linux-ext4 - [PATCH 4/4] ext4: Remove unnecessary io_end allocation from ext4

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Date:   Wed, 10 May 2017 09:41:47 +0200
From:   Jan Kara <jack@...e.cz>
To:     Ted Tso <tytso@....edu>
Cc:     <linux-ext4@...r.kernel.org>, Jan Kara <jack@...e.cz>
Subject: [PATCH 4/4] ext4: Remove unnecessary io_end allocation from ext4_writepages()

We don't have to allocate io_end when doing writeback from
ext4_writepages() without doing allocation. Remove the unnecessary
allocation. Also do_map argument is now unnecessary since we have io_end
allocated only if we want blocks to be allocated so remove it.

Signed-off-by: Jan Kara <jack@...e.cz>
---
 fs/ext4/inode.c | 15 ++-------------
 1 file changed, 2 insertions(+), 13 deletions(-)

diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index 6bce4520d569..83cddd9d7fb2 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -1643,7 +1643,6 @@ struct mpage_da_data {
 	 */
 	struct ext4_map_blocks map;
 	struct ext4_io_submit io_submit;	/* IO submission data */
-	unsigned int do_map:1;
 };
 
 static void mpage_release_unused_pages(struct mpage_da_data *mpd,
@@ -2173,7 +2172,7 @@ static bool mpage_add_bh_to_extent(struct mpage_da_data *mpd, ext4_lblk_t lblk,
 	/* First block in the extent? */
 	if (map->m_len == 0) {
 		/* We cannot map unless handle is started... */
-		if (!mpd->do_map)
+		if (!mpd->io_submit.io_end)
 			return false;
 		map->m_lblk = lblk;
 		map->m_len = 1;
@@ -2228,7 +2227,7 @@ static int mpage_process_page_bufs(struct mpage_da_data *mpd,
 			if (mpd->map.m_len)
 				return 0;
 			/* Buffer needs mapping and handle is not started? */
-			if (!mpd->do_map)
+			if (!mpd->io_submit.io_end)
 				return 0;
 			/* Everything mapped so far and we hit EOF */
 			break;
@@ -2753,17 +2752,9 @@ static int ext4_writepages(struct address_space *mapping,
 	 * in the block layer on device congestion while having transaction
 	 * started.
 	 */
-	mpd.do_map = 0;
-	mpd.io_submit.io_end = ext4_init_io_end(inode, GFP_KERNEL);
-	if (!mpd.io_submit.io_end) {
-		ret = -ENOMEM;
-		goto unplug;
-	}
 	ret = mpage_prepare_extent_to_map(&mpd);
 	/* Submit prepared bio */
 	ext4_io_submit(&mpd.io_submit);
-	ext4_put_io_end_defer(mpd.io_submit.io_end);
-	mpd.io_submit.io_end = NULL;
 	/* Unlock pages we didn't use */
 	mpage_release_unused_pages(&mpd, false);
 	if (ret < 0)
@@ -2800,7 +2791,6 @@ static int ext4_writepages(struct address_space *mapping,
 			mpd.io_submit.io_end = NULL;
 			break;
 		}
-		mpd.do_map = 1;
 
 		trace_ext4_da_write_pages(inode, mpd.first_page, mpd.wbc);
 		ret = mpage_prepare_extent_to_map(&mpd);
@@ -2831,7 +2821,6 @@ static int ext4_writepages(struct address_space *mapping,
 		if (!ext4_handle_valid(handle) || handle->h_sync == 0) {
 			ext4_journal_stop(handle);
 			handle = NULL;
-			mpd.do_map = 0;
 		}
 		/* Submit prepared bio */
 		ext4_io_submit(&mpd.io_submit);
-- 
2.12.0