Merge branch 'xfs-dio-extend-fix' into for-next

Conflicts:
	fs/xfs/xfs_file.c

1 files changed, 42 insertions, 4 deletions

diff --git a/fs/xfs/xfs_file.c b/fs/xfs/xfs_file.c
index c203839cd5be..3a5d305e60c9 100644
--- a/fs/xfs/xfs_file.c
+++ b/fs/xfs/xfs_file.c
@@ -569,20 +569,41 @@ restart:
          * write.  If zeroing is needed and we are currently holding the
          * iolock shared, we need to update it to exclusive which implies
          * having to redo all checks before.
+         *
+         * We need to serialise against EOF updates that occur in IO
+         * completions here. We want to make sure that nobody is changing the
+         * size while we do this check until we have placed an IO barrier (i.e.
+         * hold the XFS_IOLOCK_EXCL) that prevents new IO from being dispatched.
+         * The spinlock effectively forms a memory barrier once we have the
+         * XFS_IOLOCK_EXCL so we are guaranteed to see the latest EOF value
+         * and hence be able to correctly determine if we need to run zeroing.
          */
+        spin_lock(&ip->i_flags_lock);
         if (*pos > i_size_read(inode)) {
                 bool    zero = false;
 
+                spin_unlock(&ip->i_flags_lock);
                 if (*iolock == XFS_IOLOCK_SHARED) {
                         xfs_rw_iunlock(ip, *iolock);
                         *iolock = XFS_IOLOCK_EXCL;
                         xfs_rw_ilock(ip, *iolock);
+
+                        /*
+                         * We now have an IO submission barrier in place, but
+                         * AIO can do EOF updates during IO completion and hence
+                         * we now need to wait for all of them to drain. Non-AIO
+                         * DIO will have drained before we are given the
+                         * XFS_IOLOCK_EXCL, and so for most cases this wait is a
+                         * no-op.
+                         */
+                        inode_dio_wait(inode);
                         goto restart;
                 }
                 error = xfs_zero_eof(ip, *pos, i_size_read(inode), &zero);
                 if (error)
                         return error;
-        }
+        } else
+                spin_unlock(&ip->i_flags_lock);
 
         /*
          * Updating the timestamps will grab the ilock again from
@@ -644,6 +665,8 @@ xfs_file_dio_aio_write(
         int                     iolock;
         size_t                  count = iov_iter_count(from);
         loff_t                  pos = iocb->ki_pos;
+        loff_t                  end;
+        struct iov_iter         data;
         struct xfs_buftarg      *target = XFS_IS_REALTIME_INODE(ip) ?
                                         mp->m_rtdev_targp : mp->m_ddev_targp;
 
@@ -683,10 +706,11 @@ xfs_file_dio_aio_write(
         if (ret)
                 goto out;
         iov_iter_truncate(from, count);
+        end = pos + count - 1;
 
         if (mapping->nrpages) {
                 ret = filemap_write_and_wait_range(VFS_I(ip)->i_mapping,
-                                                    pos, pos + count - 1);
+                                                   pos, end);
                 if (ret)
                         goto out;
                 /*
@@ -696,7 +720,7 @@ xfs_file_dio_aio_write(
                  */
                 ret = invalidate_inode_pages2_range(VFS_I(ip)->i_mapping,
                                         pos >> PAGE_CACHE_SHIFT,
-                                        (pos + count - 1) >> PAGE_CACHE_SHIFT);
+                                        end >> PAGE_CACHE_SHIFT);
                 WARN_ON_ONCE(ret);
                 ret = 0;
         }
@@ -713,8 +737,22 @@ xfs_file_dio_aio_write(
         }
 
         trace_xfs_file_direct_write(ip, count, iocb->ki_pos, 0);
-        ret = generic_file_direct_write(iocb, from, pos);
 
+        data = *from;
+        ret = mapping->a_ops->direct_IO(WRITE, iocb, &data, pos);
+
+        /* see generic_file_direct_write() for why this is necessary */
+        if (mapping->nrpages) {
+                invalidate_inode_pages2_range(mapping,
+                                              pos >> PAGE_CACHE_SHIFT,
+                                              end >> PAGE_CACHE_SHIFT);
+        }
+
+        if (ret > 0) {
+                pos += ret;
+                iov_iter_advance(from, ret);
+                iocb->ki_pos = pos;
+        }
 out:
         xfs_rw_iunlock(ip, iolock);