7 files changed, 43 insertions, 29 deletions

diff --git a/fs/nfs/file.c b/fs/nfs/file.c
index 90f292b520d2..404c19c866a7 100644
--- a/fs/nfs/file.c
+++ b/fs/nfs/file.c
@@ -354,6 +354,15 @@ static int nfs_write_begin(struct file *file, struct address_space *mapping,
                 file->f_path.dentry->d_name.name,
                 mapping->host->i_ino, len, (long long) pos);
 
+        /*
+         * Prevent starvation issues if someone is doing a consistency
+         * sync-to-disk
+         */
+        ret = wait_on_bit(&NFS_I(mapping->host)->flags, NFS_INO_FLUSHING,
+                        nfs_wait_bit_killable, TASK_KILLABLE);
+        if (ret)
+                return ret;
+
         page = grab_cache_page_write_begin(mapping, index, flags);
         if (!page)
                 return -ENOMEM;
diff --git a/fs/nfs/inode.c b/fs/nfs/inode.c
index 00f116cdadc6..c40adc5dd609 100644
--- a/fs/nfs/inode.c
+++ b/fs/nfs/inode.c
@@ -66,6 +66,18 @@ nfs_fattr_to_ino_t(struct nfs_fattr *fattr)
 }
 
 /**
+ * nfs_wait_bit_killable - helper for functions that are sleeping on bit locks
+ * @word: long word containing the bit lock
+ */
+int nfs_wait_bit_killable(void *word)
+{
+        if (fatal_signal_pending(current))
+                return -ERESTARTSYS;
+        schedule();
+        return 0;
+}
+
+/**
  * nfs_compat_user_ino64 - returns the user-visible inode number
  * @fileid: 64-bit fileid
  *
diff --git a/fs/nfs/internal.h b/fs/nfs/internal.h
index 340ede8f608f..a55e69aa52e5 100644
--- a/fs/nfs/internal.h
+++ b/fs/nfs/internal.h
@@ -165,6 +165,7 @@ extern void nfs_clear_inode(struct inode *);
 extern void nfs4_clear_inode(struct inode *);
 #endif
 void nfs_zap_acl_cache(struct inode *inode);
+extern int nfs_wait_bit_killable(void *word);
 
 /* super.c */
 void nfs_parse_ip_address(char *, size_t, struct sockaddr *, size_t *);
diff --git a/fs/nfs/nfs4proc.c b/fs/nfs/nfs4proc.c
index 101f5f4c304f..95f171e7e05a 100644
--- a/fs/nfs/nfs4proc.c
+++ b/fs/nfs/nfs4proc.c
@@ -193,14 +193,6 @@ static void nfs4_setup_readdir(u64 cookie, __be32 *verifier, struct dentry *dent
         kunmap_atomic(start, KM_USER0);
 }
 
-static int nfs4_wait_bit_killable(void *word)
-{
-        if (fatal_signal_pending(current))
-                return -ERESTARTSYS;
-        schedule();
-        return 0;
-}
-
 static int nfs4_wait_clnt_recover(struct nfs_client *clp)
 {
         int res;
@@ -208,7 +200,7 @@ static int nfs4_wait_clnt_recover(struct nfs_client *clp)
         might_sleep();
 
         res = wait_on_bit(&clp->cl_state, NFS4CLNT_MANAGER_RUNNING,
-                        nfs4_wait_bit_killable, TASK_KILLABLE);
+                        nfs_wait_bit_killable, TASK_KILLABLE);
         return res;
 }
 
diff --git a/fs/nfs/pagelist.c b/fs/nfs/pagelist.c
index 7f079209d70a..e2975939126a 100644
--- a/fs/nfs/pagelist.c
+++ b/fs/nfs/pagelist.c
@@ -176,17 +176,6 @@ void nfs_release_request(struct nfs_page *req)
         kref_put(&req->wb_kref, nfs_free_request);
 }
 
-static int nfs_wait_bit_killable(void *word)
-{
-        int ret = 0;
-
-        if (fatal_signal_pending(current))
-                ret = -ERESTARTSYS;
-        else
-                schedule();
-        return ret;
-}
-
 /**
  * nfs_wait_on_request - Wait for a request to complete.
  * @req: request to wait upon.
diff --git a/fs/nfs/write.c b/fs/nfs/write.c
index 1a999939fedf..36fd35e0de83 100644
--- a/fs/nfs/write.c
+++ b/fs/nfs/write.c
@@ -313,19 +313,34 @@ static int nfs_writepages_callback(struct page *page, struct writeback_control *
 int nfs_writepages(struct address_space *mapping, struct writeback_control *wbc)
 {
         struct inode *inode = mapping->host;
+        unsigned long *bitlock = &NFS_I(inode)->flags;
         struct nfs_pageio_descriptor pgio;
         int err;
 
+        /* Stop dirtying of new pages while we sync */
+        err = wait_on_bit_lock(bitlock, NFS_INO_FLUSHING,
+                        nfs_wait_bit_killable, TASK_KILLABLE);
+        if (err)
+                goto out_err;
+
         nfs_inc_stats(inode, NFSIOS_VFSWRITEPAGES);
 
         nfs_pageio_init_write(&pgio, inode, wb_priority(wbc));
         err = write_cache_pages(mapping, wbc, nfs_writepages_callback, &pgio);
         nfs_pageio_complete(&pgio);
+
+        clear_bit_unlock(NFS_INO_FLUSHING, bitlock);
+        smp_mb__after_clear_bit();
+        wake_up_bit(bitlock, NFS_INO_FLUSHING);
+
         if (err < 0)
-                return err;
-        if (pgio.pg_error < 0)
-                return pgio.pg_error;
+                goto out_err;
+        err = pgio.pg_error;
+        if (err < 0)
+                goto out_err;
         return 0;
+out_err:
+        return err;
 }
 
 /*
@@ -1432,18 +1447,13 @@ static int nfs_write_mapping(struct address_space *mapping, int how)
 {
         struct writeback_control wbc = {
                 .bdi = mapping->backing_dev_info,
-                .sync_mode = WB_SYNC_NONE,
+                .sync_mode = WB_SYNC_ALL,
                 .nr_to_write = LONG_MAX,
                 .range_start = 0,
                 .range_end = LLONG_MAX,
                 .for_writepages = 1,
         };
-        int ret;
 
-        ret = __nfs_write_mapping(mapping, &wbc, how);
-        if (ret < 0)
-                return ret;
-        wbc.sync_mode = WB_SYNC_ALL;
         return __nfs_write_mapping(mapping, &wbc, how);
 }
 
diff --git a/include/linux/nfs_fs.h b/include/linux/nfs_fs.h
index c9fecd3e8f0f..933bc261c0df 100644
--- a/include/linux/nfs_fs.h
+++ b/include/linux/nfs_fs.h
@@ -206,6 +206,7 @@ struct nfs_inode {
 #define NFS_INO_STALE           (1)             /* possible stale inode */
 #define NFS_INO_ACL_LRU_SET     (2)             /* Inode is on the LRU list */
 #define NFS_INO_MOUNTPOINT      (3)             /* inode is remote mountpoint */
+#define NFS_INO_FLUSHING        (4)             /* inode is flushing out data */
 
 static inline struct nfs_inode *NFS_I(const struct inode *inode)
 {