linux-kernel - [ 31/49] udf: dont increment lenExtents while writing to a hole

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Message-Id: <20130113174302.248363034@decadent.org.uk>
Date:	Sun, 13 Jan 2013 17:43:26 +0000
From:	Ben Hutchings <ben@...adent.org.uk>
To:	linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:	akpm@...ux-foundation.org, alan@...rguk.ukuu.org.uk,
	Namjae Jeon <namjae.jeon@...sung.com>,
	Ashish Sangwan <a.sangwan@...sung.com>, Jan Kara <jack@...e.cz>
Subject: [ 31/49] udf: dont increment lenExtents while writing to a hole

3.2-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Namjae Jeon <namjae.jeon@...sung.com>

commit fb719c59bdb4fca86ee1fd1f42ab3735ca12b6b2 upstream.

Incrementing lenExtents even while writing to a hole is bad
for performance as calls to udf_discard_prealloc and
udf_truncate_tail_extent would not return from start if
isize != lenExtents

Signed-off-by: Namjae Jeon <namjae.jeon@...sung.com>
Signed-off-by: Ashish Sangwan <a.sangwan@...sung.com>
Signed-off-by: Jan Kara <jack@...e.cz>
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
---
 fs/udf/inode.c |    7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

--- a/fs/udf/inode.c
+++ b/fs/udf/inode.c
@@ -581,6 +581,7 @@ static struct buffer_head *inode_getblk(
 	struct udf_inode_info *iinfo = UDF_I(inode);
 	int goal = 0, pgoal = iinfo->i_location.logicalBlockNum;
 	int lastblock = 0;
+	bool isBeyondEOF;
 
 	prev_epos.offset = udf_file_entry_alloc_offset(inode);
 	prev_epos.block = iinfo->i_location;
@@ -659,7 +660,7 @@ static struct buffer_head *inode_getblk(
 	/* Are we beyond EOF? */
 	if (etype == -1) {
 		int ret;
-
+		isBeyondEOF = 1;
 		if (count) {
 			if (c)
 				laarr[0] = laarr[1];
@@ -702,6 +703,7 @@ static struct buffer_head *inode_getblk(
 		endnum = c + 1;
 		lastblock = 1;
 	} else {
+		isBeyondEOF = 0;
 		endnum = startnum = ((count > 2) ? 2 : count);
 
 		/* if the current extent is in position 0,
@@ -749,7 +751,8 @@ static struct buffer_head *inode_getblk(
 			*err = -ENOSPC;
 			return NULL;
 		}
-		iinfo->i_lenExtents += inode->i_sb->s_blocksize;
+		if (isBeyondEOF)
+			iinfo->i_lenExtents += inode->i_sb->s_blocksize;
 	}
 
 	/* if the extent the requsted block is located in contains multiple


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