smb: client: get rid of d_drop()+d_add()

Replace d_drop()+d_add() in cifs_tmpfile() and cifs_create() with
d_instantiate(), and in cifs_atomic_open() with d_splice_alias() if
in-lookup, otherwise d_instantiate().

Reported-by: Al Viro <viro@zeniv.linux.org.uk>
Closes: https://lore.kernel.org/r/20260408065719.GF3836593@ZenIV
Signed-off-by: Paulo Alcantara (Red Hat) <pc@manguebit.org>
Cc: David Howells <dhowells@redhat.com>
Cc: NeilBrown <neilb@ownmail.net>
Cc: linux-fsdevel@vger.kernel.org
Cc: linux-cifs@vger.kernel.org
Signed-off-by: Steve French <stfrench@microsoft.com>

diff --git a/fs/smb/client/cifsfs.h b/fs/smb/client/cifsfs.h
index 64c7a4c6ac834d6659ab2a8a9abb59f4721b73b7..18f9f93a01b41f34378e66a6c8ccaffc4aa217a3 100644 (file)
--- a/fs/smb/client/cifsfs.h
+++ b/fs/smb/client/cifsfs.h
@@ -52,9 +52,9 @@ void cifs_sb_deactive(struct super_block *sb);
 /* Functions related to inodes */
 extern const struct inode_operations cifs_dir_inode_ops;
 struct inode *cifs_root_iget(struct super_block *sb);
-int cifs_create(struct mnt_idmap *idmap, struct inode *inode,
+int cifs_create(struct mnt_idmap *idmap, struct inode *dir,
                struct dentry *direntry, umode_t mode, bool excl);
-int cifs_atomic_open(struct inode *inode, struct dentry *direntry,
+int cifs_atomic_open(struct inode *dir, struct dentry *direntry,
                     struct file *file, unsigned int oflags, umode_t mode);
 int cifs_tmpfile(struct mnt_idmap *idmap, struct inode *dir,
                 struct file *file, umode_t mode);

diff --git a/fs/smb/client/dir.c b/fs/smb/client/dir.c
index bfc887d506b61432445801adbb09d697b7a9a4aa..6ea1ae7f7a4605ee2f531ceef730df18660873af 100644 (file)
--- a/fs/smb/client/dir.c
+++ b/fs/smb/client/dir.c
@@ -219,6 +219,7 @@ static int __cifs_do_create(struct inode *dir, struct dentry *direntry,
        int rdwr_for_fscache = 0;
        __le32 lease_flags = 0;
 
+       *inode = NULL;
        *oplock = 0;
        if (tcon->ses->server->oplocks)
                *oplock = REQ_OPLOCK;
@@ -462,7 +463,6 @@ cifs_create_set_dentry:
                goto out_err;
        }
 
-       d_drop(direntry);
        *inode = newinode;
        return rc;
 
@@ -478,11 +478,11 @@ static int cifs_do_create(struct inode *dir, struct dentry *direntry,
                          unsigned int xid, struct tcon_link *tlink,
                          unsigned int oflags, umode_t mode,
                          __u32 *oplock, struct cifs_fid *fid,
-                         struct cifs_open_info_data *buf)
+                         struct cifs_open_info_data *buf,
+                         struct inode **inode)
 {
        void *page = alloc_dentry_path();
        const char *full_path;
-       struct inode *inode;
        int rc;
 
        full_path = build_path_from_dentry(direntry, page);
@@ -491,9 +491,7 @@ static int cifs_do_create(struct inode *dir, struct dentry *direntry,
        } else {
                rc = __cifs_do_create(dir, direntry, full_path, xid,
                                      tlink, oflags, mode, oplock,
-                                     fid, buf, &inode);
-               if (!rc)
-                       d_add(direntry, inode);
+                                     fid, buf, inode);
        }
        free_dentry_path(page);
        return rc;
@@ -504,13 +502,13 @@ static int cifs_do_create(struct inode *dir, struct dentry *direntry,
  * Look up, create and open a CIFS file.
  *
  * The initial dentry state is in-lookup or hashed-negative.  On success, dentry
- * will become hashed-positive by calling d_drop() & d_add(), respectively.
+ * will become hashed-positive by calling d_splice_alias() if in-lookup,
+ * otherwise d_instantiate().
  */
-int
-cifs_atomic_open(struct inode *inode, struct dentry *direntry,
-                struct file *file, unsigned int oflags, umode_t mode)
+int cifs_atomic_open(struct inode *dir, struct dentry *direntry,
+                    struct file *file, unsigned int oflags, umode_t mode)
 {
-       struct cifs_sb_info *cifs_sb = CIFS_SB(inode);
+       struct cifs_sb_info *cifs_sb = CIFS_SB(dir);
        struct cifs_open_info_data buf = {};
        struct TCP_Server_Info *server;
        struct cifsFileInfo *file_info;
@@ -519,6 +517,8 @@ cifs_atomic_open(struct inode *inode, struct dentry *direntry,
        struct tcon_link *tlink;
        struct cifs_tcon *tcon;
        unsigned int sbflags;
+       struct dentry *alias;
+       struct inode *inode;
        unsigned int xid;
        __u32 oplock;
        int rc;
@@ -545,13 +545,13 @@ cifs_atomic_open(struct inode *inode, struct dentry *direntry,
                if (!d_in_lookup(direntry))
                        return -ENOENT;
 
-               return finish_no_open(file, cifs_lookup(inode, direntry, 0));
+               return finish_no_open(file, cifs_lookup(dir, direntry, 0));
        }
 
        xid = get_xid();
 
        cifs_dbg(FYI, "parent inode = 0x%p name is: %pd and dentry = 0x%p\n",
-                inode, direntry, direntry);
+                dir, direntry, direntry);
 
        tlink = cifs_sb_tlink(cifs_sb);
        if (IS_ERR(tlink)) {
@@ -572,13 +572,21 @@ cifs_atomic_open(struct inode *inode, struct dentry *direntry,
 
        cifs_add_pending_open(&fid, tlink, &open);
 
-       rc = cifs_do_create(inode, direntry, xid, tlink, oflags, mode,
-                           &oplock, &fid, &buf);
+       rc = cifs_do_create(dir, direntry, xid, tlink, oflags, mode,
+                           &oplock, &fid, &buf, &inode);
        if (rc) {
                cifs_del_pending_open(&open);
                goto out;
        }
 
+       if (d_in_lookup(direntry)) {
+               alias = d_splice_alias(inode, direntry);
+               if (!IS_ERR_OR_NULL(alias))
+                       direntry = alias;
+       } else {
+               d_instantiate(direntry, inode);
+       }
+
        if ((oflags & (O_CREAT | O_EXCL)) == (O_CREAT | O_EXCL))
                file->f_mode |= FMODE_CREATED;
 
@@ -622,11 +630,12 @@ out_free_xid:
  * Create a CIFS file.
  *
  * The initial dentry state is hashed-negative.  On success, dentry will become
- * hashed-positive by calling d_drop() & d_add(), respectively.
+ * hashed-positive by calling d_instantiate().
  */
-int cifs_create(struct mnt_idmap *idmap, struct inode *inode,
+int cifs_create(struct mnt_idmap *idmap, struct inode *dir,
                struct dentry *direntry, umode_t mode, bool excl)
 {
+       struct cifs_sb_info *cifs_sb = CIFS_SB(dir);
        int rc;
        unsigned int xid = get_xid();
        /*
@@ -640,19 +649,20 @@ int cifs_create(struct mnt_idmap *idmap, struct inode *inode,
        struct tcon_link *tlink;
        struct cifs_tcon *tcon;
        struct TCP_Server_Info *server;
+       struct inode *inode;
        struct cifs_fid fid;
        __u32 oplock;
        struct cifs_open_info_data buf = {};
 
        cifs_dbg(FYI, "cifs_create parent inode = 0x%p name is: %pd and dentry = 0x%p\n",
-                inode, direntry, direntry);
+                dir, direntry, direntry);
 
-       if (unlikely(cifs_forced_shutdown(CIFS_SB(inode->i_sb)))) {
+       if (unlikely(cifs_forced_shutdown(cifs_sb))) {
                rc = smb_EIO(smb_eio_trace_forced_shutdown);
                goto out_free_xid;
        }
 
-       tlink = cifs_sb_tlink(CIFS_SB(inode->i_sb));
+       tlink = cifs_sb_tlink(cifs_sb);
        rc = PTR_ERR(tlink);
        if (IS_ERR(tlink))
                goto out_free_xid;
@@ -663,9 +673,13 @@ int cifs_create(struct mnt_idmap *idmap, struct inode *inode,
        if (server->ops->new_lease_key)
                server->ops->new_lease_key(&fid);
 
-       rc = cifs_do_create(inode, direntry, xid, tlink, oflags, mode, &oplock, &fid, &buf);
-       if (!rc && server->ops->close)
-               server->ops->close(xid, tcon, &fid);
+       rc = cifs_do_create(dir, direntry, xid, tlink, oflags,
+                           mode, &oplock, &fid, &buf, &inode);
+       if (!rc) {
+               d_instantiate(direntry, inode);
+               if (server->ops->close)
+                       server->ops->close(xid, tcon, &fid);
+       }
 
        cifs_free_open_info(&buf);
        cifs_put_tlink(tlink);
@@ -1035,7 +1049,7 @@ static int set_tmpfile_attr(const unsigned int xid, unsigned int oflags,
  * Create a hidden temporary CIFS file with delete-on-close bit set.
  *
  * The initial dentry state is unhashed-negative.  On success, dentry will
- * become unhashed-positive by calling d_drop() & d_instantiate(), respectively.
+ * become unhashed-positive by calling d_instantiate().
  */
 int cifs_tmpfile(struct mnt_idmap *idmap, struct inode *dir,
                 struct file *file, umode_t mode)