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[PATCH 03/17] vfs: Remove syncing from generic_file_direct_write() and g

To: LKML <linux-kernel@xxxxxxxxxxxxxxx>
Subject: [PATCH 03/17] vfs: Remove syncing from generic_file_direct_write() and generic_file_buffered_write()
From: Jan Kara <jack@xxxxxxx>
Date: Fri, 21 Aug 2009 19:23:53 +0200
Cc: hch@xxxxxx, linux-fsdevel@xxxxxxxxxxxxxxx, Jan Kara <jack@xxxxxxx>, ocfs2-devel@xxxxxxxxxxxxxx, Joel Becker <joel.becker@xxxxxxxxxx>, Felix Blyakher <felixb@xxxxxxx>, xfs@xxxxxxxxxxx
In-reply-to: <1250875447-15622-1-git-send-email-jack@xxxxxxx>
References: <1250875447-15622-1-git-send-email-jack@xxxxxxx>
generic_file_direct_write() and generic_file_buffered_write() called
generic_osync_inode() if it was called on O_SYNC file or IS_SYNC inode. But
this is superfluous since generic_file_aio_write() does the syncing as well.
Also XFS and OCFS2 which call these functions directly handle syncing
themselves. So let's have a single place where syncing happens:
generic_file_aio_write().

We slightly change the behavior by syncing only the range of file to which the
write happened for buffered writes but that should be all that is required.

CC: ocfs2-devel@xxxxxxxxxxxxxx
CC: Joel Becker <joel.becker@xxxxxxxxxx>
CC: Felix Blyakher <felixb@xxxxxxx>
CC: xfs@xxxxxxxxxxx
Signed-off-by: Jan Kara <jack@xxxxxxx>
---
 mm/filemap.c |   35 ++++++-----------------------------
 1 files changed, 6 insertions(+), 29 deletions(-)

diff --git a/mm/filemap.c b/mm/filemap.c
index 554a396..f863e1d 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -2187,20 +2187,7 @@ generic_file_direct_write(struct kiocb *iocb, const 
struct iovec *iov,
                }
                *ppos = end;
        }
-
-       /*
-        * Sync the fs metadata but not the minor inode changes and
-        * of course not the data as we did direct DMA for the IO.
-        * i_mutex is held, which protects generic_osync_inode() from
-        * livelocking.  AIO O_DIRECT ops attempt to sync metadata here.
-        */
 out:
-       if ((written >= 0 || written == -EIOCBQUEUED) &&
-           ((file->f_flags & O_SYNC) || IS_SYNC(inode))) {
-               int err = generic_osync_inode(inode, mapping, OSYNC_METADATA);
-               if (err < 0)
-                       written = err;
-       }
        return written;
 }
 EXPORT_SYMBOL(generic_file_direct_write);
@@ -2332,8 +2319,6 @@ generic_file_buffered_write(struct kiocb *iocb, const 
struct iovec *iov,
 {
        struct file *file = iocb->ki_filp;
        struct address_space *mapping = file->f_mapping;
-       const struct address_space_operations *a_ops = mapping->a_ops;
-       struct inode *inode = mapping->host;
        ssize_t status;
        struct iov_iter i;
 
@@ -2343,16 +2328,6 @@ generic_file_buffered_write(struct kiocb *iocb, const 
struct iovec *iov,
        if (likely(status >= 0)) {
                written += status;
                *ppos = pos + status;
-
-               /*
-                * For now, when the user asks for O_SYNC, we'll actually give
-                * O_DSYNC
-                */
-               if (unlikely((file->f_flags & O_SYNC) || IS_SYNC(inode))) {
-                       if (!a_ops->writepage || !is_sync_kiocb(iocb))
-                               status = generic_osync_inode(inode, mapping,
-                                               OSYNC_METADATA|OSYNC_DATA);
-               }
        }
        
        /*
@@ -2514,11 +2489,12 @@ ssize_t generic_file_aio_write_nolock(struct kiocb 
*iocb,
 
        ret = __generic_file_aio_write(iocb, iov, nr_segs, &iocb->ki_pos);
 
-       if (ret > 0 && ((file->f_flags & O_SYNC) || IS_SYNC(inode))) {
+       if ((ret > 0 || ret == -EIOCBQUEUED) &&
+           ((file->f_flags & O_SYNC) || IS_SYNC(inode))) {
                ssize_t err;
 
                err = sync_page_range_nolock(inode, mapping, pos, ret);
-               if (err < 0)
+               if (err < 0 && ret > 0)
                        ret = err;
        }
        return ret;
@@ -2550,11 +2526,12 @@ ssize_t generic_file_aio_write(struct kiocb *iocb, 
const struct iovec *iov,
        ret = __generic_file_aio_write(iocb, iov, nr_segs, &iocb->ki_pos);
        mutex_unlock(&inode->i_mutex);
 
-       if (ret > 0 && ((file->f_flags & O_SYNC) || IS_SYNC(inode))) {
+       if ((ret > 0 || ret == -EIOCBQUEUED) &&
+           ((file->f_flags & O_SYNC) || IS_SYNC(inode))) {
                ssize_t err;
 
                err = sync_page_range(inode, mapping, pos, ret);
-               if (err < 0)
+               if (err < 0 && ret > 0)
                        ret = err;
        }
        return ret;
-- 
1.6.0.2

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