cifs: improve symlink handling for smb2+

When creating inode for symlink, the client used to send below
requests to fill it in:

    * create+query_info+close (STATUS_STOPPED_ON_SYMLINK)
    * create(+reparse_flag)+query_info+close (set file attrs)
    * create+ioctl(get_reparse)+close (query reparse tag)

and then for every access to the symlink dentry, the ->link() method
would send another:

    * create+ioctl(get_reparse)+close (parse symlink)

So, in order to improve:

    (i) Get rid of unnecessary roundtrips and then resolve symlinks as
	follows:

        * create+query_info+close (STATUS_STOPPED_ON_SYMLINK +
	                           parse symlink + get reparse tag)
        * create(+reparse_flag)+query_info+close (set file attrs)

    (ii) Set the resolved symlink target directly in inode->i_link and
         use simple_get_link() for ->link() to simply return it.

Signed-off-by: Paulo Alcantara (SUSE) <pc@cjr.nz>
Reviewed-by: Ronnie Sahlberg <lsahlber@redhat.com>
Signed-off-by: Steve French <stfrench@microsoft.com>

fs/cifs/cifsfs.c

@@ -396,6 +396,7 @@ cifs_alloc_inode(struct super_block *sb)
 	cifs_inode->epoch = 0;
 	spin_lock_init(&cifs_inode->open_file_lock);
 	generate_random_uuid(cifs_inode->lease_key);
+	cifs_inode->symlink_target = NULL;
 
 	/*
 	 * Can not set i_flags here - they get immediately overwritten to zero
@@ -412,7 +413,11 @@ cifs_alloc_inode(struct super_block *sb)
 static void
 cifs_free_inode(struct inode *inode)
 {
-	kmem_cache_free(cifs_inode_cachep, CIFS_I(inode));
+	struct cifsInodeInfo *cinode = CIFS_I(inode);
+
+	if (S_ISLNK(inode->i_mode))
+		kfree(cinode->symlink_target);
+	kmem_cache_free(cifs_inode_cachep, cinode);
 }
 
 static void
@@ -1139,7 +1144,7 @@ const struct inode_operations cifs_file_inode_ops = {
 };
 
 const struct inode_operations cifs_symlink_inode_ops = {
-	.get_link = cifs_get_link,
+	.get_link = simple_get_link,
 	.permission = cifs_permission,
 	.listxattr = cifs_listxattr,
 };

fs/cifs/cifsglob.h

@@ -185,6 +185,19 @@ struct cifs_cred {
 	struct cifs_ace *aces;
 };
 
+struct cifs_open_info_data {
+	char *symlink_target;
+	union {
+		struct smb2_file_all_info fi;
+		struct smb311_posix_qinfo posix_fi;
+	};
+};
+
+static inline void cifs_free_open_info(struct cifs_open_info_data *data)
+{
+	kfree(data->symlink_target);
+}
+
 /*
  *****************************************************************
  * Except the CIFS PDUs themselves all the
@@ -307,20 +320,20 @@ struct smb_version_operations {
 	int (*is_path_accessible)(const unsigned int, struct cifs_tcon *,
 				  struct cifs_sb_info *, const char *);
 	/* query path data from the server */
-	int (*query_path_info)(const unsigned int, struct cifs_tcon *,
-			       struct cifs_sb_info *, const char *,
-			       FILE_ALL_INFO *, bool *, bool *);
+	int (*query_path_info)(const unsigned int xid, struct cifs_tcon *tcon,
+			       struct cifs_sb_info *cifs_sb, const char *full_path,
+			       struct cifs_open_info_data *data, bool *adjust_tz, bool *reparse);
 	/* query file data from the server */
-	int (*query_file_info)(const unsigned int, struct cifs_tcon *,
-			       struct cifs_fid *, FILE_ALL_INFO *);
+	int (*query_file_info)(const unsigned int xid, struct cifs_tcon *tcon,
+			       struct cifsFileInfo *cfile, struct cifs_open_info_data *data);
 	/* query reparse tag from srv to determine which type of special file */
 	int (*query_reparse_tag)(const unsigned int xid, struct cifs_tcon *tcon,
 				struct cifs_sb_info *cifs_sb, const char *path,
 				__u32 *reparse_tag);
 	/* get server index number */
-	int (*get_srv_inum)(const unsigned int, struct cifs_tcon *,
-			    struct cifs_sb_info *, const char *,
-			    u64 *uniqueid, FILE_ALL_INFO *);
+	int (*get_srv_inum)(const unsigned int xid, struct cifs_tcon *tcon,
+			    struct cifs_sb_info *cifs_sb, const char *full_path, u64 *uniqueid,
+			    struct cifs_open_info_data *data);
 	/* set size by path */
 	int (*set_path_size)(const unsigned int, struct cifs_tcon *,
 			     const char *, __u64, struct cifs_sb_info *, bool);
@@ -369,8 +382,8 @@ struct smb_version_operations {
 			     struct cifs_sb_info *, const char *,
 			     char **, bool);
 	/* open a file for non-posix mounts */
-	int (*open)(const unsigned int, struct cifs_open_parms *,
-		    __u32 *, FILE_ALL_INFO *);
+	int (*open)(const unsigned int xid, struct cifs_open_parms *oparms, __u32 *oplock,
+		    void *buf);
 	/* set fid protocol-specific info */
 	void (*set_fid)(struct cifsFileInfo *, struct cifs_fid *, __u32);
 	/* close a file */
@@ -1123,6 +1136,7 @@ struct cifs_fattr {
 	struct timespec64 cf_mtime;
 	struct timespec64 cf_ctime;
 	u32             cf_cifstag;
+	char            *cf_symlink_target;
 };
 
 /*
@@ -1385,6 +1399,7 @@ struct cifsFileInfo {
 	struct work_struct put; /* work for the final part of _put */
 	struct delayed_work deferred;
 	bool deferred_close_scheduled; /* Flag to indicate close is scheduled */
+	char *symlink_target;
 };
 
 struct cifs_io_parms {
@@ -1543,6 +1558,7 @@ struct cifsInodeInfo {
 	struct list_head deferred_closes; /* list of deferred closes */
 	spinlock_t deferred_lock; /* protection on deferred list */
 	bool lease_granted; /* Flag to indicate whether lease or oplock is granted. */
+	char *symlink_target;
 };
 
 static inline struct cifsInodeInfo *
@@ -2111,4 +2127,14 @@ static inline size_t ntlmssp_workstation_name_size(const struct cifs_ses *ses)
 	return sizeof(ses->workstation_name);
 }
 
+static inline void move_cifs_info_to_smb2(struct smb2_file_all_info *dst, const FILE_ALL_INFO *src)
+{
+	memcpy(dst, src, (size_t)((u8 *)&src->AccessFlags - (u8 *)src));
+	dst->AccessFlags = src->AccessFlags;
+	dst->CurrentByteOffset = src->CurrentByteOffset;
+	dst->Mode = src->Mode;
+	dst->AlignmentRequirement = src->AlignmentRequirement;
+	dst->FileNameLength = src->FileNameLength;
+}
+
 #endif	/* _CIFS_GLOB_H */

fs/cifs/cifsproto.h

@@ -182,10 +182,9 @@ extern int cifs_unlock_range(struct cifsFileInfo *cfile,
 extern int cifs_push_mandatory_locks(struct cifsFileInfo *cfile);
 
 extern void cifs_down_write(struct rw_semaphore *sem);
-extern struct cifsFileInfo *cifs_new_fileinfo(struct cifs_fid *fid,
-					      struct file *file,
-					      struct tcon_link *tlink,
-					      __u32 oplock);
+struct cifsFileInfo *cifs_new_fileinfo(struct cifs_fid *fid, struct file *file,
+				       struct tcon_link *tlink, __u32 oplock,
+				       const char *symlink_target);
 extern int cifs_posix_open(const char *full_path, struct inode **inode,
 			   struct super_block *sb, int mode,
 			   unsigned int f_flags, __u32 *oplock, __u16 *netfid,
@@ -200,9 +199,9 @@ extern int cifs_fattr_to_inode(struct inode *inode, struct cifs_fattr *fattr);
 extern struct inode *cifs_iget(struct super_block *sb,
 			       struct cifs_fattr *fattr);
 
-extern int cifs_get_inode_info(struct inode **inode, const char *full_path,
-			       FILE_ALL_INFO *data, struct super_block *sb,
-			       int xid, const struct cifs_fid *fid);
+int cifs_get_inode_info(struct inode **inode, const char *full_path,
+			struct cifs_open_info_data *data, struct super_block *sb, int xid,
+			const struct cifs_fid *fid);
 extern int smb311_posix_get_inode_info(struct inode **pinode, const char *search_path,
 			struct super_block *sb, unsigned int xid);
 extern int cifs_get_inode_info_unix(struct inode **pinode,

fs/cifs/dir.c

@@ -165,10 +165,9 @@ check_name(struct dentry *direntry, struct cifs_tcon *tcon)
 
 /* Inode operations in similar order to how they appear in Linux file fs.h */
 
-static int
-cifs_do_create(struct inode *inode, struct dentry *direntry, unsigned int xid,
-	       struct tcon_link *tlink, unsigned oflags, umode_t mode,
-	       __u32 *oplock, struct cifs_fid *fid)
+static int cifs_do_create(struct inode *inode, 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)
 {
 	int rc = -ENOENT;
 	int create_options = CREATE_NOT_DIR;
@@ -177,7 +176,6 @@ cifs_do_create(struct inode *inode, struct dentry *direntry, unsigned int xid,
 	struct cifs_tcon *tcon = tlink_tcon(tlink);
 	const char *full_path;
 	void *page = alloc_dentry_path();
-	FILE_ALL_INFO *buf = NULL;
 	struct inode *newinode = NULL;
 	int disposition;
 	struct TCP_Server_Info *server = tcon->ses->server;
@@ -290,12 +288,6 @@ cifs_do_create(struct inode *inode, struct dentry *direntry, unsigned int xid,
 		goto out;
 	}
 
-	buf = kmalloc(sizeof(FILE_ALL_INFO), GFP_KERNEL);
-	if (buf == NULL) {
-		rc = -ENOMEM;
-		goto out;
-	}
-
 	/*
 	 * if we're not using unix extensions, see if we need to set
 	 * ATTR_READONLY on the create call
@@ -364,8 +356,7 @@ cifs_do_create(struct inode *inode, struct dentry *direntry, unsigned int xid,
 	{
 #endif /* CONFIG_CIFS_ALLOW_INSECURE_LEGACY */
 		/* TODO: Add support for calling POSIX query info here, but passing in fid */
-		rc = cifs_get_inode_info(&newinode, full_path, buf, inode->i_sb,
-					 xid, fid);
+		rc = cifs_get_inode_info(&newinode, full_path, buf, inode->i_sb, xid, fid);
 		if (newinode) {
 			if (server->ops->set_lease_key)
 				server->ops->set_lease_key(newinode, fid);
@@ -402,7 +393,6 @@ cifs_do_create(struct inode *inode, struct dentry *direntry, unsigned int xid,
 	d_add(direntry, newinode);
 
 out:
-	kfree(buf);
 	free_dentry_path(page);
 	return rc;
 
@@ -427,6 +417,7 @@ cifs_atomic_open(struct inode *inode, struct dentry *direntry,
 	struct cifs_pending_open open;
 	__u32 oplock;
 	struct cifsFileInfo *file_info;
+	struct cifs_open_info_data buf = {};
 
 	if (unlikely(cifs_forced_shutdown(CIFS_SB(inode->i_sb))))
 		return -EIO;
@@ -484,8 +475,7 @@ 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);
-
+			    &oplock, &fid, &buf);
 	if (rc) {
 		cifs_del_pending_open(&open);
 		goto out;
@@ -510,7 +500,7 @@ cifs_atomic_open(struct inode *inode, struct dentry *direntry,
 			file->f_op = &cifs_file_direct_ops;
 		}
 
-	file_info = cifs_new_fileinfo(&fid, file, tlink, oplock);
+	file_info = cifs_new_fileinfo(&fid, file, tlink, oplock, buf.symlink_target);
 	if (file_info == NULL) {
 		if (server->ops->close)
 			server->ops->close(xid, tcon, &fid);
@@ -526,6 +516,7 @@ cifs_atomic_open(struct inode *inode, struct dentry *direntry,
 	cifs_put_tlink(tlink);
 out_free_xid:
 	free_xid(xid);
+	cifs_free_open_info(&buf);
 	return rc;
 }
 
@@ -547,6 +538,7 @@ int cifs_create(struct user_namespace *mnt_userns, struct inode *inode,
 	struct TCP_Server_Info *server;
 	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);
@@ -565,11 +557,11 @@ int cifs_create(struct user_namespace *mnt_userns, 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);
+	rc = cifs_do_create(inode, direntry, xid, tlink, oflags, mode, &oplock, &fid, &buf);
 	if (!rc && server->ops->close)
 		server->ops->close(xid, tcon, &fid);
 
+	cifs_free_open_info(&buf);
 	cifs_put_tlink(tlink);
 out_free_xid:
 	free_xid(xid);

fs/cifs/file.c

@@ -209,16 +209,14 @@ int cifs_posix_open(const char *full_path, struct inode **pinode,
 }
 #endif /* CONFIG_CIFS_ALLOW_INSECURE_LEGACY */
 
-static int
-cifs_nt_open(const char *full_path, struct inode *inode, struct cifs_sb_info *cifs_sb,
-	     struct cifs_tcon *tcon, unsigned int f_flags, __u32 *oplock,
-	     struct cifs_fid *fid, unsigned int xid)
+static int cifs_nt_open(const char *full_path, struct inode *inode, struct cifs_sb_info *cifs_sb,
+			struct cifs_tcon *tcon, unsigned int f_flags, __u32 *oplock,
+			struct cifs_fid *fid, unsigned int xid, struct cifs_open_info_data *buf)
 {
 	int rc;
 	int desired_access;
 	int disposition;
 	int create_options = CREATE_NOT_DIR;
-	FILE_ALL_INFO *buf;
 	struct TCP_Server_Info *server = tcon->ses->server;
 	struct cifs_open_parms oparms;
 
@@ -255,10 +253,6 @@ cifs_nt_open(const char *full_path, struct inode *inode, struct cifs_sb_info *ci
 
 	/* BB pass O_SYNC flag through on file attributes .. BB */
 
-	buf = kmalloc(sizeof(FILE_ALL_INFO), GFP_KERNEL);
-	if (!buf)
-		return -ENOMEM;
-
 	/* O_SYNC also has bit for O_DSYNC so following check picks up either */
 	if (f_flags & O_SYNC)
 		create_options |= CREATE_WRITE_THROUGH;
@@ -276,9 +270,8 @@ cifs_nt_open(const char *full_path, struct inode *inode, struct cifs_sb_info *ci
 	oparms.reconnect = false;
 
 	rc = server->ops->open(xid, &oparms, oplock, buf);
-
 	if (rc)
-		goto out;
+		return rc;
 
 	/* TODO: Add support for calling posix query info but with passing in fid */
 	if (tcon->unix_ext)
@@ -294,8 +287,6 @@ cifs_nt_open(const char *full_path, struct inode *inode, struct cifs_sb_info *ci
 			rc = -EOPENSTALE;
 	}
 
-out:
-	kfree(buf);
 	return rc;
 }
 
@@ -325,9 +316,9 @@ cifs_down_write(struct rw_semaphore *sem)
 
 static void cifsFileInfo_put_work(struct work_struct *work);
 
-struct cifsFileInfo *
-cifs_new_fileinfo(struct cifs_fid *fid, struct file *file,
-		  struct tcon_link *tlink, __u32 oplock)
+struct cifsFileInfo *cifs_new_fileinfo(struct cifs_fid *fid, struct file *file,
+				       struct tcon_link *tlink, __u32 oplock,
+				       const char *symlink_target)
 {
 	struct dentry *dentry = file_dentry(file);
 	struct inode *inode = d_inode(dentry);
@@ -347,6 +338,15 @@ cifs_new_fileinfo(struct cifs_fid *fid, struct file *file,
 		return NULL;
 	}
 
+	if (symlink_target) {
+		cfile->symlink_target = kstrdup(symlink_target, GFP_KERNEL);
+		if (!cfile->symlink_target) {
+			kfree(fdlocks);
+			kfree(cfile);
+			return NULL;
+		}
+	}
+
 	INIT_LIST_HEAD(&fdlocks->locks);
 	fdlocks->cfile = cfile;
 	cfile->llist = fdlocks;
@@ -440,6 +440,7 @@ static void cifsFileInfo_put_final(struct cifsFileInfo *cifs_file)
 	cifs_put_tlink(cifs_file->tlink);
 	dput(cifs_file->dentry);
 	cifs_sb_deactive(sb);
+	kfree(cifs_file->symlink_target);
 	kfree(cifs_file);
 }
 
@@ -572,6 +573,7 @@ int cifs_open(struct inode *inode, struct file *file)
 	bool posix_open_ok = false;
 	struct cifs_fid fid;
 	struct cifs_pending_open open;
+	struct cifs_open_info_data data = {};
 
 	xid = get_xid();
 
@@ -662,15 +664,15 @@ int cifs_open(struct inode *inode, struct file *file)
 		if (server->ops->get_lease_key)
 			server->ops->get_lease_key(inode, &fid);
 
-		rc = cifs_nt_open(full_path, inode, cifs_sb, tcon,
-				  file->f_flags, &oplock, &fid, xid);
+		rc = cifs_nt_open(full_path, inode, cifs_sb, tcon, file->f_flags, &oplock, &fid,
+				  xid, &data);
 		if (rc) {
 			cifs_del_pending_open(&open);
 			goto out;
 		}
 	}
 
-	cfile = cifs_new_fileinfo(&fid, file, tlink, oplock);
+	cfile = cifs_new_fileinfo(&fid, file, tlink, oplock, data.symlink_target);
 	if (cfile == NULL) {
 		if (server->ops->close)
 			server->ops->close(xid, tcon, &fid);
@@ -712,6 +714,7 @@ int cifs_open(struct inode *inode, struct file *file)
 	free_dentry_path(page);
 	free_xid(xid);
 	cifs_put_tlink(tlink);
+	cifs_free_open_info(&data);
 	return rc;
 }