Merge branch 'for-linus' of git://git.open-osd.org/linux-open-osd

* 'for-linus' of git://git.open-osd.org/linux-open-osd:
  exofs: deprecate the commands pending counter
  exofs: Write sbi->s_nextid as part of the Create command
  exofs: Add option to mount by osdname
  exofs: Override read-ahead to align on stripe_size
  exofs: simple fsync race fix
  exofs: Optimize read_4_write
  exofs: Trivial: fix some indentation and debug prints
  exofs: Remove redundant unlikely()

7 files changed, 259 insertions, 65 deletions

diff --git a/Documentation/filesystems/exofs.txt b/Documentation/filesystems/exofs.txt
index abd2a9b..23583a1 100644
--- a/Documentation/filesystems/exofs.txt
+++ b/Documentation/filesystems/exofs.txt
@@ -104,7 +104,15 @@ Where:
     exofs specific options: Options are separated by commas (,)
 		pid=<integer> - The partition number to mount/create as
                                 container of the filesystem.
-                                This option is mandatory.
+                                This option is mandatory. integer can be
+                                Hex by pre-pending an 0x to the number.
+		osdname=<id>  - Mount by a device's osdname.
+                                osdname is usually a 36 character uuid of the
+                                form "d2683732-c906-4ee1-9dbd-c10c27bb40df".
+                                It is one of the device's uuid specified in the
+                                mkfs.exofs format command.
+                                If this option is specified then the /dev/osdX
+                                above can be empty and is ignored.
                 to=<integer>  - Timeout in ticks for a single command.
                                 default is (60 * HZ) [for debugging only]
 
diff --git a/fs/exofs/common.h b/fs/exofs/common.h
index f0d5203..5e74ad3 100644
--- a/fs/exofs/common.h
+++ b/fs/exofs/common.h
@@ -53,10 +53,14 @@
 #define EXOFS_ROOT_ID	0x10002	/* object ID for root directory */
 
 /* exofs Application specific page/attribute */
+/* Inode attrs */
 # define EXOFS_APAGE_FS_DATA	(OSD_APAGE_APP_DEFINED_FIRST + 3)
 # define EXOFS_ATTR_INODE_DATA	1
 # define EXOFS_ATTR_INODE_FILE_LAYOUT	2
 # define EXOFS_ATTR_INODE_DIR_LAYOUT	3
+/* Partition attrs */
+# define EXOFS_APAGE_SB_DATA	(0xF0000000U + 3)
+# define EXOFS_ATTR_SB_STATS	1
 
 /*
  * The maximum number of files we can have is limited by the size of the
@@ -86,8 +90,8 @@ enum {
  */
 enum {EXOFS_FSCB_VER = 1, EXOFS_DT_VER = 1};
 struct exofs_fscb {
-	__le64  s_nextid;	/* Highest object ID used */
-	__le64  s_numfiles;	/* Number of files on fs */
+	__le64  s_nextid;	/* Only used after mkfs */
+	__le64  s_numfiles;	/* Only used after mkfs */
 	__le32	s_version;	/* == EXOFS_FSCB_VER */
 	__le16  s_magic;	/* Magic signature */
 	__le16  s_newfs;	/* Non-zero if this is a new fs */
@@ -98,6 +102,16 @@ struct exofs_fscb {
 } __packed;
 
 /*
+ * This struct is set on the FS partition's attributes.
+ * [EXOFS_APAGE_SB_DATA, EXOFS_ATTR_SB_STATS] and is written together
+ * with the create command, to atomically persist the sb writeable information.
+ */
+struct exofs_sb_stats {
+	__le64  s_nextid;	/* Highest object ID used */
+	__le64  s_numfiles;	/* Number of files on fs */
+} __packed;
+
+/*
  * Describes the raid used in the FS. It is part of the device table.
  * This here is taken from the pNFS-objects definition. In exofs we
  * use one raid policy through-out the filesystem. (NOTE: the funny
diff --git a/fs/exofs/dir.c b/fs/exofs/dir.c
index dcc941d..d0941c6 100644
--- a/fs/exofs/dir.c
+++ b/fs/exofs/dir.c
@@ -124,7 +124,7 @@ out:
 
 Ebadsize:
 	EXOFS_ERR("ERROR [exofs_check_page]: "
-		"size of directory #%lu is not a multiple of chunk size",
+		"size of directory(0x%lx) is not a multiple of chunk size\n",
 		dir->i_ino
 	);
 	goto fail;
@@ -142,8 +142,8 @@ Espan:
 	goto bad_entry;
 bad_entry:
 	EXOFS_ERR(
-		"ERROR [exofs_check_page]: bad entry in directory #%lu: %s - "
-		"offset=%lu, inode=%llu, rec_len=%d, name_len=%d",
+		"ERROR [exofs_check_page]: bad entry in directory(0x%lx): %s - "
+		"offset=%lu, inode=0x%llu, rec_len=%d, name_len=%d\n",
 		dir->i_ino, error, (page->index<<PAGE_CACHE_SHIFT)+offs,
 		_LLU(le64_to_cpu(p->inode_no)),
 		rec_len, p->name_len);
@@ -151,8 +151,8 @@ bad_entry:
 Eend:
 	p = (struct exofs_dir_entry *)(kaddr + offs);
 	EXOFS_ERR("ERROR [exofs_check_page]: "
-		"entry in directory #%lu spans the page boundary"
-		"offset=%lu, inode=%llu",
+		"entry in directory(0x%lx) spans the page boundary"
+		"offset=%lu, inode=0x%llx\n",
 		dir->i_ino, (page->index<<PAGE_CACHE_SHIFT)+offs,
 		_LLU(le64_to_cpu(p->inode_no)));
 fail:
@@ -261,9 +261,8 @@ exofs_readdir(struct file *filp, void *dirent, filldir_t filldir)
 		struct page *page = exofs_get_page(inode, n);
 
 		if (IS_ERR(page)) {
-			EXOFS_ERR("ERROR: "
-				   "bad page in #%lu",
-				   inode->i_ino);
+			EXOFS_ERR("ERROR: bad page in directory(0x%lx)\n",
+				  inode->i_ino);
 			filp->f_pos += PAGE_CACHE_SIZE - offset;
 			return PTR_ERR(page);
 		}
@@ -283,7 +282,8 @@ exofs_readdir(struct file *filp, void *dirent, filldir_t filldir)
 		for (; (char *)de <= limit; de = exofs_next_entry(de)) {
 			if (de->rec_len == 0) {
 				EXOFS_ERR("ERROR: "
-					"zero-length directory entry");
+				     "zero-length entry in directory(0x%lx)\n",
+				     inode->i_ino);
 				exofs_put_page(page);
 				return -EIO;
 			}
@@ -342,9 +342,9 @@ struct exofs_dir_entry *exofs_find_entry(struct inode *dir,
 			kaddr += exofs_last_byte(dir, n) - reclen;
 			while ((char *) de <= kaddr) {
 				if (de->rec_len == 0) {
-					EXOFS_ERR(
-						"ERROR: exofs_find_entry: "
-						"zero-length directory entry");
+					EXOFS_ERR("ERROR: zero-length entry in "
+						  "directory(0x%lx)\n",
+						  dir->i_ino);
 					exofs_put_page(page);
 					goto out;
 				}
@@ -472,7 +472,8 @@ int exofs_add_link(struct dentry *dentry, struct inode *inode)
 			}
 			if (de->rec_len == 0) {
 				EXOFS_ERR("ERROR: exofs_add_link: "
-					"zero-length directory entry");
+				      "zero-length entry in directory(0x%lx)\n",
+				      inode->i_ino);
 				err = -EIO;
 				goto out_unlock;
 			}
@@ -491,7 +492,8 @@ int exofs_add_link(struct dentry *dentry, struct inode *inode)
 		exofs_put_page(page);
 	}
 
-	EXOFS_ERR("exofs_add_link: BAD dentry=%p or inode=%p", dentry, inode);
+	EXOFS_ERR("exofs_add_link: BAD dentry=%p or inode=0x%lx\n",
+		  dentry, inode->i_ino);
 	return -EINVAL;
 
 got_it:
@@ -542,7 +544,8 @@ int exofs_delete_entry(struct exofs_dir_entry *dir, struct page *page)
 	while (de < dir) {
 		if (de->rec_len == 0) {
 			EXOFS_ERR("ERROR: exofs_delete_entry:"
-				"zero-length directory entry");
+				  "zero-length entry in directory(0x%lx)\n",
+				  inode->i_ino);
 			err = -EIO;
 			goto out;
 		}
diff --git a/fs/exofs/exofs.h b/fs/exofs/exofs.h
index 2dc925f..c965806 100644
--- a/fs/exofs/exofs.h
+++ b/fs/exofs/exofs.h
@@ -77,7 +77,7 @@ struct exofs_layout {
  * our extension to the in-memory superblock
  */
 struct exofs_sb_info {
-	struct exofs_fscb s_fscb;		/* Written often, pre-allocate*/
+	struct exofs_sb_stats s_ess;		/* Written often, pre-allocate*/
 	int		s_timeout;		/* timeout for OSD operations */
 	uint64_t	s_nextid;		/* highest object ID used     */
 	uint32_t	s_numfiles;		/* number of files on fs      */
@@ -256,6 +256,8 @@ static inline int exofs_oi_read(struct exofs_i_info *oi,
 }
 
 /* inode.c               */
+unsigned exofs_max_io_pages(struct exofs_layout *layout,
+			    unsigned expected_pages);
 int exofs_setattr(struct dentry *, struct iattr *);
 int exofs_write_begin(struct file *file, struct address_space *mapping,
 		loff_t pos, unsigned len, unsigned flags,
@@ -279,7 +281,7 @@ int exofs_set_link(struct inode *, struct exofs_dir_entry *, struct page *,
 		    struct inode *);
 
 /* super.c               */
-int exofs_sync_fs(struct super_block *sb, int wait);
+int exofs_sbi_write_stats(struct exofs_sb_info *sbi);
 
 /*********************
  * operation vectors *
diff --git a/fs/exofs/file.c b/fs/exofs/file.c
index b905c79..45ca323 100644
--- a/fs/exofs/file.c
+++ b/fs/exofs/file.c
@@ -45,22 +45,8 @@ static int exofs_release_file(struct inode *inode, struct file *filp)
 static int exofs_file_fsync(struct file *filp, int datasync)
 {
 	int ret;
-	struct inode *inode = filp->f_mapping->host;
-	struct super_block *sb;
-
-	if (!(inode->i_state & I_DIRTY))
-		return 0;
-	if (datasync && !(inode->i_state & I_DIRTY_DATASYNC))
-		return 0;
-
-	ret = sync_inode_metadata(inode, 1);
-
-	/* This is a good place to write the sb */
-	/* TODO: Sechedule an sb-sync on create */
-	sb = inode->i_sb;
-	if (sb->s_dirt)
-		exofs_sync_fs(sb, 1);
 
+	ret = sync_inode_metadata(filp->f_mapping->host, 1);
 	return ret;
 }
 
diff --git a/fs/exofs/inode.c b/fs/exofs/inode.c
index a755523..0c713cf 100644
--- a/fs/exofs/inode.c
+++ b/fs/exofs/inode.c
@@ -43,6 +43,17 @@ enum { BIO_MAX_PAGES_KMALLOC =
 		PAGE_SIZE / sizeof(struct page *),
 };
 
+unsigned exofs_max_io_pages(struct exofs_layout *layout,
+			    unsigned expected_pages)
+{
+	unsigned pages = min_t(unsigned, expected_pages, MAX_PAGES_KMALLOC);
+
+	/* TODO: easily support bio chaining */
+	pages =  min_t(unsigned, pages,
+		       layout->group_width * BIO_MAX_PAGES_KMALLOC);
+	return pages;
+}
+
 struct page_collect {
 	struct exofs_sb_info *sbi;
 	struct inode *inode;
@@ -97,8 +108,7 @@ static void _pcol_reset(struct page_collect *pcol)
 
 static int pcol_try_alloc(struct page_collect *pcol)
 {
-	unsigned pages = min_t(unsigned, pcol->expected_pages,
-			  MAX_PAGES_KMALLOC);
+	unsigned pages;
 
 	if (!pcol->ios) { /* First time allocate io_state */
 		int ret = exofs_get_io_state(&pcol->sbi->layout, &pcol->ios);
@@ -108,8 +118,7 @@ static int pcol_try_alloc(struct page_collect *pcol)
 	}
 
 	/* TODO: easily support bio chaining */
-	pages =  min_t(unsigned, pages,
-		       pcol->sbi->layout.group_width * BIO_MAX_PAGES_KMALLOC);
+	pages =  exofs_max_io_pages(&pcol->sbi->layout, pcol->expected_pages);
 
 	for (; pages; pages >>= 1) {
 		pcol->pages = kmalloc(pages * sizeof(struct page *),
@@ -350,8 +359,10 @@ static int readpage_strip(void *data, struct page *page)
 
 		if (!pcol->read_4_write)
 			unlock_page(page);
-		EXOFS_DBGMSG("readpage_strip(0x%lx, 0x%lx) empty page,"
-			     " splitting\n", inode->i_ino, page->index);
+		EXOFS_DBGMSG("readpage_strip(0x%lx) empty page len=%zx "
+			     "read_4_write=%d index=0x%lx end_index=0x%lx "
+			     "splitting\n", inode->i_ino, len,
+			     pcol->read_4_write, page->index, end_index);
 
 		return read_exec(pcol);
 	}
@@ -722,11 +733,28 @@ int exofs_write_begin(struct file *file, struct address_space *mapping,
 
 	 /* read modify write */
 	if (!PageUptodate(page) && (len != PAGE_CACHE_SIZE)) {
+		loff_t i_size = i_size_read(mapping->host);
+		pgoff_t end_index = i_size >> PAGE_CACHE_SHIFT;
+		size_t rlen;
+
+		if (page->index < end_index)
+			rlen = PAGE_CACHE_SIZE;
+		else if (page->index == end_index)
+			rlen = i_size & ~PAGE_CACHE_MASK;
+		else
+			rlen = 0;
+
+		if (!rlen) {
+			clear_highpage(page);
+			SetPageUptodate(page);
+			goto out;
+		}
+
 		ret = _readpage(page, true);
 		if (ret) {
 			/*SetPageError was done by _readpage. Is it ok?*/
 			unlock_page(page);
-			EXOFS_DBGMSG("__readpage_filler failed\n");
+			EXOFS_DBGMSG("__readpage failed\n");
 		}
 	}
 out:
@@ -1030,6 +1058,7 @@ struct inode *exofs_iget(struct super_block *sb, unsigned long ino)
 		memcpy(oi->i_data, fcb.i_data, sizeof(fcb.i_data));
 	}
 
+	inode->i_mapping->backing_dev_info = sb->s_bdi;
 	if (S_ISREG(inode->i_mode)) {
 		inode->i_op = &exofs_file_inode_operations;
 		inode->i_fop = &exofs_file_operations;
@@ -1073,6 +1102,7 @@ int __exofs_wait_obj_created(struct exofs_i_info *oi)
 	}
 	return unlikely(is_bad_inode(&oi->vfs_inode)) ? -EIO : 0;
 }
+
 /*
  * Callback function from exofs_new_inode().  The important thing is that we
  * set the obj_created flag so that other methods know that the object exists on
@@ -1130,7 +1160,7 @@ struct inode *exofs_new_inode(struct inode *dir, int mode)
 
 	sbi = sb->s_fs_info;
 
-	sb->s_dirt = 1;
+	inode->i_mapping->backing_dev_info = sb->s_bdi;
 	inode_init_owner(inode, dir, mode);
 	inode->i_ino = sbi->s_nextid++;
 	inode->i_blkbits = EXOFS_BLKSHIFT;
@@ -1141,6 +1171,8 @@ struct inode *exofs_new_inode(struct inode *dir, int mode)
 	spin_unlock(&sbi->s_next_gen_lock);
 	insert_inode_hash(inode);
 
+	exofs_sbi_write_stats(sbi); /* Make sure new sbi->s_nextid is on disk */
+
 	mark_inode_dirty(inode);
 
 	ret = exofs_get_io_state(&sbi->layout, &ios);
@@ -1271,7 +1303,8 @@ out:
 
 int exofs_write_inode(struct inode *inode, struct writeback_control *wbc)
 {
-	return exofs_update_inode(inode, wbc->sync_mode == WB_SYNC_ALL);
+	/* FIXME: fix fsync and use wbc->sync_mode == WB_SYNC_ALL */
+	return exofs_update_inode(inode, 1);
 }
 
 /*
diff --git a/fs/exofs/super.c b/fs/exofs/super.c
index 8c6c466..06065bd 100644
--- a/fs/exofs/super.c
+++ b/fs/exofs/super.c
@@ -48,6 +48,7 @@
  * struct to hold what we get from mount options
  */
 struct exofs_mountopt {
+	bool is_osdname;
 	const char *dev_name;
 	uint64_t pid;
 	int timeout;
@@ -56,7 +57,7 @@ struct exofs_mountopt {
 /*
  * exofs-specific mount-time options.
  */
-enum { Opt_pid, Opt_to, Opt_mkfs, Opt_format, Opt_err };
+enum { Opt_name, Opt_pid, Opt_to, Opt_err };
 
 /*
  * Our mount-time options.  These should ideally be 64-bit unsigned, but the
@@ -64,6 +65,7 @@ enum { Opt_pid, Opt_to, Opt_mkfs, Opt_format, Opt_err };
  * sufficient for most applications now.
  */
 static match_table_t tokens = {
+	{Opt_name, "osdname=%s"},
 	{Opt_pid, "pid=%u"},
 	{Opt_to, "to=%u"},
 	{Opt_err, NULL}
@@ -94,6 +96,14 @@ static int parse_options(char *options, struct exofs_mountopt *opts)
 
 		token = match_token(p, tokens, args);
 		switch (token) {
+		case Opt_name:
+			opts->dev_name = match_strdup(&args[0]);
+			if (unlikely(!opts->dev_name)) {
+				EXOFS_ERR("Error allocating dev_name");
+				return -ENOMEM;
+			}
+			opts->is_osdname = true;
+			break;
 		case Opt_pid:
 			if (0 == match_strlcpy(str, &args[0], sizeof(str)))
 				return -EINVAL;
@@ -203,6 +213,101 @@ static void destroy_inodecache(void)
 static const struct super_operations exofs_sops;
 static const struct export_operations exofs_export_ops;
 
+static const struct osd_attr g_attr_sb_stats = ATTR_DEF(
+	EXOFS_APAGE_SB_DATA,
+	EXOFS_ATTR_SB_STATS,
+	sizeof(struct exofs_sb_stats));
+
+static int __sbi_read_stats(struct exofs_sb_info *sbi)
+{
+	struct osd_attr attrs[] = {
+		[0] = g_attr_sb_stats,
+	};
+	struct exofs_io_state *ios;
+	int ret;
+
+	ret = exofs_get_io_state(&sbi->layout, &ios);
+	if (unlikely(ret)) {
+		EXOFS_ERR("%s: exofs_get_io_state failed.\n", __func__);
+		return ret;
+	}
+
+	ios->cred = sbi->s_cred;
+
+	ios->in_attr = attrs;
+	ios->in_attr_len = ARRAY_SIZE(attrs);
+
+	ret = exofs_sbi_read(ios);
+	if (unlikely(ret)) {
+		EXOFS_ERR("Error reading super_block stats => %d\n", ret);
+		goto out;
+	}
+
+	ret = extract_attr_from_ios(ios, &attrs[0]);
+	if (ret) {
+		EXOFS_ERR("%s: extract_attr of sb_stats failed\n", __func__);
+		goto out;
+	}
+	if (attrs[0].len) {
+		struct exofs_sb_stats *ess;
+
+		if (unlikely(attrs[0].len != sizeof(*ess))) {
+			EXOFS_ERR("%s: Wrong version of exofs_sb_stats "
+				  "size(%d) != expected(%zd)\n",
+				  __func__, attrs[0].len, sizeof(*ess));
+			goto out;
+		}
+
+		ess = attrs[0].val_ptr;
+		sbi->s_nextid = le64_to_cpu(ess->s_nextid);
+		sbi->s_numfiles = le32_to_cpu(ess->s_numfiles);
+	}
+
+out:
+	exofs_put_io_state(ios);
+	return ret;
+}
+
+static void stats_done(struct exofs_io_state *ios, void *p)
+{
+	exofs_put_io_state(ios);
+	/* Good thanks nothing to do anymore */
+}
+
+/* Asynchronously write the stats attribute */
+int exofs_sbi_write_stats(struct exofs_sb_info *sbi)
+{
+	struct osd_attr attrs[] = {
+		[0] = g_attr_sb_stats,
+	};
+	struct exofs_io_state *ios;
+	int ret;
+
+	ret = exofs_get_io_state(&sbi->layout, &ios);
+	if (unlikely(ret)) {
+		EXOFS_ERR("%s: exofs_get_io_state failed.\n", __func__);
+		return ret;
+	}
+
+	sbi->s_ess.s_nextid   = cpu_to_le64(sbi->s_nextid);
+	sbi->s_ess.s_numfiles = cpu_to_le64(sbi->s_numfiles);
+	attrs[0].val_ptr = &sbi->s_ess;
+
+	ios->cred = sbi->s_cred;
+	ios->done = stats_done;
+	ios->private = sbi;
+	ios->out_attr = attrs;
+	ios->out_attr_len = ARRAY_SIZE(attrs);
+
+	ret = exofs_sbi_write(ios);
+	if (unlikely(ret)) {
+		EXOFS_ERR("%s: exofs_sbi_write failed.\n", __func__);
+		exofs_put_io_state(ios);
+	}
+
+	return ret;
+}
+
 /*
  * Write the superblock to the OSD
  */
@@ -213,18 +318,25 @@ int exofs_sync_fs(struct super_block *sb, int wait)
 	struct exofs_io_state *ios;
 	int ret = -ENOMEM;
 
-	lock_super(sb);
+	fscb = kmalloc(sizeof(*fscb), GFP_KERNEL);
+	if (unlikely(!fscb))
+		return -ENOMEM;
+
 	sbi = sb->s_fs_info;
-	fscb = &sbi->s_fscb;
 
+	/* NOTE: We no longer dirty the super_block anywhere in exofs. The
+	 * reason we write the fscb here on unmount is so we can stay backwards
+	 * compatible with fscb->s_version == 1. (What we are not compatible
+	 * with is if a new version FS crashed and then we try to mount an old
+	 * version). Otherwise the exofs_fscb is read-only from mkfs time. All
+	 * the writeable info is set in exofs_sbi_write_stats() above.
+	 */
 	ret = exofs_get_io_state(&sbi->layout, &ios);
-	if (ret)
+	if (unlikely(ret))
 		goto out;
 
-	/* Note: We only write the changing part of the fscb. .i.e upto the
-	 *       the fscb->s_dev_table_oid member. There is no read-modify-write
-	 *       here.
-	 */
+	lock_super(sb);
+
 	ios->length = offsetof(struct exofs_fscb, s_dev_table_oid);
 	memset(fscb, 0, ios->length);
 	fscb->s_nextid = cpu_to_le64(sbi->s_nextid);
@@ -239,16 +351,17 @@ int exofs_sync_fs(struct super_block *sb, int wait)
 	ios->cred = sbi->s_cred;
 
 	ret = exofs_sbi_write(ios);
-	if (unlikely(ret)) {
+	if (unlikely(ret))
 		EXOFS_ERR("%s: exofs_sbi_write failed.\n", __func__);
-		goto out;
-	}
-	sb->s_dirt = 0;
+	else
+		sb->s_dirt = 0;
+
 
+	unlock_super(sb);
 out:
 	EXOFS_DBGMSG("s_nextid=0x%llx ret=%d\n", _LLU(sbi->s_nextid), ret);
 	exofs_put_io_state(ios);
-	unlock_super(sb);
+	kfree(fscb);
 	return ret;
 }
 
@@ -292,13 +405,14 @@ static void exofs_put_super(struct super_block *sb)
 	int num_pend;
 	struct exofs_sb_info *sbi = sb->s_fs_info;
 
-	if (sb->s_dirt)
-		exofs_write_super(sb);
-
 	/* make sure there are no pending commands */
 	for (num_pend = atomic_read(&sbi->s_curr_pending); num_pend > 0;
 	     num_pend = atomic_read(&sbi->s_curr_pending)) {
 		wait_queue_head_t wq;
+
+		printk(KERN_NOTICE "%s: !!Pending operations in flight. "
+		       "This is a BUG. please report to osd-dev@open-osd.org\n",
+		       __func__);
 		init_waitqueue_head(&wq);
 		wait_event_timeout(wq,
 				  (atomic_read(&sbi->s_curr_pending) == 0),
@@ -390,6 +504,23 @@ static int _read_and_match_data_map(struct exofs_sb_info *sbi, unsigned numdevs,
 	return 0;
 }
 
+static unsigned __ra_pages(struct exofs_layout *layout)
+{
+	const unsigned _MIN_RA = 32; /* min 128K read-ahead */
+	unsigned ra_pages = layout->group_width * layout->stripe_unit /
+				PAGE_SIZE;
+	unsigned max_io_pages = exofs_max_io_pages(layout, ~0);
+
+	ra_pages *= 2; /* two stripes */
+	if (ra_pages < _MIN_RA)
+		ra_pages = roundup(_MIN_RA, ra_pages / 2);
+
+	if (ra_pages > max_io_pages)
+		ra_pages = max_io_pages;
+
+	return ra_pages;
+}
+
 /* @odi is valid only as long as @fscb_dev is valid */
 static int exofs_devs_2_odi(struct exofs_dt_device_info *dt_dev,
 			     struct osd_dev_info *odi)
@@ -495,7 +626,7 @@ static int exofs_read_lookup_dev_table(struct exofs_sb_info **psbi,
 		}
 
 		od = osduld_info_lookup(&odi);
-		if (unlikely(IS_ERR(od))) {
+		if (IS_ERR(od)) {
 			ret = PTR_ERR(od);
 			EXOFS_ERR("ERROR: device requested is not found "
 				  "osd_name-%s =>%d\n", odi.osdname, ret);
@@ -558,9 +689,17 @@ static int exofs_fill_super(struct super_block *sb, void *data, int silent)
 		goto free_bdi;
 
 	/* use mount options to fill superblock */
-	od = osduld_path_lookup(opts->dev_name);
+	if (opts->is_osdname) {
+		struct osd_dev_info odi = {.systemid_len = 0};
+
+		odi.osdname_len = strlen(opts->dev_name);
+		odi.osdname = (u8 *)opts->dev_name;
+		od = osduld_info_lookup(&odi);
+	} else {
+		od = osduld_path_lookup(opts->dev_name);
+	}
 	if (IS_ERR(od)) {
-		ret = PTR_ERR(od);
+		ret = -EINVAL;
 		goto free_sbi;
 	}
 
@@ -594,6 +733,7 @@ static int exofs_fill_super(struct super_block *sb, void *data, int silent)
 		goto free_sbi;
 
 	sb->s_magic = le16_to_cpu(fscb.s_magic);
+	/* NOTE: we read below to be backward compatible with old versions */
 	sbi->s_nextid = le64_to_cpu(fscb.s_nextid);
 	sbi->s_numfiles = le32_to_cpu(fscb.s_numfiles);
 
@@ -604,7 +744,7 @@ static int exofs_fill_super(struct super_block *sb, void *data, int silent)
 		ret = -EINVAL;
 		goto free_sbi;
 	}
-	if (le32_to_cpu(fscb.s_version) != EXOFS_FSCB_VER) {
+	if (le32_to_cpu(fscb.s_version) > EXOFS_FSCB_VER) {
 		EXOFS_ERR("ERROR: Bad FSCB version expected-%d got-%d\n",
 			  EXOFS_FSCB_VER, le32_to_cpu(fscb.s_version));
 		ret = -EINVAL;
@@ -622,7 +762,10 @@ static int exofs_fill_super(struct super_block *sb, void *data, int silent)
 			goto free_sbi;
 	}
 
+	__sbi_read_stats(sbi);
+
 	/* set up operation vectors */
+	sbi->bdi.ra_pages = __ra_pages(&sbi->layout);
 	sb->s_bdi = &sbi->bdi;
 	sb->s_fs_info = sbi;
 	sb->s_op = &exofs_sops;
@@ -652,6 +795,8 @@ static int exofs_fill_super(struct super_block *sb, void *data, int silent)
 
 	_exofs_print_device("Mounting", opts->dev_name, sbi->layout.s_ods[0],
 			    sbi->layout.s_pid);
+	if (opts->is_osdname)
+		kfree(opts->dev_name);
 	return 0;
 
 free_sbi:
@@ -660,6 +805,8 @@ free_bdi:
 	EXOFS_ERR("Unable to mount exofs on %s pid=0x%llx err=%d\n",
 		  opts->dev_name, sbi->layout.s_pid, ret);
 	exofs_free_sbi(sbi);
+	if (opts->is_osdname)
+		kfree(opts->dev_name);
 	return ret;
 }
 
@@ -677,7 +824,8 @@ static struct dentry *exofs_mount(struct file_system_type *type,
 	if (ret)
 		return ERR_PTR(ret);
 
-	opts.dev_name = dev_name;
+	if (!opts.dev_name)
+		opts.dev_name = dev_name;
 	return mount_nodev(type, flags, &opts, exofs_fill_super);
 }