1 files changed, 164 insertions, 55 deletions

diff --git a/fs/libfs.c b/fs/libfs.c
index 6e8d17e1dc4..304a5132ca2 100644
--- a/fs/libfs.c
+++ b/fs/libfs.c
@@ -5,8 +5,10 @@
 
 #include <linux/module.h>
 #include <linux/pagemap.h>
+#include <linux/slab.h>
 #include <linux/mount.h>
 #include <linux/vfs.h>
+#include <linux/quotaops.h>
 #include <linux/mutex.h>
 #include <linux/exportfs.h>
 #include <linux/writeback.h>
@@ -57,11 +59,6 @@ struct dentry *simple_lookup(struct inode *dir, struct dentry *dentry, struct na
 	return NULL;
 }
 
-int simple_sync_file(struct file * file, struct dentry *dentry, int datasync)
-{
-	return 0;
-}
- 
 int dcache_dir_open(struct inode *inode, struct file *file)
 {
 	static struct qstr cursor_name = {.len = 1, .name = "."};
@@ -189,7 +186,7 @@ const struct file_operations simple_dir_operations = {
 	.llseek		= dcache_dir_lseek,
 	.read		= generic_read_dir,
 	.readdir	= dcache_readdir,
-	.fsync		= simple_sync_file,
+	.fsync		= noop_fsync,
 };
 
 const struct inode_operations simple_dir_inode_operations = {
@@ -258,7 +255,7 @@ int simple_link(struct dentry *old_dentry, struct inode *dir, struct dentry *den
 
 	inode->i_ctime = dir->i_ctime = dir->i_mtime = CURRENT_TIME;
 	inc_nlink(inode);
-	atomic_inc(&inode->i_count);
+	ihold(inode);
 	dget(dentry);
 	d_instantiate(dentry, inode);
 	return 0;
@@ -329,6 +326,39 @@ int simple_rename(struct inode *old_dir, struct dentry *old_dentry,
 	return 0;
 }
 
+/**
+ * simple_setattr - setattr for simple filesystem
+ * @dentry: dentry
+ * @iattr: iattr structure
+ *
+ * Returns 0 on success, -error on failure.
+ *
+ * simple_setattr is a simple ->setattr implementation without a proper
+ * implementation of size changes.
+ *
+ * It can either be used for in-memory filesystems or special files
+ * on simple regular filesystems.  Anything that needs to change on-disk
+ * or wire state on size changes needs its own setattr method.
+ */
+int simple_setattr(struct dentry *dentry, struct iattr *iattr)
+{
+	struct inode *inode = dentry->d_inode;
+	int error;
+
+	WARN_ON_ONCE(inode->i_op->truncate);
+
+	error = inode_change_ok(inode, iattr);
+	if (error)
+		return error;
+
+	if (iattr->ia_valid & ATTR_SIZE)
+		truncate_setsize(inode, iattr->ia_size);
+	setattr_copy(inode, iattr);
+	mark_inode_dirty(inode);
+	return 0;
+}
+EXPORT_SYMBOL(simple_setattr);
+
 int simple_readpage(struct file *file, struct page *page)
 {
 	clear_highpage(page);
@@ -338,28 +368,14 @@ int simple_readpage(struct file *file, struct page *page)
 	return 0;
 }
 
-int simple_prepare_write(struct file *file, struct page *page,
-			unsigned from, unsigned to)
-{
-	if (!PageUptodate(page)) {
-		if (to - from != PAGE_CACHE_SIZE)
-			zero_user_segments(page,
-				0, from,
-				to, PAGE_CACHE_SIZE);
-	}
-	return 0;
-}
-
 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_write_begin(mapping, index, flags);
 	if (!page)
@@ -367,43 +383,59 @@ int simple_write_begin(struct file *file, struct address_space *mapping,
 
 	*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;
+	if (!PageUptodate(page) && (len != PAGE_CACHE_SIZE)) {
+		unsigned from = pos & (PAGE_CACHE_SIZE - 1);
 
-	if (!PageUptodate(page))
-		SetPageUptodate(page);
-	/*
-	 * No need to use i_size_read() here, the i_size
-	 * cannot change under us because we hold the i_mutex.
-	 */
-	if (pos > inode->i_size)
-		i_size_write(inode, pos);
-	set_page_dirty(page);
+		zero_user_segments(page, 0, from, from + len, PAGE_CACHE_SIZE);
+	}
 	return 0;
 }
 
+/**
+ * simple_write_end - .write_end helper for non-block-device FSes
+ * @available: See .write_end of address_space_operations
+ * @file: 		"
+ * @mapping: 		"
+ * @pos: 		"
+ * @len: 		"
+ * @copied: 		"
+ * @page: 		"
+ * @fsdata: 		"
+ *
+ * simple_write_end does the minimum needed for updating a page after writing is
+ * done. It has the same API signature as the .write_end of
+ * address_space_operations vector. So it can just be set onto .write_end for
+ * FSes that don't need any other processing. i_mutex is assumed to be held.
+ * Block based filesystems should use generic_write_end().
+ * NOTE: Even though i_size might get updated by this function, mark_inode_dirty
+ * is not called, so a filesystem that actually does store data in .write_inode
+ * should extend on what's done here with a call to mark_inode_dirty() in the
+ * case that i_size has changed.
+ */
 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);
+	struct inode *inode = page->mapping->host;
+	loff_t last_pos = pos + copied;
 
 	/* 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);
+		unsigned from = pos & (PAGE_CACHE_SIZE - 1);
+
+		zero_user(page, from + copied, len - copied);
 	}
 
-	simple_commit_write(file, page, from, from+copied);
+	if (!PageUptodate(page))
+		SetPageUptodate(page);
+	/*
+	 * No need to use i_size_read() here, the i_size
+	 * cannot change under us because we hold the i_mutex.
+	 */
+	if (last_pos > inode->i_size)
+		i_size_write(inode, last_pos);
 
+	set_page_dirty(page);
 	unlock_page(page);
 	page_cache_release(page);
 
@@ -415,7 +447,8 @@ int simple_write_end(struct file *file, struct address_space *mapping,
  * 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)
+int simple_fill_super(struct super_block *s, unsigned long magic,
+		      struct tree_descr *files)
 {
 	struct inode *inode;
 	struct dentry *root;
@@ -544,6 +577,40 @@ ssize_t simple_read_from_buffer(void __user *to, size_t count, loff_t *ppos,
 }
 
 /**
+ * simple_write_to_buffer - copy data from user space to the buffer
+ * @to: the buffer to write to
+ * @available: the size of the buffer
+ * @ppos: the current position in the buffer
+ * @from: the user space buffer to read from
+ * @count: the maximum number of bytes to read
+ *
+ * The simple_write_to_buffer() function reads up to @count bytes from the user
+ * space address starting at @from into the buffer @to at offset @ppos.
+ *
+ * On success, the number of bytes written is returned and the offset @ppos is
+ * advanced by this number, or negative value is returned on error.
+ **/
+ssize_t simple_write_to_buffer(void *to, size_t available, loff_t *ppos,
+		const void __user *from, size_t count)
+{
+	loff_t pos = *ppos;
+	size_t res;
+
+	if (pos < 0)
+		return -EINVAL;
+	if (pos >= available || !count)
+		return 0;
+	if (count > available - pos)
+		count = available - pos;
+	res = copy_from_user(to + pos, from, count);
+	if (res == count)
+		return -EFAULT;
+	count -= res;
+	*ppos = pos + count;
+	return count;
+}
+
+/**
  * memory_read_from_buffer - copy data from the buffer
  * @to: the kernel space buffer to read to
  * @count: the maximum number of bytes to read
@@ -814,13 +881,18 @@ struct dentry *generic_fh_to_parent(struct super_block *sb, struct fid *fid,
 }
 EXPORT_SYMBOL_GPL(generic_fh_to_parent);
 
-int simple_fsync(struct file *file, struct dentry *dentry, int datasync)
+/**
+ * generic_file_fsync - generic fsync implementation for simple filesystems
+ * @file:	file to synchronize
+ * @datasync:	only synchronize essential metadata if true
+ *
+ * This is a generic implementation of the fsync method for simple
+ * filesystems which track all non-inode metadata in the buffers list
+ * hanging off the address_space structure.
+ */
+int generic_file_fsync(struct file *file, int datasync)
 {
-	struct writeback_control wbc = {
-		.sync_mode = WB_SYNC_ALL,
-		.nr_to_write = 0, /* metadata-only; caller takes care of data */
-	};
-	struct inode *inode = dentry->d_inode;
+	struct inode *inode = file->f_mapping->host;
 	int err;
 	int ret;
 
@@ -830,12 +902,49 @@ int simple_fsync(struct file *file, struct dentry *dentry, int datasync)
 	if (datasync && !(inode->i_state & I_DIRTY_DATASYNC))
 		return ret;
 
-	err = sync_inode(inode, &wbc);
+	err = sync_inode_metadata(inode, 1);
 	if (ret == 0)
 		ret = err;
 	return ret;
 }
-EXPORT_SYMBOL(simple_fsync);
+EXPORT_SYMBOL(generic_file_fsync);
+
+/**
+ * generic_check_addressable - Check addressability of file system
+ * @blocksize_bits:	log of file system block size
+ * @num_blocks:		number of blocks in file system
+ *
+ * Determine whether a file system with @num_blocks blocks (and a
+ * block size of 2**@blocksize_bits) is addressable by the sector_t
+ * and page cache of the system.  Return 0 if so and -EFBIG otherwise.
+ */
+int generic_check_addressable(unsigned blocksize_bits, u64 num_blocks)
+{
+	u64 last_fs_block = num_blocks - 1;
+	u64 last_fs_page =
+		last_fs_block >> (PAGE_CACHE_SHIFT - blocksize_bits);
+
+	if (unlikely(num_blocks == 0))
+		return 0;
+
+	if ((blocksize_bits < 9) || (blocksize_bits > PAGE_CACHE_SHIFT))
+		return -EINVAL;
+
+	if ((last_fs_block > (sector_t)(~0ULL) >> (blocksize_bits - 9)) ||
+	    (last_fs_page > (pgoff_t)(~0ULL))) {
+		return -EFBIG;
+	}
+	return 0;
+}
+EXPORT_SYMBOL(generic_check_addressable);
+
+/*
+ * No-op implementation of ->fsync for in-memory filesystems.
+ */
+int noop_fsync(struct file *file, int datasync)
+{
+	return 0;
+}
 
 EXPORT_SYMBOL(dcache_dir_close);
 EXPORT_SYMBOL(dcache_dir_lseek);
@@ -853,15 +962,15 @@ EXPORT_SYMBOL(simple_getattr);
 EXPORT_SYMBOL(simple_link);
 EXPORT_SYMBOL(simple_lookup);
 EXPORT_SYMBOL(simple_pin_fs);
-EXPORT_UNUSED_SYMBOL(simple_prepare_write);
 EXPORT_SYMBOL(simple_readpage);
 EXPORT_SYMBOL(simple_release_fs);
 EXPORT_SYMBOL(simple_rename);
 EXPORT_SYMBOL(simple_rmdir);
 EXPORT_SYMBOL(simple_statfs);
-EXPORT_SYMBOL(simple_sync_file);
+EXPORT_SYMBOL(noop_fsync);
 EXPORT_SYMBOL(simple_unlink);
 EXPORT_SYMBOL(simple_read_from_buffer);
+EXPORT_SYMBOL(simple_write_to_buffer);
 EXPORT_SYMBOL(memory_read_from_buffer);
 EXPORT_SYMBOL(simple_transaction_set);
 EXPORT_SYMBOL(simple_transaction_get);