Merge branch 'wimax-2.6.35.y' of git://git.kernel.org/pub/scm/linux/kernel/git/inaky...

[safe/jmp/linux-2.6] / fs / libfs.c

diff --git a/fs/libfs.c b/fs/libfs.c
index cd88abd..232bea4 100644 (file)
--- a/fs/libfs.c
+++ b/fs/libfs.c
@@ -5,6 +5,7 @@
 
 #include <linux/module.h>
 #include <linux/pagemap.h>
+#include <linux/slab.h>
 #include <linux/mount.h>
 #include <linux/vfs.h>
 #include <linux/mutex.h>
@@ -338,28 +339,14 @@ 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)
@@ -367,7 +354,12 @@ int simple_write_begin(struct file *file, struct address_space *mapping,
 
        *pagep = page;
 
-       return simple_prepare_write(file, page, from, from+len);
+       if (!PageUptodate(page) && (len != PAGE_CACHE_SIZE)) {
+               unsigned from = pos & (PAGE_CACHE_SIZE - 1);
+
+               zero_user_segments(page, 0, from, from + len, PAGE_CACHE_SIZE);
+       }
+       return 0;
 }
 
 /**
@@ -555,6 +547,40 @@ 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
@@ -864,7 +890,6 @@ 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);
@@ -873,6 +898,7 @@ EXPORT_SYMBOL(simple_statfs);
 EXPORT_SYMBOL(simple_sync_file);
 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);