NFS: Cleanup: add common helper nfs_page_length()

Clean up a lot of ad-hoc page length calculations in fs/nfs/write.c

Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

1 files changed, 18 insertions, 0 deletions

diff --git a/fs/nfs/internal.h b/fs/nfs/internal.h
index d205466233f6..a28f6ce2e131 100644
--- a/fs/nfs/internal.h
+++ b/fs/nfs/internal.h
@@ -217,3 +217,21 @@ void nfs_super_set_maxbytes(struct super_block *sb, __u64 maxfilesize)
         if (sb->s_maxbytes > MAX_LFS_FILESIZE || sb->s_maxbytes <= 0)
                 sb->s_maxbytes = MAX_LFS_FILESIZE;
 }
+
+/*
+ * Determine the number of bytes of data the page contains
+ */
+static inline
+unsigned int nfs_page_length(struct page *page)
+{
+        loff_t i_size = i_size_read(page->mapping->host);
+
+        if (i_size > 0) {
+                pgoff_t end_index = (i_size - 1) >> PAGE_CACHE_SHIFT;
+                if (page->index < end_index)
+                        return PAGE_CACHE_SIZE;
+                if (page->index == end_index)
+                        return ((i_size - 1) & ~PAGE_CACHE_MASK) + 1;
+        }
+        return 0;
+}