linux-ext4 - [RFC PATCH 1/4] ext4: check and update i

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Date:   Tue, 6 Jul 2021 10:42:07 +0800
From:   Zhang Yi <yi.zhang@...wei.com>
To:     <linux-ext4@...r.kernel.org>
CC:     <tytso@....edu>, <adilger.kernel@...ger.ca>, <jack@...e.cz>,
        <yi.zhang@...wei.com>, <yukuai3@...wei.com>
Subject: [RFC PATCH 1/4] ext4: check and update i_disksize properly

After commit 3da40c7b0898 ("ext4: only call ext4_truncate when size <=
isize"), i_disksize could always be updated to i_size in ext4_setattr(),
and it seems that there is no other way that could appear
i_disksize < i_size besides the delalloc write. In the case of delay
alloc write, ext4_writepages() could update i_disksize for the new delay
allocated blocks properly. So we could switch to check i_size instead
of i_disksize in ext4_da_write_end() when write to the end of the file.
we also could remove ext4_mark_inode_dirty() together because
generic_write_end() will dirty the inode.

Signed-off-by: Zhang Yi <yi.zhang@...wei.com>
---
 fs/ext4/inode.c | 21 ++++++++-------------
 1 file changed, 8 insertions(+), 13 deletions(-)

diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index d8de607849df..6f6a61f3ae5f 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -3087,32 +3087,27 @@ static int ext4_da_write_end(struct file *file,
 	 * generic_write_end() will run mark_inode_dirty() if i_size
 	 * changes.  So let's piggyback the i_disksize mark_inode_dirty
 	 * into that.
+	 *
+	 * Check i_size not i_disksize here because ext4_writepages() could
+	 * update i_disksize from i_size for delay allocated blocks properly.
 	 */
 	new_i_size = pos + copied;
-	if (copied && new_i_size > EXT4_I(inode)->i_disksize) {
+	if (copied && new_i_size > inode->i_size) {
 		if (ext4_has_inline_data(inode) ||
-		    ext4_da_should_update_i_disksize(page, end)) {
+		    ext4_da_should_update_i_disksize(page, end))
 			ext4_update_i_disksize(inode, new_i_size);
-			/* We need to mark inode dirty even if
-			 * new_i_size is less that inode->i_size
-			 * bu greater than i_disksize.(hint delalloc)
-			 */
-			ret = ext4_mark_inode_dirty(handle, inode);
-		}
 	}
 
 	if (write_mode != CONVERT_INLINE_DATA &&
 	    ext4_test_inode_state(inode, EXT4_STATE_MAY_INLINE_DATA) &&
 	    ext4_has_inline_data(inode))
-		ret2 = ext4_da_write_inline_data_end(inode, pos, len, copied,
+		ret = ext4_da_write_inline_data_end(inode, pos, len, copied,
 						     page);
 	else
-		ret2 = generic_write_end(file, mapping, pos, len, copied,
+		ret = generic_write_end(file, mapping, pos, len, copied,
 							page, fsdata);
 
-	copied = ret2;
-	if (ret2 < 0)
-		ret = ret2;
+	copied = ret;
 	ret2 = ext4_journal_stop(handle);
 	if (unlikely(ret2 && !ret))
 		ret = ret2;
-- 
2.31.1