> -----Original Message----- > From: Jaegeuk Kim [mailto:jaeg...@kernel.org] > Sent: Thursday, December 31, 2015 2:28 AM > To: Fan Li > Cc: linux-f2fs-devel@lists.sourceforge.net > Subject: Re: [f2fs-dev] [PATCH 1/3] f2fs: avoid calling i_size_read when it's > unnecessary > > Hi Fan, > > On Wed, Dec 30, 2015 at 04:49:56PM +0800, Fan Li wrote: > > i_size_read does more than reading a value, it's best that we use it > > only when we need it. > > > > Signed-off-by: Fan li <fanofcode...@samsung.com> > > --- > > fs/f2fs/data.c | 4 +++- > > 1 file changed, 3 insertions(+), 1 deletion(-) > > > > diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c index d67c599..a9a4d89 > > 100644 > > --- a/fs/f2fs/data.c > > +++ b/fs/f2fs/data.c > > @@ -780,7 +780,7 @@ int f2fs_fiemap(struct inode *inode, struct > > fiemap_extent_info *fieinfo, { > > struct buffer_head map_bh; > > sector_t start_blk, last_blk; > > - loff_t isize = i_size_read(inode); > > + loff_t isize; > > u64 logical = 0, phys = 0, size = 0; > > u32 flags = 0; > > int ret = 0; > > @@ -795,6 +795,8 @@ int f2fs_fiemap(struct inode *inode, struct > > fiemap_extent_info *fieinfo, > > return ret; > > } > > > > + isize = i_size_read(inode); > > It seems that we need to get isize after grabbing i_mutex below in order to > avoid data race.
See if I got this right, isize should remain unchanged during the entire procedure, so we need to add i_mutex upon it, and since there is already a i_mutex, we can get inode->i_size directly instead of calling i_read_size. Is that right? > > Thanks, > > > + > > mutex_lock(&inode->i_mutex); > > if (start >= isize) > > goto out; > > -- > > 1.7.9.5 > > ------------------------------------------------------------------------------ _______________________________________________ Linux-f2fs-devel mailing list Linux-f2fs-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/linux-f2fs-devel
