lkml.org 
[lkml]   [2014]   [Jan]   [28]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
From
SubjectRE: [f2fs-dev] [PATCH] f2fs: use inode mutex to keep atomicity of f2fs_falloc
Date
Hi,

> -----Original Message-----
> From: Jaegeuk Kim [mailto:jaegeuk.kim@samsung.com]
> Sent: Tuesday, January 28, 2014 2:00 PM
> To: Chao Yu
> Cc: linux-fsdevel@vger.kernel.org; linux-kernel@vger.kernel.org;
> linux-f2fs-devel@lists.sourceforge.net
> Subject: Re: [f2fs-dev] [PATCH] f2fs: use inode mutex to keep atomicity of f2fs_falloc
>
> Hi,
>
> 2014-01-28 (화), 10:29 +0800, Chao Yu:
> > Previously without protection of inode mutex, f2fs_falloc and other data
> > correlated operations will interfere with each other.
>
> Could you explain a little bit more what kind of scenarios wrt this?

1. Without protection of i_mutex, status(e.g. i_size) of inode could be changed
by other operation(e.g. vfs_write()/vfs_truncate()) when we fallocate a file, it
may cause us walk into wrong branch code after we check these status of inode,
and vice versa.
2. i_size_write()/inode_newsize_ok() is called in f2fs_fallocate(), usually we
use i_mutex to protect these functions.

>
>
> > So let's use inode mutex to keep atomicity of f2fs_falloc.
> >
> > Signed-off-by: Chao Yu <chao2.yu@samsung.com>
> > ---
> > fs/f2fs/file.c | 5 +++++
> > 1 file changed, 5 insertions(+)
> >
> > diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c
> > index 85e91ca..ece380f 100644
> > --- a/fs/f2fs/file.c
> > +++ b/fs/f2fs/file.c
> > @@ -559,6 +559,8 @@ static long f2fs_fallocate(struct file *file, int mode,
> > if (mode & ~(FALLOC_FL_KEEP_SIZE | FALLOC_FL_PUNCH_HOLE))
> > return -EOPNOTSUPP;
> >
> > + mutex_lock(&inode->i_mutex);
> > +
> > if (mode & FALLOC_FL_PUNCH_HOLE)
> > ret = punch_hole(inode, offset, len);
> > else
> > @@ -568,6 +570,9 @@ static long f2fs_fallocate(struct file *file, int mode,
> > inode->i_mtime = inode->i_ctime = CURRENT_TIME;
> > mark_inode_dirty(inode);
> > }
> > +
> > + mutex_unlock(&inode->i_mutex);
> > +
> > trace_f2fs_fallocate(inode, mode, offset, len, ret);
> > return ret;
> > }
>
> --
> Jaegeuk Kim
> Samsung

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

\
 
 \ /
  Last update: 2014-01-28 10:21    [W:0.054 / U:0.176 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site