ocfs2: Initialize the cluster we're writing to in a non-sparse extend

In a non-sparse extend, we correctly allocate (and zero) the clusters between
the old_i_size and pos, but we don't zero the portions of the cluster we're
writing to outside of pos<->len.

It handles clustersize > pagesize and blocksize < pagesize.

[Cleaned up by Joel Becker.]

Signed-off-by: Sunil Mushran <sunil.mushran@oracle.com>
Signed-off-by: Joel Becker <joel.becker@oracle.com>

1 files changed, 47 insertions, 19 deletions

diff --git a/fs/ocfs2/aops.c b/fs/ocfs2/aops.c
index e511df10145..b401654011a 100644
--- a/fs/ocfs2/aops.c
+++ b/fs/ocfs2/aops.c
@@ -895,18 +895,17 @@ struct ocfs2_write_cluster_desc {
          */
         unsigned        c_new;
         unsigned        c_unwritten;
+        unsigned        c_needs_zero;
 };
 
-static inline int ocfs2_should_zero_cluster(struct ocfs2_write_cluster_desc *d)
-{
-        return d->c_new || d->c_unwritten;
-}
-
 struct ocfs2_write_ctxt {
         /* Logical cluster position / len of write */
         u32                             w_cpos;
         u32                             w_clen;
 
+        /* First cluster allocated in a nonsparse extend */
+        u32                             w_first_new_cpos;
+
         struct ocfs2_write_cluster_desc w_desc[OCFS2_MAX_CLUSTERS_PER_PAGE];
 
         /*
@@ -984,6 +983,7 @@ static int ocfs2_alloc_write_ctxt(struct ocfs2_write_ctxt **wcp,
                 return -ENOMEM;
 
         wc->w_cpos = pos >> osb->s_clustersize_bits;
+        wc->w_first_new_cpos = UINT_MAX;
         cend = (pos + len - 1) >> osb->s_clustersize_bits;
         wc->w_clen = cend - wc->w_cpos + 1;
         get_bh(di_bh);
@@ -1218,20 +1218,18 @@ out:
  */
 static int ocfs2_write_cluster(struct address_space *mapping,
                                u32 phys, unsigned int unwritten,
+                               unsigned int should_zero,
                                struct ocfs2_alloc_context *data_ac,
                                struct ocfs2_alloc_context *meta_ac,
                                struct ocfs2_write_ctxt *wc, u32 cpos,
                                loff_t user_pos, unsigned user_len)
 {
-        int ret, i, new, should_zero = 0;
+        int ret, i, new;
         u64 v_blkno, p_blkno;
         struct inode *inode = mapping->host;
         struct ocfs2_extent_tree et;
 
         new = phys == 0 ? 1 : 0;
-        if (new || unwritten)
-                should_zero = 1;
-
         if (new) {
                 u32 tmp_pos;
 
@@ -1342,7 +1340,9 @@ static int ocfs2_write_cluster_by_desc(struct address_space *mapping,
                         local_len = osb->s_clustersize - cluster_off;
 
                 ret = ocfs2_write_cluster(mapping, desc->c_phys,
-                                          desc->c_unwritten, data_ac, meta_ac,
+                                          desc->c_unwritten,
+                                          desc->c_needs_zero,
+                                          data_ac, meta_ac,
                                           wc, desc->c_cpos, pos, local_len);
                 if (ret) {
                         mlog_errno(ret);
@@ -1392,14 +1392,14 @@ static void ocfs2_set_target_boundaries(struct ocfs2_super *osb,
                  * newly allocated cluster.
                  */
                 desc = &wc->w_desc[0];
-                if (ocfs2_should_zero_cluster(desc))
+                if (desc->c_needs_zero)
                         ocfs2_figure_cluster_boundaries(osb,
                                                         desc->c_cpos,
                                                         &wc->w_target_from,
                                                         NULL);
 
                 desc = &wc->w_desc[wc->w_clen - 1];
-                if (ocfs2_should_zero_cluster(desc))
+                if (desc->c_needs_zero)
                         ocfs2_figure_cluster_boundaries(osb,
                                                         desc->c_cpos,
                                                         NULL,
@@ -1467,13 +1467,28 @@ static int ocfs2_populate_write_desc(struct inode *inode,
                         phys++;
                 }
 
+                /*
+                 * If w_first_new_cpos is < UINT_MAX, we have a non-sparse
+                 * file that got extended.  w_first_new_cpos tells us
+                 * where the newly allocated clusters are so we can
+                 * zero them.
+                 */
+                if (desc->c_cpos >= wc->w_first_new_cpos) {
+                        BUG_ON(phys == 0);
+                        desc->c_needs_zero = 1;
+                }
+
                 desc->c_phys = phys;
                 if (phys == 0) {
                         desc->c_new = 1;
+                        desc->c_needs_zero = 1;
                         *clusters_to_alloc = *clusters_to_alloc + 1;
                 }
-                if (ext_flags & OCFS2_EXT_UNWRITTEN)
+
+                if (ext_flags & OCFS2_EXT_UNWRITTEN) {
                         desc->c_unwritten = 1;
+                        desc->c_needs_zero = 1;
+                }
 
                 num_clusters--;
         }
@@ -1633,10 +1648,13 @@ static int ocfs2_expand_nonsparse_inode(struct inode *inode, loff_t pos,
         if (newsize <= i_size_read(inode))
                 return 0;
 
-        ret = ocfs2_extend_no_holes(inode, newsize, newsize - len);
+        ret = ocfs2_extend_no_holes(inode, newsize, pos);
         if (ret)
                 mlog_errno(ret);
 
+        wc->w_first_new_cpos =
+                ocfs2_clusters_for_bytes(inode->i_sb, i_size_read(inode));
+
         return ret;
 }
 
@@ -1645,7 +1663,7 @@ int ocfs2_write_begin_nolock(struct address_space *mapping,
                              struct page **pagep, void **fsdata,
                              struct buffer_head *di_bh, struct page *mmap_page)
 {
-        int ret, credits = OCFS2_INODE_UPDATE_CREDITS;
+        int ret, cluster_of_pages, credits = OCFS2_INODE_UPDATE_CREDITS;
         unsigned int clusters_to_alloc, extents_to_split;
         struct ocfs2_write_ctxt *wc;
         struct inode *inode = mapping->host;
@@ -1723,8 +1741,19 @@ int ocfs2_write_begin_nolock(struct address_space *mapping,
 
         }
 
-        ocfs2_set_target_boundaries(osb, wc, pos, len,
-                                    clusters_to_alloc + extents_to_split);
+        /*
+         * We have to zero sparse allocated clusters, unwritten extent clusters,
+         * and non-sparse clusters we just extended.  For non-sparse writes,
+         * we know zeros will only be needed in the first and/or last cluster.
+         */
+        if (clusters_to_alloc || extents_to_split ||
+            wc->w_desc[0].c_needs_zero ||
+            wc->w_desc[wc->w_clen - 1].c_needs_zero)
+                cluster_of_pages = 1;
+        else
+                cluster_of_pages = 0;
+
+        ocfs2_set_target_boundaries(osb, wc, pos, len, cluster_of_pages);
 
         handle = ocfs2_start_trans(osb, credits);
         if (IS_ERR(handle)) {
@@ -1757,8 +1786,7 @@ int ocfs2_write_begin_nolock(struct address_space *mapping,
          * extent.
          */
         ret = ocfs2_grab_pages_for_write(mapping, wc, wc->w_cpos, pos,
-                                         clusters_to_alloc + extents_to_split,
-                                         mmap_page);
+                                         cluster_of_pages, mmap_page);
         if (ret) {
                 mlog_errno(ret);
                 goto out_quota;