NFS: Cleanup: add common helper nfs_page_length()

[mirror_ubuntu-jammy-kernel.git] / fs / nfs / internal.h

diff --git a/fs/nfs/internal.h b/fs/nfs/internal.h
index d205466233f67f932460d51f124cade1bec0a516..a28f6ce2e131e4df24e40223ebdc36d7d986da6f 100644 (file)
--- 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;
+}