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Fri, 25 Oct 2024 20:40:29 +0000 (UTC) From: David Howells To: Christian Brauner , Steve French , Matthew Wilcox Cc: David Howells , Jeff Layton , Gao Xiang , Dominique Martinet , Marc Dionne , Paulo Alcantara , Shyam Prasad N , Tom Talpey , Eric Van Hensbergen , Ilya Dryomov , netfs@lists.linux.dev, linux-afs@lists.infradead.org, linux-cifs@vger.kernel.org, linux-nfs@vger.kernel.org, ceph-devel@vger.kernel.org, v9fs@lists.linux.dev, linux-erofs@lists.ozlabs.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, Christian Brauner Subject: [PATCH v2 02/31] netfs: Fix a few minor bugs in netfs_page_mkwrite() Date: Fri, 25 Oct 2024 21:39:29 +0100 Message-ID: <20241025204008.4076565-3-dhowells@redhat.com> In-Reply-To: <20241025204008.4076565-1-dhowells@redhat.com> References: <20241025204008.4076565-1-dhowells@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 3.0 on 10.30.177.15 X-Stat-Signature: ennj36mm9z9ig5w5o6p9mo5pj1ai48z4 X-Rspamd-Queue-Id: 8A90840019 X-Rspam-User: X-Rspamd-Server: rspam10 X-HE-Tag: 1729888827-166262 X-HE-Meta: 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 /05luAHe ENe1f4hVjqYeQmBk1p07+zfy/40JwIwSnu2zVjcasA2Z/ui6binXrLerTSChPW/mRazRoQCgJSdPZ+oWy0uksAMG1/Je8NwcKvCUPP0GJ7cB0d8iKaXBmeYRMic2QeUEda8BnhkLbi9MTY0YKcnJGZK6LAdOChGCrxEaQBaZPyibiDcNp44CR4EaPZxEVYkhft2NsDKF7S67TiEwitPGuo59YeD1CTp6cVARwTWpHRlZ5U+omB5QDcmcBC43R91y6fSdowKYCflHChxFQN8IzDZVKjkQ3vH/jcXQqzRXfSksI+DzJFkKbWAwBe2SUAuGP1E0XeSlsqN4RPvOdjLFsRg62AfA7+D/oAVkC5UDfJkV7C48JCWftKDk9jkiUP4WXwgLuLUyDIRBwRyK/ySzkYM3FxmFyDlmmoaqCL4Qc/ZCNrg8= X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: From: "Matthew Wilcox (Oracle)" We can't return with VM_FAULT_SIGBUS | VM_FAULT_LOCKED; the core code will not unlock the folio in this instance. Introduce a new "unlock" error exit to handle this case. Use it to handle the "folio is truncated" check, and change the "writeback interrupted by a fatal signal" to do a NOPAGE exit instead of letting the core code install the folio currently under writeback before killing the process. Signed-off-by: Matthew Wilcox (Oracle) Link: https://lore.kernel.org/r/20241005182307.3190401-3-willy@infradead.org Signed-off-by: Christian Brauner --- fs/netfs/buffered_write.c | 27 +++++++++++++-------------- 1 file changed, 13 insertions(+), 14 deletions(-) diff --git a/fs/netfs/buffered_write.c b/fs/netfs/buffered_write.c index b3910dfcb56d..ff2814da88b1 100644 --- a/fs/netfs/buffered_write.c +++ b/fs/netfs/buffered_write.c @@ -491,7 +491,9 @@ EXPORT_SYMBOL(netfs_file_write_iter); /* * Notification that a previously read-only page is about to become writable. - * Note that the caller indicates a single page of a multipage folio. + * The caller indicates the precise page that needs to be written to, but + * we only track group on a per-folio basis, so we block more often than + * we might otherwise. */ vm_fault_t netfs_page_mkwrite(struct vm_fault *vmf, struct netfs_group *netfs_group) { @@ -501,7 +503,7 @@ vm_fault_t netfs_page_mkwrite(struct vm_fault *vmf, struct netfs_group *netfs_gr struct address_space *mapping = file->f_mapping; struct inode *inode = file_inode(file); struct netfs_inode *ictx = netfs_inode(inode); - vm_fault_t ret = VM_FAULT_RETRY; + vm_fault_t ret = VM_FAULT_NOPAGE; int err; _enter("%lx", folio->index); @@ -510,21 +512,15 @@ vm_fault_t netfs_page_mkwrite(struct vm_fault *vmf, struct netfs_group *netfs_gr if (folio_lock_killable(folio) < 0) goto out; - if (folio->mapping != mapping) { - folio_unlock(folio); - ret = VM_FAULT_NOPAGE; - goto out; - } - - if (folio_wait_writeback_killable(folio)) { - ret = VM_FAULT_LOCKED; - goto out; - } + if (folio->mapping != mapping) + goto unlock; + if (folio_wait_writeback_killable(folio) < 0) + goto unlock; /* Can we see a streaming write here? */ if (WARN_ON(!folio_test_uptodate(folio))) { - ret = VM_FAULT_SIGBUS | VM_FAULT_LOCKED; - goto out; + ret = VM_FAULT_SIGBUS; + goto unlock; } group = netfs_folio_group(folio); @@ -559,5 +555,8 @@ vm_fault_t netfs_page_mkwrite(struct vm_fault *vmf, struct netfs_group *netfs_gr out: sb_end_pagefault(inode->i_sb); return ret; +unlock: + folio_unlock(folio); + goto out; } EXPORT_SYMBOL(netfs_page_mkwrite);