NTFS: Fixup handling of sparse, compressed, and encrypted attributes in

      fs/ntfs/aops.c::ntfs_writepage().

Signed-off-by: Anton Altaparmakov <aia21@cantab.net>

diff --git a/fs/ntfs/ChangeLog b/fs/ntfs/ChangeLog
index b176664..4b8666d 100644 (file)
--- a/fs/ntfs/ChangeLog
+++ b/fs/ntfs/ChangeLog
@@ -79,6 +79,8 @@ ToDo/Notes:
          fs/ntfs/inode.c::ntfs_read_locked_{,attr_,index_}inode().
        - Make ntfs_write_block() not instantiate sparse blocks if they contain
          only zeroes.
+       - Fixup handling of sparse, compressed, and encrypted attributes in
+         fs/ntfs/aops.c::ntfs_writepage().
 
 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/aops.c b/fs/ntfs/aops.c
index f3ad36d..6f2954a 100644 (file)
--- a/fs/ntfs/aops.c
+++ b/fs/ntfs/aops.c
@@ -1301,38 +1301,42 @@ retry_writepage:
                ntfs_debug("Write outside i_size - truncated?");
                return 0;
        }
+       /*
+        * Only $DATA attributes can be encrypted and only unnamed $DATA
+        * attributes can be compressed.  Index root can have the flags set but
+        * this means to create compressed/encrypted files, not that the
+        * attribute is compressed/encrypted.
+        */
+       if (ni->type != AT_INDEX_ROOT) {
+               /* If file is encrypted, deny access, just like NT4. */
+               if (NInoEncrypted(ni)) {
+                       unlock_page(page);
+                       BUG_ON(ni->type != AT_DATA);
+                       ntfs_debug("Denying write access to encrypted "
+                                       "file.");
+                       return -EACCES;
+               }
+               /* Compressed data streams are handled in compress.c. */
+               if (NInoNonResident(ni) && NInoCompressed(ni)) {
+                       BUG_ON(ni->type != AT_DATA);
+                       BUG_ON(ni->name_len);
+                       // TODO: Implement and replace this with
+                       // return ntfs_write_compressed_block(page);
+                       unlock_page(page);
+                       ntfs_error(vi->i_sb, "Writing to compressed files is "
+                                       "not supported yet.  Sorry.");
+                       return -EOPNOTSUPP;
+               }
+               // TODO: Implement and remove this check.
+               if (NInoNonResident(ni) && NInoSparse(ni)) {
+                       unlock_page(page);
+                       ntfs_error(vi->i_sb, "Writing to sparse files is not "
+                                       "supported yet.  Sorry.");
+                       return -EOPNOTSUPP;
+               }
+       }
        /* NInoNonResident() == NInoIndexAllocPresent() */
        if (NInoNonResident(ni)) {
-               /*
-                * Only unnamed $DATA attributes can be compressed, encrypted,
-                * and/or sparse.
-                */
-               if (ni->type == AT_DATA && !ni->name_len) {
-                       /* If file is encrypted, deny access, just like NT4. */
-                       if (NInoEncrypted(ni)) {
-                               unlock_page(page);
-                               ntfs_debug("Denying write access to encrypted "
-                                               "file.");
-                               return -EACCES;
-                       }
-                       /* Compressed data streams are handled in compress.c. */
-                       if (NInoCompressed(ni)) {
-                               // TODO: Implement and replace this check with
-                               // return ntfs_write_compressed_block(page);
-                               unlock_page(page);
-                               ntfs_error(vi->i_sb, "Writing to compressed "
-                                               "files is not supported yet. "
-                                               "Sorry.");
-                               return -EOPNOTSUPP;
-                       }
-                       // TODO: Implement and remove this check.
-                       if (NInoSparse(ni)) {
-                               unlock_page(page);
-                               ntfs_error(vi->i_sb, "Writing to sparse files "
-                                               "is not supported yet. Sorry.");
-                               return -EOPNOTSUPP;
-                       }
-               }
                /* We have to zero every time due to mmap-at-end-of-file. */
                if (page->index >= (i_size >> PAGE_CACHE_SHIFT)) {
                        /* The page straddles i_size. */
@@ -1345,14 +1349,16 @@ retry_writepage:
                /* Handle mst protected attributes. */
                if (NInoMstProtected(ni))
                        return ntfs_write_mst_block(page, wbc);
-               /* Normal data stream. */
+               /* Normal, non-resident data stream. */
                return ntfs_write_block(page, wbc);
        }
        /*
-        * Attribute is resident, implying it is not compressed, encrypted,
-        * sparse, or mst protected.  This also means the attribute is smaller
-        * than an mft record and hence smaller than a page, so can simply
-        * return error on any pages with index above 0.
+        * Attribute is resident, implying it is not compressed, encrypted, or
+        * mst protected.  This also means the attribute is smaller than an mft
+        * record and hence smaller than a page, so can simply return error on
+        * any pages with index above 0.  Note the attribute can actually be
+        * marked compressed but if it is resident the actual data is not
+        * compressed so we are ok to ignore the compressed flag here.
         */
        BUG_ON(page_has_buffers(page));
        BUG_ON(!PageUptodate(page));
@@ -1401,30 +1407,14 @@ retry_writepage:
        BUG_ON(PageWriteback(page));
        set_page_writeback(page);
        unlock_page(page);
-
        /*
-        * Here, we don't need to zero the out of bounds area everytime because
-        * the below memcpy() already takes care of the mmap-at-end-of-file
-        * requirements. If the file is converted to a non-resident one, then
-        * the code path use is switched to the non-resident one where the
-        * zeroing happens on each ntfs_writepage() invocation.
-        *
-        * The above also applies nicely when i_size is decreased.
-        *
-        * When i_size is increased, the memory between the old and new i_size
-        * _must_ be zeroed (or overwritten with new data). Otherwise we will
-        * expose data to userspace/disk which should never have been exposed.
-        *
-        * FIXME: Ensure that i_size increases do the zeroing/overwriting and
-        * if we cannot guarantee that, then enable the zeroing below.  If the
-        * zeroing below is enabled, we MUST move the unlock_page() from above
-        * to after the kunmap_atomic(), i.e. just before the
-        * end_page_writeback().
-        * UPDATE: ntfs_prepare/commit_write() do the zeroing on i_size
-        * increases for resident attributes so those are ok.
-        * TODO: ntfs_truncate(), others?
+        * Here, we do not need to zero the out of bounds area everytime
+        * because the below memcpy() already takes care of the
+        * mmap-at-end-of-file requirements.  If the file is converted to a
+        * non-resident one, then the code path use is switched to the
+        * non-resident one where the zeroing happens on each ntfs_writepage()
+        * invocation.
         */
-
        attr_len = le32_to_cpu(ctx->attr->data.resident.value_length);
        i_size = i_size_read(vi);
        if (unlikely(attr_len > i_size)) {