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>

1 files changed, 36 insertions, 10 deletions

diff --git a/fs/cifs/cifsglob.h b/fs/cifs/cifsglob.h
index 52ddf4163b98..9c0253835f1c 100644
--- a/fs/cifs/cifsglob.h
+++ b/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 */