mm/filemap.c: fix criteria of calling iov_shorten() in generic_file_direct_write()

From 35947e6535d92c54cf523470cc8811e8b5fee3e5 Mon Sep 17 00:00:00 2001
From: Gu Zheng <[email protected]>
Date: Tue, 23 Apr 2013 16:09:04 +0800
Subject: [PATCH] mm/filemap.c: fix criteria of calling iov_shorten() in generic_file_direct_write()

generic_file_direct_write() compares 'count'(the max count we actually can write) with 'ocount'(the count we request to write) to see if there is need to call iov_shorten() to reduce number of segments and the iovec's length. If the 'count' is equal or greater than 'ocount', there is no need to call iov_shorten() indeed. So the judgement should be changed:
'if (count != ocount)' --> 'if (count < ocount)'

Signed-off-by Gu Zheng <[email protected]>

---
 mm/filemap.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

mm/filemap.c +1 -1

index e1979fd..c566b9c 100644
@@ -2183,7 +2183,7 @@ generic_file_direct_write(struct kiocb *iocb, const struct iovec *iov,
 	size_t		write_len;
 	pgoff_t		end;
 
-	if (count != ocount)
+	if (count < ocount)
 		*nr_segs = iov_shorten((struct iovec *)iov, *nr_segs, count);
 
 	write_len = iov_length(iov, *nr_segs);

Signature · 7 lines

1.7.7

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to [email protected]
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/

Quoted 11 lines · Gu Zheng

From 35947e6535d92c54cf523470cc8811e8b5fee3e5 Mon Sep 17 00:00:00 2001
From: Gu Zheng <[email protected]>
Date: Tue, 23 Apr 2013 16:09:04 +0800
Subject: [PATCH] mm/filemap.c: fix criteria of calling iov_shorten() in generic_file_direct_write()

generic_file_direct_write() compares 'count'(the max count we actually can write) with 'ocount'(the count we request to write) to see if there is need to call iov_shorten() to reduce number of segments and the iovec's length. If the 'count' is equal or greater than 'ocount', there is no need to call iov_shorten() indeed. So the judgement should be changed:
'if (count != ocount)' --> 'if (count < ocount)'

Thanks for the patch but it shouldn't be really possible that count >
ocount, should it? So your patch doesn't really fix anything. Or am I missing something?

Honza

Quoted 22 lines

Signed-off-by Gu Zheng <[email protected]>

---
 mm/filemap.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

mm/filemap.c +1 -1

index e1979fd..c566b9c 100644
@@ -2183,7 +2183,7 @@ generic_file_direct_write(struct kiocb *iocb, const struct iovec *iov,
 	size_t		write_len;
 	pgoff_t		end;
 
-	if (count != ocount)
+	if (count < ocount)
 		*nr_segs = iov_shorten((struct iovec *)iov, *nr_segs, count);
 
 	write_len = iov_length(iov, *nr_segs);

Signature · 1 line

1.7.7

Quoted 5 lines

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected]
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/