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Mon, 28 Sep 2026 22:44:28 -0400 (EDT) From: NeilBrown To: Paulo Alcantara , Namjae Jeon , Alexander Viro , Christian Brauner Cc: Jeff Layton , Jan Kara , linux-fsdevel@vger.kernel.org, linux-cifs@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH v2 2/3] smb/client: use d_alloc_trylock in cifs_silly_fullpath() Date: Tue, 29 Sep 2026 12:40:02 +1000 Message-ID: <20260929024352.1433257-3-neilb@ownmail.net> X-Mailer: git-send-email 2.50.0.107.gf914562f5916.dirty In-Reply-To: <20260929024352.1433257-1-neilb@ownmail.net> References: <20260929024352.1433257-1-neilb@ownmail.net> Reply-To: NeilBrown Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit From: NeilBrown Rather than performing a normal lookup (which will be awkward with future locking changes) use d_alloc_trylock() to find a dentry for an unused name, and use an open-coded lookup_slow() to see if it is free on the server. Signed-off-by: NeilBrown --- fs/smb/client/dir.c | 29 +++++++++++++++++++++-------- 1 file changed, 21 insertions(+), 8 deletions(-) diff --git a/fs/smb/client/dir.c b/fs/smb/client/dir.c index 88fff65320f5..70ca3da28913 100644 --- a/fs/smb/client/dir.c +++ b/fs/smb/client/dir.c @@ -1183,23 +1183,36 @@ char *cifs_silly_fullpath(struct dentry *dentry) unsigned char name[CIFS_SILLYNAME_LEN + 1]; int retries = 0, max_retries = 16; size_t namesize = sizeof(name); - struct dentry *sdentry = NULL; + struct dentry *sdentry = NULL, *alias; char *path; do { dput(sdentry); scnprintf(name, namesize, CIFS_SILLYNAME_PREFIX "%x", atomic_inc_return(&cifs_sillycounter)); - sdentry = lookup_noperm(&QSTR(name), dentry->d_parent); + sdentry = d_alloc_trylock(dentry->d_parent, &QSTR(name)); + if (sdentry == ERR_PTR(-EWOULDBLOCK)) { + sdentry = NULL; + continue; + } if (IS_ERR(sdentry)) return ERR_CAST(sdentry); - if (d_is_negative(sdentry)) { - dput(sdentry); - path = alloc_parent_path(dentry, CIFS_SILLYNAME_LEN); - if (!IS_ERR(path)) - strcat(path, name); - return path; + if (!d_in_lookup(sdentry)) + continue; + alias = cifs_lookup(sdentry->d_parent->d_inode, sdentry, 0); + d_lookup_done(sdentry); + /* It is safest to return -EBUSY if there is an error in lookup */ + if (IS_ERR(alias)) + break; + if (alias || d_is_positive(sdentry)) { + dput(alias); + continue; } + dput(sdentry); + path = alloc_parent_path(dentry, CIFS_SILLYNAME_LEN); + if (!IS_ERR(path)) + strcat(path, name); + return path; } while (++retries < max_retries); dput(sdentry); return ERR_PTR(-EBUSY); -- 2.50.0.107.gf914562f5916.dirty