nfsd: Pull write-gathering code out of nfsd_vfs_write

This is a relatively self-contained piece of code that handles a special
case--move it to its own function.

Signed-off-by: J. Bruce Fields <bfields@citi.umich.edu>

1 files changed, 39 insertions, 30 deletions

diff --git a/fs/nfsd/vfs.c b/fs/nfsd/vfs.c
index ebf56c6040ca..6ad76a4cfc01 100644
--- a/fs/nfsd/vfs.c
+++ b/fs/nfsd/vfs.c
@@ -963,6 +963,43 @@ 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,
@@ -1026,36 +1063,8 @@ nfsd_vfs_write(struct svc_rqst *rqstp, struct svc_fh *fhp, struct file *file,
         if (host_err >= 0 && (inode->i_mode & (S_ISUID | S_ISGID)))
                 kill_suid(dentry);
 
-        if (host_err >= 0 && stable && use_wgather) {
-                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 (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);
-                }
-                last_ino = inode->i_ino;
-                last_dev = inode->i_sb->s_dev;
-        }
+        if (host_err >= 0 && stable && use_wgather)
+                host_err = wait_for_concurrent_writes(file);
 
         dprintk("nfsd: write complete host_err=%d\n", host_err);
         if (host_err >= 0)