When data integrity operation happens (sync, fsync, fdatasync calls)
writeback control is set to WB_SYNC_ALL. In that case all write
requests are marked with WRITE_SYNC (WRITE | REQ_SYNC | REQ_NOIDLE)
indicating that caller is waiting for completion and block layer or
block device should prioritize the IO avoiding any possible delays.

But mpage writeback path ignores marking requests as WRITE_SYNC.

This patch fixes this.

Signed-off-by: Roman Pen <r.peni...@gmail.com>
Reviewed-by: Jan Kara <j...@suse.cz>
Cc: Jens Axboe <ax...@kernel.dk>
Cc: Tejun Heo <t...@kernel.org>
Cc: Andrew Morton <a...@linux-foundation.org>
Cc: linux-fsde...@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
---
 fs/mpage.c | 23 +++++++++++++++--------
 1 file changed, 15 insertions(+), 8 deletions(-)

diff --git a/fs/mpage.c b/fs/mpage.c
index 4979ffa..4e0af5a 100644
--- a/fs/mpage.c
+++ b/fs/mpage.c
@@ -462,6 +462,7 @@ static int __mpage_writepage(struct page *page, struct 
writeback_control *wbc,
        struct buffer_head map_bh;
        loff_t i_size = i_size_read(inode);
        int ret = 0;
+       int wr = (wbc->sync_mode == WB_SYNC_ALL ?  WRITE_SYNC : WRITE);
 
        if (page_has_buffers(page)) {
                struct buffer_head *head = page_buffers(page);
@@ -570,7 +571,7 @@ page_is_mapped:
         * This page will go to BIO.  Do we need to send this BIO off first?
         */
        if (bio && mpd->last_block_in_bio != blocks[0] - 1)
-               bio = mpage_bio_submit(WRITE, bio);
+               bio = mpage_bio_submit(wr, bio);
 
 alloc_new:
        if (bio == NULL) {
@@ -587,7 +588,7 @@ alloc_new:
         */
        length = first_unmapped << blkbits;
        if (bio_add_page(bio, page, length, 0) < length) {
-               bio = mpage_bio_submit(WRITE, bio);
+               bio = mpage_bio_submit(wr, bio);
                goto alloc_new;
        }
 
@@ -620,7 +621,7 @@ alloc_new:
        set_page_writeback(page);
        unlock_page(page);
        if (boundary || (first_unmapped != blocks_per_page)) {
-               bio = mpage_bio_submit(WRITE, bio);
+               bio = mpage_bio_submit(wr, bio);
                if (boundary_block) {
                        write_boundary_block(boundary_bdev,
                                        boundary_block, 1 << blkbits);
@@ -632,7 +633,7 @@ alloc_new:
 
 confused:
        if (bio)
-               bio = mpage_bio_submit(WRITE, bio);
+               bio = mpage_bio_submit(wr, bio);
 
        if (mpd->use_writepage) {
                ret = mapping->a_ops->writepage(page, wbc);
@@ -688,8 +689,11 @@ mpage_writepages(struct address_space *mapping,
                };
 
                ret = write_cache_pages(mapping, wbc, __mpage_writepage, &mpd);
-               if (mpd.bio)
-                       mpage_bio_submit(WRITE, mpd.bio);
+               if (mpd.bio) {
+                       int wr = (wbc->sync_mode == WB_SYNC_ALL ?
+                                 WRITE_SYNC : WRITE);
+                       mpage_bio_submit(wr, mpd.bio);
+               }
        }
        blk_finish_plug(&plug);
        return ret;
@@ -706,8 +710,11 @@ int mpage_writepage(struct page *page, get_block_t 
get_block,
                .use_writepage = 0,
        };
        int ret = __mpage_writepage(page, wbc, &mpd);
-       if (mpd.bio)
-               mpage_bio_submit(WRITE, mpd.bio);
+       if (mpd.bio) {
+               int wr = (wbc->sync_mode == WB_SYNC_ALL ?
+                         WRITE_SYNC : WRITE);
+               mpage_bio_submit(wr, mpd.bio);
+       }
        return ret;
 }
 EXPORT_SYMBOL(mpage_writepage);
-- 
1.9.0

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