From: "Kani, Toshi" Subject: Re: [PATCH 2/2] ext4, dax: set ext4_dax_aops for dax files Date: Tue, 11 Sep 2018 18:41:26 +0000 Message-ID: References: <20180911154246.6844-1-toshi.kani@hpe.com> <20180911154246.6844-3-toshi.kani@hpe.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Cc: "tytso-3s7WtUTddSA@public.gmane.org" , "linux-nvdimm-hn68Rpc1hR1g9hUCZPvPmw@public.gmane.org" , "linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org" , "adilger.kernel-m1MBpc4rdrD3fQ9qLvQP4Q@public.gmane.org" , "jack-AlSwsSmVLrQ@public.gmane.org" , "linux-ext4-u79uwXL29TY76Z2rM5mHXA@public.gmane.org" To: "dan.j.williams-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org" Return-path: In-Reply-To: Content-Language: en-US Content-ID: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: linux-nvdimm-bounces-hn68Rpc1hR1g9hUCZPvPmw@public.gmane.org Sender: "Linux-nvdimm" List-Id: linux-ext4.vger.kernel.org On Tue, 2018-09-11 at 11:15 -0700, Dan Williams wrote: > On Tue, Sep 11, 2018 at 8:42 AM, Toshi Kani wrote: > > Sync syscall to an existing DAX file needs to flush processor cache, > > but it does not currently. This is because 'ext4_da_aops' is set to > > address_space_operations of existing DAX files, instead of 'ext4_dax_aops', > > since S_DAX flag is set after ext4_set_aops() in the open path. > > > > New file > > -------- > > lookup_open > > ext4_create > > __ext4_new_inode > > ext4_set_inode_flags // Set S_DAX flag > > ext4_set_aops // Set aops to ext4_dax_aops > > > > Existing file > > ------------- > > lookup_open > > ext4_lookup > > ext4_iget > > ext4_set_aops // Set aops to ext4_da_aops > > ext4_set_inode_flags // Set S_DAX flag > > > > Change ext4_iget() to call ext4_set_inode_flags() before ext4_set_aops(). > > > > Fixes: 5f0663bb4a64f588f0a2dd6d1be68d40f9af0086 > > Same format nit: > > Fixes: 5f0663bb4a64 ("ext4, dax: introduce ext4_dax_aops") > Cc: Will do. > > Signed-off-by: Toshi Kani > > Cc: Jan Kara > > Cc: Dan Williams > > Cc: "Theodore Ts'o" > > Cc: Andreas Dilger > > --- > > fs/ext4/inode.c | 3 ++- > > 1 file changed, 2 insertions(+), 1 deletion(-) > > > > diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c > > index 775cd9b4af55..93cbbb859c40 100644 > > --- a/fs/ext4/inode.c > > +++ b/fs/ext4/inode.c > > @@ -4998,6 +4998,8 @@ struct inode *ext4_iget(struct super_block *sb, unsigned long ino) > > if (ret) > > goto bad_inode; > > > > + ext4_set_inode_flags(inode); > > + > > Hmm, does this have unintended behavior changes? > > I notice that there are some checks for flags "IS_APPEND(inode) || > IS_IMMUTABLE(inode)" *before* the call to ext4_set_inode_flags(). I > didn't look too much deeper at whether those checks are bogus, but it > would seem safer to do something like this for a lower risk fix. > > Thoughts? Good catch! Agreed. Thanks! -Toshi