NTFS: Fixup the resident attribute resizing code in

      fs/ntfs/aops.c::ntfs_{prepare,commit}_write()() and re-enable it.
      It should be safe now.  (Famous last words...)

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

diff --git a/fs/ntfs/ChangeLog b/fs/ntfs/ChangeLog
index 051c681..8a249df 100644 (file)
--- a/fs/ntfs/ChangeLog
+++ b/fs/ntfs/ChangeLog
@@ -51,6 +51,11 @@ ToDo/Notes:
          value afterwards when reading the size of the bitmap inode.
        - Use i_size_{read,write}() in fs/ntfs/{aops.c,mft.c} and protect
          access to the i_size and other size fields using the size_lock.
+       - Implement extension of resident files in the regular file write code
+         paths (fs/ntfs/aops.c::ntfs_{prepare,commit}_write()).  At present
+         this only works until the data attribute becomes too big for the mft
+         record after which we abort the write returning -EOPNOTSUPP from
+         ntfs_prepare_write().
 
 2.1.22 - Many bug and race fixes and error handling improvements.
 

diff --git a/fs/ntfs/aops.c b/fs/ntfs/aops.c
index ac65806..9221522 100644 (file)
--- a/fs/ntfs/aops.c
+++ b/fs/ntfs/aops.c
@@ -872,6 +872,7 @@ static int ntfs_write_mst_block(struct page *page,
                if (likely(block < rec_block)) {
                        if (unlikely(block >= dblock)) {
                                clear_buffer_dirty(bh);
+                               set_buffer_uptodate(bh);
                                continue;
                        }
                        /*
@@ -1830,6 +1831,7 @@ static int ntfs_prepare_write(struct file *file, struct page *page,
                unsigned from, unsigned to)
 {
        s64 new_size;
+       unsigned long flags;
        struct inode *vi = page->mapping->host;
        ntfs_inode *base_ni = NULL, *ni = NTFS_I(vi);
        ntfs_volume *vol = ni->vol;
@@ -1903,12 +1905,6 @@ static int ntfs_prepare_write(struct file *file, struct page *page,
        /* If we do not need to resize the attribute allocation we are done. */
        if (new_size <= i_size_read(vi))
                goto done;
-
-       // FIXME: We abort for now as this code is not safe.
-       ntfs_error(vi->i_sb, "Changing the file size is not supported yet.  "
-                       "Sorry.");
-       return -EOPNOTSUPP;
-
        /* Map, pin, and lock the (base) mft record. */
        if (!NInoAttr(ni))
                base_ni = ni;
@@ -1937,7 +1933,17 @@ static int ntfs_prepare_write(struct file *file, struct page *page,
        a = ctx->attr;
        /* The total length of the attribute value. */
        attr_len = le32_to_cpu(a->data.resident.value_length);
-       BUG_ON(i_size_read(vi) != attr_len);
+       /* Fix an eventual previous failure of ntfs_commit_write(). */
+       read_lock_irqsave(&ni->size_lock, flags);
+       if (unlikely(ni->initialized_size < attr_len)) {
+               attr_len = ni->initialized_size;
+               a->data.resident.value_length = cpu_to_le32(attr_len);
+               BUG_ON(attr_len < i_size_read(vi));
+       }
+       read_unlock_irqrestore(&ni->size_lock, flags);
+       /* If we do not need to resize the attribute allocation we are done. */
+       if (new_size <= attr_len)
+               goto done_unm;
        /* Check if new size is allowed in $AttrDef. */
        err = ntfs_attr_size_bounds_check(vol, ni->type, new_size);
        if (unlikely(err)) {
@@ -1995,6 +2001,7 @@ static int ntfs_prepare_write(struct file *file, struct page *page,
        }
        flush_dcache_mft_record_page(ctx->ntfs_ino);
        mark_mft_record_dirty(ctx->ntfs_ino);
+done_unm:
        ntfs_attr_put_search_ctx(ctx);
        unmap_mft_record(base_ni);
        /*