X-Git-Url: https://err.no/cgi-bin/gitweb.cgi?a=blobdiff_plain;f=fs%2Flibfs.c;h=ae51481e45e5f679e240d64e5f8e1f39e7c0e2c7;hb=ddbcc7e8e50aefe467c01cac3dec71f118cd8ac2;hp=d93842d3c0a0b66943a0491622e0793971d70de5;hpb=227c5fe7993a5430e582dfd4c3acd9484004c6fc;p=linux-2.6

diff --git a/fs/libfs.c b/fs/libfs.c
index d93842d3c0..ae51481e45 100644
--- a/fs/libfs.c
+++ b/fs/libfs.c
@@ -159,7 +159,10 @@ int dcache_readdir(struct file * filp, void * dirent, filldir_t filldir)
 					continue;
 
 				spin_unlock(&dcache_lock);
-				if (filldir(dirent, next->d_name.name, next->d_name.len, filp->f_pos, next->d_inode->i_ino, dt_type(next->d_inode)) < 0)
+				if (filldir(dirent, next->d_name.name, 
+					    next->d_name.len, filp->f_pos, 
+					    next->d_inode->i_ino, 
+					    dt_type(next->d_inode)) < 0)
 					return 0;
 				spin_lock(&dcache_lock);
 				/* next is still alive */
@@ -220,6 +223,12 @@ int get_sb_pseudo(struct file_system_type *fs_type, char *name,
 	root = new_inode(s);
 	if (!root)
 		goto Enomem;
+	/*
+	 * since this is the first inode, make it number 1. New inodes created
+	 * after this must take care not to collide with it (by passing
+	 * max_reserved of 1 to iunique).
+	 */
+	root->i_ino = 1;
 	root->i_mode = S_IFDIR | S_IRUSR | S_IWUSR;
 	root->i_uid = root->i_gid = 0;
 	root->i_atime = root->i_mtime = root->i_ctime = CURRENT_TIME;
@@ -342,8 +351,28 @@ int simple_prepare_write(struct file *file, struct page *page,
 	return 0;
 }
 
-int simple_commit_write(struct file *file, struct page *page,
-			unsigned from, unsigned to)
+int simple_write_begin(struct file *file, struct address_space *mapping,
+			loff_t pos, unsigned len, unsigned flags,
+			struct page **pagep, void **fsdata)
+{
+	struct page *page;
+	pgoff_t index;
+	unsigned from;
+
+	index = pos >> PAGE_CACHE_SHIFT;
+	from = pos & (PAGE_CACHE_SIZE - 1);
+
+	page = __grab_cache_page(mapping, index);
+	if (!page)
+		return -ENOMEM;
+
+	*pagep = page;
+
+	return simple_prepare_write(file, page, from, from+len);
+}
+
+static int simple_commit_write(struct file *file, struct page *page,
+			       unsigned from, unsigned to)
 {
 	struct inode *inode = page->mapping->host;
 	loff_t pos = ((loff_t)page->index << PAGE_CACHE_SHIFT) + to;
@@ -360,6 +389,33 @@ int simple_commit_write(struct file *file, struct page *page,
 	return 0;
 }
 
+int simple_write_end(struct file *file, struct address_space *mapping,
+			loff_t pos, unsigned len, unsigned copied,
+			struct page *page, void *fsdata)
+{
+	unsigned from = pos & (PAGE_CACHE_SIZE - 1);
+
+	/* zero the stale part of the page if we did a short copy */
+	if (copied < len) {
+		void *kaddr = kmap_atomic(page, KM_USER0);
+		memset(kaddr + from + copied, 0, len - copied);
+		flush_dcache_page(page);
+		kunmap_atomic(kaddr, KM_USER0);
+	}
+
+	simple_commit_write(file, page, from, from+copied);
+
+	unlock_page(page);
+	page_cache_release(page);
+
+	return copied;
+}
+
+/*
+ * the inodes created here are not hashed. If you use iunique to generate
+ * unique inode values later for this filesystem, then you must take care
+ * to pass it an appropriate max_reserved value to avoid collisions.
+ */
 int simple_fill_super(struct super_block *s, int magic, struct tree_descr *files)
 {
 	struct inode *inode;
@@ -376,6 +432,11 @@ int simple_fill_super(struct super_block *s, int magic, struct tree_descr *files
 	inode = new_inode(s);
 	if (!inode)
 		return -ENOMEM;
+	/*
+	 * because the root inode is 1, the files array must not contain an
+	 * entry at index 1
+	 */
+	inode->i_ino = 1;
 	inode->i_mode = S_IFDIR | 0755;
 	inode->i_uid = inode->i_gid = 0;
 	inode->i_blocks = 0;
@@ -391,6 +452,13 @@ int simple_fill_super(struct super_block *s, int magic, struct tree_descr *files
 	for (i = 0; !files->name || files->name[0]; i++, files++) {
 		if (!files->name)
 			continue;
+
+		/* warn if it tries to conflict with the root inode */
+		if (unlikely(i == 1))
+			printk(KERN_WARNING "%s: %s passed in a files array"
+				"with an index of 1!\n", __func__,
+				s->s_type->name);
+
 		dentry = d_alloc_name(root, files->name);
 		if (!dentry)
 			goto out;
@@ -616,7 +684,8 @@ EXPORT_SYMBOL(dcache_dir_open);
 EXPORT_SYMBOL(dcache_readdir);
 EXPORT_SYMBOL(generic_read_dir);
 EXPORT_SYMBOL(get_sb_pseudo);
-EXPORT_SYMBOL(simple_commit_write);
+EXPORT_SYMBOL(simple_write_begin);
+EXPORT_SYMBOL(simple_write_end);
 EXPORT_SYMBOL(simple_dir_inode_operations);
 EXPORT_SYMBOL(simple_dir_operations);
 EXPORT_SYMBOL(simple_empty);