9p: getattr client implementation for 9P2000.L protocol.

        SYNOPSIS

              size[4] Tgetattr tag[2] fid[4] request_mask[8]

              size[4] Rgetattr tag[2] lstat[n]

           DESCRIPTION

              The getattr transaction inquires about the file identified by fid.
              request_mask is a bit mask that specifies which fields of the
              stat structure is the client interested in.

              The reply will contain a machine-independent directory entry,
              laid out as follows:

                 st_result_mask[8]
                    Bit mask that indicates which fields in the stat structure
                    have been populated by the server

                 qid.type[1]
                    the type of the file (directory, etc.), represented as a bit
                    vector corresponding to the high 8 bits of the file's mode
                    word.

                 qid.vers[4]
                    version number for given path

                 qid.path[8]
                    the file server's unique identification for the file

                 st_mode[4]
                    Permission and flags

                 st_uid[4]
                    User id of owner

                 st_gid[4]
                    Group ID of owner

                 st_nlink[8]
                    Number of hard links

                 st_rdev[8]
                    Device ID (if special file)

                 st_size[8]
                    Size, in bytes

                 st_blksize[8]
                    Block size for file system IO

                 st_blocks[8]
                    Number of file system blocks allocated

                 st_atime_sec[8]
                    Time of last access, seconds

                 st_atime_nsec[8]
                    Time of last access, nanoseconds

                 st_mtime_sec[8]
                    Time of last modification, seconds

                 st_mtime_nsec[8]
                    Time of last modification, nanoseconds

                 st_ctime_sec[8]
                    Time of last status change, seconds

                 st_ctime_nsec[8]
                    Time of last status change, nanoseconds

                 st_btime_sec[8]
                    Time of creation (birth) of file, seconds

                 st_btime_nsec[8]
                    Time of creation (birth) of file, nanoseconds

                 st_gen[8]
                    Inode generation

                 st_data_version[8]
                    Data version number

              request_mask and result_mask bit masks contain the following bits
                 #define P9_STATS_MODE          0x00000001ULL
                 #define P9_STATS_NLINK         0x00000002ULL
                 #define P9_STATS_UID           0x00000004ULL
                 #define P9_STATS_GID           0x00000008ULL
                 #define P9_STATS_RDEV          0x00000010ULL
                 #define P9_STATS_ATIME         0x00000020ULL
                 #define P9_STATS_MTIME         0x00000040ULL
                 #define P9_STATS_CTIME         0x00000080ULL
                 #define P9_STATS_INO           0x00000100ULL
                 #define P9_STATS_SIZE          0x00000200ULL
                 #define P9_STATS_BLOCKS        0x00000400ULL

                 #define P9_STATS_BTIME         0x00000800ULL
                 #define P9_STATS_GEN           0x00001000ULL
                 #define P9_STATS_DATA_VERSION  0x00002000ULL

                 #define P9_STATS_BASIC         0x000007ffULL
                 #define P9_STATS_ALL           0x00003fffULL

        This patch implements the client side of getattr implementation for
        9P2000.L. It introduces a new structure p9_stat_dotl for getting
        Linux stat information along with QID. The data layout is similar to
        stat structure in Linux user space with the following major
        differences:

        inode (st_ino) is not part of data. Instead qid is.

        device (st_dev) is not part of data because this doesn't make sense
        on the client.

        All time variables are 64 bit wide on the wire. The kernel seems to use
        32 bit variables for these variables. However, some of the architectures
        have used 64 bit variables and glibc exposes 64 bit variables to user
        space on some architectures. Hence to be on the safer side we have made
        these 64 bit in the protocol. Refer to the comments in
        include/asm-generic/stat.h

        There are some additional fields: st_btime_sec, st_btime_nsec, st_gen,
        st_data_version apart from the bitmask, st_result_mask. The bit mask
        is filled by the server to indicate which stat fields have been
        populated by the server. Currently there is no clean way for the
        server to obtain these additional fields, so it sends back just the
        basic fields.

Signed-off-by: Sripathi Kodi <sripathik@in.ibm.com>
Signed-off-by: Eric Van Hensbegren <ericvh@gmail.com>

fs/9p/v9fs_vfs.h

@@ -55,6 +55,7 @@ struct inode *v9fs_get_inode(struct super_block *sb, int mode);
 void v9fs_clear_inode(struct inode *inode);
 ino_t v9fs_qid2ino(struct p9_qid *qid);
 void v9fs_stat2inode(struct p9_wstat *, struct inode *, struct super_block *);
+void v9fs_stat2inode_dotl(struct p9_stat_dotl *, struct inode *);
 int v9fs_dir_release(struct inode *inode, struct file *filp);
 int v9fs_file_open(struct inode *inode, struct file *file);
 void v9fs_inode2stat(struct inode *inode, struct p9_wstat *stat);

fs/9p/vfs_inode.c

@@ -396,23 +396,14 @@ void v9fs_clear_inode(struct inode *inode)
 #endif
 }
 
-/**
- * v9fs_inode_from_fid - populate an inode by issuing a attribute request
- * @v9ses: session information
- * @fid: fid to issue attribute request for
- * @sb: superblock on which to create inode
- *
- */
-
 static struct inode *
-v9fs_inode_from_fid(struct v9fs_session_info *v9ses, struct p9_fid *fid,
+v9fs_inode(struct v9fs_session_info *v9ses, struct p9_fid *fid,
 	struct super_block *sb)
 {
 	int err, umode;
-	struct inode *ret;
+	struct inode *ret = NULL;
 	struct p9_wstat *st;
 
-	ret = NULL;
 	st = p9_client_stat(fid);
 	if (IS_ERR(st))
 		return ERR_CAST(st);
@@ -433,15 +424,62 @@ v9fs_inode_from_fid(struct v9fs_session_info *v9ses, struct p9_fid *fid,
 #endif
 	p9stat_free(st);
 	kfree(st);
-
 	return ret;
-
 error:
 	p9stat_free(st);
 	kfree(st);
 	return ERR_PTR(err);
 }
 
+static struct inode *
+v9fs_inode_dotl(struct v9fs_session_info *v9ses, struct p9_fid *fid,
+	struct super_block *sb)
+{
+	struct inode *ret = NULL;
+	int err;
+	struct p9_stat_dotl *st;
+
+	st = p9_client_getattr_dotl(fid, P9_STATS_BASIC);
+	if (IS_ERR(st))
+		return ERR_CAST(st);
+
+	ret = v9fs_get_inode(sb, st->st_mode);
+	if (IS_ERR(ret)) {
+		err = PTR_ERR(ret);
+		goto error;
+	}
+
+	v9fs_stat2inode_dotl(st, ret);
+	ret->i_ino = v9fs_qid2ino(&st->qid);
+#ifdef CONFIG_9P_FSCACHE
+	v9fs_vcookie_set_qid(ret, &st->qid);
+	v9fs_cache_inode_get_cookie(ret);
+#endif
+	kfree(st);
+	return ret;
+error:
+	kfree(st);
+	return ERR_PTR(err);
+}
+
+/**
+ * v9fs_inode_from_fid - Helper routine to populate an inode by
+ * issuing a attribute request
+ * @v9ses: session information
+ * @fid: fid to issue attribute request for
+ * @sb: superblock on which to create inode
+ *
+ */
+static inline struct inode *
+v9fs_inode_from_fid(struct v9fs_session_info *v9ses, struct p9_fid *fid,
+			struct super_block *sb)
+{
+	if (v9fs_proto_dotl(v9ses))
+		return v9fs_inode_dotl(v9ses, fid, sb);
+	else
+		return v9fs_inode(v9ses, fid, sb);
+}
+
 /**
  * v9fs_remove - helper function to remove files and directories
  * @dir: directory inode that is being deleted
@@ -853,6 +891,42 @@ v9fs_vfs_getattr(struct vfsmount *mnt, struct dentry *dentry,
 	return 0;
 }
 
+static int
+v9fs_vfs_getattr_dotl(struct vfsmount *mnt, struct dentry *dentry,
+		 struct kstat *stat)
+{
+	int err;
+	struct v9fs_session_info *v9ses;
+	struct p9_fid *fid;
+	struct p9_stat_dotl *st;
+
+	P9_DPRINTK(P9_DEBUG_VFS, "dentry: %p\n", dentry);
+	err = -EPERM;
+	v9ses = v9fs_inode2v9ses(dentry->d_inode);
+	if (v9ses->cache == CACHE_LOOSE || v9ses->cache == CACHE_FSCACHE)
+		return simple_getattr(mnt, dentry, stat);
+
+	fid = v9fs_fid_lookup(dentry);
+	if (IS_ERR(fid))
+		return PTR_ERR(fid);
+
+	/* Ask for all the fields in stat structure. Server will return
+	 * whatever it supports
+	 */
+
+	st = p9_client_getattr_dotl(fid, P9_STATS_ALL);
+	if (IS_ERR(st))
+		return PTR_ERR(st);
+
+	v9fs_stat2inode_dotl(st, dentry->d_inode);
+	generic_fillattr(dentry->d_inode, stat);
+	/* Change block size to what the server returned */
+	stat->blksize = st->st_blksize;
+
+	kfree(st);
+	return 0;
+}
+
 /**
  * v9fs_vfs_setattr - set file metadata
  * @dentry: file whose metadata to set
@@ -979,6 +1053,77 @@ v9fs_stat2inode(struct p9_wstat *stat, struct inode *inode,
 	inode->i_blocks = (i_size_read(inode) + 512 - 1) >> 9;
 }
 
+/**
+ * v9fs_stat2inode_dotl - populate an inode structure with stat info
+ * @stat: stat structure
+ * @inode: inode to populate
+ * @sb: superblock of filesystem
+ *
+ */
+
+void
+v9fs_stat2inode_dotl(struct p9_stat_dotl *stat, struct inode *inode)
+{
+
+	if ((stat->st_result_mask & P9_STATS_BASIC) == P9_STATS_BASIC) {
+		inode->i_atime.tv_sec = stat->st_atime_sec;
+		inode->i_atime.tv_nsec = stat->st_atime_nsec;
+		inode->i_mtime.tv_sec = stat->st_mtime_sec;
+		inode->i_mtime.tv_nsec = stat->st_mtime_nsec;
+		inode->i_ctime.tv_sec = stat->st_ctime_sec;
+		inode->i_ctime.tv_nsec = stat->st_ctime_nsec;
+		inode->i_uid = stat->st_uid;
+		inode->i_gid = stat->st_gid;
+		inode->i_nlink = stat->st_nlink;
+		inode->i_mode = stat->st_mode;
+		inode->i_rdev = new_decode_dev(stat->st_rdev);
+
+		if ((S_ISBLK(inode->i_mode)) || (S_ISCHR(inode->i_mode)))
+			init_special_inode(inode, inode->i_mode, inode->i_rdev);
+
+		i_size_write(inode, stat->st_size);
+		inode->i_blocks = stat->st_blocks;
+	} else {
+		if (stat->st_result_mask & P9_STATS_ATIME) {
+			inode->i_atime.tv_sec = stat->st_atime_sec;
+			inode->i_atime.tv_nsec = stat->st_atime_nsec;
+		}
+		if (stat->st_result_mask & P9_STATS_MTIME) {
+			inode->i_mtime.tv_sec = stat->st_mtime_sec;
+			inode->i_mtime.tv_nsec = stat->st_mtime_nsec;
+		}
+		if (stat->st_result_mask & P9_STATS_CTIME) {
+			inode->i_ctime.tv_sec = stat->st_ctime_sec;
+			inode->i_ctime.tv_nsec = stat->st_ctime_nsec;
+		}
+		if (stat->st_result_mask & P9_STATS_UID)
+			inode->i_uid = stat->st_uid;
+		if (stat->st_result_mask & P9_STATS_GID)
+			inode->i_gid = stat->st_gid;
+		if (stat->st_result_mask & P9_STATS_NLINK)
+			inode->i_nlink = stat->st_nlink;
+		if (stat->st_result_mask & P9_STATS_MODE) {
+			inode->i_mode = stat->st_mode;
+			if ((S_ISBLK(inode->i_mode)) ||
+						(S_ISCHR(inode->i_mode)))
+				init_special_inode(inode, inode->i_mode,
+								inode->i_rdev);
+		}
+		if (stat->st_result_mask & P9_STATS_RDEV)
+			inode->i_rdev = new_decode_dev(stat->st_rdev);
+		if (stat->st_result_mask & P9_STATS_SIZE)
+			i_size_write(inode, stat->st_size);
+		if (stat->st_result_mask & P9_STATS_BLOCKS)
+			inode->i_blocks = stat->st_blocks;
+	}
+	if (stat->st_result_mask & P9_STATS_GEN)
+			inode->i_generation = stat->st_gen;
+
+	/* Currently we don't support P9_STATS_BTIME and P9_STATS_DATA_VERSION
+	 * because the inode structure does not have fields for them.
+	 */
+}
+
 /**
  * v9fs_qid2ino - convert qid into inode number
  * @qid: qid to hash
@@ -1254,7 +1399,7 @@ static const struct inode_operations v9fs_dir_inode_operations_dotl = {
 	.rmdir = v9fs_vfs_rmdir,
 	.mknod = v9fs_vfs_mknod,
 	.rename = v9fs_vfs_rename,
-	.getattr = v9fs_vfs_getattr,
+	.getattr = v9fs_vfs_getattr_dotl,
 	.setattr = v9fs_vfs_setattr,
 };
 
@@ -1276,7 +1421,7 @@ static const struct inode_operations v9fs_file_inode_operations = {
 };
 
 static const struct inode_operations v9fs_file_inode_operations_dotl = {
-	.getattr = v9fs_vfs_getattr,
+	.getattr = v9fs_vfs_getattr_dotl,
 	.setattr = v9fs_vfs_setattr,
 };
 
@@ -1292,6 +1437,6 @@ static const struct inode_operations v9fs_symlink_inode_operations_dotl = {
 	.readlink = generic_readlink,
 	.follow_link = v9fs_vfs_follow_link,
 	.put_link = v9fs_vfs_put_link,
-	.getattr = v9fs_vfs_getattr,
+	.getattr = v9fs_vfs_getattr_dotl,
 	.setattr = v9fs_vfs_setattr,
 };

fs/9p/vfs_super.c

@@ -107,7 +107,6 @@ static int v9fs_get_sb(struct file_system_type *fs_type, int flags,
 	struct inode *inode = NULL;
 	struct dentry *root = NULL;
 	struct v9fs_session_info *v9ses = NULL;
-	struct p9_wstat *st = NULL;
 	int mode = S_IRWXUGO | S_ISVTX;
 	struct p9_fid *fid;
 	int retval = 0;
@@ -124,16 +123,10 @@ static int v9fs_get_sb(struct file_system_type *fs_type, int flags,
 		goto close_session;
 	}
 
-	st = p9_client_stat(fid);
-	if (IS_ERR(st)) {
-		retval = PTR_ERR(st);
-		goto clunk_fid;
-	}
-
 	sb = sget(fs_type, NULL, v9fs_set_super, v9ses);
 	if (IS_ERR(sb)) {
 		retval = PTR_ERR(sb);
-		goto free_stat;
+		goto clunk_fid;
 	}
 	v9fs_fill_super(sb, v9ses, flags, data);
 
@@ -151,22 +144,38 @@ static int v9fs_get_sb(struct file_system_type *fs_type, int flags,
 	}
 
 	sb->s_root = root;
-	root->d_inode->i_ino = v9fs_qid2ino(&st->qid);
 
-	v9fs_stat2inode(st, root->d_inode, sb);
+	if (v9fs_proto_dotl(v9ses)) {
+		struct p9_stat_dotl *st = NULL;
+		st = p9_client_getattr_dotl(fid, P9_STATS_BASIC);
+		if (IS_ERR(st)) {
+			retval = PTR_ERR(st);
+			goto clunk_fid;
+		}
+
+		v9fs_stat2inode_dotl(st, root->d_inode);
+		kfree(st);
+	} else {
+		struct p9_wstat *st = NULL;
+		st = p9_client_stat(fid);
+		if (IS_ERR(st)) {
+			retval = PTR_ERR(st);
+			goto clunk_fid;
+		}
+
+		root->d_inode->i_ino = v9fs_qid2ino(&st->qid);
+		v9fs_stat2inode(st, root->d_inode, sb);
+
+		p9stat_free(st);
+		kfree(st);
+	}
 
 	v9fs_fid_add(root, fid);
-	p9stat_free(st);
-	kfree(st);
 
 P9_DPRINTK(P9_DEBUG_VFS, " simple set mount, return 0\n");
 	simple_set_mnt(mnt, sb);
 	return 0;
 
-free_stat:
-	p9stat_free(st);
-	kfree(st);
-
 clunk_fid:
 	p9_client_clunk(fid);
 
@@ -176,8 +185,6 @@ P9_DPRINTK(P9_DEBUG_VFS, " simple set mount, return 0\n");
 	return retval;
 
 release_sb:
-	p9stat_free(st);
-	kfree(st);
 	deactivate_locked_super(sb);
 	return retval;
 }

include/net/9p/9p.h

@@ -133,6 +133,8 @@ enum p9_msg_t {
 	P9_RSTATFS,
 	P9_TRENAME = 20,
 	P9_RRENAME,
+	P9_TGETATTR = 24,
+	P9_RGETATTR,
 	P9_TREADDIR = 40,
 	P9_RREADDIR,
 	P9_TVERSION = 100,
@@ -362,6 +364,48 @@ struct p9_wstat {
 	u32 n_muid;		/* 9p2000.u extensions */
 };
 
+struct p9_stat_dotl {
+	u64 st_result_mask;
+	struct p9_qid qid;
+	u32 st_mode;
+	u32 st_uid;
+	u32 st_gid;
+	u64 st_nlink;
+	u64 st_rdev;
+	u64 st_size;
+	u64 st_blksize;
+	u64 st_blocks;
+	u64 st_atime_sec;
+	u64 st_atime_nsec;
+	u64 st_mtime_sec;
+	u64 st_mtime_nsec;
+	u64 st_ctime_sec;
+	u64 st_ctime_nsec;
+	u64 st_btime_sec;
+	u64 st_btime_nsec;
+	u64 st_gen;
+	u64 st_data_version;
+};
+
+#define P9_STATS_MODE		0x00000001ULL
+#define P9_STATS_NLINK		0x00000002ULL
+#define P9_STATS_UID		0x00000004ULL
+#define P9_STATS_GID		0x00000008ULL
+#define P9_STATS_RDEV		0x00000010ULL
+#define P9_STATS_ATIME		0x00000020ULL
+#define P9_STATS_MTIME		0x00000040ULL
+#define P9_STATS_CTIME		0x00000080ULL
+#define P9_STATS_INO		0x00000100ULL
+#define P9_STATS_SIZE		0x00000200ULL
+#define P9_STATS_BLOCKS		0x00000400ULL
+
+#define P9_STATS_BTIME		0x00000800ULL
+#define P9_STATS_GEN		0x00001000ULL
+#define P9_STATS_DATA_VERSION	0x00002000ULL
+
+#define P9_STATS_BASIC		0x000007ffULL /* Mask for fields up to BLOCKS */
+#define P9_STATS_ALL		0x00003fffULL /* Mask for All fields above */
+
 /* Structures for Protocol Operations */
 struct p9_tstatfs {
 	u32 fid;

include/net/9p/client.h

@@ -238,6 +238,9 @@ int p9dirent_read(char *buf, int len, struct p9_dirent *dirent,
 struct p9_wstat *p9_client_stat(struct p9_fid *fid);
 int p9_client_wstat(struct p9_fid *fid, struct p9_wstat *wst);
 
+struct p9_stat_dotl *p9_client_getattr_dotl(struct p9_fid *fid,
+							u64 request_mask);
+
 struct p9_req_t *p9_tag_lookup(struct p9_client *, u16);
 void p9_client_cb(struct p9_client *c, struct p9_req_t *req);