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.d...@oracle.com>
Reviewed-by: Junxiao Bi <junxiao...@oracle.com>
cc: Joseph Qi <joseph...@huawei.com>
---
fs/ocfs2/aops.c | 22 ++++++++++++----------
1 files changed, 12 insertions(+), 10 deletions(-)
diff --git a/fs/ocfs2/aops.c b/fs/ocfs2/aops.c
index b65ebb1..0f022dc 100644
--- a/fs/ocfs2/aops.c
+++ b/fs/ocfs2/aops.c
@@ -1204,7 +1204,7 @@ struct ocfs2_write_cluster_desc {
* filled.
*/
unsigned c_new;
- unsigned c_unwritten;
+ unsigned c_clear_unwritten;
unsigned c_needs_zero;
};
@@ -1580,19 +1580,19 @@ 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;
@@ -1602,9 +1602,9 @@ 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
@@ -1621,7 +1621,7 @@ 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,
@@ -1704,7 +1704,8 @@ 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);
@@ -1849,11 +1850,12 @@ 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;
}
--
1.7.1
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