From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (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 97CA8372B2F; Fri, 4 Sep 2026 05:14:51 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788498892; cv=none; b=o2A5PBIu5pYKzwJdCW3ck5Z3BdoUk1wKhLA3juLxkGwAM4hYguPn1bZzVB/PdT9OLNs3Yia9wajzdVcL3Hp+5pQrgmvYoHnaGegAlsJY+h/Li4bWR3s8xjTz1GskU4z52+mFP+hkds84MOl33nOboPwh+vN+4x1R0DiLF09XNxU= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788498892; c=relaxed/simple; bh=Od66aEHobwRQDebB8RaRyLxRgmE1ae9nTxQ9sQae9Ak=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=CZRi7khfw611ot5f8jWWkgFvH6/b0DCypcRJRtKSwdlHXItWwJdmluMBhGz0v6vRVmJmvpaH2F3xnGMAMsrGlB16oEnTSVdK7HzqOh2UHFtQpOlICMevFjg+tSpTXw1z1lh7OeXlqhcpRSyNlBTyXOl7lgLuO+Q9DPOXnJOSRQw= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=1EILiho2; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="1EILiho2" Received: by smtp.kernel.org (Postfix) with ESMTPSA id F1FDC1F00A3D; Fri, 4 Sep 2026 05:14:50 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1788498891; bh=wYUrzHsnDKKtTfTqQAMmIXxN79zC2eMueAHeijWErPI=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=1EILiho2j7VYFxmnPBQTj9+xn2t45INpWODbf32nxj99258iJnYDqKvxJCije6awr gHdQrbDdgNxUb8zSWV5r5O34YEPO1VvKzI9CVfHMyV/vUG8nK8+XYzQdaR6pwnKExU I9pSG6EsyCjd1JtMxIMVtW9gT537HeG9FDGxK7Sg= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Max Kellermann , Alex Markuze , Ilya Dryomov Subject: [PATCH 7.2 217/713] ceph: force a cap message when a deferred revoke cant be acked immediately Date: Fri, 4 Sep 2026 06:53:05 +0200 Message-ID: <20260904045808.681813964@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260904045803.810145556@linuxfoundation.org> References: <20260904045803.810145556@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 7.2-stable review patch. If anyone has any objections, please let me know. ------------------ From: Max Kellermann commit 8fdf946445732c2bcd685abc8bd0e509d2ebc158 upstream. When the MDS revokes capabilities, handle_cap_grant() normally guarantees a response by setting `CHECK_CAPS_FLUSH_FORCE` (see commit 31634d7597d8 ("ceph: force sending a cap update msg back to MDS for revoke op")), so ceph_check_caps() sends a cap message even if the client would otherwise decide it has nothing to do. That guarantee is skipped whenever the revoke has to be deferred (via revoke_wait): revoking Fb while dirty data is still buffered (writeback is queued first) or revoking Fc while pages are cached (async invalidation is queued first). In those cases, the ack is left to the deferred completion (ceph_put_wrbuffer_cap_refs() after writeback, or the invalidate worker after invalidation); both of which call ceph_check_caps(ci,0) i.e. without `CHECK_CAPS_FLUSH_FORCE`. Nothing gets sent under one of the following conditions: - the inode is retaining caps because the file was used recently (file_wanted != 0; retain |= CEPH_CAP_ANY) - the revoked cap is still used because the page was re-cached (e.g. a file being re-read) - the MDS has meanwhile re-granted, so `issued==implemented` and the client sees nothing being revoked The client then never emits the cap message which the MDS is waiting for. The MDS blocks on the revoke indefinitely and logs, for minutes or hours: client.NNN isn't responding to mclientcaps(revoke), ino 0x... pending pAsxLsXsxFsxcrwb issued pAsxLsXsxFsxcrwb, sent 964.899182 seconds ago The client-side state at that point shows the full cap set still issued, nothing in the revoking/flushing sets. Thus nothing gets sent. This patch fixes it by remembering that a forced response is expected. When a revoke is deferred, set `CEPH_I_FLUSH_FORCE` on the inode. ceph_check_caps() replays it as `CHECK_CAPS_FLUSH_FORCE`, so whichever path re-checks the inode next (the writeback/invalidate completion, the delayed worker, or any other caller) is guaranteed to send a cap message to the MDS. __prep_cap() clears the flag once a message is actually built. This is the deferred-path counterpart of the existing `CHECK_CAPS_FLUSH_FORCE` handling; a normal (non-deferred) revoke still forces the response inline as before. Cc: stable@vger.kernel.org Fixes: 31634d7597d8 ("ceph: force sending a cap update msg back to MDS for revoke op") Fixes: 257e6172ab36 ("ceph: don't let check_caps skip sending responses for revoke msgs") Signed-off-by: Max Kellermann Reviewed-by: Alex Markuze Signed-off-by: Ilya Dryomov Signed-off-by: Greg Kroah-Hartman --- fs/ceph/caps.c | 63 +++++++++++++++++++++++++++++++++++++++++++++++++------- fs/ceph/super.h | 5 ++++ 2 files changed, 61 insertions(+), 7 deletions(-) --- a/fs/ceph/caps.c +++ b/fs/ceph/caps.c @@ -979,6 +979,27 @@ int __ceph_caps_revoking_other(struct ce return 0; } +/* + * Return true if any cap of this inode holds caps which the MDS has + * revoked, but which we have not released yet. + */ +static bool __ceph_is_any_revoking(const struct ceph_inode_info *ci) +{ + const struct rb_node *p; + + lockdep_assert_held(&ci->i_ceph_lock); + + for (p = rb_first(&ci->i_caps); p; p = rb_next(p)) { + const struct ceph_cap *cap = + rb_entry(p, struct ceph_cap, ci_node); + + if (cap->implemented & ~cap->issued) + return true; + } + + return false; +} + int __ceph_caps_used(struct ceph_inode_info *ci) { int used = 0; @@ -1421,6 +1442,9 @@ static void __prep_cap(struct cap_msg_ar cap->implemented &= cap->issued | used; cap->mds_wanted = want; + if ((ci->i_ceph_flags & CEPH_I_FLUSH_FORCE) != 0 && !__ceph_is_any_revoking(ci)) + clear_bit(CEPH_I_FLUSH_FORCE_BIT, &ci->i_ceph_flags); + arg->session = cap->session; arg->ino = ceph_vino(inode).ino; arg->cid = cap->cap_id; @@ -2038,6 +2062,14 @@ void ceph_check_caps(struct ceph_inode_i if (ci->i_ceph_flags & CEPH_I_FLUSH) flags |= CHECK_CAPS_FLUSH; + /* + * A revoke whose response was deferred (see handle_cap_grant()) must + * still be acknowledged. Replay the forced flush here so that even a + * check triggered by writeback/invalidation completion sends a cap + * message to the MDS. + */ + if (ci->i_ceph_flags & CEPH_I_FLUSH_FORCE) + flags |= CHECK_CAPS_FLUSH_FORCE; retry: /* Caps wanted by virtue of active open files. */ file_wanted = __ceph_caps_file_wanted(ci); @@ -3764,13 +3796,30 @@ static void handle_cap_grant(struct inod BUG_ON(cap->issued & ~cap->implemented); /* don't let check_caps skip sending a response to MDS for revoke msgs */ - if (!revoke_wait && le32_to_cpu(grant->op) == CEPH_CAP_OP_REVOKE) { - cap->mds_wanted = 0; - flags |= CHECK_CAPS_FLUSH_FORCE; - if (cap == ci->i_auth_cap) - check_caps = 1; /* check auth cap only */ - else - check_caps = 2; /* check all caps */ + if (le32_to_cpu(grant->op) == CEPH_CAP_OP_REVOKE) { + if (revoke_wait) { + /* + * We can't ack the revoke yet: the response is deferred + * until the writeback or cache invalidation queued above + * completes. Set the CEPH_I_FLUSH_FORCE flag to remember + * that a forced cap message is owed so that deferred + * completion (ceph_put_wrbuffer_cap_refs() or the + * invalidate worker, both of which call ceph_check_caps()) + * actually sends one, even if by then the revoked caps look + * unused, the inode is retaining caps, or the MDS has + * re-granted them. Without this, the cap message is never + * sent and the MDS hangs ("isn't responding to + * mclientcaps(revoke)"). + */ + set_bit(CEPH_I_FLUSH_FORCE_BIT, &ci->i_ceph_flags); + } else { + cap->mds_wanted = 0; + flags |= CHECK_CAPS_FLUSH_FORCE; + if (cap == ci->i_auth_cap) + check_caps = 1; /* check auth cap only */ + else + check_caps = 2; /* check all caps */ + } } if (extra_info->inline_version > 0 && --- a/fs/ceph/super.h +++ b/fs/ceph/super.h @@ -687,6 +687,10 @@ static inline struct inode *ceph_find_in #define CEPH_I_ASYNC_CREATE_BIT (12) /* async create in flight for this */ #define CEPH_I_SHUTDOWN_BIT (13) /* inode is no longer usable */ #define CEPH_I_ASYNC_CHECK_CAPS_BIT (14) /* check caps after async creating finishes */ +#define CEPH_I_FLUSH_FORCE_BIT (15) /* a revoke's response was deferred; + * force a cap message to the MDS once + * the deferred work completes + */ #define CEPH_I_DIR_ORDERED (1 << CEPH_I_DIR_ORDERED_BIT) #define CEPH_I_FLUSH (1 << CEPH_I_FLUSH_BIT) @@ -699,6 +703,7 @@ static inline struct inode *ceph_find_in #define CEPH_I_ODIRECT (1 << CEPH_I_ODIRECT_BIT) #define CEPH_I_ASYNC_CREATE (1 << CEPH_I_ASYNC_CREATE_BIT) #define CEPH_I_SHUTDOWN (1 << CEPH_I_SHUTDOWN_BIT) +#define CEPH_I_FLUSH_FORCE (1 << CEPH_I_FLUSH_FORCE_BIT) /* * Masks of ceph inode work.