akpm at linux-foundation.org
2016-Mar-23 20:11 UTC
[Ocfs2-devel] [patch 02/25] ocfs2: use c_new to indicate newly allocated extents
From: Ryan Ding <ryan.ding at oracle.com>
Subject: 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 at oracle.com>
Reviewed-by: Junxiao Bi <junxiao.bi at oracle.com>
Cc: Joseph Qi <joseph.qi at huawei.com>
Cc: Mark Fasheh <mfasheh at suse.de>
Cc: Joel Becker <jlbec at evilplan.org>
Signed-off-by: Andrew Morton <akpm at linux-foundation.org>
---
fs/ocfs2/aops.c | 22 ++++++++++++----------
1 file changed, 12 insertions(+), 10 deletions(-)
diff -puN fs/ocfs2/aops.c~ocfs2-use-c_new-to-indicate-newly-allocated-extents
fs/ocfs2/aops.c
--- a/fs/ocfs2/aops.c~ocfs2-use-c_new-to-indicate-newly-allocated-extents
+++ a/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 ad
*/
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 ad
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(s
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(str
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;
}
_