linux-ext4 - Re: [PATCH] ext4: deleted unnecessary assignments and useless "if" statement

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Message-ID: <20130620144421.GC28309@thunk.org>
Date:	Thu, 20 Jun 2013 10:44:21 -0400
From:	Theodore Ts'o <tytso@....edu>
To:	jon ernst <jonernst07@....com>
Cc:	linux-ext4@...r.kernel.org
Subject: Re: [PATCH] ext4: deleted unnecessary assignments and useless "if"
 statement

On Thu, Jun 20, 2013 at 01:44:56AM -0400, jon ernst wrote:
> comparing unsigned variable with 0 always return false.
> err = 0 is duplicated and unnecessary.
> 
> Signed-off-by: "Jon Ernst" <jonernst07@....com>

I've applied this with a few changes.

(a) your patch was white space corrupted
(b) one of the err = 0 which you removed was actually necessary.

I've reworked the error handling in ext4_block_zero_page_range() so
it's a bit more obvious.

Also your change showed up a potential issue with ext4_write_end(), in
that ext4_write_inline_data_end() returns an int, which can be
negative in the case of an error, and it's assigning this to copied,
which is an unsigned int.

				- Ted

>From 6e4837a3e8bc04a1c49f8668c32ce3239968a8ce Mon Sep 17 00:00:00 2001
From: jon ernst <jonernst07@....com>
Date: Thu, 20 Jun 2013 10:42:05 -0400
Subject: [PATCH] ext4: delete unnecessary C statements

Comparing unsigned variable with 0 always returns false.
err = 0 is duplicated and unnecessary.

Signed-off-by: "Jon Ernst" <jonernst07@....com>
Signed-off-by: "Theodore Ts'o" <tytso@....edu>
----
---
 fs/ext4/inode.c | 12 ++----------
 1 file changed, 2 insertions(+), 10 deletions(-)

diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index 78cf398..baf5c2b 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -1100,8 +1100,6 @@ static int ext4_write_end(struct file *file,
 	if (i_size_changed)
 		ext4_mark_inode_dirty(handle, inode);
 
-	if (copied < 0)
-		ret = copied;
 	if (pos + len > inode->i_size && ext4_can_truncate(inode))
 		/* if we have allocated more blocks and copied
 		 * less. We will have blocks allocated outside
@@ -3336,7 +3334,7 @@ int ext4_block_zero_page_range(handle_t *handle,
 	struct inode *inode = mapping->host;
 	struct buffer_head *bh;
 	struct page *page;
-	int err = 0;
+	int err;
 
 	page = find_or_create_page(mapping, from >> PAGE_CACHE_SHIFT,
 				   mapping_gfp_mask(mapping) & ~__GFP_FS);
@@ -3366,13 +3364,10 @@ int ext4_block_zero_page_range(handle_t *handle,
 		iblock++;
 		pos += blocksize;
 	}
-
-	err = 0;
 	if (buffer_freed(bh)) {
 		BUFFER_TRACE(bh, "freed: skip");
 		goto unlock;
 	}
-
 	if (!buffer_mapped(bh)) {
 		BUFFER_TRACE(bh, "unmapped");
 		ext4_get_block(inode, iblock, bh, 0);
@@ -3395,22 +3390,19 @@ int ext4_block_zero_page_range(handle_t *handle,
 		if (!buffer_uptodate(bh))
 			goto unlock;
 	}
-
 	if (ext4_should_journal_data(inode)) {
 		BUFFER_TRACE(bh, "get write access");
 		err = ext4_journal_get_write_access(handle, bh);
 		if (err)
 			goto unlock;
 	}
-
 	zero_user(page, offset, length);
-
 	BUFFER_TRACE(bh, "zeroed end of block");
 
-	err = 0;
 	if (ext4_should_journal_data(inode)) {
 		err = ext4_handle_dirty_metadata(handle, inode, bh);
 	} else {
+		err = 0;
 		mark_buffer_dirty(bh);
 		if (ext4_test_inode_state(inode, EXT4_STATE_ORDERED_MODE))
 			err = ext4_jbd2_file_inode(handle, inode);
-- 
1.7.12.rc0.22.gcdd159b

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