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>

diff --git a/fs/nfs/direct.c b/fs/nfs/direct.c
index 85e4e4b..b8797ae 100644 (file)
--- 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;
 }