NFS: Ensure PG_writeback is cleared when writeback fails

If the writebacks are cancelled via nfs_cancel_dirty_list, or due to the
memory allocation failing in nfs_flush_one/nfs_flush_multi, then we must
ensure that the PG_writeback flag is cleared.

Also ensure that we actually own the PG_writeback flag whenever we
schedule a new writeback by making nfs_set_page_writeback() return the
value of test_set_page_writeback().
The PG_writeback page flag ends up replacing the functionality of the
PG_FLUSHING nfs_page flag, so we rip that out too.

Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/fs/nfs/write.c b/fs/nfs/write.c
index 2867e6b7096f006c174ca58a087c584f3cc561b2..e5d7cac569aa4ba6ba699d57e673b08427493b83 100644 (file)
--- a/fs/nfs/write.c
+++ b/fs/nfs/write.c
@@ -218,9 +218,11 @@ int nfs_congestion_kb;
 #define NFS_CONGESTION_OFF_THRESH      \
        (NFS_CONGESTION_ON_THRESH - (NFS_CONGESTION_ON_THRESH >> 2))
 
-static void nfs_set_page_writeback(struct page *page)
+static int nfs_set_page_writeback(struct page *page)
 {
-       if (!test_set_page_writeback(page)) {
+       int ret = test_set_page_writeback(page);
+
+       if (!ret) {
                struct inode *inode = page->mapping->host;
                struct nfs_server *nfss = NFS_SERVER(inode);
 
@@ -228,6 +230,7 @@ static void nfs_set_page_writeback(struct page *page)
                                NFS_CONGESTION_ON_THRESH)
                        set_bdi_congested(&nfss->backing_dev_info, WRITE);
        }
+       return ret;
 }
 
 static void nfs_end_page_writeback(struct page *page)
@@ -277,10 +280,8 @@ static int nfs_page_mark_flush(struct page *page)
                spin_lock(req_lock);
        }
        spin_unlock(req_lock);
-       if (test_and_set_bit(PG_FLUSHING, &req->wb_flags) == 0) {
+       if (nfs_set_page_writeback(page) == 0)
                nfs_mark_request_dirty(req);
-               nfs_set_page_writeback(page);
-       }
        ret = test_bit(PG_NEED_FLUSH, &req->wb_flags);
        nfs_unlock_request(req);
        return ret;
@@ -424,7 +425,6 @@ nfs_mark_request_dirty(struct nfs_page *req)
 static void
 nfs_redirty_request(struct nfs_page *req)
 {
-       clear_bit(PG_FLUSHING, &req->wb_flags);
        __set_page_dirty_nobuffers(req->wb_page);
 }
 
@@ -434,7 +434,11 @@ nfs_redirty_request(struct nfs_page *req)
 static inline int
 nfs_dirty_request(struct nfs_page *req)
 {
-       return test_bit(PG_FLUSHING, &req->wb_flags) == 0;
+       struct page *page = req->wb_page;
+
+       if (page == NULL)
+               return 0;
+       return !PageWriteback(req->wb_page);
 }
 
 #if defined(CONFIG_NFS_V3) || defined(CONFIG_NFS_V4)
@@ -500,6 +504,7 @@ static void nfs_cancel_dirty_list(struct list_head *head)
        while(!list_empty(head)) {
                req = nfs_list_entry(head->next);
                nfs_list_remove_request(req);
+               nfs_end_page_writeback(req->wb_page);
                nfs_inode_remove_request(req);
                nfs_clear_page_writeback(req);
        }
@@ -890,6 +895,7 @@ out_bad:
                list_del(&data->pages);
                nfs_writedata_release(data);
        }
+       nfs_end_page_writeback(req->wb_page);
        nfs_redirty_request(req);
        nfs_clear_page_writeback(req);
        return -ENOMEM;
@@ -935,6 +941,7 @@ static int nfs_flush_one(struct inode *inode, struct list_head *head, int how)
        while (!list_empty(head)) {
                struct nfs_page *req = nfs_list_entry(head->next);
                nfs_list_remove_request(req);
+               nfs_end_page_writeback(req->wb_page);
                nfs_redirty_request(req);
                nfs_clear_page_writeback(req);
        }
@@ -970,6 +977,7 @@ out_err:
        while (!list_empty(head)) {
                req = nfs_list_entry(head->next);
                nfs_list_remove_request(req);
+               nfs_end_page_writeback(req->wb_page);
                nfs_redirty_request(req);
                nfs_clear_page_writeback(req);
        }

diff --git a/include/linux/nfs_page.h b/include/linux/nfs_page.h
index 2e555d49c9b732fa4379b8b1c17a98cb430ce857..d111be6391409a194602a99723842ff47c2c564b 100644 (file)
--- a/include/linux/nfs_page.h
+++ b/include/linux/nfs_page.h
@@ -31,7 +31,6 @@
 #define PG_NEED_COMMIT         1
 #define PG_NEED_RESCHED                2
 #define PG_NEED_FLUSH          3
-#define PG_FLUSHING            4
 
 struct nfs_inode;
 struct nfs_page {