx; + + spin_lock(&ses->se_lock); + idx = ffs(ses->se_cb_slot_avail) - 1; + if (idx < 0 || idx > ses->se_cb_highest_slot) { + spin_unlock(&ses->se_lock); + return -1; + } + /* clear the bit for the slot */ + ses->se_cb_slot_avail &= ~BIT(idx); + spin_unlock(&ses->se_lock); + return idx; +} + /* * There's currently a single callback channel slot. * If the slot is available, then mark it busy. Otherwise, set the @@ -1211,28 +1266,32 @@ void nfsd4_change_callback(struct nfs4_client *clp, struct nfs4_cb_conn *conn) static bool nfsd41_cb_get_slot(struct nfsd4_callback *cb, struct rpc_task *task) { struct nfs4_client *clp = cb->cb_clp; + struct nfsd4_session *ses = clp->cl_cb_session; - if (!cb->cb_holds_slot && - test_and_set_bit(0, &clp->cl_cb_slot_busy) != 0) { + if (cb->cb_held_slot >= 0) + return true; + cb->cb_held_slot = grab_slot(ses); + if (cb->cb_held_slot < 0) { rpc_sleep_on(&clp->cl_cb_waitq, task, NULL); /* Race breaker */ - if (test_and_set_bit(0, &clp->cl_cb_slot_busy) != 0) { - dprintk("%s slot is busy\n", __func__); + cb->cb_held_slot = grab_slot(ses); + if (cb->cb_held_slot < 0) return false; - } rpc_wake_up_queued_task(&clp->cl_cb_waitq, task); } - cb->cb_holds_slot = true; return true; } static void nfsd41_cb_release_slot(struct nfsd4_callback *cb) { struct nfs4_client *clp = cb->cb_clp; + struct nfsd4_session *ses = clp->cl_cb_session; - if (cb->cb_holds_slot) { - cb->cb_holds_slot = false; - clear_bit(0, &clp->cl_cb_slot_busy); + if (cb->cb_held_slot >= 0) { + spin_lock(&ses->se_lock); + ses->se_cb_slot_avail |= BIT(cb->cb_held_slot); + spin_unlock(&ses->se_lock); + cb->cb_held_slot = -1; rpc_wake_up_next(&clp->cl_cb_waitq); } } @@ -1249,8 +1308,8 @@ static void nfsd41_destroy_cb(struct nfsd4_callback *cb) } /* - * TODO: cb_sequence should support referring call lists, cachethis, multiple - * slots, and mark callback channel down on communication errors. + * TODO: cb_sequence should support referring call lists, cachethis, + * and mark callback channel down on communication errors. */ static void nfsd4_cb_prepare(struct rpc_task *task, void *calldata) { @@ -1292,7 +1351,7 @@ static bool nfsd4_cb_sequence_done(struct rpc_task *task, struct nfsd4_callback return true; } - if (!cb->cb_holds_slot) + if (cb->cb_held_slot < 0) goto need_restart; /* This is the operation status code for CB_SEQUENCE */ @@ -1306,10 +1365,10 @@ static bool nfsd4_cb_sequence_done(struct rpc_task *task, struct nfsd4_callback * If CB_SEQUENCE returns an error, then the state of the slot * (sequence ID, cached reply) MUST NOT change. */ - ++session->se_cb_seq_nr; + ++session->se_cb_seq_nr[cb->cb_held_slot]; break; case -ESERVERFAULT: - ++session->se_cb_seq_nr; + ++session->se_cb_seq_nr[cb->cb_held_slot]; nfsd4_mark_cb_fault(cb->cb_clp); ret = false; break; @@ -1335,17 +1394,16 @@ static bool nfsd4_cb_sequence_done(struct rpc_task *task, struct nfsd4_callback case -NFS4ERR_BADSLOT: goto retry_nowait; case -NFS4ERR_SEQ_MISORDERED: - if (session->se_cb_seq_nr != 1) { - session->se_cb_seq_nr = 1; + if (session->se_cb_seq_nr[cb->cb_held_slot] != 1) { + session->se_cb_seq_nr[cb->cb_held_slot] = 1; goto retry_nowait; } break; default: nfsd4_mark_cb_fault(cb->cb_clp); } - nfsd41_cb_release_slot(cb); - trace_nfsd_cb_free_slot(task, cb); + nfsd41_cb_release_slot(cb); if (RPC_SIGNALLED(task)) goto need_restart; @@ -1565,7 +1623,7 @@ void nfsd4_init_cb(struct nfsd4_callback *cb, struct nfs4_client *clp, INIT_WORK(&cb->cb_work, nfsd4_run_cb_work); cb->cb_status = 0; cb->cb_need_restart = false; - cb->cb_holds_slot = false; + cb->cb_held_slot = -1; } /** diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c index 2ce6c367e2596cee3f47da6f197120bef4986160..e0daf8b3982cd218ee128bbc0323a1f375e5935a 100644 --- a/fs/nfsd/nfs4state.c +++ b/fs/nfsd/nfs4state.c @@ -2010,6 +2010,10 @@ static struct nfsd4_session *alloc_session(struct nfsd4_channel_attrs *fattrs, } memcpy(&new->se_fchannel, fattrs, sizeof(struct nfsd4_channel_attrs)); + new->se_cb_slot_avail = ~0U; + new->se_cb_highest_slot = min(battrs->maxreqs - 1, + NFSD_BC_SLOT_TABLE_SIZE - 1); + spin_lock_init(&new->se_lock); return new; out_free: while (i--) @@ -2140,11 +2144,14 @@ static void init_session(struct svc_rqst *rqstp, struct nfsd4_session *new, stru INIT_LIST_HEAD(&new->se_conns); - new->se_cb_seq_nr = 1; + atomic_set(&new->se_ref, 0); new->se_dead = false; new->se_cb_prog = cses->callback_prog; new->se_cb_sec = cses->cb_sec; - atomic_set(&new->se_ref, 0); + + for (idx = 0; idx < NFSD_BC_SLOT_TABLE_SIZE; ++idx) + new->se_cb_seq_nr[idx] = 1; + idx = hash_sessionid(&new->se_sessionid); list_add(&new->se_hash, &nn->sessionid_hashtbl[idx]); spin_lock(&clp->cl_lock); @@ -3167,7 +3174,6 @@ static struct nfs4_client *create_client(struct xdr_netobj name, kref_init(&clp->cl_nfsdfs.cl_ref); nfsd4_init_cb(&clp->cl_cb_null, clp, NULL, NFSPROC4_CLNT_CB_NULL); clp->cl_time = ktime_get_boottime_seconds(); - clear_bit(0, &clp->cl_cb_slot_busy); copy_verf(clp, verf); memcpy(&clp->cl_addr, sa, sizeof(struct sockaddr_storage)); clp->cl_cb_session = NULL; @@ -3949,6 +3955,8 @@ nfsd4_create_session(struct svc_rqst *rqstp, cr_ses->flags &= ~SESSION4_PERSIST; /* Upshifting from TCP to RDMA is not supported */ cr_ses->flags &= ~SESSION4_RDMA; + /* Report the correct number of backchannel slots */ + cr_ses->back_channel.maxreqs = new->se_cb_highest_slot + 1; init_session(rqstp, new, conf, cr_ses); nfsd4_get_session_locked(new); diff --git a/fs/nfsd/state.h b/fs/nfsd/state.h index 66b7a4df23f93c3cd18537129d94514268e9c326..554041da8593e14987439cb1c152d1a072bd00ad 100644 --- a/fs/nfsd/state.h +++ b/fs/nfsd/state.h @@ -71,8 +71,8 @@ struct nfsd4_callback { struct work_struct cb_work; int cb_seq_status; int cb_status; + int cb_held_slot; bool cb_need_restart; - bool cb_holds_slot; }; struct nfsd4_callback_ops { @@ -322,6 +322,9 @@ struct nfsd4_conn { unsigned char cn_flags; }; +/* Maximum number of slots that nfsd will use in the backchannel */ +#define NFSD_BC_SLOT_TABLE_SIZE (sizeof(u32) * 8) + /* * Representation of a v4.1+ session. These are refcounted in a similar fashion * to the nfs4_client. References are only taken when the server is actively @@ -329,6 +332,10 @@ struct nfsd4_conn { */ struct nfsd4_session { atomic_t se_ref; + spinlock_t se_lock; + u32 se_cb_slot_avail; /* bitmap of available slots */ + u32 se_cb_highest_slot; /* highest slot client wants */ + u32 se_cb_prog; bool se_dead; struct list_head se_hash; /* hash by sessionid */ struct list_head se_perclnt; @@ -337,8 +344,7 @@ struct nfsd4_session { struct nfsd4_channel_attrs se_fchannel; struct nfsd4_cb_sec se_cb_sec; struct list_head se_conns; - u32 se_cb_prog; - u32 se_cb_seq_nr; + u32 se_cb_seq_nr[NFSD_BC_SLOT_TABLE_SIZE]; struct nfsd4_slot *se_slots[]; /* forward channel slots */ }; @@ -472,9 +478,6 @@ struct nfs4_client { */ struct dentry *cl_nfsd_info_dentry; - /* for nfs41 callbacks */ - /* We currently support a single back channel with a single slot */ - unsigned long cl_cb_slot_busy; struct rpc_wait_queue cl_cb_waitq; /* backchannel callers may */ /* wait here for slots */ struct net *net; diff --git a/fs/nfsd/trace.h b/fs/nfsd/trace.h index 6b7bf8129e4910119959e4c97916991671287837..696c89f68a9e68ecf6b2cd78b39abd3e5d7d4d28 100644 --- a/fs/nfsd/trace.h +++ b/fs/nfsd/trace.h @@ -1697,7 +1697,7 @@ TRACE_EVENT(nfsd_cb_free_slot, __entry->cl_id = sid->clientid.cl_id; __entry->seqno = sid->sequence; __entry->reserved = sid->reserved; - __entry->slot_seqno = session->se_cb_seq_nr; + __entry->slot_seqno = session->se_cb_seq_nr[cb->cb_held_slot]; ), TP_printk(SUNRPC_TRACE_TASK_SPECIFIER " sessionid=%08x:%08x:%08x:%08x new slot seqno=%u",