NTFS: Add fs/ntfs/attrib.[hc]::ntfs_resident_attr_value_resize().
Signed-off-by: Anton Altaparmakov <aia21@cantab.net>
diff --git a/fs/ntfs/ChangeLog b/fs/ntfs/ChangeLog
index 96224c0..29841bf 100644
--- a/fs/ntfs/ChangeLog
+++ b/fs/ntfs/ChangeLog
@@ -59,6 +59,7 @@
index entry is in the index root, we forgot to set the @ir pointer in
the index context. Thanks to Yura Pakhuchiy for finding this bug.
- Remove bogus setting of PageError in ntfs_read_compressed_block().
+ - Add fs/ntfs/attrib.[hc]::ntfs_resident_attr_value_resize().
2.1.23 - Implement extension of resident files and make writing safe as well as
many bug fixes, cleanups, and enhancements...
diff --git a/fs/ntfs/attrib.c b/fs/ntfs/attrib.c
index cd0f9e7..79dda39 100644
--- a/fs/ntfs/attrib.c
+++ b/fs/ntfs/attrib.c
@@ -1247,6 +1247,46 @@
}
/**
+ * ntfs_resident_attr_value_resize - resize the value of a resident attribute
+ * @m: mft record containing attribute record
+ * @a: attribute record whose value to resize
+ * @new_size: new size in bytes to which to resize the attribute value of @a
+ *
+ * Resize the value of the attribute @a in the mft record @m to @new_size bytes.
+ * If the value is made bigger, the newly allocated space is cleared.
+ *
+ * Return 0 on success and -errno on error. The following error codes are
+ * defined:
+ * -ENOSPC - Not enough space in the mft record @m to perform the resize.
+ *
+ * Note: On error, no modifications have been performed whatsoever.
+ *
+ * Warning: If you make a record smaller without having copied all the data you
+ * are interested in the data may be overwritten.
+ */
+int ntfs_resident_attr_value_resize(MFT_RECORD *m, ATTR_RECORD *a,
+ const u32 new_size)
+{
+ u32 old_size;
+
+ /* Resize the resident part of the attribute record. */
+ if (ntfs_attr_record_resize(m, a,
+ le16_to_cpu(a->data.resident.value_offset) + new_size))
+ return -ENOSPC;
+ /*
+ * The resize succeeded! If we made the attribute value bigger, clear
+ * the area between the old size and @new_size.
+ */
+ old_size = le32_to_cpu(a->data.resident.value_length);
+ if (new_size > old_size)
+ memset((u8*)a + le16_to_cpu(a->data.resident.value_offset) +
+ old_size, 0, new_size - old_size);
+ /* Finally update the length of the attribute value. */
+ a->data.resident.value_length = cpu_to_le32(new_size);
+ return 0;
+}
+
+/**
* ntfs_attr_make_non_resident - convert a resident to a non-resident attribute
* @ni: ntfs inode describing the attribute to convert
*
diff --git a/fs/ntfs/attrib.h b/fs/ntfs/attrib.h
index 0e4ac6d..0618ed6 100644
--- a/fs/ntfs/attrib.h
+++ b/fs/ntfs/attrib.h
@@ -99,6 +99,8 @@
const ATTR_TYPE type);
extern int ntfs_attr_record_resize(MFT_RECORD *m, ATTR_RECORD *a, u32 new_size);
+extern int ntfs_resident_attr_value_resize(MFT_RECORD *m, ATTR_RECORD *a,
+ const u32 new_size);
extern int ntfs_attr_make_non_resident(ntfs_inode *ni);