NFS: Allow redirtying of a completed unstable write.
Currently, if an unstable write completes, we cannot redirty the page in
order to reflect a new change in the page data until after we've sent a
COMMIT request.
This patch allows a page rewrite to proceed without the unnecessary COMMIT
step, putting it immediately back onto the dirty page list, undoing the
VM unstable write accounting, and removing the NFS_PAGE_TAG_COMMIT tag from
the NFS radix tree.
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
diff --git a/fs/nfs/write.c b/fs/nfs/write.c
index 04f51e5..feca8c6 100644
--- a/fs/nfs/write.c
+++ b/fs/nfs/write.c
@@ -242,12 +242,9 @@
return ret;
spin_lock(&inode->i_lock);
}
- if (test_bit(PG_NEED_COMMIT, &req->wb_flags)) {
- /* This request is marked for commit */
+ if (test_bit(PG_CLEAN, &req->wb_flags)) {
spin_unlock(&inode->i_lock);
- nfs_clear_page_tag_locked(req);
- nfs_pageio_complete(pgio);
- return 0;
+ BUG();
}
if (nfs_set_page_writeback(page) != 0) {
spin_unlock(&inode->i_lock);
@@ -391,19 +388,6 @@
__set_page_dirty_nobuffers(req->wb_page);
}
-/*
- * Check if a request is dirty
- */
-static inline int
-nfs_dirty_request(struct nfs_page *req)
-{
- struct page *page = req->wb_page;
-
- if (page == NULL || test_bit(PG_NEED_COMMIT, &req->wb_flags))
- return 0;
- return !PageWriteback(page);
-}
-
#if defined(CONFIG_NFS_V3) || defined(CONFIG_NFS_V4)
/*
* Add a request to the inode's commit list.
@@ -416,7 +400,7 @@
spin_lock(&inode->i_lock);
nfsi->ncommit++;
- set_bit(PG_NEED_COMMIT, &(req)->wb_flags);
+ set_bit(PG_CLEAN, &(req)->wb_flags);
radix_tree_tag_set(&nfsi->nfs_page_tree,
req->wb_index,
NFS_PAGE_TAG_COMMIT);
@@ -426,6 +410,19 @@
__mark_inode_dirty(inode, I_DIRTY_DATASYNC);
}
+static int
+nfs_clear_request_commit(struct nfs_page *req)
+{
+ struct page *page = req->wb_page;
+
+ if (test_and_clear_bit(PG_CLEAN, &(req)->wb_flags)) {
+ dec_zone_page_state(page, NR_UNSTABLE_NFS);
+ dec_bdi_stat(page->mapping->backing_dev_info, BDI_RECLAIMABLE);
+ return 1;
+ }
+ return 0;
+}
+
static inline
int nfs_write_need_commit(struct nfs_write_data *data)
{
@@ -435,7 +432,7 @@
static inline
int nfs_reschedule_unstable_write(struct nfs_page *req)
{
- if (test_bit(PG_NEED_COMMIT, &req->wb_flags)) {
+ if (test_and_clear_bit(PG_NEED_COMMIT, &req->wb_flags)) {
nfs_mark_request_commit(req);
return 1;
}
@@ -451,6 +448,12 @@
{
}
+static inline int
+nfs_clear_request_commit(struct nfs_page *req)
+{
+ return 0;
+}
+
static inline
int nfs_write_need_commit(struct nfs_write_data *data)
{
@@ -508,11 +511,8 @@
while(!list_empty(head)) {
req = nfs_list_entry(head->next);
- dec_zone_page_state(req->wb_page, NR_UNSTABLE_NFS);
- dec_bdi_stat(req->wb_page->mapping->backing_dev_info,
- BDI_RECLAIMABLE);
nfs_list_remove_request(req);
- clear_bit(PG_NEED_COMMIT, &(req)->wb_flags);
+ nfs_clear_request_commit(req);
nfs_inode_remove_request(req);
nfs_unlock_request(req);
}
@@ -584,8 +584,7 @@
* Note: nfs_flush_incompatible() will already
* have flushed out requests having wrong owners.
*/
- if (!nfs_dirty_request(req)
- || offset > rqend
+ if (offset > rqend
|| end < req->wb_offset)
goto out_flushme;
@@ -601,6 +600,10 @@
spin_lock(&inode->i_lock);
}
+ if (nfs_clear_request_commit(req))
+ radix_tree_tag_clear(&NFS_I(inode)->nfs_page_tree,
+ req->wb_index, NFS_PAGE_TAG_COMMIT);
+
/* Okay, the request matches. Update the region */
if (offset < req->wb_offset) {
req->wb_offset = offset;
@@ -682,8 +685,7 @@
req = nfs_page_find_request(page);
if (req == NULL)
return 0;
- do_flush = req->wb_page != page || req->wb_context != ctx
- || !nfs_dirty_request(req);
+ do_flush = req->wb_page != page || req->wb_context != ctx;
nfs_release_request(req);
if (!do_flush)
return 0;
@@ -1288,10 +1290,7 @@
while (!list_empty(&data->pages)) {
req = nfs_list_entry(data->pages.next);
nfs_list_remove_request(req);
- clear_bit(PG_NEED_COMMIT, &(req)->wb_flags);
- dec_zone_page_state(req->wb_page, NR_UNSTABLE_NFS);
- dec_bdi_stat(req->wb_page->mapping->backing_dev_info,
- BDI_RECLAIMABLE);
+ nfs_clear_request_commit(req);
dprintk("NFS: commit (%s/%lld %d@%lld)",
req->wb_context->path.dentry->d_inode->i_sb->s_id,
@@ -1467,7 +1466,7 @@
req = nfs_page_find_request(page);
if (req == NULL)
goto out;
- if (test_bit(PG_NEED_COMMIT, &req->wb_flags)) {
+ if (test_bit(PG_CLEAN, &req->wb_flags)) {
nfs_release_request(req);
break;
}