fs: always maintain i_dio_count

Maintain i_dio_count for all filesystems, not just those using DIO_LOCKING.
This these filesystems to also protect truncate against direct I/O requests
by using common code.  Right now the only non-DIO_LOCKING filesystem that
appears to do so is XFS, which uses an opencoded variant of the i_dio_count
scheme.

Behaviour doesn't change for filesystems never calling inode_dio_wait.
For ext4 behaviour changes when using the dioread_nonlock option, which
previously was missing any protection between truncate and direct I/O reads.
For ocfs2 that handcrafted i_dio_count manipulations are replaced with
the common code now enable.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

1 files changed, 3 insertions, 9 deletions

diff --git a/fs/ocfs2/file.c b/fs/ocfs2/file.c
index 736283ca4a4c..22d604601957 100644
--- a/fs/ocfs2/file.c
+++ b/fs/ocfs2/file.c
@@ -2240,7 +2240,6 @@ static ssize_t ocfs2_file_aio_write(struct kiocb *iocb,
 relock:
         /* to match setattr's i_mutex -> rw_lock ordering */
         if (direct_io) {
-                atomic_inc(&inode->i_dio_count);
                 have_alloc_sem = 1;
                 /* communicate with ocfs2_dio_end_io */
                 ocfs2_iocb_set_sem_locked(iocb);
@@ -2292,7 +2291,6 @@ relock:
          */
         if (direct_io && !can_do_direct) {
                 ocfs2_rw_unlock(inode, rw_level);
-                inode_dio_done(inode);
 
                 have_alloc_sem = 0;
                 rw_level = -1;
@@ -2379,10 +2377,8 @@ out:
                 ocfs2_rw_unlock(inode, rw_level);
 
 out_sems:
-        if (have_alloc_sem) {
-                inode_dio_done(inode);
+        if (have_alloc_sem)
                 ocfs2_iocb_clear_sem_locked(iocb);
-        }
 
         mutex_unlock(&inode->i_mutex);
 
@@ -2533,7 +2529,6 @@ static ssize_t ocfs2_file_aio_read(struct kiocb *iocb,
          */
         if (filp->f_flags & O_DIRECT) {
                 have_alloc_sem = 1;
-                atomic_inc(&inode->i_dio_count);
                 ocfs2_iocb_set_sem_locked(iocb);
 
                 ret = ocfs2_rw_lock(inode, 0);
@@ -2575,10 +2570,9 @@ static ssize_t ocfs2_file_aio_read(struct kiocb *iocb,
         }
 
 bail:
-        if (have_alloc_sem) {
-                inode_dio_done(inode);
+        if (have_alloc_sem)
                 ocfs2_iocb_clear_sem_locked(iocb);
-        }
+
         if (rw_level != -1)
                 ocfs2_rw_unlock(inode, rw_level);