Linux-2.6.12-rc2v2.6.12-rc2

Initial git repository build. I'm not bothering with the full history,
even though we have it. We can create a separate "historical" git
archive of that later if we want to, and in the meantime it's about
3.2GB when imported into git - space that would just make the early
git days unnecessarily complicated, when we don't have a lot of good
infrastructure for it.

Let it rip!

2 files changed, 546 insertions, 0 deletions

diff --git a/fs/exportfs/Makefile b/fs/exportfs/Makefile
new file mode 100644
index 000000000000..d7c5d4ddb34b
--- /dev/null
+++ b/fs/exportfs/Makefile
@@ -0,0 +1,6 @@
+#
+# Makefile for the filesystem export support routines.
+
+obj-$(CONFIG_EXPORTFS) += exportfs.o
+
+exportfs-objs := expfs.o
diff --git a/fs/exportfs/expfs.c b/fs/exportfs/expfs.c
new file mode 100644
index 000000000000..c49d6254379a
--- /dev/null
+++ b/fs/exportfs/expfs.c
@@ -0,0 +1,540 @@
+
+#include <linux/fs.h>
+#include <linux/file.h>
+#include <linux/module.h>
+#include <linux/smp_lock.h>
+#include <linux/namei.h>
+
+struct export_operations export_op_default;
+
+#define	CALL(ops,fun) ((ops->fun)?(ops->fun):export_op_default.fun)
+
+#define dprintk(fmt, args...) do{}while(0)
+
+/**
+ * find_exported_dentry - helper routine to implement export_operations->decode_fh
+ * @sb:		The &super_block identifying the filesystem
+ * @obj:	An opaque identifier of the object to be found - passed to
+ *		get_inode
+ * @parent:	An optional opqaue identifier of the parent of the object.
+ * @acceptable:	A function used to test possible &dentries to see if they are
+ *		acceptable
+ * @context:	A parameter to @acceptable so that it knows on what basis to
+ *		judge.
+ *
+ * find_exported_dentry is the central helper routine to enable file systems
+ * to provide the decode_fh() export_operation.  It's main task is to take
+ * an &inode, find or create an appropriate &dentry structure, and possibly
+ * splice this into the dcache in the correct place.
+ *
+ * The decode_fh() operation provided by the filesystem should call
+ * find_exported_dentry() with the same parameters that it received except
+ * that instead of the file handle fragment, pointers to opaque identifiers
+ * for the object and optionally its parent are passed.  The default decode_fh
+ * routine passes one pointer to the start of the filehandle fragment, and
+ * one 8 bytes into the fragment.  It is expected that most filesystems will
+ * take this approach, though the offset to the parent identifier may well be
+ * different.
+ *
+ * find_exported_dentry() will call get_dentry to get an dentry pointer from
+ * the file system.  If any &dentry in the d_alias list is acceptable, it will
+ * be returned.  Otherwise find_exported_dentry() will attempt to splice a new
+ * &dentry into the dcache using get_name() and get_parent() to find the
+ * appropriate place.
+ */
+
+struct dentry *
+find_exported_dentry(struct super_block *sb, void *obj, void *parent,
+		     int (*acceptable)(void *context, struct dentry *de),
+		     void *context)
+{
+	struct dentry *result = NULL;
+	struct dentry *target_dir;
+	int err;
+	struct export_operations *nops = sb->s_export_op;
+	struct list_head *le, *head;
+	struct dentry *toput = NULL;
+	int noprogress;
+	char nbuf[NAME_MAX+1];
+
+	/*
+	 * Attempt to find the inode.
+	 */
+	result = CALL(sb->s_export_op,get_dentry)(sb,obj);
+	err = -ESTALE;
+	if (result == NULL)
+		goto err_out;
+	if (IS_ERR(result)) {
+		err = PTR_ERR(result);
+		goto err_out;
+	}
+	if (S_ISDIR(result->d_inode->i_mode) &&
+	    (result->d_flags & DCACHE_DISCONNECTED)) {
+		/* it is an unconnected directory, we must connect it */
+		;
+	} else {
+		if (acceptable(context, result))
+			return result;
+		if (S_ISDIR(result->d_inode->i_mode)) {
+			/* there is no other dentry, so fail */
+			goto err_result;
+		}
+		/* try any other aliases */
+		spin_lock(&dcache_lock);
+		head = &result->d_inode->i_dentry;
+		list_for_each(le, head) {
+			struct dentry *dentry = list_entry(le, struct dentry, d_alias);
+			dget_locked(dentry);
+			spin_unlock(&dcache_lock);
+			if (toput)
+				dput(toput);
+			toput = NULL;
+			if (dentry != result &&
+			    acceptable(context, dentry)) {
+				dput(result);
+				return dentry;
+			}
+			spin_lock(&dcache_lock);
+			toput = dentry;
+		}
+		spin_unlock(&dcache_lock);
+		if (toput)
+			dput(toput);
+	}			
+
+	/* It's a directory, or we are required to confirm the file's
+	 * location in the tree based on the parent information
+ 	 */
+	dprintk("find_exported_dentry: need to look harder for %s/%d\n",sb->s_id,*(int*)obj);
+	if (S_ISDIR(result->d_inode->i_mode))
+		target_dir = dget(result);
+	else {
+		if (parent == NULL)
+			goto err_result;
+
+		target_dir = CALL(sb->s_export_op,get_dentry)(sb,parent);
+		if (IS_ERR(target_dir))
+			err = PTR_ERR(target_dir);
+		if (target_dir == NULL || IS_ERR(target_dir))
+			goto err_result;
+	}
+	/*
+	 * Now we need to make sure that target_dir is properly connected.
+	 * It may already be, as the flag isn't always updated when connection
+	 * happens.
+	 * So, we walk up parent links until we find a connected directory,
+	 * or we run out of directories.  Then we find the parent, find
+	 * the name of the child in that parent, and do a lookup.
+	 * This should connect the child into the parent
+	 * We then repeat.
+	 */
+
+	/* it is possible that a confused file system might not let us complete 
+	 * the path to the root.  For example, if get_parent returns a directory
+	 * in which we cannot find a name for the child.  While this implies a
+	 * very sick filesystem we don't want it to cause knfsd to spin.  Hence
+	 * the noprogress counter.  If we go through the loop 10 times (2 is
+	 * probably enough) without getting anywhere, we just give up
+	 */
+	noprogress= 0;
+	while (target_dir->d_flags & DCACHE_DISCONNECTED && noprogress++ < 10) {
+		struct dentry *pd = target_dir;
+
+		dget(pd);
+		spin_lock(&pd->d_lock);
+		while (!IS_ROOT(pd) &&
+				(pd->d_parent->d_flags&DCACHE_DISCONNECTED)) {
+			struct dentry *parent = pd->d_parent;
+
+			dget(parent);
+			spin_unlock(&pd->d_lock);
+			dput(pd);
+			pd = parent;
+			spin_lock(&pd->d_lock);
+		}
+		spin_unlock(&pd->d_lock);
+
+		if (!IS_ROOT(pd)) {
+			/* must have found a connected parent - great */
+			spin_lock(&pd->d_lock);
+			pd->d_flags &= ~DCACHE_DISCONNECTED;
+			spin_unlock(&pd->d_lock);
+			noprogress = 0;
+		} else if (pd == sb->s_root) {
+			printk(KERN_ERR "export: Eeek filesystem root is not connected, impossible\n");
+			spin_lock(&pd->d_lock);
+			pd->d_flags &= ~DCACHE_DISCONNECTED;
+			spin_unlock(&pd->d_lock);
+			noprogress = 0;
+		} else {
+			/* we have hit the top of a disconnected path.  Try
+			 * to find parent and connect
+			 * note: racing with some other process renaming a
+			 * directory isn't much of a problem here.  If someone
+			 * renames the directory, it will end up properly
+			 * connected, which is what we want
+			 */
+			struct dentry *ppd;
+			struct dentry *npd;
+
+			down(&pd->d_inode->i_sem);
+			ppd = CALL(nops,get_parent)(pd);
+			up(&pd->d_inode->i_sem);
+
+			if (IS_ERR(ppd)) {
+				err = PTR_ERR(ppd);
+				dprintk("find_exported_dentry: get_parent of %ld failed, err %d\n",
+					pd->d_inode->i_ino, err);
+				dput(pd);
+				break;
+			}
+			dprintk("find_exported_dentry: find name of %lu in %lu\n", pd->d_inode->i_ino, ppd->d_inode->i_ino);
+			err = CALL(nops,get_name)(ppd, nbuf, pd);
+			if (err) {
+				dput(ppd);
+				dput(pd);
+				if (err == -ENOENT)
+					/* some race between get_parent and
+					 * get_name?  just try again
+					 */
+					continue;
+				break;
+			}
+			dprintk("find_exported_dentry: found name: %s\n", nbuf);
+			down(&ppd->d_inode->i_sem);
+			npd = lookup_one_len(nbuf, ppd, strlen(nbuf));
+			up(&ppd->d_inode->i_sem);
+			if (IS_ERR(npd)) {
+				err = PTR_ERR(npd);
+				dprintk("find_exported_dentry: lookup failed: %d\n", err);
+				dput(ppd);
+				dput(pd);
+				break;
+			}
+			/* we didn't really want npd, we really wanted
+			 * a side-effect of the lookup.
+			 * hopefully, npd == pd, though it isn't really
+			 * a problem if it isn't
+			 */
+			if (npd == pd)
+				noprogress = 0;
+			else
+				printk("find_exported_dentry: npd != pd\n");
+			dput(npd);
+			dput(ppd);
+			if (IS_ROOT(pd)) {
+				/* something went wrong, we have to give up */
+				dput(pd);
+				break;
+			}
+		}
+		dput(pd);
+	}
+
+	if (target_dir->d_flags & DCACHE_DISCONNECTED) {
+		/* something went wrong - oh-well */
+		if (!err)
+			err = -ESTALE;
+		goto err_target;
+	}
+	/* if we weren't after a directory, have one more step to go */
+	if (result != target_dir) {
+		struct dentry *nresult;
+		err = CALL(nops,get_name)(target_dir, nbuf, result);
+		if (!err) {
+			down(&target_dir->d_inode->i_sem);
+			nresult = lookup_one_len(nbuf, target_dir, strlen(nbuf));
+			up(&target_dir->d_inode->i_sem);
+			if (!IS_ERR(nresult)) {
+				if (nresult->d_inode) {
+					dput(result);
+					result = nresult;
+				} else
+					dput(nresult);
+			}
+		}
+	}
+	dput(target_dir);
+	/* now result is properly connected, it is our best bet */
+	if (acceptable(context, result))
+		return result;
+	/* one last try of the aliases.. */
+	spin_lock(&dcache_lock);
+	toput = NULL;
+	head = &result->d_inode->i_dentry;
+	list_for_each(le, head) {
+		struct dentry *dentry = list_entry(le, struct dentry, d_alias);
+		dget_locked(dentry);
+		spin_unlock(&dcache_lock);
+		if (toput) dput(toput);
+		if (dentry != result &&
+		    acceptable(context, dentry)) {
+			dput(result);
+			return dentry;
+		}
+		spin_lock(&dcache_lock);
+		toput = dentry;
+	}
+	spin_unlock(&dcache_lock);
+	if (toput)
+		dput(toput);
+
+	/* drat - I just cannot find anything acceptable */
+	dput(result);
+	/* It might be justifiable to return ESTALE here,
+	 * but the filehandle at-least looks reasonable good
+	 * and it just be a permission problem, so returning
+	 * -EACCESS is safer
+	 */
+	return ERR_PTR(-EACCES);
+
+ err_target:
+	dput(target_dir);
+ err_result:
+	dput(result);
+ err_out:
+	return ERR_PTR(err);
+}
+
+
+
+static struct dentry *get_parent(struct dentry *child)
+{
+	/* get_parent cannot be supported generically, the locking
+	 * is too icky.
+	 * instead, we just return EACCES.  If server reboots or inodes
+	 * get flushed, you lose
+	 */
+	return ERR_PTR(-EACCES);
+}
+
+
+struct getdents_callback {
+	char *name;		/* name that was found. It already points to a
+				   buffer NAME_MAX+1 is size */
+	unsigned long ino;	/* the inum we are looking for */
+	int found;		/* inode matched? */
+	int sequence;		/* sequence counter */
+};
+
+/*
+ * A rather strange filldir function to capture
+ * the name matching the specified inode number.
+ */
+static int filldir_one(void * __buf, const char * name, int len,
+			loff_t pos, ino_t ino, unsigned int d_type)
+{
+	struct getdents_callback *buf = __buf;
+	int result = 0;
+
+	buf->sequence++;
+	if (buf->ino == ino) {
+		memcpy(buf->name, name, len);
+		buf->name[len] = '\0';
+		buf->found = 1;
+		result = -1;
+	}
+	return result;
+}
+
+/**
+ * get_name - default export_operations->get_name function
+ * @dentry: the directory in which to find a name
+ * @name:   a pointer to a %NAME_MAX+1 char buffer to store the name
+ * @child:  the dentry for the child directory.
+ *
+ * calls readdir on the parent until it finds an entry with
+ * the same inode number as the child, and returns that.
+ */
+static int get_name(struct dentry *dentry, char *name,
+			struct dentry *child)
+{
+	struct inode *dir = dentry->d_inode;
+	int error;
+	struct file *file;
+	struct getdents_callback buffer;
+
+	error = -ENOTDIR;
+	if (!dir || !S_ISDIR(dir->i_mode))
+		goto out;
+	error = -EINVAL;
+	if (!dir->i_fop)
+		goto out;
+	/*
+	 * Open the directory ...
+	 */
+	file = dentry_open(dget(dentry), NULL, O_RDONLY);
+	error = PTR_ERR(file);
+	if (IS_ERR(file))
+		goto out;
+
+	error = -EINVAL;
+	if (!file->f_op->readdir)
+		goto out_close;
+
+	buffer.name = name;
+	buffer.ino = child->d_inode->i_ino;
+	buffer.found = 0;
+	buffer.sequence = 0;
+	while (1) {
+		int old_seq = buffer.sequence;
+
+		error = vfs_readdir(file, filldir_one, &buffer);
+
+		if (error < 0)
+			break;
+
+		error = 0;
+		if (buffer.found)
+			break;
+		error = -ENOENT;
+		if (old_seq == buffer.sequence)
+			break;
+	}
+
+out_close:
+	fput(file);
+out:
+	return error;
+}
+
+
+static struct dentry *export_iget(struct super_block *sb, unsigned long ino, __u32 generation)
+{
+
+	/* iget isn't really right if the inode is currently unallocated!!
+	 * This should really all be done inside each filesystem
+	 *
+	 * ext2fs' read_inode has been strengthed to return a bad_inode if
+	 * the inode had been deleted.
+	 *
+	 * Currently we don't know the generation for parent directory, so
+	 * a generation of 0 means "accept any"
+	 */
+	struct inode *inode;
+	struct dentry *result;
+	if (ino == 0)
+		return ERR_PTR(-ESTALE);
+	inode = iget(sb, ino);
+	if (inode == NULL)
+		return ERR_PTR(-ENOMEM);
+	if (is_bad_inode(inode)
+	    || (generation && inode->i_generation != generation)
+		) {
+		/* we didn't find the right inode.. */
+		dprintk("fh_verify: Inode %lu, Bad count: %d %d or version  %u %u\n",
+			inode->i_ino,
+			inode->i_nlink, atomic_read(&inode->i_count),
+			inode->i_generation,
+			generation);
+
+		iput(inode);
+		return ERR_PTR(-ESTALE);
+	}
+	/* now to find a dentry.
+	 * If possible, get a well-connected one
+	 */
+	result = d_alloc_anon(inode);
+	if (!result) {
+		iput(inode);
+		return ERR_PTR(-ENOMEM);
+	}
+	return result;
+}
+
+
+static struct dentry *get_object(struct super_block *sb, void *vobjp)
+{
+	__u32 *objp = vobjp;
+	unsigned long ino = objp[0];
+	__u32 generation = objp[1];
+
+	return export_iget(sb, ino, generation);
+}
+
+
+/**
+ * export_encode_fh - default export_operations->encode_fh function
+ * @dentry:  the dentry to encode
+ * @fh:      where to store the file handle fragment
+ * @max_len: maximum length to store there
+ * @connectable: whether to store parent information
+ *
+ * This default encode_fh function assumes that the 32 inode number
+ * is suitable for locating an inode, and that the generation number
+ * can be used to check that it is still valid.  It places them in the
+ * filehandle fragment where export_decode_fh expects to find them.
+ */
+static int export_encode_fh(struct dentry *dentry, __u32 *fh, int *max_len,
+		   int connectable)
+{
+	struct inode * inode = dentry->d_inode;
+	int len = *max_len;
+	int type = 1;
+	
+	if (len < 2 || (connectable && len < 4))
+		return 255;
+
+	len = 2;
+	fh[0] = inode->i_ino;
+	fh[1] = inode->i_generation;
+	if (connectable && !S_ISDIR(inode->i_mode)) {
+		struct inode *parent;
+
+		spin_lock(&dentry->d_lock);
+		parent = dentry->d_parent->d_inode;
+		fh[2] = parent->i_ino;
+		fh[3] = parent->i_generation;
+		spin_unlock(&dentry->d_lock);
+		len = 4;
+		type = 2;
+	}
+	*max_len = len;
+	return type;
+}
+
+
+/**
+ * export_decode_fh - default export_operations->decode_fh function
+ * @sb:  The superblock
+ * @fh:  pointer to the file handle fragment
+ * @fh_len: length of file handle fragment
+ * @acceptable: function for testing acceptability of dentrys
+ * @context:   context for @acceptable
+ *
+ * This is the default decode_fh() function.
+ * a fileid_type of 1 indicates that the filehandlefragment
+ * just contains an object identifier understood by  get_dentry.
+ * a fileid_type of 2 says that there is also a directory
+ * identifier 8 bytes in to the filehandlefragement.
+ */
+static struct dentry *export_decode_fh(struct super_block *sb, __u32 *fh, int fh_len,
+			      int fileid_type,
+			 int (*acceptable)(void *context, struct dentry *de),
+			 void *context)
+{
+	__u32 parent[2];
+	parent[0] = parent[1] = 0;
+	if (fh_len < 2 || fileid_type > 2)
+		return NULL;
+	if (fileid_type == 2) {
+		if (fh_len > 2) parent[0] = fh[2];
+		if (fh_len > 3) parent[1] = fh[3];
+	}
+	return find_exported_dentry(sb, fh, parent,
+				   acceptable, context);
+}
+
+struct export_operations export_op_default = {
+	.decode_fh	= export_decode_fh,
+	.encode_fh	= export_encode_fh,
+
+	.get_name	= get_name,
+	.get_parent	= get_parent,
+	.get_dentry	= get_object,
+};
+
+EXPORT_SYMBOL(export_op_default);
+EXPORT_SYMBOL(find_exported_dentry);
+
+MODULE_LICENSE("GPL");