nfs: page cache invalidation for dio

Make sure to properly invalidate the pagecache before performing direct I/O,
so that no stale pages are left around.  This matches what the generic
direct I/O code does.  Also take the i_mutex over the direct write submission
to avoid the lifelock vs truncate waiting for i_dio_count to decrease, and
to avoid having the pagecache easily repopulated while direct I/O is in
progrss.  Again matching the generic direct I/O code.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>

1 files changed, 27 insertions, 2 deletions

diff --git a/fs/nfs/direct.c b/fs/nfs/direct.c
index 85e4e4be401a..b8797ae6831f 100644
--- a/fs/nfs/direct.c
+++ b/fs/nfs/direct.c
@@ -939,9 +939,12 @@ ssize_t nfs_file_direct_write(struct kiocb *iocb, const struct iovec *iov,
         struct inode *inode = mapping->host;
         struct nfs_direct_req *dreq;
         struct nfs_lock_context *l_ctx;
+        loff_t end;
         size_t count;
 
         count = iov_length(iov, nr_segs);
+        end = (pos + count - 1) >> PAGE_CACHE_SHIFT;
+
         nfs_add_stats(mapping->host, NFSIOS_DIRECTWRITTENBYTES, count);
 
         dfprintk(FILE, "NFS: direct write(%pD2, %zd@%Ld)\n",
@@ -958,16 +961,25 @@ ssize_t nfs_file_direct_write(struct kiocb *iocb, const struct iovec *iov,
         if (!count)
                 goto out;
 
+        mutex_lock(&inode->i_mutex);
+
         result = nfs_sync_mapping(mapping);
         if (result)
-                goto out;
+                goto out_unlock;
+
+        if (mapping->nrpages) {
+                result = invalidate_inode_pages2_range(mapping,
+                                        pos >> PAGE_CACHE_SHIFT, end);
+                if (result)
+                        goto out_unlock;
+        }
 
         task_io_account_write(count);
 
         result = -ENOMEM;
         dreq = nfs_direct_req_alloc();
         if (!dreq)
-                goto out;
+                goto out_unlock;
 
         dreq->inode = inode;
         dreq->bytes_left = count;
@@ -982,6 +994,14 @@ ssize_t nfs_file_direct_write(struct kiocb *iocb, const struct iovec *iov,
                 dreq->iocb = iocb;
 
         result = nfs_direct_write_schedule_iovec(dreq, iov, nr_segs, pos, uio);
+
+        if (mapping->nrpages) {
+                invalidate_inode_pages2_range(mapping,
+                                              pos >> PAGE_CACHE_SHIFT, end);
+        }
+
+        mutex_unlock(&inode->i_mutex);
+
         if (!result) {
                 result = nfs_direct_wait(dreq);
                 if (result > 0) {
@@ -994,8 +1014,13 @@ ssize_t nfs_file_direct_write(struct kiocb *iocb, const struct iovec *iov,
                         spin_unlock(&inode->i_lock);
                 }
         }
+        nfs_direct_req_release(dreq);
+        return result;
+
 out_release:
         nfs_direct_req_release(dreq);
+out_unlock:
+        mutex_unlock(&inode->i_mutex);
 out:
         return result;
 }