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Thu, 5 Nov 2026 16:27:05 -0500 (EST) From: Ian Bridges To: linkinjeon@kernel.org Cc: senozhatsky@chromium.org, tom@talpey.com, chenxiaosong@chenxiaosong.com, linux-cifs@vger.kernel.org, linux-kernel@vger.kernel.org, stable@vger.kernel.org, Ian Bridges Subject: Re: [PATCH 1/2] ksmbd: skip metadata-only opens in sharing checks Date: Thu, 5 Nov 2026 15:26:52 -0600 Message-ID: <20261105212652.697079-1-icb@fastmail.org> X-Mailer: git-send-email 2.47.3 In-Reply-To: References: <20261104183702.192452-1-icb@fastmail.org> <20261104183702.192452-2-icb@fastmail.org> X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Hi Namjae, You're right. With this patch a CREATE for READ_CONTROL with FILE_OVERWRITE or FILE_SUPERSEDE skips the sharing check, and smb2_open() then truncates the file. In your example, with an existing FILE_READ_DATA open at ShareAccess 0, the second CREATE for READ_CONTROL and FILE_OVERWRITE at ShareAccess 0 succeeds and the file's data is lost. A test that runs smb2_open() confirms it. I'll send a v2 that does what you suggest: the sharing check counts an open that truncates the file as holding FILE_WRITE_DATA, and the returned handle keeps the open's own access. An open of a directory or a named stream, or one for attributes only, gets O_TRUNC but is not truncated, so it is not counted. A truncating open is already on the inode's open list before it truncates, so v2 also counts it as holding FILE_WRITE_DATA, for as long as it is open, when deciding whether a later open is checked against it. Patch 2 does not change. Thanks, Ian