[Ocfs2-devel] [patch 06/25] ocfs2: record UNWRITTEN extents when populate write desc
akpm at linux-foundation.org
akpm at linux-foundation.org
Wed Mar 23 13:12:00 PDT 2016
From: Ryan Ding <ryan.ding at oracle.com>
Subject: ocfs2: record UNWRITTEN extents when populate write desc
To support direct io in ocfs2_write_begin_nolock & ocfs2_write_end_nolock.
There is still one issue in the direct write procedure.
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
When there are 2 direct write A(0~3KB),B(4~7KB) writing to the same
cluster 0~7KB (cluster size 8KB). Write request A arrive phase 2 first,
it will zero the region (4~7KB). Before request A enter to phase 3,
request B arrive phase 2, it will zero region (0~3KB). This is just like
request B steps request A.
To resolve this issue, we should let request B knows this cluster is already
under zero, to prevent it from steps the previous write request.
This patch will add function ocfs2_unwritten_check() to do this job. It
will record all clusters that are under direct write(it will be recorded
in the 'ip_unwritten_list' member of inode info), and prevent the later
direct write writing to the same cluster to do the zero work again.
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 | 104 ++++++++++++++++++++++++++++++++++++++++++---
fs/ocfs2/inode.c | 3 +
fs/ocfs2/inode.h | 3 +
fs/ocfs2/super.c | 1
4 files changed, 106 insertions(+), 5 deletions(-)
diff -puN fs/ocfs2/aops.c~ocfs2-record-unwritten-extents-when-populate-write-desc fs/ocfs2/aops.c
--- a/fs/ocfs2/aops.c~ocfs2-record-unwritten-extents-when-populate-write-desc
+++ a/fs/ocfs2/aops.c
@@ -1201,6 +1201,13 @@ next_bh:
#define OCFS2_MAX_CLUSTERS_PER_PAGE (PAGE_CACHE_SIZE / OCFS2_MIN_CLUSTERSIZE)
+struct ocfs2_unwritten_extent {
+ struct list_head ue_node;
+ struct list_head ue_ip_node;
+ u32 ue_cpos;
+ u32 ue_phys;
+};
+
/*
* Describe the state of a single cluster to be written to.
*/
@@ -1275,6 +1282,8 @@ struct ocfs2_write_ctxt {
struct buffer_head *w_di_bh;
struct ocfs2_cached_dealloc_ctxt w_dealloc;
+
+ struct list_head w_unwritten_list;
};
void ocfs2_unlock_and_free_pages(struct page **pages, int num_pages)
@@ -1313,8 +1322,25 @@ static void ocfs2_unlock_pages(struct oc
ocfs2_unlock_and_free_pages(wc->w_pages, wc->w_num_pages);
}
-static void ocfs2_free_write_ctxt(struct ocfs2_write_ctxt *wc)
+static void ocfs2_free_unwritten_list(struct inode *inode,
+ struct list_head *head)
+{
+ struct ocfs2_inode_info *oi = OCFS2_I(inode);
+ struct ocfs2_unwritten_extent *dz = NULL, *tmp = NULL;
+
+ list_for_each_entry_safe(dz, tmp, head, ue_node) {
+ list_del(&dz->ue_node);
+ spin_lock(&oi->ip_lock);
+ list_del(&dz->ue_ip_node);
+ spin_unlock(&oi->ip_lock);
+ kfree(dz);
+ }
+}
+
+static void ocfs2_free_write_ctxt(struct inode *inode,
+ struct ocfs2_write_ctxt *wc)
{
+ ocfs2_free_unwritten_list(inode, &wc->w_unwritten_list);
ocfs2_unlock_pages(wc);
brelse(wc->w_di_bh);
kfree(wc);
@@ -1346,6 +1372,7 @@ static int ocfs2_alloc_write_ctxt(struct
wc->w_large_pages = 0;
ocfs2_init_dealloc_ctxt(&wc->w_dealloc);
+ INIT_LIST_HEAD(&wc->w_unwritten_list);
*wcp = wc;
@@ -1796,6 +1823,66 @@ static void ocfs2_set_target_boundaries(
}
/*
+ * Check if this extent is marked UNWRITTEN by direct io. If so, we need not to
+ * do the zero work. And should not to clear UNWRITTEN since it will be cleared
+ * by the direct io procedure.
+ * If this is a new extent that allocated by direct io, we should mark it in
+ * the ip_unwritten_list.
+ */
+static int ocfs2_unwritten_check(struct inode *inode,
+ struct ocfs2_write_ctxt *wc,
+ struct ocfs2_write_cluster_desc *desc)
+{
+ struct ocfs2_inode_info *oi = OCFS2_I(inode);
+ struct ocfs2_unwritten_extent *dz = NULL, *new = NULL;
+ int ret = 0;
+
+ if (!desc->c_needs_zero)
+ return 0;
+
+retry:
+ spin_lock(&oi->ip_lock);
+ /* Needs not to zero no metter buffer or direct. The one who is zero
+ * the cluster is doing zero. And he will clear unwritten after all
+ * cluster io finished. */
+ list_for_each_entry(dz, &oi->ip_unwritten_list, ue_ip_node) {
+ if (desc->c_cpos == dz->ue_cpos) {
+ BUG_ON(desc->c_new);
+ desc->c_needs_zero = 0;
+ desc->c_clear_unwritten = 0;
+ goto unlock;
+ }
+ }
+
+ if (wc->w_type != OCFS2_WRITE_DIRECT)
+ goto unlock;
+
+ if (new == NULL) {
+ spin_unlock(&oi->ip_lock);
+ new = kmalloc(sizeof(struct ocfs2_unwritten_extent),
+ GFP_NOFS);
+ if (new == NULL) {
+ ret = -ENOMEM;
+ goto out;
+ }
+ goto retry;
+ }
+ /* This direct write will doing zero. */
+ new->ue_cpos = desc->c_cpos;
+ new->ue_phys = desc->c_phys;
+ desc->c_clear_unwritten = 0;
+ list_add_tail(&new->ue_ip_node, &oi->ip_unwritten_list);
+ list_add_tail(&new->ue_node, &wc->w_unwritten_list);
+ new = NULL;
+unlock:
+ spin_unlock(&oi->ip_lock);
+out:
+ if (new)
+ kfree(new);
+ return ret;
+}
+
+/*
* Populate each single-cluster write descriptor in the write context
* with information about the i/o to be done.
*
@@ -1879,6 +1966,12 @@ static int ocfs2_populate_write_desc(str
desc->c_needs_zero = 1;
}
+ ret = ocfs2_unwritten_check(inode, wc, desc);
+ if (ret) {
+ mlog_errno(ret);
+ goto out;
+ }
+
num_clusters--;
}
@@ -2215,9 +2308,8 @@ try_again:
* 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_clen && (wc->w_desc[0].c_needs_zero ||
- wc->w_desc[wc->w_clen - 1].c_needs_zero)))
+ if (wc->w_clen && (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;
@@ -2296,7 +2388,7 @@ out_commit:
ocfs2_commit_trans(osb, handle);
out:
- ocfs2_free_write_ctxt(wc);
+ ocfs2_free_write_ctxt(inode, wc);
if (data_ac) {
ocfs2_free_alloc_context(data_ac);
@@ -2406,6 +2498,8 @@ int ocfs2_write_end_nolock(struct addres
handle_t *handle = wc->w_handle;
struct page *tmppage;
+ BUG_ON(!list_empty(&wc->w_unwritten_list));
+
if (handle) {
ret = ocfs2_journal_access_di(handle, INODE_CACHE(inode),
wc->w_di_bh, OCFS2_JOURNAL_ACCESS_WRITE);
diff -puN fs/ocfs2/inode.c~ocfs2-record-unwritten-extents-when-populate-write-desc fs/ocfs2/inode.c
--- a/fs/ocfs2/inode.c~ocfs2-record-unwritten-extents-when-populate-write-desc
+++ a/fs/ocfs2/inode.c
@@ -1170,6 +1170,9 @@ static void ocfs2_clear_inode(struct ino
mlog_bug_on_msg(!list_empty(&oi->ip_io_markers),
"Clear inode of %llu, inode has io markers\n",
(unsigned long long)oi->ip_blkno);
+ mlog_bug_on_msg(!list_empty(&oi->ip_unwritten_list),
+ "Clear inode of %llu, inode has unwritten extents\n",
+ (unsigned long long)oi->ip_blkno);
ocfs2_extent_map_trunc(inode, 0);
diff -puN fs/ocfs2/inode.h~ocfs2-record-unwritten-extents-when-populate-write-desc fs/ocfs2/inode.h
--- a/fs/ocfs2/inode.h~ocfs2-record-unwritten-extents-when-populate-write-desc
+++ a/fs/ocfs2/inode.h
@@ -57,6 +57,9 @@ struct ocfs2_inode_info
u32 ip_flags; /* see below */
u32 ip_attr; /* inode attributes */
+ /* Record unwritten extents during direct io. */
+ struct list_head ip_unwritten_list;
+
/* protected by recovery_lock. */
struct inode *ip_next_orphan;
diff -puN fs/ocfs2/super.c~ocfs2-record-unwritten-extents-when-populate-write-desc fs/ocfs2/super.c
--- a/fs/ocfs2/super.c~ocfs2-record-unwritten-extents-when-populate-write-desc
+++ a/fs/ocfs2/super.c
@@ -1745,6 +1745,7 @@ static void ocfs2_inode_init_once(void *
spin_lock_init(&oi->ip_lock);
ocfs2_extent_map_init(&oi->vfs_inode);
INIT_LIST_HEAD(&oi->ip_io_markers);
+ INIT_LIST_HEAD(&oi->ip_unwritten_list);
oi->ip_dir_start_lookup = 0;
mutex_init(&oi->ip_unaligned_aio);
init_rwsem(&oi->ip_alloc_sem);
_
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