1 files changed, 50 insertions, 43 deletions

diff --git a/fs/nfsd/vfs.c b/fs/nfsd/vfs.c
index 99f835753596..4145083dcf88 100644
--- a/fs/nfsd/vfs.c
+++ b/fs/nfsd/vfs.c
@@ -966,6 +966,43 @@ static void kill_suid(struct dentry *dentry)
         mutex_unlock(&dentry->d_inode->i_mutex);
 }
 
+/*
+ * Gathered writes: If another process is currently writing to the file,
+ * there's a high chance this is another nfsd (triggered by a bulk write
+ * from a client's biod). Rather than syncing the file with each write
+ * request, we sleep for 10 msec.
+ *
+ * I don't know if this roughly approximates C. Juszak's idea of
+ * gathered writes, but it's a nice and simple solution (IMHO), and it
+ * seems to work:-)
+ *
+ * Note: we do this only in the NFSv2 case, since v3 and higher have a
+ * better tool (separate unstable writes and commits) for solving this
+ * problem.
+ */
+static int wait_for_concurrent_writes(struct file *file)
+{
+        struct inode *inode = file->f_path.dentry->d_inode;
+        static ino_t last_ino;
+        static dev_t last_dev;
+        int err = 0;
+
+        if (atomic_read(&inode->i_writecount) > 1
+            || (last_ino == inode->i_ino && last_dev == inode->i_sb->s_dev)) {
+                dprintk("nfsd: write defer %d\n", task_pid_nr(current));
+                msleep(10);
+                dprintk("nfsd: write resume %d\n", task_pid_nr(current));
+        }
+
+        if (inode->i_state & I_DIRTY) {
+                dprintk("nfsd: write sync %d\n", task_pid_nr(current));
+                err = nfsd_sync(file);
+        }
+        last_ino = inode->i_ino;
+        last_dev = inode->i_sb->s_dev;
+        return err;
+}
+
 static __be32
 nfsd_vfs_write(struct svc_rqst *rqstp, struct svc_fh *fhp, struct file *file,
                                 loff_t offset, struct kvec *vec, int vlen,
@@ -978,6 +1015,7 @@ nfsd_vfs_write(struct svc_rqst *rqstp, struct svc_fh *fhp, struct file *file,
         __be32                  err = 0;
         int                     host_err;
         int                     stable = *stablep;
+        int                     use_wgather;
 
 #ifdef MSNFS
         err = nfserr_perm;
@@ -996,9 +1034,10 @@ nfsd_vfs_write(struct svc_rqst *rqstp, struct svc_fh *fhp, struct file *file,
          *  -   the sync export option has been set, or
          *  -   the client requested O_SYNC behavior (NFSv3 feature).
          *  -   The file system doesn't support fsync().
-         * When gathered writes have been configured for this volume,
+         * When NFSv2 gathered writes have been configured for this volume,
          * flushing the data to disk is handled separately below.
          */
+        use_wgather = (rqstp->rq_vers == 2) && EX_WGATHER(exp);
 
         if (!file->f_op->fsync) {/* COMMIT3 cannot work */
                stable = 2;
@@ -1007,7 +1046,7 @@ nfsd_vfs_write(struct svc_rqst *rqstp, struct svc_fh *fhp, struct file *file,
 
         if (!EX_ISSYNC(exp))
                 stable = 0;
-        if (stable && !EX_WGATHER(exp)) {
+        if (stable && !use_wgather) {
                 spin_lock(&file->f_lock);
                 file->f_flags |= O_SYNC;
                 spin_unlock(&file->f_lock);
@@ -1017,52 +1056,20 @@ nfsd_vfs_write(struct svc_rqst *rqstp, struct svc_fh *fhp, struct file *file,
         oldfs = get_fs(); set_fs(KERNEL_DS);
         host_err = vfs_writev(file, (struct iovec __user *)vec, vlen, &offset);
         set_fs(oldfs);
-        if (host_err >= 0) {
-                *cnt = host_err;
-                nfsdstats.io_write += host_err;
-                fsnotify_modify(file->f_path.dentry);
-        }
+        if (host_err < 0)
+                goto out_nfserr;
+        *cnt = host_err;
+        nfsdstats.io_write += host_err;
+        fsnotify_modify(file->f_path.dentry);
 
         /* clear setuid/setgid flag after write */
-        if (host_err >= 0 && (inode->i_mode & (S_ISUID | S_ISGID)))
+        if (inode->i_mode & (S_ISUID | S_ISGID))
                 kill_suid(dentry);
 
-        if (host_err >= 0 && stable) {
-                static ino_t    last_ino;
-                static dev_t    last_dev;
-
-                /*
-                 * Gathered writes: If another process is currently
-                 * writing to the file, there's a high chance
-                 * this is another nfsd (triggered by a bulk write
-                 * from a client's biod). Rather than syncing the
-                 * file with each write request, we sleep for 10 msec.
-                 *
-                 * I don't know if this roughly approximates
-                 * C. Juszak's idea of gathered writes, but it's a
-                 * nice and simple solution (IMHO), and it seems to
-                 * work:-)
-                 */
-                if (EX_WGATHER(exp)) {
-                        if (atomic_read(&inode->i_writecount) > 1
-                            || (last_ino == inode->i_ino && last_dev == inode->i_sb->s_dev)) {
-                                dprintk("nfsd: write defer %d\n", task_pid_nr(current));
-                                msleep(10);
-                                dprintk("nfsd: write resume %d\n", task_pid_nr(current));
-                        }
-
-                        if (inode->i_state & I_DIRTY) {
-                                dprintk("nfsd: write sync %d\n", task_pid_nr(current));
-                                host_err=nfsd_sync(file);
-                        }
-#if 0
-                        wake_up(&inode->i_wait);
-#endif
-                }
-                last_ino = inode->i_ino;
-                last_dev = inode->i_sb->s_dev;
-        }
+        if (stable && use_wgather)
+                host_err = wait_for_concurrent_writes(file);
 
+out_nfserr:
         dprintk("nfsd: write complete host_err=%d\n", host_err);
         if (host_err >= 0)
                 err = 0;