ocfs2: use c_new to indicate newly allocated extents

To support direct io in ocfs2_write_begin_nolock & ocfs2_write_end_nolock.

There is a problem in ocfs2's direct io implement: if system crashed
after extents allocated, and before data return, we will get a extent
with dirty data on disk.  This problem violate the journal=order
semantics, which means meta changes take effect after data written to
disk.  To resolve this issue, direct write can use the UNWRITTEN flag to
describe a extent during direct data writeback.  The direct write
procedure should act in the following order:

phase 1: alloc extent with UNWRITTEN flag
phase 2: submit direct data to disk, add zero page to page cache
phase 3: clear UNWRITTEN flag when data has been written to disk

This patch is to change the 'c_unwritten' member of
ocfs2_write_cluster_desc to 'c_clear_unwritten'.  Means whether to clear
the unwritten flag.  It do not care if a extent is allocated or not.
And use 'c_new' to specify a newly allocated extent.  So the direct io
procedure can use c_clear_unwritten to control the UNWRITTEN bit on
extent.

Signed-off-by: Ryan Ding <ryan.ding@oracle.com>
Reviewed-by: Junxiao Bi <junxiao.bi@oracle.com>
Cc: Joseph Qi <joseph.qi@huawei.com>
Cc: Mark Fasheh <mfasheh@suse.de>
Cc: Joel Becker <jlbec@evilplan.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 12 insertions, 10 deletions

diff --git a/fs/ocfs2/aops.c b/fs/ocfs2/aops.c
index 69d7392f56d8..516ea896f13c 100644
--- a/fs/ocfs2/aops.c
+++ b/fs/ocfs2/aops.c
@@ -1212,7 +1212,7 @@ struct ocfs2_write_cluster_desc {
          * filled.
          */
         unsigned        c_new;
-        unsigned        c_unwritten;
+        unsigned        c_clear_unwritten;
         unsigned        c_needs_zero;
 };
 
@@ -1588,19 +1588,19 @@ out:
  * Prepare a single cluster for write one cluster into the file.
  */
 static int ocfs2_write_cluster(struct address_space *mapping,
-                               u32 phys, unsigned int unwritten,
+                               u32 phys, unsigned int new,
+                               unsigned int clear_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;
+        int ret, i;
         u64 v_blkno, p_blkno;
         struct inode *inode = mapping->host;
         struct ocfs2_extent_tree et;
 
-        new = phys == 0 ? 1 : 0;
         if (new) {
                 u32 tmp_pos;
 
@@ -1610,9 +1610,9 @@ static int ocfs2_write_cluster(struct address_space *mapping,
                  */
                 tmp_pos = cpos;
                 ret = ocfs2_add_inode_data(OCFS2_SB(inode->i_sb), inode,
-                                           &tmp_pos, 1, 0, wc->w_di_bh,
-                                           wc->w_handle, data_ac,
-                                           meta_ac, NULL);
+                                           &tmp_pos, 1, !clear_unwritten,
+                                           wc->w_di_bh, wc->w_handle,
+                                           data_ac, meta_ac, NULL);
                 /*
                  * This shouldn't happen because we must have already
                  * calculated the correct meta data allocation required. The
@@ -1629,7 +1629,7 @@ static int ocfs2_write_cluster(struct address_space *mapping,
                         mlog_errno(ret);
                         goto out;
                 }
-        } else if (unwritten) {
+        } else if (clear_unwritten) {
                 ocfs2_init_dinode_extent_tree(&et, INODE_CACHE(inode),
                                               wc->w_di_bh);
                 ret = ocfs2_mark_extent_written(inode, &et,
@@ -1712,7 +1712,8 @@ 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,
+                                          desc->c_new,
+                                          desc->c_clear_unwritten,
                                           desc->c_needs_zero,
                                           data_ac, meta_ac,
                                           wc, desc->c_cpos, pos, local_len);
@@ -1857,11 +1858,12 @@ static int ocfs2_populate_write_desc(struct inode *inode,
                 if (phys == 0) {
                         desc->c_new = 1;
                         desc->c_needs_zero = 1;
+                        desc->c_clear_unwritten = 1;
                         *clusters_to_alloc = *clusters_to_alloc + 1;
                 }
 
                 if (ext_flags & OCFS2_EXT_UNWRITTEN) {
-                        desc->c_unwritten = 1;
+                        desc->c_clear_unwritten = 1;
                         desc->c_needs_zero = 1;
                 }