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

[sagit-ice-cold/kernel_xiaomi_msm8998.git] / fs / xfs / xfs_file.c

diff --git a/fs/xfs/xfs_file.c b/fs/xfs/xfs_file.c
index c203839..3a5d305 100644 (file)
--- 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);