diff mbox

libext2fs: don't flush to device opened in read-only mode

Message ID 118AAB5F26BFB34DB5CDA7DA33334DB9B5FF41@vmsk-exch-01.paragon-software.com
State Superseded, archived
Headers show

Commit Message

Konstantin Chistyakov May 22, 2017, 9:48 a.m. UTC 
From: Konstantin Chistyakov <Konstantin.Chistyakov@Paragon-software.com>
Date: Tue, 19 May 2017 09:23:29 -0600
Subject: [PATCH] libext2fs: don't flush to device opened in read-only mode

From: Konstantin Chistyakov <Konstantin.Chistyakov@Paragon-software.com>

If the e2fsck is called with both -f -n options, the checking completing with a flushing error (retcode 8).

Catch error from the unix_flush() fsync(data->dev) when data->dev is opened in read-only mode:

...
e2fsck -n -f /dev/sdd1
e2fsck 1.43.4 (31-Jan-2017)
Pass 1: Checking inodes, blocks, and sizes
Pass 2: Checking directory structure
Pass 3: Checking directory connectivity
Pass 4: Checking reference counts
Pass 5: Checking group summary information
Error flushing writes to storage device: Permission denied

---
lib/ext2fs/unix_io.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

(limited to 'lib/ext2fs/unix_io.c')

Comments

Theodore Ts'o May 24, 2017, 9:56 p.m. UTC | #1 
On Mon, May 22, 2017 at 09:48:00AM +0000, Konstantin Chistyakov wrote:
> From: Konstantin Chistyakov <Konstantin.Chistyakov@Paragon-software.com>
> Date: Tue, 19 May 2017 09:23:29 -0600
> Subject: [PATCH] libext2fs: don't flush to device opened in read-only mode
> 
> From: Konstantin Chistyakov <Konstantin.Chistyakov@Paragon-software.com>
> 
> If the e2fsck is called with both -f -n options, the checking completing with a flushing error (retcode 8).
> 
> Catch error from the unix_flush() fsync(data->dev) when data->dev is opened in read-only mode:

I can't reproduce this problem.  What storage device or operating
system are you using?

That being said, this is probably the wrong place to fix it.  The
better fix is in e2fsck/unix.c, by adding a read-only test.

       	      	 		   	  - Ted
Konstantin Chistyakov May 25, 2017, 5:50 a.m. UTC | #2 
Thanks for suggestion how to fix the bug correctly. Platform for reproducing: CYGWin build (x86, x64, cygwin1.dll v.2.8.0), Windows 8.1 x64 and Windows  10 x64 (x86 not tested).

-----Original Message-----
From: Theodore Ts'o [mailto:tytso@mit.edu] 
Sent: Thursday, May 25, 2017 12:56 AM
To: Konstantin Chistyakov <Konstantin.Chistyakov@paragon-software.com>
Cc: linux-ext4@vger.kernel.org
Subject: Re: libext2fs: don't flush to device opened in read-only mode

On Mon, May 22, 2017 at 09:48:00AM +0000, Konstantin Chistyakov wrote:
> From: Konstantin Chistyakov 
> <Konstantin.Chistyakov@Paragon-software.com>
> Date: Tue, 19 May 2017 09:23:29 -0600
> Subject: [PATCH] libext2fs: don't flush to device opened in read-only 
> mode
> 
> From: Konstantin Chistyakov 
> <Konstantin.Chistyakov@Paragon-software.com>
> 
> If the e2fsck is called with both -f -n options, the checking completing with a flushing error (retcode 8).
> 
> Catch error from the unix_flush() fsync(data->dev) when data->dev is opened in read-only mode:

I can't reproduce this problem.  What storage device or operating system are you using?

That being said, this is probably the wrong place to fix it.  The better fix is in e2fsck/unix.c, by adding a read-only test.

       	      	 		   	  - Ted
diff mbox

Patch

diff -up lib/ext2fs/unix_io.c{.orig,}
--- lib/ext2fs/unix_io.c.orig        2017-05-19 14:32:12.550414900 +0300
+++ lib/ext2fs/unix_io.c              2017-05-19 14:33:48.520878000 +0300
@@ -1030,7 +1030,7 @@  static errcode_t unix_flush(io_channel channel)
#ifndef NO_IO_CACHE
 	retval = flush_cached_blocks(channel, data, 0);
#endif
-	if (!retval && fsync(data->dev) != 0)
+	if (!retval && (data->flags & IO_FLAG_RW) && fsync(data->dev) != 0)
 		return errno;
 	return retval;
}