linux-kernel - [PATCH 44/49] ext4: fix uniniatilized extent splitting error

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Message-Id: <1200970948-17903-45-git-send-email-tytso@mit.edu>
Date:	Mon, 21 Jan 2008 22:02:23 -0500
From:	"Theodore Ts'o" <tytso@....EDU>
To:	linux-kernel@...r.kernel.org
Cc:	Dmitry Monakhov <dmonakhov@...nvz.org>,
	Mingming Cao <cmm@...ibm.com>, "Theodore Ts'o" <tytso@....edu>
Subject: [PATCH 44/49] ext4: fix uniniatilized extent splitting error

From: Dmitry Monakhov <dmonakhov@...nvz.org>

Fix bug reported by Dmitry Monakhov caused by lost error code

    Testcase:

    blksize = 0x1000;
    fd = open(argv[1], O_RDWR|O_CREAT, 0700);
    unsigned long long sz = 0x10000000UL;
    /* allocating big blocks chunk */
    syscall(__NR_fallocate, fd, 0, 0UL, sz)

    /* grab all other available filesystem space */
    tfd = open("tmp", O_RDWR|O_CREAT|O_DIRECT, 0700);
    while( write(tfd, buf, 4096) > 0); /* loop untill ENOSPC */
    fsync(fd); /* just in case */
    while (pos < sz) {
    	/* each seek+ write operation result in splits uninitialized extent
    	in three extents. Splitting may result in new extent allocation
    	which probably will fail because of ENOSPC*/

    	lseek(fd, blksize*2 -1, SEEK_CUR);
    	if ((ret = write(fd, 'a', 1)) != 1)
    		exit(1);
    	pos += blksize * 2;
    }

Signed-off-by: Dmitry Monakhov <dmonakhov@...nvz.org>
Signed-off-by: Mingming Cao <cmm@...ibm.com>
Signed-off-by: "Theodore Ts'o" <tytso@....edu>
---
 fs/ext4/extents.c |    5 +++--
 1 files changed, 3 insertions(+), 2 deletions(-)

diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c
index 8cf5545..13e3e8c 100644
--- a/fs/ext4/extents.c
+++ b/fs/ext4/extents.c
@@ -2373,9 +2373,10 @@ int ext4_ext_get_blocks(handle_t *handle, struct inode *inode,
 			ret = ext4_ext_convert_to_initialized(handle, inode,
 								path, iblock,
 								max_blocks);
-			if (ret <= 0)
+			if (ret <= 0) {
+				err = ret;
 				goto out2;
-			else
+			} else
 				allocated = ret;
 			goto outnew;
 		}
-- 
1.5.4.rc3.31.g1271-dirty

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