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 115053DCDAB for ; Thu, 4 Jun 2026 20:24:07 +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=1780604649; cv=none; b=joxQQOapmxfyLzxeXIC7J4IKBicW0ArNHVhSl/M3gF1LZyfCe6k6BWwiv/xrZ7w86pxPU5OjY9xjjHWqf1MotggLnCxf+jcSkO5uhZRQn5eIhqYtx/czIoPTSmiS1AbDvdSLgeY+K4JWU5H0CqCQ0abbC/B5uBYyOCYvfb2yX5Y= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1780604649; c=relaxed/simple; bh=2x3nCaA9q1Rfx35a4ZXPboLzJEGR/wbl+zgT8sV8sPs=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=JqnZKK4kuVU9X4hcAmBSrRmhK5zgNKlmjQvKZBblQvlsoprVujpaRW5ZXM1F3SVxgU9Uol30DS/IhmVF++U3XoODMvDBJzZuMjHjQN8TQH4V+yNEq6/oV5HRuslKYZAK5E0FsNHq8XpFY6Yqw8HNgA1M4WETHORAE0WsetOaRh0= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=kthY1V0T; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="kthY1V0T" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 79B911F00893; Thu, 4 Jun 2026 20:24:07 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1780604647; bh=SwZE2C2lYlzWm2jMR0V0ptBfUMYyL6MhYJHv/DeMVRI=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=kthY1V0TNSv9HdlYYuD77l2l/lK+GyVK0yZ2O4OrZpkc5QJfViAjXYlkeARrdrTwm FnDy/hD7t3SGpc1ZIjNEWcJZ6hPVoOJzgZcyvepWbWYQDV12S2DDz9LlVUFzT7beCg XJQdJisnY8i4YY+wX5yRsO150mMpTYVJBGloJtjy5U5NYzDooMCw/RB7ljGZthFwfi iLGuvDcFMeDrJmGGVyfPNEqpY+net/s+0lVz0jGl/wAd3zntz3zR+cu+z5MWNhNIrG jWzja+ILcLT/owLHHVSCK7qXKliQmmC1xxnMNFIrqnv34qdJHtEYFgW0M0raliOH8L litPUmwYB9v3A== From: Mike Snitzer To: Trond Myklebust , Anna Schumaker Cc: linux-nfs@vger.kernel.org Subject: [PATCH 2/2] NFSv4/flexfiles: honor FF_FLAGS_NO_IO_THRU_MDS in pg_get_mirror_count_write Date: Thu, 4 Jun 2026 16:24:03 -0400 Message-ID: <20260604202403.20856-3-snitzer@kernel.org> X-Mailer: git-send-email 2.44.0 In-Reply-To: <20260604202403.20856-1-snitzer@kernel.org> References: <20260604202403.20856-1-snitzer@kernel.org> Precedence: bulk X-Mailing-List: linux-nfs@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit The FF_FLAGS_NO_IO_THRU_MDS flag lives on each lseg, so any fallback decision made when there is no current lseg (e.g. between LAYOUTRETURN and the next LAYOUTGET) cannot run the per-lseg check. Introduce a sticky hdr-level ditto for FF_FLAGS_NO_IO_THRU_MDS in struct nfs4_flexfile_layout::flags (NFS4_FF_HDR_NO_IO_THRU_MDS bit), set whenever ff_layout_alloc_lseg() parses an lseg with the flag. The bit is never cleared for the lifetime of the layout hdr; the server is assumed to be consistent in its no-fallback policy per file. kzalloc() in ff_layout_alloc_layout_hdr() zero-initializes the field. Use the new ff_layout_hdr_no_fallback_to_mds() helper to gate ff_layout_pg_get_mirror_count_write(): when pnfs_update_layout() returns NULL (e.g. NFS_LAYOUT_BULK_RECALL, pnfs_layout_io_test_failed, pnfs_layoutgets_blocked) the existing code unconditionally calls nfs_pageio_reset_write_mds(). This is a source of unwanted WRITE to MDS. Fix it by checking NFS4_FF_HDR_NO_IO_THRU_MDS bit, and if set surface -EAGAIN instead; the writepage-side caller (nfs_do_writepage() for buffered, nfs_direct_write_reschedule() for O_DIRECT) then redirties the request so writeback retries via pNFS. Fixes: 260074cd8413 ("pNFS/flexfiles: Add support for FF_FLAGS_NO_IO_THRU_MDS") Assisted-by: Claude:claude-opus-4-7 Signed-off-by: Mike Snitzer --- fs/nfs/flexfilelayout/flexfilelayout.c | 13 +++++++++++++ fs/nfs/flexfilelayout/flexfilelayout.h | 16 ++++++++++++++++ 2 files changed, 29 insertions(+) diff --git a/fs/nfs/flexfilelayout/flexfilelayout.c b/fs/nfs/flexfilelayout/flexfilelayout.c index 38bcd260e0a91..a63f90be11dfd 100644 --- a/fs/nfs/flexfilelayout/flexfilelayout.c +++ b/fs/nfs/flexfilelayout/flexfilelayout.c @@ -636,6 +636,9 @@ ff_layout_alloc_lseg(struct pnfs_layout_hdr *lh, if (!p) goto out_sort_mirrors; fls->flags = be32_to_cpup(p); + if (fls->flags & FF_FLAGS_NO_IO_THRU_MDS) + set_bit(NFS4_FF_HDR_NO_IO_THRU_MDS, + &FF_LAYOUT_FROM_HDR(lh)->flags); p = xdr_inline_decode(&stream, 4); if (!p) @@ -1185,6 +1188,16 @@ ff_layout_pg_get_mirror_count_write(struct nfs_pageio_descriptor *pgio, 0, NFS4_MAX_UINT64, IOMODE_RW, NFS_I(pgio->pg_inode)->layout, pgio->pg_lseg); + if (NFS_I(pgio->pg_inode)->layout && + ff_layout_hdr_no_fallback_to_mds(NFS_I(pgio->pg_inode)->layout)) { + /* + * FF_FLAGS_NO_IO_THRU_MDS: no current lseg but the server's + * policy forbids MDS fallback. Surface -EAGAIN so writeback + * retries rather than silently issuing the WRITE via MDS. + */ + pgio->pg_error = -EAGAIN; + goto out; + } /* no lseg means that pnfs is not in use, so no mirroring here */ nfs_pageio_reset_write_mds(pgio); out: diff --git a/fs/nfs/flexfilelayout/flexfilelayout.h b/fs/nfs/flexfilelayout/flexfilelayout.h index 17a008c8e97ce..a5bd00f69e824 100644 --- a/fs/nfs/flexfilelayout/flexfilelayout.h +++ b/fs/nfs/flexfilelayout/flexfilelayout.h @@ -112,12 +112,16 @@ struct nfs4_ff_layout_segment { struct nfs4_ff_layout_mirror *mirror_array[] __counted_by(mirror_array_cnt); }; +/* nfs4_flexfile_layout::flags bit indices */ +#define NFS4_FF_HDR_NO_IO_THRU_MDS 0 /* any lseg has had FF_FLAGS_NO_IO_THRU_MDS */ + struct nfs4_flexfile_layout { struct pnfs_layout_hdr generic_hdr; struct pnfs_ds_commit_info commit_info; struct list_head mirrors; struct list_head error_list; /* nfs4_ff_layout_ds_err */ ktime_t last_report_time; /* Layoutstat report times */ + unsigned long flags; }; struct nfs4_flexfile_layoutreturn_args { @@ -184,6 +188,18 @@ ff_layout_no_fallback_to_mds(struct pnfs_layout_segment *lseg) return FF_LAYOUT_LSEG(lseg)->flags & FF_FLAGS_NO_IO_THRU_MDS; } +/* + * Sticky hdr-level mirror of FF_FLAGS_NO_IO_THRU_MDS so callers that have + * no current lseg (e.g. between LAYOUTRETURN and the next LAYOUTGET) can + * still honor the no-MDS-fallback policy. + */ +static inline bool +ff_layout_hdr_no_fallback_to_mds(struct pnfs_layout_hdr *lo) +{ + return test_bit(NFS4_FF_HDR_NO_IO_THRU_MDS, + &FF_LAYOUT_FROM_HDR(lo)->flags); +} + static inline bool ff_layout_no_read_on_rw(struct pnfs_layout_segment *lseg) { -- 2.44.0